Creating crypto_exchange module

browser/BUILD.gn

@@ -312,6 +312,12 @@ source_set("browser_process") {
     ]
   }
 
+  if (gemini_enabled || binance_enabled) {
+    deps += [
+      "//brave/components/crypto_exchange/browser",
+    ]
+  }
+
   if (brave_together_enabled) {
     sources += [
       "brave_together/brave_together_util.cc",

components/crypto_exchange/browser/BUILD.gn

@@ -0,0 +1,14 @@
+source_set("browser") {
+  # Remove when https://github.com/brave/brave-browser/issues/10640 is resolved
+  check_includes = false
+
+  sources = [
+    "crypto_exchange_oauth_util.cc",
+    "crypto_exchange_oauth_util.h",
+  ]
+
+  deps = [
+    "//base",
+    "//crypto",
+  ]
+}

components/crypto_exchange/browser/crypto_exchange_oauth_util.cc

@@ -0,0 +1,57 @@
+/* Copyright (c) 2020 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <string>
+
+#include "brave/components/crypto_exchange/browser/crypto_exchange_oauth_util.h"
+
+#include "base/base64.h"
+#include "base/strings/string_number_conversions.h"
+#include "crypto/random.h"
+#include "crypto/sha2.h"
+
+namespace crypto_exchange {
+
+std::string GetCryptoRandomString(bool hex_encode) {
+  const size_t kSeedByteLength = 32;
+  uint8_t random_seed_bytes[kSeedByteLength];
+  crypto::RandBytes(random_seed_bytes, kSeedByteLength);
+
+  if (!hex_encode) {
+    std::string encoded_string;
+    base::Base64Encode(
+      reinterpret_cast<char*>(random_seed_bytes), &encoded_string);
+    return encoded_string;
+  }
+
+  return base::HexEncode(
+      reinterpret_cast<char*>(random_seed_bytes), kSeedByteLength);
+}
+
+std::string GetCodeChallenge(
+    const std::string& code_verifier, bool strip_chars) {
+  std::string code_challenge;
+  char raw[crypto::kSHA256Length] = {0};
+  crypto::SHA256HashString(code_verifier,
+                           raw,
+                           crypto::kSHA256Length);
+  base::Base64Encode(base::StringPiece(raw,
+                                       crypto::kSHA256Length),
+                                       &code_challenge);
+
+  if (strip_chars) {
+    std::replace(code_challenge.begin(), code_challenge.end(), '+', '-');
+    std::replace(code_challenge.begin(), code_challenge.end(), '/', '_');
+
+    code_challenge.erase(std::find_if(code_challenge.rbegin(),
+        code_challenge.rend(), [](int ch) {
+      return ch != '=';
+    }).base(), code_challenge.end());
+  }
+
+  return code_challenge;
+}
+
+}  // namespace crypto_exchange

components/crypto_exchange/browser/crypto_exchange_oauth_util.h

@@ -0,0 +1,20 @@
+/* Copyright (c) 2020 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_CRYPTO_EXCHANGE_BROWSER_CRYPTO_EXCHANGE_OAUTH_UTIL_H_
+#define BRAVE_COMPONENTS_CRYPTO_EXCHANGE_BROWSER_CRYPTO_EXCHANGE_OAUTH_UTIL_H_
+
+#include <string>
+
+namespace crypto_exchange {
+
+std::string GetCryptoRandomString(bool hex_encode);
+
+std::string GetCodeChallenge(
+    const std::string& code_verifier, bool strip_chars);
+
+}
+
+#endif  // BRAVE_COMPONENTS_CRYPTO_EXCHANGE_BROWSER_CRYPTO_EXCHANGE_OAUTH_UTIL_H_