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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
commit 63cd3b2788
3 changed files with 64 additions and 16 deletions
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40
js/libtextsecure.js
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@ -34490,10 +34490,20 @@ 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 ***
@ -34759,7 +34769,9 @@ 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);
@ -35274,12 +35286,24 @@ axolotlInternal.RecipientRecord = function() {
});
};
var verifyMAC = function(data, key, mac) {
var verifyMAC = function(data, key, mac, length) {
return calculateMAC(key, data).then(function(calculated_mac) {
if (!isEqual(calculated_mac, mac, true))
if (mac.byteLength != length || calculated_mac.byteLength < length) {
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");
}
});
}
};
window.textsecure = window.textsecure || {};
window.textsecure.crypto = {
@ -35305,7 +35329,7 @@ axolotlInternal.RecipientRecord = function() {
var ivAndCiphertext = decodedMessage.slice(0, decodedMessage.byteLength - 10);
var mac = decodedMessage.slice(decodedMessage.byteLength - 10, decodedMessage.byteLength);
return verifyMAC(ivAndCiphertext, mac_key, mac).then(function() {
return verifyMAC(ivAndCiphertext, mac_key, mac, 10).then(function() {
return decrypt(aes_key, ciphertext, iv);
});
},
@ -35326,7 +35350,7 @@ axolotlInternal.RecipientRecord = function() {
var ivAndCiphertext = encryptedBin.slice(0, encryptedBin.byteLength - 32);
var mac = encryptedBin.slice(encryptedBin.byteLength - 32, encryptedBin.byteLength);
return verifyMAC(ivAndCiphertext, mac_key, mac).then(function() {
return verifyMAC(ivAndCiphertext, mac_key, mac, 32).then(function() {
return decrypt(aes_key, ciphertext, iv);
});
},