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ECDHE through NaCL

This commit is contained in:
Matt Corallo 2014-01-22 07:37:14 +00:00
parent 8db3885659
commit e0d0df3b4a
1 changed files with 53 additions and 33 deletions
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86
js/helpers.js
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@ -293,9 +293,6 @@ function getRandomBytes(size) {
var createNewKeyPair = function(callback) {
//TODO
var privKey = getRandomBytes(32);
privKey[0] &= 248;
privKey[31] &= 127;
privKey[31] |= 64;
postNaclMessage({command: "bytesToPriv", priv: privKey}, function(message) {
postNaclMessage({command: "privToPub", priv: message.res}, function(message) {
callback({ pubKey: message.res, privKey: privKey });
@ -346,8 +343,10 @@ function getRandomBytes(size) {
/*****************************
*** Internal Crypto stuff ***
*****************************/
var ECDHE = function(pubKey, privKey) {
return "ECDHE";//TODO
var ECDHE = function(pubKey, privKey, callback) {
postNaclMessage({command: "ECDHE", priv: privKey, pub: pubKey}, function(message) {
callback(message.res);
});
}
var HKDF = function(input, salt, info) {
@ -376,35 +375,53 @@ function getRandomBytes(size) {
/******************************
*** Ratchet implementation ***
******************************/
var initSession = function(isInitiator, theirIdentityPubKey, ourEphemeralPrivKey, theirEphemeralPubKey) {
var initSession = function(isInitiator, theirIdentityPubKey, ourEphemeralPrivKey, theirEphemeralPubKey, callback) {
var ourIdentityPrivKey = crypto_storage.getIdentityPrivKey();
var sharedSecret = ECDHE(theirEphemeralPubKey, ourIdentityPrivKey);
if (isInitiator)
sharedSecret = sharedSecret + ECDHE(theirIdentityPubKey, ourEphemeralPrivKey);
else
sharedSecret = ECDHE(theirIdentityPubKey, ourEphemeralPrivKey) + sharedSecret;
sharedSecret += ECDHE(theirEphemeralPubKey, ourEphemeralPrivKey);
var sharedSecret;
ECDHE(theirEphemeralPubKey, ourIdentityPrivKey, function(ecRes) {
sharedSecret = ecRes;
var masterKey = HKDF(sharedSecret, '', "WhisperText");
return { rootKey: masterKey[0], chainKey: masterKey[1] };
function finishInit() {
ECDHE(theirEphemeralPubKey, ourEphemeralPrivKey, function(ecRes) {
sharedSecret += ecRes;
var masterKey = HKDF(sharedSecret, '', "WhisperText");
callback({ rootKey: masterKey[0], chainKey: masterKey[1] });
});
}
if (isInitiator) {
ECDHE(theirIdentityPubKey, ourEphemeralPrivKey, function(ecRes) {
sharedSecret = sharedSecret + ecRes;
finishInit();
});
} else {
ECDHE(theirIdentityPubKey, ourEphemeralPrivKey, function(ecRes) {
sharedSecret = ecRes + sharedSecret;
finishInit();
});
}
});
}
var initSessionFromPreKeyWhisperMessage = function(encodedNumber, message) {
var initSessionFromPreKeyWhisperMessage = function(encodedNumber, message, callback) {
//TODO: Check remote identity key matches known-good key
var preKeyPair = crypto_storage.getAndRemovePreKeyPair(preKeyProto.preKeyId);
if (preKeyPair === undefined)
throw "Missing preKey for PreKeyWhisperMessage";
var firstRatchet = initSession(false, message.identityKey, preKeyPair.privKey, message.baseKey);
initSession(false, message.identityKey, preKeyPair.privKey, message.baseKey, function(firstRatchet) {
var session = {currentRatchet: { rootKey: firstRatchet.rootKey, ephemeralKeyPair: preKeyPair,
lastRemoteEphemeralKey: message.baseKey },
oldRatchetList: []
};
session[preKeyPair.pubKey] = { messageKeys: {}, chainKey: { counter: 0, key: firstRatchet.chainKey } };
storage.saveSession(encodedNumber, session);
var session = {currentRatchet: { rootKey: firstRatchet.rootKey, ephemeralKeyPair: preKeyPair,
lastRemoteEphemeralKey: message.baseKey },
oldRatchetList: []
};
session[preKeyPair.pubKey] = { messageKeys: {}, chainKey: { counter: 0, key: firstRatchet.chainKey } };
storage.saveSession(encodedNumber, session);
callback();
});
}
var fillMessageKeys = function(chain, counter) {
@ -433,18 +450,20 @@ function getRandomBytes(size) {
delete session[ratchet.ephemeralKeyPair.pubKey];
var masterKey = HKDF(ECDHE(remoteKey, ratchet.ephemeralKeyPair.privKey), ratchet.rootKey, "WhisperRatchet");
session[remoteKey] = { messageKeys: {}, chainKey: { counter: 0, key: masterKey.substring(32, 64) } };
ECDHE(remoteKey, ratchet.ephemeralKeyPair.privKey, function(sharedSecret) {
var masterKey = HKDF(sharedSecret, ratchet.rootKey, "WhisperRatchet");
session[remoteKey] = { messageKeys: {}, chainKey: { counter: 0, key: masterKey.substring(32, 64) } };
createNewKeyPair(function(keyPair) {
ratchet.ephemeralKeyPair = keyPair;
createNewKeyPair(function(keyPair) {
ratchet.ephemeralKeyPair = keyPair;
masterKey = HKDF(ECDHE(remoteKey, ratchet.ephemeralKeyPair.privKey), masterKey.substring(0, 32), "WhisperRatchet");
ratchet.rootKey = masterKey.substring(0, 32);
session[nextRatchet.ephemeralKeyPair.pubKey] = { messageKeys: {}, chainKey: { counter: 0, key: masterKey.substring(32, 64) } };
masterKey = HKDF(ECDHE(remoteKey, ratchet.ephemeralKeyPair.privKey), masterKey.substring(0, 32), "WhisperRatchet");
ratchet.rootKey = masterKey.substring(0, 32);
session[nextRatchet.ephemeralKeyPair.pubKey] = { messageKeys: {}, chainKey: { counter: 0, key: masterKey.substring(32, 64) } };
ratchet.lastRemoteEphemeralKey = remoteKey;
callback();
ratchet.lastRemoteEphemeralKey = remoteKey;
callback();
});
});
}
@ -531,8 +550,9 @@ function getRandomBytes(size) {
break;
case 3: //TYPE_MESSAGE_PREKEY_BUNDLE
var preKeyProto = decodePreKeyWhisperMessageProtobuf(getString(proto.message));
initSessionFromPreKeyWhisperMessage(proto.source, preKeyProto);
decryptWhisperMessage(proto.source, getString(preKeyProto.message), function(result) { callback(result); });
initSessionFromPreKeyWhisperMessage(proto.source, preKeyProto, function() {
decryptWhisperMessage(proto.source, getString(preKeyProto.message), function(result) { callback(result); });
});
break;
}
}