Add a configuration option 'sharingKeyLength' under the hood. Use thi…

…s setting to generate a more complex sharing key.

src/backend/middlewares/SharingMWs.ts

@@ -83,14 +83,14 @@ export class SharingMWs {
       );
     }
 
-    let sharingKey = SharingMWs.generateKey();
+    let sharingKey = SharingMWs.generateKey(Config.Sharing.sharingKeyLength);
 
     // create one not yet used
     // eslint-disable-next-line no-constant-condition
     while (true) {
       try {
         await ObjectManagers.getInstance().SharingManager.findOne(sharingKey);
-        sharingKey = this.generateKey();
+        sharingKey = this.generateKey(Config.Sharing.sharingKeyLength);
       } catch (err) {
         break;
       }
@@ -279,13 +279,14 @@ export class SharingMWs {
     }
   }
 
-  private static generateKey(): string {
-    function s4(): string {
-      return Math.floor((1 + Math.random()) * 0x10000)
-        .toString(16)
-        .substring(1);
+  private static generateKey(length:number): string {
+    function randomInt(max:number): number {
+      return Math.floor(Math.random() * max);
     }
-
-    return s4() + s4();
+    const characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
+    return [...Array(length).keys()].reduce(
+      (result) => result + characters.charAt(randomInt(characters.length)),
+      ""
+    );
   }
 }

src/common/config/public/ClientConfig.ts

@@ -304,6 +304,16 @@ export class ClientSharingConfig {
     description: $localize`Requires password protected sharing links.`,
   })
   passwordRequired: boolean = false;
+  @ConfigProperty({
+    type: 'unsignedInt', min: 8, max: 64,
+    tags:
+      {
+        name: $localize`Sharing key length`,
+        priority: ConfigPriority.underTheHood
+      },
+    description: $localize`The longer the keys are, the more secure the share links will be.`,
+  })
+  sharingKeyLength: number = 32;
 }
 
 @SubConfigClass({tags: {client: true}, softReadonly: true})