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Use constant time mac comparison

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In libtextsecure and in libaxolotl.

// FREEBIE
This commit is contained in:
lilia
2015-11-24 16:14:12 -08:00
parent d4e0c11ebc
commit 63cd3b2788
3 changed files with 64 additions and 16 deletions
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18
libtextsecure/libaxolotl.js
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@@ -34392,10 +34392,20 @@ window.axolotl.protocol = function(storage_interface) {
var verifyMAC = function(data, key, mac) {
return axolotlInternal.crypto.sign(key, data).then(function(calculated_mac) {
if (!isEqual(calculated_mac, mac, true))
if (calculated_mac.byteLength < mac.byteLength) {
throw new Error("Bad MAC length");
}
var a = new Uint8Array(calculated_mac);
var b = new Uint8Array(mac);
var result = 0;
for (var i=0; i < mac.byteLength; ++i) {
result = result | (a[i] ^ b[i]);
}
if (result !== 0) {
throw new Error("Bad MAC");
}
});
}
};
/******************************
*** Ratchet implementation ***
@@ -34661,7 +34671,9 @@ window.axolotl.protocol = function(storage_interface) {
throw new Error("Bad version number on WhisperMessage");
var messageProto = messageBytes.substring(1, messageBytes.length - 8);
var mac = messageBytes.substring(messageBytes.length - 8, messageBytes.length);
var mac = axolotlInternal.utils.convertToArrayBuffer(
messageBytes.substring(messageBytes.length - 8, messageBytes.length)
);
var message = axolotlInternal.protobuf.WhisperMessage.decode(messageProto, 'binary');
var remoteEphemeralKey = axolotlInternal.utils.convertToArrayBuffer(message.ephemeralKey);