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Refactor some low-level crypto things

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This commit is contained in:
Matt Corallo 2014-05-09 03:43:23 -04:00
parent 905357a2e1
commit 5583e82a20
4 changed files with 42 additions and 53 deletions
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59
js/crypto.js
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@ -1,30 +1,3 @@
function HmacSHA256(key, input) {
input = assertIsArrayBuffer(input);
key = assertIsArrayBuffer(key);
return window.crypto.subtle.sign({name: "HMAC", hash: "SHA-256"}, key, input);
}
function encryptAESCTR(input, key, counter) {
input = assertIsArrayBuffer(input);
key = assertIsArrayBuffer(key);
counter = assertIsArrayBuffer(counter);
return window.crypto.subtle.encrypt({name: "AES-CTR", counter: counter}, key, input);
}
function decryptAESCTR(input, key, counter) {
input = assertIsArrayBuffer(input);
key = assertIsArrayBuffer(key);
counter = assertIsArrayBuffer(counter);
return window.crypto.subtle.decrypt({name: "AES-CTR", counter: counter}, key, input);
}
function decryptAESCBC(input, key, iv) {
input = assertIsArrayBuffer(input);
key = assertIsArrayBuffer(key);
iv = assertIsArrayBuffer(iv);
return window.crypto.subtle.decrypt({name: "AES-CBC", iv: iv}, key, input);
}
// functions exposed for replacement and direct calling in test code
var crypto_tests = {};
@ -42,6 +15,11 @@ window.crypto = (function() {
}
}
function HmacSHA256(key, input) {
return window.crypto.subtle.sign({name: "HMAC", hash: "SHA-256"}, key, input);
}
crypto_tests.privToPub = function(privKey, isIdentity) {
if (privKey.byteLength != 32)
throw new Error("Invalid private key");
@ -168,11 +146,11 @@ window.crypto = (function() {
crypto_tests.HKDF = function(input, salt, info) {
// Specific implementation of RFC 5869 that only returns exactly 64 bytes
return HmacSHA256(salt, input).then(function(PRK) {
return HmacSHA256(salt, toArrayBuffer(input)).then(function(PRK) {
var infoString = getString(info);
// TextSecure implements a slightly tweaked version of RFC 5869: the 0 and 1 should be 1 and 2 here
return HmacSHA256(PRK, infoString + String.fromCharCode(0)).then(function(T1) {
return HmacSHA256(PRK, getString(T1) + infoString + String.fromCharCode(1)).then(function(T2) {
return HmacSHA256(PRK, toArrayBuffer(infoString + String.fromCharCode(0))).then(function(T1) {
return HmacSHA256(PRK, toArrayBuffer(getString(T1) + infoString + String.fromCharCode(1))).then(function(T2) {
return [ T1, T2 ];
});
});
@ -200,7 +178,7 @@ window.crypto = (function() {
if (version === undefined)
version = 1;
return HmacSHA256(key, String.fromCharCode(version) + getString(data)).then(function(calculated_mac) {
return HmacSHA256(key, toArrayBuffer(String.fromCharCode(version) + getString(data))).then(function(calculated_mac) {
var macString = getString(mac);
if (calculated_mac.substring(0, macString.length) != macString)
@ -212,7 +190,7 @@ window.crypto = (function() {
if (version === undefined)
version = 1;
return HmacSHA256(key, String.fromCharCode(version) + getString(data));
return HmacSHA256(key, toArrayBuffer(String.fromCharCode(version) + getString(data)));
}
/******************************
@ -294,8 +272,9 @@ window.crypto = (function() {
return new Promise(function(resolve) { resolve() }); // Stalker, much?
if (chain.chainKey.counter < counter) {
return HmacSHA256(chain.chainKey.key, String.fromCharCode(1)).then(function(mac) {
return HmacSHA256(chain.chainKey.key, String.fromCharCode(2)).then(function(key) {
var key = toArrayBuffer(chain.chainKey.key);
return HmacSHA256(key, toArrayBuffer(String.fromCharCode(1))).then(function(mac) {
return HmacSHA256(key, toArrayBuffer(String.fromCharCode(2))).then(function(key) {
chain.messageKeys[chain.chainKey.counter + 1] = mac;
chain.chainKey.key = key
chain.chainKey.counter += 1;
@ -367,8 +346,10 @@ window.crypto = (function() {
delete chain.messageKeys[message.counter];
verifyMACWithVersionByte(messageProto, keys[1], mac, (2 << 4) | 2);
var iv = getString(intToArrayBuffer(message.counter));
return decryptAESCTR(message.ciphertext, keys[0], iv).then(function(plaintext) {
var counter = intToArrayBuffer(message.counter);
return window.crypto.subtle.decrypt({name: "AES-CTR", counter: counter}, keys[0], toArrayBuffer(message.ciphertext))
.then(function(plaintext) {
//TODO: removeOldChains(session);
delete session['pendingPreKey'];
@ -399,7 +380,7 @@ window.crypto = (function() {
var mac = decodedMessage.subarray(decodedMessage.length - 10, decodedMessage.length);
return verifyMACWithVersionByte(ivAndCipherText, mac_key, mac).then(function() {
return decryptAESCBC(ciphertext, aes_key, iv);
return window.crypto.subtle.decrypt({name: "AES-CBC", iv: iv}, aes_key, ciphertext);
});
};
@ -440,8 +421,8 @@ window.crypto = (function() {
msg.counter = chain.chainKey.counter;
msg.previousCounter = session.currentRatchet.previousCounter;
var iv = intToArrayBuffer(chain.chainKey.counter);
return encryptAESCTR(plaintext, keys[0], iv).then(function(ciphertext) {
var counter = intToArrayBuffer(chain.chainKey.counter);
return window.crypto.subtle.encrypt({name: "AES-CTR", counter: counter}, keys[0], plaintext).then(function(ciphertext) {
msg.ciphertext = ciphertext;
var encodedMsg = getString(msg.encode());