1 files changed, 76 insertions, 0 deletions
diff --git a/comm/mailnews/base/src/MailCryptoUtils.jsm b/comm/mailnews/base/src/MailCryptoUtils.jsm
new file mode 100644
index 0000000000..6c378e6703
--- /dev/null
+++ b/comm/mailnews/base/src/MailCryptoUtils.jsm
@@ -0,0 +1,76 @@
+/* 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/. */
+
+const EXPORTED_SYMBOLS = ["MailCryptoUtils"];
+
+var MailCryptoUtils = {
+  /**
+   * Converts a binary string into a Uint8Array.
+   *
+   * @param {BinaryString} str - The string to convert.
+   * @returns {Uint8Array}.
+   */
+  binaryStringToTypedArray(str) {
+    let arr = new Uint8Array(str.length);
+    for (let i = 0; i < str.length; i++) {
+      arr[i] = str.charCodeAt(i);
+    }
+    return arr;
+  },
+
+  /**
+   * The HMAC-MD5 transform works like:
+   *
+   * MD5(K XOR opad, MD5(K XOR ipad, m))
+   *
+   * where
+   *  K is an n byte key
+   *  ipad is the byte 0x36 repeated 64 times
+   *  opad is the byte 0x5c repeated 64 times
+   *  m is the message being processed
+
+   * @param {Uint8Array} key
+   * @param {Uint8Array} data
+   * @returns {Uint8Array}
+   */
+  hmacMd5(key, data) {
+    let hasher = Cc["@mozilla.org/security/hash;1"].createInstance(
+      Ci.nsICryptoHash
+    );
+    let digest;
+
+    // If key is longer than 64 bytes, reset it to MD5(key).
+    if (key.length > 64) {
+      hasher.init(Ci.nsICryptoHash.MD5);
+      hasher.update(key, key.length);
+      digest = hasher.finish(false);
+      key = this.binaryStringToTypedArray(digest);
+    }
+
+    // Generate innerPad and outerPad.
+    let innerPad = new Uint8Array(64);
+    let outerPad = new Uint8Array(64);
+    for (let i = 0; i < 64; i++) {
+      let base = key[i] || 0;
+      innerPad[i] = base ^ 0x36;
+      outerPad[i] = base ^ 0x5c;
+    }
+
+    // Perform inner MD5.
+    hasher.init(Ci.nsICryptoHash.MD5);
+    hasher.update(innerPad, 64);
+    hasher.update(data, data.length);
+    digest = hasher.finish(false);
+
+    let result = this.binaryStringToTypedArray(digest);
+
+    // Perform outer MD5.
+    hasher.init(Ci.nsICryptoHash.MD5);
+    hasher.update(outerPad, 64);
+    hasher.update(result, result.length);
+    digest = hasher.finish(false);
+
+    return this.binaryStringToTypedArray(digest);
+  },
+};