From c4a67ced0a4b9b8643f24a2549c46e76a4e82c4e Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 12:48:28 -0700
Subject: [PATCH 01/18] feat: Add platform support for async hashing.

---
 .../shared/common/src/api/platform/Crypto.ts  | 21 ++++++++++--
 .../__tests__/context/addAutoEnv.test.ts      | 28 +++++++--------
 .../flag-manager/FlagPersistence.test.ts      | 34 ++++++++++++++-----
 .../__tests__/storage/namespaceUtils.test.ts  | 14 ++++----
 .../sdk-client/src/context/addAutoEnv.ts      | 15 +++++---
 .../sdk-client/src/context/ensureKey.ts       |  2 +-
 .../src/flag-manager/FlagManager.ts           | 30 ++++++++++++----
 .../src/flag-manager/FlagPersistence.ts       | 19 +++++++----
 .../sdk-client/src/flag-manager/FlagStore.ts  |  5 +--
 .../sdk-client/src/storage/namespaceUtils.ts  | 34 ++++++++++++-------
 .../sdk-server/src/BigSegmentsManager.ts      |  4 +++
 .../shared/sdk-server/src/LDClientImpl.ts     |  5 +++
 .../sdk-server/src/evaluation/Bucketer.ts     |  4 +++
 13 files changed, 146 insertions(+), 69 deletions(-)

diff --git a/packages/shared/common/src/api/platform/Crypto.ts b/packages/shared/common/src/api/platform/Crypto.ts
index 417fe03fbd..984e2f1aad 100644
--- a/packages/shared/common/src/api/platform/Crypto.ts
+++ b/packages/shared/common/src/api/platform/Crypto.ts
@@ -7,7 +7,19 @@
  */
 export interface Hasher {
   update(data: string): Hasher;
-  digest(encoding: string): string;
+  /**
+   * Note: All server SDKs MUST implement synchronous digest.
+   *
+   * Server SDKs have high performance requirements for bucketing users.
+   */
+  digest?(encoding: string): string;
+
+  /**
+   * Note: Client-side SDKs MUST implement either synchronous or asynchronous digest.
+   *
+   * Client SDKs do not have high throughput hashing operations.
+   */
+  asyncDigest?(encoding: string): Promise<string>;
 }
 
 /**
@@ -17,7 +29,7 @@ export interface Hasher {
  *
  * The has implementation must support digesting to 'hex'.
  */
-export interface Hmac extends Hasher {
+export interface Hmac {
   update(data: string): Hasher;
   digest(encoding: string): string;
 }
@@ -27,6 +39,9 @@ export interface Hmac extends Hasher {
  */
 export interface Crypto {
   createHash(algorithm: string): Hasher;
-  createHmac(algorithm: string, key: string): Hmac;
+  /**
+   * Note: Server SDKs MUST implement createHmac.
+   */
+  createHmac?(algorithm: string, key: string): Hmac;
   randomUUID(): string;
 }
diff --git a/packages/shared/sdk-client/__tests__/context/addAutoEnv.test.ts b/packages/shared/sdk-client/__tests__/context/addAutoEnv.test.ts
index 555f7d0b24..b5414b543f 100644
--- a/packages/shared/sdk-client/__tests__/context/addAutoEnv.test.ts
+++ b/packages/shared/sdk-client/__tests__/context/addAutoEnv.test.ts
@@ -337,7 +337,7 @@ describe('automatic environment attributes', () => {
   });
 
   describe('addApplicationInfo', () => {
-    test('add id, version, name, versionName', () => {
+    test('add id, version, name, versionName', async () => {
       config = new Configuration({
         applicationInfo: {
           id: 'com.from-config.ld',
@@ -346,7 +346,7 @@ describe('automatic environment attributes', () => {
           versionName: 'test-ld-version-name',
         },
       });
-      const ldApplication = addApplicationInfo(mockPlatform, config);
+      const ldApplication = await addApplicationInfo(mockPlatform, config);
 
       expect(ldApplication).toEqual({
         envAttributesVersion: '1.0',
@@ -358,8 +358,8 @@ describe('automatic environment attributes', () => {
       });
     });
 
-    test('add auto env application id, name, version', () => {
-      const ldApplication = addApplicationInfo(mockPlatform, config);
+    test('add auto env application id, name, version', async () => {
+      const ldApplication = await addApplicationInfo(mockPlatform, config);
 
       expect(ldApplication).toEqual({
         envAttributesVersion: '1.0',
@@ -370,7 +370,7 @@ describe('automatic environment attributes', () => {
       });
     });
 
-    test('final return value should not contain falsy values', () => {
+    test('final return value should not contain falsy values', async () => {
       const mockData = info.platformData();
       info.platformData = jest.fn().mockReturnValueOnce({
         ...mockData,
@@ -384,7 +384,7 @@ describe('automatic environment attributes', () => {
         },
       });
 
-      const ldApplication = addApplicationInfo(mockPlatform, config);
+      const ldApplication = await addApplicationInfo(mockPlatform, config);
 
       expect(ldApplication).toEqual({
         envAttributesVersion: '1.0',
@@ -393,15 +393,15 @@ describe('automatic environment attributes', () => {
       });
     });
 
-    test('omit if customer and auto env data are unavailable', () => {
+    test('omit if customer and auto env data are unavailable', async () => {
       info.platformData = jest.fn().mockReturnValueOnce({});
 
-      const ldApplication = addApplicationInfo(mockPlatform, config);
+      const ldApplication = await addApplicationInfo(mockPlatform, config);
 
       expect(ldApplication).toBeUndefined();
     });
 
-    test('omit if customer unavailable and auto env data are falsy', () => {
+    test('omit if customer unavailable and auto env data are falsy', async () => {
       const mockData = info.platformData();
       info.platformData = jest.fn().mockReturnValueOnce({
         ld_application: {
@@ -412,27 +412,27 @@ describe('automatic environment attributes', () => {
         },
       });
 
-      const ldApplication = addApplicationInfo(mockPlatform, config);
+      const ldApplication = await addApplicationInfo(mockPlatform, config);
 
       expect(ldApplication).toBeUndefined();
     });
 
-    test('omit if customer data is unavailable and auto env data only contains key and attributesVersion', () => {
+    test('omit if customer data is unavailable and auto env data only contains key and attributesVersion', async () => {
       info.platformData = jest.fn().mockReturnValueOnce({
         ld_application: { key: 'key-from-sdk', envAttributesVersion: '0.0.1' },
       });
 
-      const ldApplication = addApplicationInfo(mockPlatform, config);
+      const ldApplication = await addApplicationInfo(mockPlatform, config);
 
       expect(ldApplication).toBeUndefined();
     });
 
-    test('omit if no id specified', () => {
+    test('omit if no id specified', async () => {
       info.platformData = jest
         .fn()
         .mockReturnValueOnce({ ld_application: { version: null, locale: '' } });
       config = new Configuration({ applicationInfo: { version: '1.2.3' } });
-      const ldApplication = addApplicationInfo(mockPlatform, config);
+      const ldApplication = await addApplicationInfo(mockPlatform, config);
 
       expect(ldApplication).toBeUndefined();
     });
diff --git a/packages/shared/sdk-client/__tests__/flag-manager/FlagPersistence.test.ts b/packages/shared/sdk-client/__tests__/flag-manager/FlagPersistence.test.ts
index c0daf17c61..6e90c10af3 100644
--- a/packages/shared/sdk-client/__tests__/flag-manager/FlagPersistence.test.ts
+++ b/packages/shared/sdk-client/__tests__/flag-manager/FlagPersistence.test.ts
@@ -141,8 +141,12 @@ describe('FlagPersistence tests', () => {
 
     await fpUnderTest.init(context, flags);
 
-    const contextDataKey = namespaceForContextData(mockPlatform.crypto, TEST_NAMESPACE, context);
-    const contextIndexKey = namespaceForContextIndex(TEST_NAMESPACE);
+    const contextDataKey = await namespaceForContextData(
+      mockPlatform.crypto,
+      TEST_NAMESPACE,
+      context,
+    );
+    const contextIndexKey = await namespaceForContextIndex(TEST_NAMESPACE);
     expect(await memoryStorage.get(contextIndexKey)).toContain(contextDataKey);
     expect(await memoryStorage.get(contextDataKey)).toContain('flagA');
   });
@@ -175,9 +179,17 @@ describe('FlagPersistence tests', () => {
     await fpUnderTest.init(context1, flags);
     await fpUnderTest.init(context2, flags);
 
-    const context1DataKey = namespaceForContextData(mockPlatform.crypto, TEST_NAMESPACE, context1);
-    const context2DataKey = namespaceForContextData(mockPlatform.crypto, TEST_NAMESPACE, context2);
-    const contextIndexKey = namespaceForContextIndex(TEST_NAMESPACE);
+    const context1DataKey = await namespaceForContextData(
+      mockPlatform.crypto,
+      TEST_NAMESPACE,
+      context1,
+    );
+    const context2DataKey = await namespaceForContextData(
+      mockPlatform.crypto,
+      TEST_NAMESPACE,
+      context2,
+    );
+    const contextIndexKey = await namespaceForContextIndex(TEST_NAMESPACE);
 
     const indexData = await memoryStorage.get(contextIndexKey);
     expect(indexData).not.toContain(context1DataKey);
@@ -213,7 +225,7 @@ describe('FlagPersistence tests', () => {
 
     await fpUnderTest.init(context, flags);
     await fpUnderTest.init(context, flags);
-    const contextIndexKey = namespaceForContextIndex(TEST_NAMESPACE);
+    const contextIndexKey = await namespaceForContextIndex(TEST_NAMESPACE);
 
     const indexData = await memoryStorage.get(contextIndexKey);
     expect(indexData).toContain(`"timestamp":2`);
@@ -248,7 +260,11 @@ describe('FlagPersistence tests', () => {
     await fpUnderTest.init(context, flags);
     await fpUnderTest.upsert(context, 'flagA', { version: 2, flag: flagAv2 });
 
-    const contextDataKey = namespaceForContextData(mockPlatform.crypto, TEST_NAMESPACE, context);
+    const contextDataKey = await namespaceForContextData(
+      mockPlatform.crypto,
+      TEST_NAMESPACE,
+      context,
+    );
 
     // check memory flag store and persistence
     expect(flagStore.get('flagA')?.version).toEqual(2);
@@ -286,12 +302,12 @@ describe('FlagPersistence tests', () => {
       flag: makeMockFlag(),
     });
 
-    const activeContextDataKey = namespaceForContextData(
+    const activeContextDataKey = await namespaceForContextData(
       mockPlatform.crypto,
       TEST_NAMESPACE,
       activeContext,
     );
-    const inactiveContextDataKey = namespaceForContextData(
+    const inactiveContextDataKey = await namespaceForContextData(
       mockPlatform.crypto,
       TEST_NAMESPACE,
       inactiveContext,
diff --git a/packages/shared/sdk-client/__tests__/storage/namespaceUtils.test.ts b/packages/shared/sdk-client/__tests__/storage/namespaceUtils.test.ts
index 0ee0c70cf2..c7a6421953 100644
--- a/packages/shared/sdk-client/__tests__/storage/namespaceUtils.test.ts
+++ b/packages/shared/sdk-client/__tests__/storage/namespaceUtils.test.ts
@@ -1,23 +1,25 @@
 import { concatNamespacesAndValues } from '../../src/storage/namespaceUtils';
 
-const mockHash = (input: string) => `${input}Hashed`;
-const noop = (input: string) => input;
+const mockHash = async (input: string) => `${input}Hashed`;
+const noop = async (input: string) => input;
 
 describe('concatNamespacesAndValues tests', () => {
   test('it handles one part', async () => {
-    const result = concatNamespacesAndValues([{ value: 'LaunchDarkly', transform: mockHash }]);
+    const result = await concatNamespacesAndValues([
+      { value: 'LaunchDarkly', transform: mockHash },
+    ]);
 
     expect(result).toEqual('LaunchDarklyHashed');
   });
 
   test('it handles empty parts', async () => {
-    const result = concatNamespacesAndValues([]);
+    const result = await concatNamespacesAndValues([]);
 
     expect(result).toEqual('');
   });
 
   test('it handles many parts', async () => {
-    const result = concatNamespacesAndValues([
+    const result = await concatNamespacesAndValues([
       { value: 'LaunchDarkly', transform: mockHash },
       { value: 'ContextKeys', transform: mockHash },
       { value: 'aKind', transform: mockHash },
@@ -27,7 +29,7 @@ describe('concatNamespacesAndValues tests', () => {
   });
 
   test('it handles mixture of hashing and no hashing', async () => {
-    const result = concatNamespacesAndValues([
+    const result = await concatNamespacesAndValues([
       { value: 'LaunchDarkly', transform: mockHash },
       { value: 'ContextKeys', transform: noop },
       { value: 'aKind', transform: mockHash },
diff --git a/packages/shared/sdk-client/src/context/addAutoEnv.ts b/packages/shared/sdk-client/src/context/addAutoEnv.ts
index c769b1b6be..1c9d89673a 100644
--- a/packages/shared/sdk-client/src/context/addAutoEnv.ts
+++ b/packages/shared/sdk-client/src/context/addAutoEnv.ts
@@ -36,10 +36,10 @@ export const toMulti = (c: LDSingleKindContext) => {
  * @param config
  * @return An LDApplication object with populated key, envAttributesVersion, id and version.
  */
-export const addApplicationInfo = (
+export const addApplicationInfo = async (
   { crypto, info }: Platform,
   { applicationInfo }: Configuration,
-): LDApplication | undefined => {
+): Promise<LDApplication | undefined> => {
   const { ld_application } = info.platformData();
   let app = deepCompact<LDApplication>(ld_application) ?? ({} as LDApplication);
   const id = applicationInfo?.id || app?.id;
@@ -60,7 +60,12 @@ export const addApplicationInfo = (
 
     const hasher = crypto.createHash('sha256');
     hasher.update(id);
-    app.key = hasher.digest('base64');
+    const digest = hasher.digest || hasher.asyncDigest;
+    if(!digest) {
+      // This represents an error in platform implementation.
+      throw new Error("Platform must implement digest or asyncDigest");
+    }
+    app.key = await digest('base64');
     app.envAttributesVersion = app.envAttributesVersion || defaultAutoEnvSchemaVersion;
 
     return app;
@@ -95,7 +100,7 @@ export const addDeviceInfo = async (platform: Platform) => {
 
   // Check if device has any meaningful data before we return it.
   if (Object.keys(device).filter((k) => k !== 'key' && k !== 'envAttributesVersion').length) {
-    const ldDeviceNamespace = namespaceForGeneratedContextKey('ld_device');
+    const ldDeviceNamespace = await namespaceForGeneratedContextKey('ld_device');
     device.key = await getOrGenerateKey(ldDeviceNamespace, platform);
     device.envAttributesVersion = device.envAttributesVersion || defaultAutoEnvSchemaVersion;
     return device;
@@ -118,7 +123,7 @@ export const addAutoEnv = async (context: LDContext, platform: Platform, config:
     (isSingleKind(context) && context.kind !== 'ld_application') ||
     (isMultiKind(context) && !context.ld_application)
   ) {
-    ld_application = addApplicationInfo(platform, config);
+    ld_application = await addApplicationInfo(platform, config);
   } else {
     config.logger.warn(
       'Not adding ld_application environment attributes because it already exists.',
diff --git a/packages/shared/sdk-client/src/context/ensureKey.ts b/packages/shared/sdk-client/src/context/ensureKey.ts
index 7b7f18cf3d..5ba0f2309f 100644
--- a/packages/shared/sdk-client/src/context/ensureKey.ts
+++ b/packages/shared/sdk-client/src/context/ensureKey.ts
@@ -31,7 +31,7 @@ const ensureKeyCommon = async (kind: string, c: LDContextCommon, platform: Platf
   const { anonymous, key } = c;
 
   if (anonymous && !key) {
-    const storageKey = namespaceForAnonymousGeneratedContextKey(kind);
+    const storageKey = await namespaceForAnonymousGeneratedContextKey(kind);
     // This mutates a cloned copy of the original context from ensureyKey so this is safe.
     // eslint-disable-next-line no-param-reassign
     c.key = await getOrGenerateKey(storageKey, platform);
diff --git a/packages/shared/sdk-client/src/flag-manager/FlagManager.ts b/packages/shared/sdk-client/src/flag-manager/FlagManager.ts
index c90b32c51e..b87cb2667a 100644
--- a/packages/shared/sdk-client/src/flag-manager/FlagManager.ts
+++ b/packages/shared/sdk-client/src/flag-manager/FlagManager.ts
@@ -15,7 +15,7 @@ import { ItemDescriptor } from './ItemDescriptor';
 export default class FlagManager {
   private flagStore = new DefaultFlagStore();
   private flagUpdater: FlagUpdater;
-  private flagPersistence: FlagPersistence;
+  private flagPersistence: Promise<FlagPersistence>;
 
   /**
    * @param platform implementation of various platform provided functionality
@@ -31,10 +31,26 @@ export default class FlagManager {
     logger: LDLogger,
     private readonly timeStamper: () => number = () => Date.now(),
   ) {
-    const environmentNamespace = namespaceForEnvironment(platform.crypto, sdkKey);
-
     this.flagUpdater = new FlagUpdater(this.flagStore, logger);
-    this.flagPersistence = new FlagPersistence(
+    this.flagPersistence = this.initPersistence(
+      platform,
+      sdkKey,
+      maxCachedContexts,
+      logger,
+      timeStamper,
+    );
+  }
+
+  private async initPersistence(
+    platform: Platform,
+    sdkKey: string,
+    maxCachedContexts: number,
+    logger: LDLogger,
+    timeStamper: () => number = () => Date.now(),
+  ): Promise<FlagPersistence> {
+    const environmentNamespace = await namespaceForEnvironment(platform.crypto, sdkKey);
+
+    return new FlagPersistence(
       platform,
       environmentNamespace,
       maxCachedContexts,
@@ -64,7 +80,7 @@ export default class FlagManager {
    * Persistence initialization is handled by {@link FlagPersistence}
    */
   async init(context: Context, newFlags: { [key: string]: ItemDescriptor }): Promise<void> {
-    return this.flagPersistence.init(context, newFlags);
+    return (await this.flagPersistence).init(context, newFlags);
   }
 
   /**
@@ -72,14 +88,14 @@ export default class FlagManager {
    * it is of an older version, then an update will not be performed.
    */
   async upsert(context: Context, key: string, item: ItemDescriptor): Promise<boolean> {
-    return this.flagPersistence.upsert(context, key, item);
+    return (await this.flagPersistence).upsert(context, key, item);
   }
 
   /**
    * Asynchronously load cached values from persistence.
    */
   async loadCached(context: Context): Promise<boolean> {
-    return this.flagPersistence.loadCached(context);
+    return (await this.flagPersistence).loadCached(context);
   }
 
   /**
diff --git a/packages/shared/sdk-client/src/flag-manager/FlagPersistence.ts b/packages/shared/sdk-client/src/flag-manager/FlagPersistence.ts
index e7d903e240..847bee23db 100644
--- a/packages/shared/sdk-client/src/flag-manager/FlagPersistence.ts
+++ b/packages/shared/sdk-client/src/flag-manager/FlagPersistence.ts
@@ -14,7 +14,7 @@ import { ItemDescriptor } from './ItemDescriptor';
  */
 export default class FlagPersistence {
   private contextIndex: ContextIndex | undefined;
-  private indexKey: string;
+  private indexKey?: string;
 
   constructor(
     private readonly platform: Platform,
@@ -24,8 +24,13 @@ export default class FlagPersistence {
     private readonly flagUpdater: FlagUpdater,
     private readonly logger: LDLogger,
     private readonly timeStamper: () => number = () => Date.now(),
-  ) {
-    this.indexKey = namespaceForContextIndex(this.environmentNamespace);
+  ) {}
+
+  private async getIndexKey() {
+    if (!this.indexKey) {
+      this.indexKey = await namespaceForContextIndex(this.environmentNamespace);
+    }
+    return this.indexKey;
   }
 
   /**
@@ -55,7 +60,7 @@ export default class FlagPersistence {
    * {@link FlagUpdater} this {@link FlagPersistence} was constructed with.
    */
   async loadCached(context: Context): Promise<boolean> {
-    const storageKey = namespaceForContextData(
+    const storageKey = await namespaceForContextData(
       this.platform.crypto,
       this.environmentNamespace,
       context,
@@ -103,7 +108,7 @@ export default class FlagPersistence {
       return this.contextIndex;
     }
 
-    const json = await this.platform.storage?.get(this.indexKey);
+    const json = await this.platform.storage?.get(await this.getIndexKey());
     if (!json) {
       this.contextIndex = new ContextIndex();
       return this.contextIndex;
@@ -121,7 +126,7 @@ export default class FlagPersistence {
 
   private async storeCache(context: Context): Promise<void> {
     const index = await this.loadIndex();
-    const storageKey = namespaceForContextData(
+    const storageKey = await namespaceForContextData(
       this.platform.crypto,
       this.environmentNamespace,
       context,
@@ -132,7 +137,7 @@ export default class FlagPersistence {
     await Promise.all(pruned.map(async (it) => this.platform.storage?.clear(it.id)));
 
     // store index
-    await this.platform.storage?.set(this.indexKey, index.toJson());
+    await this.platform.storage?.set(await this.getIndexKey(), index.toJson());
     const allFlags = this.flagStore.getAll();
 
     // mapping item descriptors to flags
diff --git a/packages/shared/sdk-client/src/flag-manager/FlagStore.ts b/packages/shared/sdk-client/src/flag-manager/FlagStore.ts
index f58959721a..d9ce91b110 100644
--- a/packages/shared/sdk-client/src/flag-manager/FlagStore.ts
+++ b/packages/shared/sdk-client/src/flag-manager/FlagStore.ts
@@ -31,10 +31,7 @@ export class DefaultFlagStore implements FlagStore {
   }
 
   get(key: string): ItemDescriptor | undefined {
-    if (Object.prototype.hasOwnProperty.call(this.flags, key)) {
-      return this.flags[key];
-    }
-    return undefined;
+    return this.flags[key];
   }
 
   getAll(): { [key: string]: ItemDescriptor } {
diff --git a/packages/shared/sdk-client/src/storage/namespaceUtils.ts b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
index c977bf18ac..eb33627168 100644
--- a/packages/shared/sdk-client/src/storage/namespaceUtils.ts
+++ b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
@@ -5,20 +5,28 @@ export type Namespace = 'LaunchDarkly' | 'AnonymousKeys' | 'ContextKeys' | 'Cont
 /**
  * Hashes the input and encodes it as base64
  */
-function hashAndBase64Encode(crypto: Crypto): (input: string) => string {
-  return (input) => crypto.createHash('sha256').update(input).digest('base64');
+function hashAndBase64Encode(crypto: Crypto): (input: string) => Promise<string> {
+  return async (input) => {
+    const hasher = crypto.createHash('sha256').update(input);
+    const digestMethod = hasher.digest ?? hasher.asyncDigest;
+    if(digestMethod) {
+      // This represents an error in platform implementation.
+      throw new Error("Platform must implement digest or asyncDigest");
+    }
+    return digestMethod!('base64');
+  };
 }
 
-const noop = (input: string) => input; // no-op transform
+const noop = async (input: string) => input; // no-op transform
 
-export function concatNamespacesAndValues(
-  parts: { value: Namespace | string; transform: (value: string) => string }[],
-): string {
-  const processedParts = parts.map((part) => part.transform(part.value)); // use the transform from each part to transform the value
+export async function concatNamespacesAndValues(
+  parts: { value: Namespace | string; transform: (value: string) => Promise<string> }[],
+): Promise<string> {
+  const processedParts = await Promise.all(parts.map((part) => part.transform(part.value))); // use the transform from each part to transform the value
   return processedParts.join('_');
 }
 
-export function namespaceForEnvironment(crypto: Crypto, sdkKey: string): string {
+export async function namespaceForEnvironment(crypto: Crypto, sdkKey: string): Promise<string> {
   return concatNamespacesAndValues([
     { value: 'LaunchDarkly', transform: noop },
     { value: sdkKey, transform: hashAndBase64Encode(crypto) }, // hash sdk key and encode it
@@ -33,7 +41,7 @@ export function namespaceForEnvironment(crypto: Crypto, sdkKey: string): string
  * when the data under the LaunchDarkly_AnonymousKeys namespace is merged with data under the
  * LaunchDarkly_ContextKeys namespace.
  */
-export function namespaceForAnonymousGeneratedContextKey(kind: string): string {
+export async function namespaceForAnonymousGeneratedContextKey(kind: string): Promise<string> {
   return concatNamespacesAndValues([
     { value: 'LaunchDarkly', transform: noop },
     { value: 'AnonymousKeys', transform: noop },
@@ -41,7 +49,7 @@ export function namespaceForAnonymousGeneratedContextKey(kind: string): string {
   ]);
 }
 
-export function namespaceForGeneratedContextKey(kind: string): string {
+export async function namespaceForGeneratedContextKey(kind: string): Promise<string> {
   return concatNamespacesAndValues([
     { value: 'LaunchDarkly', transform: noop },
     { value: 'ContextKeys', transform: noop },
@@ -49,18 +57,18 @@ export function namespaceForGeneratedContextKey(kind: string): string {
   ]);
 }
 
-export function namespaceForContextIndex(environmentNamespace: string): string {
+export async function namespaceForContextIndex(environmentNamespace: string): Promise<string> {
   return concatNamespacesAndValues([
     { value: environmentNamespace, transform: noop },
     { value: 'ContextIndex', transform: noop },
   ]);
 }
 
-export function namespaceForContextData(
+export async function namespaceForContextData(
   crypto: Crypto,
   environmentNamespace: string,
   context: Context,
-): string {
+): Promise<string> {
   return concatNamespacesAndValues([
     { value: environmentNamespace, transform: noop }, // use existing namespace as is, don't transform
     { value: context.canonicalKey, transform: hashAndBase64Encode(crypto) }, // hash and encode canonical key
diff --git a/packages/shared/sdk-server/src/BigSegmentsManager.ts b/packages/shared/sdk-server/src/BigSegmentsManager.ts
index 10cedd57bd..0724e702f4 100644
--- a/packages/shared/sdk-server/src/BigSegmentsManager.ts
+++ b/packages/shared/sdk-server/src/BigSegmentsManager.ts
@@ -144,6 +144,10 @@ export default class BigSegmentsManager {
   private hashForUserKey(userKey: string): string {
     const hasher = this.crypto.createHash('sha256');
     hasher.update(userKey);
+    if(!hasher.digest) {
+      // This represents an error in platform implementation.
+      throw new Error("Platform must implement digest or asyncDigest");
+    }
     return hasher.digest('base64');
   }
 
diff --git a/packages/shared/sdk-server/src/LDClientImpl.ts b/packages/shared/sdk-server/src/LDClientImpl.ts
index 688a36b40f..f9801b94e0 100644
--- a/packages/shared/sdk-server/src/LDClientImpl.ts
+++ b/packages/shared/sdk-server/src/LDClientImpl.ts
@@ -689,7 +689,12 @@ export default class LDClientImpl implements LDClient {
   secureModeHash(context: LDContext): string {
     const checkedContext = Context.fromLDContext(context);
     const key = checkedContext.valid ? checkedContext.canonicalKey : undefined;
+    if(!this.platform.crypto.createHmac) {
+      // This represents an error in platform implementation.
+      throw new Error("Platform must implement createHmac");
+    }
     const hmac = this.platform.crypto.createHmac('sha256', this.sdkKey);
+
     if (key === undefined) {
       throw new LDClientError('Could not generate secure mode hash for invalid context');
     }
diff --git a/packages/shared/sdk-server/src/evaluation/Bucketer.ts b/packages/shared/sdk-server/src/evaluation/Bucketer.ts
index 1d10fba2b7..16e4b8b622 100644
--- a/packages/shared/sdk-server/src/evaluation/Bucketer.ts
+++ b/packages/shared/sdk-server/src/evaluation/Bucketer.ts
@@ -26,6 +26,10 @@ export default class Bucketer {
   private sha1Hex(value: string) {
     const hash = this.crypto.createHash('sha1');
     hash.update(value);
+    if(!hash.digest) {
+      // This represents an error in platform implementation.
+      throw new Error("Platform must implement digest or asyncDigest");
+    }
     return hash.digest('hex');
   }
 

From 5d111060bac897c058380949199dbe45afce6113 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 13:29:58 -0700
Subject: [PATCH 02/18] Lint

---
 packages/sdk/browser/jest.config.js                  |  9 ++++-----
 packages/sdk/cloudflare/jsr.json                     | 12 ++----------
 packages/shared/sdk-client/src/context/addAutoEnv.ts |  4 ++--
 .../shared/sdk-client/src/storage/namespaceUtils.ts  |  4 ++--
 packages/shared/sdk-server/src/BigSegmentsManager.ts |  4 ++--
 packages/shared/sdk-server/src/LDClientImpl.ts       |  4 ++--
 .../shared/sdk-server/src/evaluation/Bucketer.ts     |  4 ++--
 7 files changed, 16 insertions(+), 25 deletions(-)

diff --git a/packages/sdk/browser/jest.config.js b/packages/sdk/browser/jest.config.js
index 364918be3a..1f0bda3723 100644
--- a/packages/sdk/browser/jest.config.js
+++ b/packages/sdk/browser/jest.config.js
@@ -1,12 +1,11 @@
-
 export default {
   preset: 'ts-jest',
   testEnvironment: 'jest-environment-jsdom',
   transform: {
-      "^.+\\.tsx?$": "ts-jest"
-  // process `*.tsx` files with `ts-jest`
+    '^.+\\.tsx?$': 'ts-jest',
+    // process `*.tsx` files with `ts-jest`
   },
   moduleNameMapper: {
-      '\\.(gif|ttf|eot|svg|png)$': '<rootDir>/test/__ mocks __/fileMock.js',
+    '\\.(gif|ttf|eot|svg|png)$': '<rootDir>/test/__ mocks __/fileMock.js',
   },
-}
+};
diff --git a/packages/sdk/cloudflare/jsr.json b/packages/sdk/cloudflare/jsr.json
index 8f0b8980b1..cde7947a83 100644
--- a/packages/sdk/cloudflare/jsr.json
+++ b/packages/sdk/cloudflare/jsr.json
@@ -3,15 +3,7 @@
   "version": "2.5.13",
   "exports": "./src/index.ts",
   "publish": {
-    "include": [
-      "LICENSE",
-      "README.md",
-      "package.json",
-      "jsr.json",
-      "src/**/*.ts"
-    ],
-    "exclude": [
-      "src/**/*.test.ts"
-    ]
+    "include": ["LICENSE", "README.md", "package.json", "jsr.json", "src/**/*.ts"],
+    "exclude": ["src/**/*.test.ts"]
   }
 }
diff --git a/packages/shared/sdk-client/src/context/addAutoEnv.ts b/packages/shared/sdk-client/src/context/addAutoEnv.ts
index 1c9d89673a..2fdea1f5c4 100644
--- a/packages/shared/sdk-client/src/context/addAutoEnv.ts
+++ b/packages/shared/sdk-client/src/context/addAutoEnv.ts
@@ -61,9 +61,9 @@ export const addApplicationInfo = async (
     const hasher = crypto.createHash('sha256');
     hasher.update(id);
     const digest = hasher.digest || hasher.asyncDigest;
-    if(!digest) {
+    if (!digest) {
       // This represents an error in platform implementation.
-      throw new Error("Platform must implement digest or asyncDigest");
+      throw new Error('Platform must implement digest or asyncDigest');
     }
     app.key = await digest('base64');
     app.envAttributesVersion = app.envAttributesVersion || defaultAutoEnvSchemaVersion;
diff --git a/packages/shared/sdk-client/src/storage/namespaceUtils.ts b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
index eb33627168..c6ee0c60a9 100644
--- a/packages/shared/sdk-client/src/storage/namespaceUtils.ts
+++ b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
@@ -9,9 +9,9 @@ function hashAndBase64Encode(crypto: Crypto): (input: string) => Promise<string>
   return async (input) => {
     const hasher = crypto.createHash('sha256').update(input);
     const digestMethod = hasher.digest ?? hasher.asyncDigest;
-    if(digestMethod) {
+    if (digestMethod) {
       // This represents an error in platform implementation.
-      throw new Error("Platform must implement digest or asyncDigest");
+      throw new Error('Platform must implement digest or asyncDigest');
     }
     return digestMethod!('base64');
   };
diff --git a/packages/shared/sdk-server/src/BigSegmentsManager.ts b/packages/shared/sdk-server/src/BigSegmentsManager.ts
index 0724e702f4..d3311cc8e6 100644
--- a/packages/shared/sdk-server/src/BigSegmentsManager.ts
+++ b/packages/shared/sdk-server/src/BigSegmentsManager.ts
@@ -144,9 +144,9 @@ export default class BigSegmentsManager {
   private hashForUserKey(userKey: string): string {
     const hasher = this.crypto.createHash('sha256');
     hasher.update(userKey);
-    if(!hasher.digest) {
+    if (!hasher.digest) {
       // This represents an error in platform implementation.
-      throw new Error("Platform must implement digest or asyncDigest");
+      throw new Error('Platform must implement digest or asyncDigest');
     }
     return hasher.digest('base64');
   }
diff --git a/packages/shared/sdk-server/src/LDClientImpl.ts b/packages/shared/sdk-server/src/LDClientImpl.ts
index f9801b94e0..ef6c85840f 100644
--- a/packages/shared/sdk-server/src/LDClientImpl.ts
+++ b/packages/shared/sdk-server/src/LDClientImpl.ts
@@ -689,9 +689,9 @@ export default class LDClientImpl implements LDClient {
   secureModeHash(context: LDContext): string {
     const checkedContext = Context.fromLDContext(context);
     const key = checkedContext.valid ? checkedContext.canonicalKey : undefined;
-    if(!this.platform.crypto.createHmac) {
+    if (!this.platform.crypto.createHmac) {
       // This represents an error in platform implementation.
-      throw new Error("Platform must implement createHmac");
+      throw new Error('Platform must implement createHmac');
     }
     const hmac = this.platform.crypto.createHmac('sha256', this.sdkKey);
 
diff --git a/packages/shared/sdk-server/src/evaluation/Bucketer.ts b/packages/shared/sdk-server/src/evaluation/Bucketer.ts
index 16e4b8b622..c9febf4f07 100644
--- a/packages/shared/sdk-server/src/evaluation/Bucketer.ts
+++ b/packages/shared/sdk-server/src/evaluation/Bucketer.ts
@@ -26,9 +26,9 @@ export default class Bucketer {
   private sha1Hex(value: string) {
     const hash = this.crypto.createHash('sha1');
     hash.update(value);
-    if(!hash.digest) {
+    if (!hash.digest) {
       // This represents an error in platform implementation.
-      throw new Error("Platform must implement digest or asyncDigest");
+      throw new Error('Platform must implement digest or asyncDigest');
     }
     return hash.digest('hex');
   }

From 2c0a4b168332658305f6bea8cbe7d791770ec30b Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 14:36:46 -0700
Subject: [PATCH 03/18] Fix hasher check for client.

---
 packages/shared/sdk-client/src/storage/namespaceUtils.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/shared/sdk-client/src/storage/namespaceUtils.ts b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
index c6ee0c60a9..c683ffc60c 100644
--- a/packages/shared/sdk-client/src/storage/namespaceUtils.ts
+++ b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
@@ -9,7 +9,7 @@ function hashAndBase64Encode(crypto: Crypto): (input: string) => Promise<string>
   return async (input) => {
     const hasher = crypto.createHash('sha256').update(input);
     const digestMethod = hasher.digest ?? hasher.asyncDigest;
-    if (digestMethod) {
+    if (!digestMethod) {
       // This represents an error in platform implementation.
       throw new Error('Platform must implement digest or asyncDigest');
     }

From 3215c2456d6da93442313e74be9e311c9ecaf32c Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 14:50:43 -0700
Subject: [PATCH 04/18] Fix hasher selection.

---
 packages/shared/sdk-client/src/context/addAutoEnv.ts | 11 ++++++++---
 .../shared/sdk-client/src/storage/namespaceUtils.ts  | 12 ++++++++----
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/packages/shared/sdk-client/src/context/addAutoEnv.ts b/packages/shared/sdk-client/src/context/addAutoEnv.ts
index 2fdea1f5c4..a6e28c1e08 100644
--- a/packages/shared/sdk-client/src/context/addAutoEnv.ts
+++ b/packages/shared/sdk-client/src/context/addAutoEnv.ts
@@ -60,11 +60,16 @@ export const addApplicationInfo = async (
 
     const hasher = crypto.createHash('sha256');
     hasher.update(id);
-    const digest = hasher.digest || hasher.asyncDigest;
-    if (!digest) {
+    const digest = async (encoding: string) => {
+      if (hasher.digest) {
+        return hasher.digest(encoding);
+      } else if (hasher.asyncDigest) {
+        return hasher.asyncDigest(encoding);
+      }
       // This represents an error in platform implementation.
       throw new Error('Platform must implement digest or asyncDigest');
-    }
+    };
+
     app.key = await digest('base64');
     app.envAttributesVersion = app.envAttributesVersion || defaultAutoEnvSchemaVersion;
 
diff --git a/packages/shared/sdk-client/src/storage/namespaceUtils.ts b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
index c683ffc60c..b78e2b4d12 100644
--- a/packages/shared/sdk-client/src/storage/namespaceUtils.ts
+++ b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
@@ -8,12 +8,16 @@ export type Namespace = 'LaunchDarkly' | 'AnonymousKeys' | 'ContextKeys' | 'Cont
 function hashAndBase64Encode(crypto: Crypto): (input: string) => Promise<string> {
   return async (input) => {
     const hasher = crypto.createHash('sha256').update(input);
-    const digestMethod = hasher.digest ?? hasher.asyncDigest;
-    if (!digestMethod) {
+    const digest = async (encoding: string) => {
+      if (hasher.digest) {
+        return hasher.digest(encoding);
+      } else if (hasher.asyncDigest) {
+        return hasher.asyncDigest(encoding);
+      }
       // This represents an error in platform implementation.
       throw new Error('Platform must implement digest or asyncDigest');
-    }
-    return digestMethod!('base64');
+    };
+    return digest('base64');
   };
 }
 

From 5bdb00cbef25c88b8c2e2e0e7260ec48baa8d5e0 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:11:39 -0700
Subject: [PATCH 05/18] Lint

---
 packages/shared/sdk-client/src/context/addAutoEnv.ts     | 3 ++-
 packages/shared/sdk-client/src/storage/namespaceUtils.ts | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/packages/shared/sdk-client/src/context/addAutoEnv.ts b/packages/shared/sdk-client/src/context/addAutoEnv.ts
index a6e28c1e08..70a92ad0be 100644
--- a/packages/shared/sdk-client/src/context/addAutoEnv.ts
+++ b/packages/shared/sdk-client/src/context/addAutoEnv.ts
@@ -63,7 +63,8 @@ export const addApplicationInfo = async (
     const digest = async (encoding: string) => {
       if (hasher.digest) {
         return hasher.digest(encoding);
-      } else if (hasher.asyncDigest) {
+      }
+      if (hasher.asyncDigest) {
         return hasher.asyncDigest(encoding);
       }
       // This represents an error in platform implementation.
diff --git a/packages/shared/sdk-client/src/storage/namespaceUtils.ts b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
index b78e2b4d12..c97ac884e0 100644
--- a/packages/shared/sdk-client/src/storage/namespaceUtils.ts
+++ b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
@@ -11,7 +11,8 @@ function hashAndBase64Encode(crypto: Crypto): (input: string) => Promise<string>
     const digest = async (encoding: string) => {
       if (hasher.digest) {
         return hasher.digest(encoding);
-      } else if (hasher.asyncDigest) {
+      }
+      if (hasher.asyncDigest) {
         return hasher.asyncDigest(encoding);
       }
       // This represents an error in platform implementation.

From 5fe646c7c86fbb71dbe1cb2d585abe5dd07ba4e3 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:15:27 -0700
Subject: [PATCH 06/18] Fix merge

---
 packages/shared/sdk-client/src/flag-manager/FlagStore.ts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/shared/sdk-client/src/flag-manager/FlagStore.ts b/packages/shared/sdk-client/src/flag-manager/FlagStore.ts
index d9ce91b110..f58959721a 100644
--- a/packages/shared/sdk-client/src/flag-manager/FlagStore.ts
+++ b/packages/shared/sdk-client/src/flag-manager/FlagStore.ts
@@ -31,7 +31,10 @@ export class DefaultFlagStore implements FlagStore {
   }
 
   get(key: string): ItemDescriptor | undefined {
-    return this.flags[key];
+    if (Object.prototype.hasOwnProperty.call(this.flags, key)) {
+      return this.flags[key];
+    }
+    return undefined;
   }
 
   getAll(): { [key: string]: ItemDescriptor } {

From e7f757a67b376af0307f935404b1649cc509cc33 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:16:27 -0700
Subject: [PATCH 07/18] More corrections.

---
 packages/sdk/browser/jest.config.js |  9 +++++----
 packages/sdk/cloudflare/jsr.json    | 12 ++++++++++--
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/packages/sdk/browser/jest.config.js b/packages/sdk/browser/jest.config.js
index 1f0bda3723..364918be3a 100644
--- a/packages/sdk/browser/jest.config.js
+++ b/packages/sdk/browser/jest.config.js
@@ -1,11 +1,12 @@
+
 export default {
   preset: 'ts-jest',
   testEnvironment: 'jest-environment-jsdom',
   transform: {
-    '^.+\\.tsx?$': 'ts-jest',
-    // process `*.tsx` files with `ts-jest`
+      "^.+\\.tsx?$": "ts-jest"
+  // process `*.tsx` files with `ts-jest`
   },
   moduleNameMapper: {
-    '\\.(gif|ttf|eot|svg|png)$': '<rootDir>/test/__ mocks __/fileMock.js',
+      '\\.(gif|ttf|eot|svg|png)$': '<rootDir>/test/__ mocks __/fileMock.js',
   },
-};
+}
diff --git a/packages/sdk/cloudflare/jsr.json b/packages/sdk/cloudflare/jsr.json
index cde7947a83..8f0b8980b1 100644
--- a/packages/sdk/cloudflare/jsr.json
+++ b/packages/sdk/cloudflare/jsr.json
@@ -3,7 +3,15 @@
   "version": "2.5.13",
   "exports": "./src/index.ts",
   "publish": {
-    "include": ["LICENSE", "README.md", "package.json", "jsr.json", "src/**/*.ts"],
-    "exclude": ["src/**/*.test.ts"]
+    "include": [
+      "LICENSE",
+      "README.md",
+      "package.json",
+      "jsr.json",
+      "src/**/*.ts"
+    ],
+    "exclude": [
+      "src/**/*.test.ts"
+    ]
   }
 }

From 7bd42589b515372deb2eb7002175e2b3bf2d3117 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:20:12 -0700
Subject: [PATCH 08/18] Consistent promise approach.

---
 .../sdk-client/src/flag-manager/FlagManager.ts     | 10 +++++-----
 .../sdk-client/src/flag-manager/FlagPersistence.ts | 14 +++++---------
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/packages/shared/sdk-client/src/flag-manager/FlagManager.ts b/packages/shared/sdk-client/src/flag-manager/FlagManager.ts
index b87cb2667a..267895b656 100644
--- a/packages/shared/sdk-client/src/flag-manager/FlagManager.ts
+++ b/packages/shared/sdk-client/src/flag-manager/FlagManager.ts
@@ -15,7 +15,7 @@ import { ItemDescriptor } from './ItemDescriptor';
 export default class FlagManager {
   private flagStore = new DefaultFlagStore();
   private flagUpdater: FlagUpdater;
-  private flagPersistence: Promise<FlagPersistence>;
+  private flagPersistencePromise: Promise<FlagPersistence>;
 
   /**
    * @param platform implementation of various platform provided functionality
@@ -32,7 +32,7 @@ export default class FlagManager {
     private readonly timeStamper: () => number = () => Date.now(),
   ) {
     this.flagUpdater = new FlagUpdater(this.flagStore, logger);
-    this.flagPersistence = this.initPersistence(
+    this.flagPersistencePromise = this.initPersistence(
       platform,
       sdkKey,
       maxCachedContexts,
@@ -80,7 +80,7 @@ export default class FlagManager {
    * Persistence initialization is handled by {@link FlagPersistence}
    */
   async init(context: Context, newFlags: { [key: string]: ItemDescriptor }): Promise<void> {
-    return (await this.flagPersistence).init(context, newFlags);
+    return (await this.flagPersistencePromise).init(context, newFlags);
   }
 
   /**
@@ -88,14 +88,14 @@ export default class FlagManager {
    * it is of an older version, then an update will not be performed.
    */
   async upsert(context: Context, key: string, item: ItemDescriptor): Promise<boolean> {
-    return (await this.flagPersistence).upsert(context, key, item);
+    return (await this.flagPersistencePromise).upsert(context, key, item);
   }
 
   /**
    * Asynchronously load cached values from persistence.
    */
   async loadCached(context: Context): Promise<boolean> {
-    return (await this.flagPersistence).loadCached(context);
+    return (await this.flagPersistencePromise).loadCached(context);
   }
 
   /**
diff --git a/packages/shared/sdk-client/src/flag-manager/FlagPersistence.ts b/packages/shared/sdk-client/src/flag-manager/FlagPersistence.ts
index 847bee23db..c761847a4c 100644
--- a/packages/shared/sdk-client/src/flag-manager/FlagPersistence.ts
+++ b/packages/shared/sdk-client/src/flag-manager/FlagPersistence.ts
@@ -15,6 +15,7 @@ import { ItemDescriptor } from './ItemDescriptor';
 export default class FlagPersistence {
   private contextIndex: ContextIndex | undefined;
   private indexKey?: string;
+  private indexKeyPromise: Promise<string>;
 
   constructor(
     private readonly platform: Platform,
@@ -24,13 +25,8 @@ export default class FlagPersistence {
     private readonly flagUpdater: FlagUpdater,
     private readonly logger: LDLogger,
     private readonly timeStamper: () => number = () => Date.now(),
-  ) {}
-
-  private async getIndexKey() {
-    if (!this.indexKey) {
-      this.indexKey = await namespaceForContextIndex(this.environmentNamespace);
-    }
-    return this.indexKey;
+  ) {
+    this.indexKeyPromise = namespaceForContextIndex(this.environmentNamespace);
   }
 
   /**
@@ -108,7 +104,7 @@ export default class FlagPersistence {
       return this.contextIndex;
     }
 
-    const json = await this.platform.storage?.get(await this.getIndexKey());
+    const json = await this.platform.storage?.get(await this.indexKeyPromise);
     if (!json) {
       this.contextIndex = new ContextIndex();
       return this.contextIndex;
@@ -137,7 +133,7 @@ export default class FlagPersistence {
     await Promise.all(pruned.map(async (it) => this.platform.storage?.clear(it.id)));
 
     // store index
-    await this.platform.storage?.set(await this.getIndexKey(), index.toJson());
+    await this.platform.storage?.set(await this.indexKeyPromise, index.toJson());
     const allFlags = this.flagStore.getAll();
 
     // mapping item descriptors to flags

From dba54b2a465340b9912c2d8abaca493c6bb75831 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:25:05 -0700
Subject: [PATCH 09/18] Refactoring.

---
 .../shared/sdk-client/src/context/addAutoEnv.ts  | 16 ++--------------
 packages/shared/sdk-client/src/crypto/digest.ts  | 12 ++++++++++++
 .../sdk-client/src/storage/namespaceUtils.ts     | 14 ++------------
 3 files changed, 16 insertions(+), 26 deletions(-)
 create mode 100644 packages/shared/sdk-client/src/crypto/digest.ts

diff --git a/packages/shared/sdk-client/src/context/addAutoEnv.ts b/packages/shared/sdk-client/src/context/addAutoEnv.ts
index 70a92ad0be..f1bfea55d2 100644
--- a/packages/shared/sdk-client/src/context/addAutoEnv.ts
+++ b/packages/shared/sdk-client/src/context/addAutoEnv.ts
@@ -14,6 +14,7 @@ import {
 import Configuration from '../configuration';
 import { getOrGenerateKey } from '../storage/getOrGenerateKey';
 import { namespaceForGeneratedContextKey } from '../storage/namespaceUtils';
+import digest from '../crypto/digest';
 
 const { isLegacyUser, isSingleKind, isMultiKind } = internal;
 const defaultAutoEnvSchemaVersion = '1.0';
@@ -58,20 +59,7 @@ export const addApplicationInfo = async (
       ...(versionName ? { versionName } : {}),
     };
 
-    const hasher = crypto.createHash('sha256');
-    hasher.update(id);
-    const digest = async (encoding: string) => {
-      if (hasher.digest) {
-        return hasher.digest(encoding);
-      }
-      if (hasher.asyncDigest) {
-        return hasher.asyncDigest(encoding);
-      }
-      // This represents an error in platform implementation.
-      throw new Error('Platform must implement digest or asyncDigest');
-    };
-
-    app.key = await digest('base64');
+    app.key = await digest(crypto.createHash('sha256').update(id), 'base64');
     app.envAttributesVersion = app.envAttributesVersion || defaultAutoEnvSchemaVersion;
 
     return app;
diff --git a/packages/shared/sdk-client/src/crypto/digest.ts b/packages/shared/sdk-client/src/crypto/digest.ts
new file mode 100644
index 0000000000..24625ec049
--- /dev/null
+++ b/packages/shared/sdk-client/src/crypto/digest.ts
@@ -0,0 +1,12 @@
+import { Hasher } from '@launchdarkly/js-sdk-common';
+
+export default function digest(hasher: Hasher, encoding: string) {
+  if (hasher.digest) {
+    return hasher.digest(encoding);
+  }
+  if (hasher.asyncDigest) {
+    return hasher.asyncDigest(encoding);
+  }
+  // This represents an error in platform implementation.
+  throw new Error('Platform must implement digest or asyncDigest');
+}
diff --git a/packages/shared/sdk-client/src/storage/namespaceUtils.ts b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
index c97ac884e0..cf02e5c11a 100644
--- a/packages/shared/sdk-client/src/storage/namespaceUtils.ts
+++ b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
@@ -1,4 +1,5 @@
 import { Context, Crypto } from '@launchdarkly/js-sdk-common';
+import digest from '../crypto/digest';
 
 export type Namespace = 'LaunchDarkly' | 'AnonymousKeys' | 'ContextKeys' | 'ContextIndex';
 
@@ -7,18 +8,7 @@ export type Namespace = 'LaunchDarkly' | 'AnonymousKeys' | 'ContextKeys' | 'Cont
  */
 function hashAndBase64Encode(crypto: Crypto): (input: string) => Promise<string> {
   return async (input) => {
-    const hasher = crypto.createHash('sha256').update(input);
-    const digest = async (encoding: string) => {
-      if (hasher.digest) {
-        return hasher.digest(encoding);
-      }
-      if (hasher.asyncDigest) {
-        return hasher.asyncDigest(encoding);
-      }
-      // This represents an error in platform implementation.
-      throw new Error('Platform must implement digest or asyncDigest');
-    };
-    return digest('base64');
+    return digest(crypto.createHash('sha256').update(input), 'base64');
   };
 }
 

From c12b4385624086386abbbddf809683dfdaf6a679 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:31:31 -0700
Subject: [PATCH 10/18] Linting

---
 packages/sdk/browser/jest.config.js                  |  9 ++++-----
 packages/sdk/cloudflare/jsr.json                     | 12 ++----------
 packages/shared/sdk-client/src/context/addAutoEnv.ts |  2 +-
 .../shared/sdk-client/src/storage/namespaceUtils.ts  |  1 +
 4 files changed, 8 insertions(+), 16 deletions(-)

diff --git a/packages/sdk/browser/jest.config.js b/packages/sdk/browser/jest.config.js
index 364918be3a..1f0bda3723 100644
--- a/packages/sdk/browser/jest.config.js
+++ b/packages/sdk/browser/jest.config.js
@@ -1,12 +1,11 @@
-
 export default {
   preset: 'ts-jest',
   testEnvironment: 'jest-environment-jsdom',
   transform: {
-      "^.+\\.tsx?$": "ts-jest"
-  // process `*.tsx` files with `ts-jest`
+    '^.+\\.tsx?$': 'ts-jest',
+    // process `*.tsx` files with `ts-jest`
   },
   moduleNameMapper: {
-      '\\.(gif|ttf|eot|svg|png)$': '<rootDir>/test/__ mocks __/fileMock.js',
+    '\\.(gif|ttf|eot|svg|png)$': '<rootDir>/test/__ mocks __/fileMock.js',
   },
-}
+};
diff --git a/packages/sdk/cloudflare/jsr.json b/packages/sdk/cloudflare/jsr.json
index 8f0b8980b1..cde7947a83 100644
--- a/packages/sdk/cloudflare/jsr.json
+++ b/packages/sdk/cloudflare/jsr.json
@@ -3,15 +3,7 @@
   "version": "2.5.13",
   "exports": "./src/index.ts",
   "publish": {
-    "include": [
-      "LICENSE",
-      "README.md",
-      "package.json",
-      "jsr.json",
-      "src/**/*.ts"
-    ],
-    "exclude": [
-      "src/**/*.test.ts"
-    ]
+    "include": ["LICENSE", "README.md", "package.json", "jsr.json", "src/**/*.ts"],
+    "exclude": ["src/**/*.test.ts"]
   }
 }
diff --git a/packages/shared/sdk-client/src/context/addAutoEnv.ts b/packages/shared/sdk-client/src/context/addAutoEnv.ts
index f1bfea55d2..f66f61b01e 100644
--- a/packages/shared/sdk-client/src/context/addAutoEnv.ts
+++ b/packages/shared/sdk-client/src/context/addAutoEnv.ts
@@ -12,9 +12,9 @@ import {
 } from '@launchdarkly/js-sdk-common';
 
 import Configuration from '../configuration';
+import digest from '../crypto/digest';
 import { getOrGenerateKey } from '../storage/getOrGenerateKey';
 import { namespaceForGeneratedContextKey } from '../storage/namespaceUtils';
-import digest from '../crypto/digest';
 
 const { isLegacyUser, isSingleKind, isMultiKind } = internal;
 const defaultAutoEnvSchemaVersion = '1.0';
diff --git a/packages/shared/sdk-client/src/storage/namespaceUtils.ts b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
index cf02e5c11a..51b1e57494 100644
--- a/packages/shared/sdk-client/src/storage/namespaceUtils.ts
+++ b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
@@ -1,4 +1,5 @@
 import { Context, Crypto } from '@launchdarkly/js-sdk-common';
+
 import digest from '../crypto/digest';
 
 export type Namespace = 'LaunchDarkly' | 'AnonymousKeys' | 'ContextKeys' | 'ContextIndex';

From 5c36b6e2e286b3a7814d5d3c469ff7900bc5abce Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:32:06 -0700
Subject: [PATCH 11/18] Remove ancillary linting.

---
 packages/sdk/browser/jest.config.js |  9 +++++----
 packages/sdk/cloudflare/jsr.json    | 12 ++++++++++--
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/packages/sdk/browser/jest.config.js b/packages/sdk/browser/jest.config.js
index 1f0bda3723..364918be3a 100644
--- a/packages/sdk/browser/jest.config.js
+++ b/packages/sdk/browser/jest.config.js
@@ -1,11 +1,12 @@
+
 export default {
   preset: 'ts-jest',
   testEnvironment: 'jest-environment-jsdom',
   transform: {
-    '^.+\\.tsx?$': 'ts-jest',
-    // process `*.tsx` files with `ts-jest`
+      "^.+\\.tsx?$": "ts-jest"
+  // process `*.tsx` files with `ts-jest`
   },
   moduleNameMapper: {
-    '\\.(gif|ttf|eot|svg|png)$': '<rootDir>/test/__ mocks __/fileMock.js',
+      '\\.(gif|ttf|eot|svg|png)$': '<rootDir>/test/__ mocks __/fileMock.js',
   },
-};
+}
diff --git a/packages/sdk/cloudflare/jsr.json b/packages/sdk/cloudflare/jsr.json
index cde7947a83..8f0b8980b1 100644
--- a/packages/sdk/cloudflare/jsr.json
+++ b/packages/sdk/cloudflare/jsr.json
@@ -3,7 +3,15 @@
   "version": "2.5.13",
   "exports": "./src/index.ts",
   "publish": {
-    "include": ["LICENSE", "README.md", "package.json", "jsr.json", "src/**/*.ts"],
-    "exclude": ["src/**/*.test.ts"]
+    "include": [
+      "LICENSE",
+      "README.md",
+      "package.json",
+      "jsr.json",
+      "src/**/*.ts"
+    ],
+    "exclude": [
+      "src/**/*.test.ts"
+    ]
   }
 }

From e1585a93ec156b6042ff4668c49700e32ec05598 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:36:28 -0700
Subject: [PATCH 12/18] More lint

---
 packages/shared/sdk-client/src/storage/namespaceUtils.ts | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/packages/shared/sdk-client/src/storage/namespaceUtils.ts b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
index 51b1e57494..e5a28123c4 100644
--- a/packages/shared/sdk-client/src/storage/namespaceUtils.ts
+++ b/packages/shared/sdk-client/src/storage/namespaceUtils.ts
@@ -8,9 +8,7 @@ export type Namespace = 'LaunchDarkly' | 'AnonymousKeys' | 'ContextKeys' | 'Cont
  * Hashes the input and encodes it as base64
  */
 function hashAndBase64Encode(crypto: Crypto): (input: string) => Promise<string> {
-  return async (input) => {
-    return digest(crypto.createHash('sha256').update(input), 'base64');
-  };
+  return async (input) => digest(crypto.createHash('sha256').update(input), 'base64');
 }
 
 const noop = async (input: string) => input; // no-op transform

From 80537103c315cef9a7e76acc03510f0e99f7f13e Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:43:45 -0700
Subject: [PATCH 13/18] feat: Implement browser crypto

---
 .../__tests__/platform/BrowserHasher.test.ts  | 53 ++++++++++
 .../__tests__/platform/randomUuidV4.test.ts   | 29 ++++++
 packages/sdk/browser/package.json             |  4 +-
 .../sdk/browser/src/platform/BrowserCrypto.ts | 14 +++
 .../sdk/browser/src/platform/BrowserHasher.ts | 44 +++++++++
 .../browser/src/platform/BrowserPlatform.ts   |  6 +-
 .../sdk/browser/src/platform/randomUuidV4.ts  | 99 +++++++++++++++++++
 7 files changed, 245 insertions(+), 4 deletions(-)
 create mode 100644 packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts
 create mode 100644 packages/sdk/browser/__tests__/platform/randomUuidV4.test.ts
 create mode 100644 packages/sdk/browser/src/platform/BrowserCrypto.ts
 create mode 100644 packages/sdk/browser/src/platform/BrowserHasher.ts
 create mode 100644 packages/sdk/browser/src/platform/randomUuidV4.ts

diff --git a/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts b/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts
new file mode 100644
index 0000000000..091e9f0864
--- /dev/null
+++ b/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts
@@ -0,0 +1,53 @@
+// TextEncoder should be part of jsdom, but it is not. So we can import it from node in the tests.
+import { webcrypto } from 'node:crypto';
+import { TextEncoder } from 'node:util';
+
+import BrowserHasher from '../../src/platform/BrowserHasher';
+
+global.TextEncoder = TextEncoder;
+
+// Crypto is injectable as it is also not correctly available with the combination of node and jsdom.
+
+/**
+ * The links below are different from js-sha256 and are useful to verify the
+ * correctness of hash and encoding output:
+ * https://www.liavaag.org/English/SHA-Generator/
+ */
+describe('PlatformHasher', () => {
+  test('sha256 produces correct base64 output', async () => {
+    // @ts-ignore
+    const h = new BrowserHasher(webcrypto, 'sha256');
+
+    h.update('test-app-id');
+    const output = await h.asyncDigest('base64');
+
+    expect(output).toEqual('XVm6ZNk6ejx6+IVtL7zfwYwRQ2/ck9+y7FaN32EcudQ=');
+  });
+
+  test('sha256 produces correct hex output', async () => {
+    // @ts-ignore
+    const h = new BrowserHasher(webcrypto, 'sha256');
+
+    h.update('test-app-id');
+    const output = await h.asyncDigest('hex');
+
+    expect(output).toEqual('5d59ba64d93a7a3c7af8856d2fbcdfc18c11436fdc93dfb2ec568ddf611cb9d4');
+  });
+
+  test('unsupported hash algorithm', async () => {
+    expect(() => {
+      // @ts-ignore
+      // eslint-disable-next-line no-new
+      new BrowserHasher(webcrypto, 'sha1');
+    }).toThrow(/unsupported/i);
+  });
+
+  test('unsupported output algorithm', async () => {
+    expect(async () => {
+      // @ts-ignore
+      const h = new BrowserHasher(webcrypto, 'sha256');
+      h.update('test-app-id');
+      await h.asyncDigest('base122');
+    }).toThrow(/unsupported/i);
+  });
+});
diff --git a/packages/sdk/browser/__tests__/platform/randomUuidV4.test.ts b/packages/sdk/browser/__tests__/platform/randomUuidV4.test.ts
new file mode 100644
index 0000000000..03ec22d120
--- /dev/null
+++ b/packages/sdk/browser/__tests__/platform/randomUuidV4.test.ts
@@ -0,0 +1,29 @@
+/* eslint-disable no-bitwise */
+import { fallbackUuidV4, formatDataAsUuidV4 } from '../../src/platform/randomUuidV4';
+
+it('formats conformant UUID', () => {
+  // For this test we remove the random component and just inspect the variant and version.
+  const idA = formatDataAsUuidV4(Array(16).fill(0x00));
+  const idB = formatDataAsUuidV4(Array(16).fill(0xff));
+  const idC = fallbackUuidV4();
+
+  // 32 characters and 4 dashes
+  expect(idC).toHaveLength(36);
+  const versionA = idA[14];
+  const versionB = idB[14];
+  const versionC = idB[14];
+
+  expect(versionA).toEqual('4');
+  expect(versionB).toEqual('4');
+  expect(versionC).toEqual('4');
+
+  // Keep only the top 2 bits.
+  const specifierA = parseInt(idA[19], 16) & 0xc;
+  const specifierB = parseInt(idB[19], 16) & 0xc;
+  const specifierC = parseInt(idC[19], 16) & 0xc;
+
+  // bit 6 should be 0 and bit 8 should be one, which is 0x8
+  expect(specifierA).toEqual(0x8);
+  expect(specifierB).toEqual(0x8);
+  expect(specifierC).toEqual(0x8);
+});
diff --git a/packages/sdk/browser/package.json b/packages/sdk/browser/package.json
index 8723526a35..1d1c44388e 100644
--- a/packages/sdk/browser/package.json
+++ b/packages/sdk/browser/package.json
@@ -27,7 +27,7 @@
   ],
   "scripts": {
     "clean": "rimraf dist",
-    "build": "vite build",
+    "build": "tsc --noEmit && vite build",
     "lint": "eslint . --ext .ts,.tsx",
     "prettier": "prettier --write '**/*.@(js|ts|tsx|json|css)' --ignore-path ../../../.prettierignore",
     "test": "jest",
@@ -35,7 +35,7 @@
     "check": "yarn prettier && yarn lint && yarn build && yarn test"
   },
   "dependencies": {
-    "@launchdarkly/js-client-sdk-common": "1.5.0"
+    "@launchdarkly/js-client-sdk-common": "1.7.0"
   },
   "devDependencies": {
     "@launchdarkly/private-js-mocks": "0.0.1",
diff --git a/packages/sdk/browser/src/platform/BrowserCrypto.ts b/packages/sdk/browser/src/platform/BrowserCrypto.ts
new file mode 100644
index 0000000000..e241bc50a2
--- /dev/null
+++ b/packages/sdk/browser/src/platform/BrowserCrypto.ts
@@ -0,0 +1,14 @@
+import { Crypto } from '@launchdarkly/js-client-sdk-common';
+
+import BrowserHasher from './BrowserHasher';
+import randomUuidV4 from './randomUuidV4';
+
+export default class BrowserCrypto implements Crypto {
+  createHash(algorithm: string): BrowserHasher {
+    return new BrowserHasher(window.crypto, algorithm);
+  }
+
+  randomUUID(): string {
+    return randomUuidV4();
+  }
+}
diff --git a/packages/sdk/browser/src/platform/BrowserHasher.ts b/packages/sdk/browser/src/platform/BrowserHasher.ts
new file mode 100644
index 0000000000..fc46d8d878
--- /dev/null
+++ b/packages/sdk/browser/src/platform/BrowserHasher.ts
@@ -0,0 +1,44 @@
+import { Hasher } from '@launchdarkly/js-client-sdk-common';
+
+export default class BrowserHasher implements Hasher {
+  private data: string[] = [];
+  private algorithm: string;
+  constructor(
+    private readonly webcrypto: Crypto,
+    algorithm: string,
+  ) {
+    switch (algorithm) {
+      case 'sha1':
+        this.algorithm = 'SHA-1';
+        break;
+      case 'sha256':
+        this.algorithm = 'SHA-256';
+        break;
+      default:
+        throw new Error(`Algorithm is not supported ${algorithm}`);
+    }
+  }
+
+  async asyncDigest(encoding: string): Promise<string> {
+    const combinedData = this.data.join('');
+    const encoded = new TextEncoder().encode(combinedData);
+    const digestedBuffer = await this.webcrypto.subtle.digest(this.algorithm, encoded);
+    switch (encoding) {
+      case 'base64':
+        return btoa(String.fromCharCode(...new Uint8Array(digestedBuffer)));
+      case 'hex':
+        // Convert the buffer to an array of uint8 values, then convert each of those to hex.
+        // The map function on a Uint8Array directly only maps to other Uint8Arrays.
+        return [...new Uint8Array(digestedBuffer)]
+          .map((val) => val.toString(16).padStart(2, '0'))
+          .join('');
+      default:
+        throw new Error(`Encoding is not supported ${encoding}`);
+    }
+  }
+
+  update(data: string): Hasher {
+    this.data.push(data);
+    return this as Hasher;
+  }
+}
diff --git a/packages/sdk/browser/src/platform/BrowserPlatform.ts b/packages/sdk/browser/src/platform/BrowserPlatform.ts
index 419840d5d3..8865ebc3c8 100644
--- a/packages/sdk/browser/src/platform/BrowserPlatform.ts
+++ b/packages/sdk/browser/src/platform/BrowserPlatform.ts
@@ -1,16 +1,18 @@
 import {
+  Crypto,
+  /* platform */
   LDOptions,
   Storage,
-  /* platform */
 } from '@launchdarkly/js-client-sdk-common';
 
+import BrowserCrypto from './BrowserCrypto';
 import LocalStorage, { isLocalStorageSupported } from './LocalStorage';
 
 export default class BrowserPlatform /* implements platform.Platform */ {
   // encoding?: Encoding;
   // info: Info;
   // fileSystem?: Filesystem;
-  // crypto: Crypto;
+  crypto: Crypto = new BrowserCrypto();
   // requests: Requests;
   storage?: Storage;
 
diff --git a/packages/sdk/browser/src/platform/randomUuidV4.ts b/packages/sdk/browser/src/platform/randomUuidV4.ts
new file mode 100644
index 0000000000..0659d58f72
--- /dev/null
+++ b/packages/sdk/browser/src/platform/randomUuidV4.ts
@@ -0,0 +1,99 @@
+// The implementation in this file generates UUIDs in v4 format and is suitable
+// for use as a UUID in LaunchDarkly events. It is not a rigorous implementation.
+
+// It uses crypto.randomUUID when available.
+// If crypto.randomUUID is not available, then it uses random values and forms
+// the UUID itself.
+// When possible it uses crypto.getRandomValues, but it can use Math.random
+// if crypto.getRandomValues is not available.
+
+// UUIDv4 Struct definition.
+// https://www.rfc-archive.org/getrfc.php?rfc=4122
+// Appendix A.  Appendix A - Sample Implementation
+const timeLow = {
+  start: 0,
+  end: 3,
+};
+const timeMid = {
+  start: 4,
+  end: 5,
+};
+const timeHiAndVersion = {
+  start: 6,
+  end: 7,
+};
+const clockSeqHiAndReserved = {
+  start: 8,
+  end: 8,
+};
+const clockSeqLow = {
+  start: 9,
+  end: 9,
+};
+const nodes = {
+  start: 10,
+  end: 15,
+};
+
+function getRandom128bit(): number[] {
+  if (crypto && crypto.getRandomValues) {
+    const typedArray = new Uint8Array(16);
+    crypto.getRandomValues(typedArray);
+    return [...typedArray.values()];
+  }
+  const values = [];
+  for (let index = 0; index < 16; index += 1) {
+    // Math.random is 0-1 with inclusive min and exclusive max.
+    values.push(Math.floor(Math.random() * 256));
+  }
+  return values;
+}
+
+function hex(bytes: number[], range: { start: number; end: number }): string {
+  let strVal = '';
+  for (let index = range.start; index <= range.end; index += 1) {
+    strVal += bytes[index].toString(16).padStart(2, '0');
+  }
+  return strVal;
+}
+
+/**
+ * Given a list of 16 random bytes generate a UUID in v4 format.
+ *
+ * Note: The input bytes are modified to conform to the requirements of UUID v4.
+ *
+ * @param bytes A list of 16 bytes.
+ * @returns A UUID v4 string.
+ */
+export function formatDataAsUuidV4(bytes: number[]): string {
+  // https://www.rfc-archive.org/getrfc.php?rfc=4122
+  // 4.4.  Algorithms for Creating a UUID from Truly Random or
+  // Pseudo-Random Numbers
+
+  // Set the two most significant bits (bits 6 and 7) of the clock_seq_hi_and_reserved to zero and
+  // one, respectively.
+  // eslint-disable-next-line no-bitwise, no-param-reassign
+  bytes[clockSeqHiAndReserved.start] = (bytes[clockSeqHiAndReserved.start] | 0x80) & 0xbf;
+  // Set the four most significant bits (bits 12 through 15) of the time_hi_and_version field to
+  // the 4-bit version number from Section 4.1.3.
+  // eslint-disable-next-line no-bitwise, no-param-reassign
+  bytes[timeHiAndVersion.start] = (bytes[timeHiAndVersion.start] & 0x0f) | 0x40;
+
+  return (
+    `${hex(bytes, timeLow)}-${hex(bytes, timeMid)}-${hex(bytes, timeHiAndVersion)}-` +
+    `${hex(bytes, clockSeqHiAndReserved)}${hex(bytes, clockSeqLow)}-${hex(bytes, nodes)}`
+  );
+}
+
+export function fallbackUuidV4(): string {
+  const bytes = getRandom128bit();
+  return formatDataAsUuidV4(bytes);
+}
+
+export default function randomUuidV4(): string {
+  if (typeof crypto !== undefined && typeof crypto.randomUUID === 'function') {
+    return crypto.randomUUID();
+  }
+
+  return fallbackUuidV4();
+}

From 232b7eee29be7056f74d9aa5989d893b729cc179 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Fri, 6 Sep 2024 15:58:19 -0700
Subject: [PATCH 14/18] fix tests

---
 .../__tests__/platform/BrowserHasher.test.ts  | 28 ++++++++++++++++---
 packages/sdk/browser/tsconfig.json            |  2 +-
 2 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts b/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts
index 091e9f0864..986a84d32d 100644
--- a/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts
+++ b/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts
@@ -34,20 +34,40 @@ describe('PlatformHasher', () => {
     expect(output).toEqual('5d59ba64d93a7a3c7af8856d2fbcdfc18c11436fdc93dfb2ec568ddf611cb9d4');
   });
 
+  test('sha1 produces correct base64 output', async () => {
+    // @ts-ignore
+    const h = new BrowserHasher(webcrypto, 'sha1');
+
+    h.update('test-app-id');
+    const output = await h.asyncDigest('base64');
+
+    expect(output).toEqual('kydC7cRd9+LWbu4Ss/t1FiFmDcs=');
+  });
+
+  test('sha1 produces correct hex output', async () => {
+    // @ts-ignore
+    const h = new BrowserHasher(webcrypto, 'sha1');
+
+    h.update('test-app-id');
+    const output = await h.asyncDigest('hex');
+
+    expect(output).toEqual('932742edc45df7e2d66eee12b3fb751621660dcb');
+  });
+
   test('unsupported hash algorithm', async () => {
     expect(() => {
       // @ts-ignore
       // eslint-disable-next-line no-new
-      new BrowserHasher(webcrypto, 'sha1');
-    }).toThrow(/unsupported/i);
+      new BrowserHasher(webcrypto, 'sha512');
+    }).toThrow(/Algorithm is not supported/i);
   });
 
   test('unsupported output algorithm', async () => {
-    expect(async () => {
+    await expect(async () => {
       // @ts-ignore
       const h = new BrowserHasher(webcrypto, 'sha256');
       h.update('test-app-id');
       await h.asyncDigest('base122');
-    }).toThrow(/unsupported/i);
+    }).rejects.toThrow(/Encoding is not supported/i);
   });
 });
diff --git a/packages/sdk/browser/tsconfig.json b/packages/sdk/browser/tsconfig.json
index b1c92fdd99..79420d3d43 100644
--- a/packages/sdk/browser/tsconfig.json
+++ b/packages/sdk/browser/tsconfig.json
@@ -4,7 +4,7 @@
     "declaration": true,
     "declarationMap": true,
     "jsx": "react-jsx",
-    "lib": ["es6", "dom"],
+    "lib": ["ES2017", "dom"],
     "module": "ES6",
     "moduleResolution": "node",
     "noImplicitOverride": true,

From 6c153b829c357276a88af28701cc883206ffc836 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Mon, 9 Sep 2024 08:48:39 -0700
Subject: [PATCH 15/18] PR Feedback.

---
 packages/shared/sdk-client/src/crypto/digest.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/shared/sdk-client/src/crypto/digest.ts b/packages/shared/sdk-client/src/crypto/digest.ts
index 24625ec049..c6b38292a5 100644
--- a/packages/shared/sdk-client/src/crypto/digest.ts
+++ b/packages/shared/sdk-client/src/crypto/digest.ts
@@ -1,6 +1,6 @@
 import { Hasher } from '@launchdarkly/js-sdk-common';
 
-export default function digest(hasher: Hasher, encoding: string) {
+export default async function digest(hasher: Hasher, encoding: string): Promise<string> {
   if (hasher.digest) {
     return hasher.digest(encoding);
   }

From 21d3db78db9c6e3f584cfc91347cc5abe7fc997e Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Mon, 9 Sep 2024 09:22:45 -0700
Subject: [PATCH 16/18] Add browser encoding.

---
 .../browser/src/platform/BrowserEncoding.ts    | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 packages/sdk/browser/src/platform/BrowserEncoding.ts

diff --git a/packages/sdk/browser/src/platform/BrowserEncoding.ts b/packages/sdk/browser/src/platform/BrowserEncoding.ts
new file mode 100644
index 0000000000..f673c13273
--- /dev/null
+++ b/packages/sdk/browser/src/platform/BrowserEncoding.ts
@@ -0,0 +1,18 @@
+import { Encoding } from '@launchdarkly/js-client-sdk-common';
+
+function bytesToBase64(bytes: Uint8Array) {
+  const binString = Array.from(bytes, (byte) => String.fromCodePoint(byte)).join('');
+  return btoa(binString);
+}
+
+/**
+ * Implementation Note: This btoa handles unicode characters, which the base btoa in the browser
+ * does not.
+ * Background: https://developer.mozilla.org/en-US/docs/Glossary/Base64#the_unicode_problem
+ */
+
+export default class BrowserEncoding implements Encoding {
+  btoa(data: string): string {
+    return bytesToBase64(new TextEncoder().encode(data));
+  }
+}

From 5767037033e88e34dc114615b7e31dd307ca8742 Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Mon, 9 Sep 2024 09:33:10 -0700
Subject: [PATCH 17/18] Add tests for browser encoding.

---
 .../__tests__/platform/BrowserEncoding.test.ts | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 packages/sdk/browser/__tests__/platform/BrowserEncoding.test.ts

diff --git a/packages/sdk/browser/__tests__/platform/BrowserEncoding.test.ts b/packages/sdk/browser/__tests__/platform/BrowserEncoding.test.ts
new file mode 100644
index 0000000000..a248656098
--- /dev/null
+++ b/packages/sdk/browser/__tests__/platform/BrowserEncoding.test.ts
@@ -0,0 +1,18 @@
+// TextEncoder should be part of jsdom, but it is not. So we can import it from node in the tests.
+import { TextEncoder } from 'node:util';
+
+import BrowserEncoding from '../../src/platform/BrowserEncoding';
+
+global.TextEncoder = TextEncoder;
+
+it('can base64 a basic ASCII string', () => {
+  const encoding = new BrowserEncoding();
+  expect(encoding.btoa('toaster')).toEqual('dG9hc3Rlcg==');
+});
+
+it('can base64 a unicode string containing multi-byte character', () => {
+  const encoding = new BrowserEncoding();
+  expect(encoding.btoa('✇⽊❽⾵⊚▴ⶊ↺➹≈⋟⚥⤅⊈ⲏⷨ⾭Ⲗ⑲▯ⶋₐℛ⬎⿌🦄')).toEqual(
+    '4pyH4r2K4p294r614oqa4pa04raK4oa64p654omI4ouf4pql4qSF4oqI4rKP4reo4r6t4rKW4pGy4pav4raL4oKQ4oSb4qyO4r+M8J+mhA==',
+  );
+});

From 5506bbe415a3f09dd2ee31a64fb830ad582c56ff Mon Sep 17 00:00:00 2001
From: Ryan Lamb <4955475+kinyoklion@users.noreply.github.com>
Date: Mon, 9 Sep 2024 09:46:27 -0700
Subject: [PATCH 18/18] Test vector generation comment.

---
 packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts b/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts
index 986a84d32d..cb143f119f 100644
--- a/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts
+++ b/packages/sdk/browser/__tests__/platform/BrowserHasher.test.ts
@@ -9,8 +9,7 @@ global.TextEncoder = TextEncoder;
 // Crypto is injectable as it is also not correctly available with the combination of node and jsdom.
 
 /**
- * The links below are different from js-sha256 and are useful to verify the
- * correctness of hash and encoding output:
+ * Test vectors generated using.
  * https://www.liavaag.org/English/SHA-Generator/
  */
 describe('PlatformHasher', () => {