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Cleanup of AES-CFB code in integrity protected packet

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This commit is contained in:
Tankred Hase 2016-03-25 16:10:27 +08:00
parent 10bf9ec41e
commit 4070e27959
1 changed files with 75 additions and 56 deletions
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131
src/packet/sym_encrypted_integrity_protected.js
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@ -41,11 +41,14 @@ import asmCrypto from 'asmcrypto-lite';
const nodeCrypto = util.getNodeCrypto();
const Buffer = util.getNodeBuffer();
const VERSION = 1; // A one-octet version number of the data packet.
/**
* @constructor
*/
export default function SymEncryptedIntegrityProtected() {
this.tag = enums.packet.symEncryptedIntegrityProtected;
this.version = VERSION;
/** The encrypted payload. */
this.encrypted = null; // string
/**
@ -60,9 +63,7 @@ export default function SymEncryptedIntegrityProtected() {
SymEncryptedIntegrityProtected.prototype.read = function (bytes) {
// - A one-octet version number. The only currently defined value is 1.
var version = bytes[0];
if (version !== 1) {
if (bytes[0] !== VERSION) {
throw new Error('Invalid packet version.');
}
@ -73,82 +74,57 @@ SymEncryptedIntegrityProtected.prototype.read = function (bytes) {
};
SymEncryptedIntegrityProtected.prototype.write = function () {
// 1 = Version
return util.concatUint8Array([new Uint8Array([1]), this.encrypted]);
return util.concatUint8Array([new Uint8Array([VERSION]), this.encrypted]);
};
/**
* Encrypt the payload in the packet.
* @param {String} sessionKeyAlgorithm The selected symmetric encryption algorithm to be used e.g. 'aes128'
* @param {Uint8Array} key The key of cipher blocksize length to be used
* @return {Promise}
*/
SymEncryptedIntegrityProtected.prototype.encrypt = function (sessionKeyAlgorithm, key) {
var bytes = this.packets.write();
const bytes = this.packets.write();
const prefixrandom = crypto.getPrefixRandom(sessionKeyAlgorithm);
const repeat = new Uint8Array([prefixrandom[prefixrandom.length - 2], prefixrandom[prefixrandom.length - 1]]);
const prefix = util.concatUint8Array([prefixrandom, repeat]);
const mdc = new Uint8Array([0xD3, 0x14]); // modification detection code packet
var prefixrandom = crypto.getPrefixRandom(sessionKeyAlgorithm);
var repeat = new Uint8Array([prefixrandom[prefixrandom.length - 2], prefixrandom[prefixrandom.length - 1]]);
var prefix = util.concatUint8Array([prefixrandom, repeat]);
// Modification detection code packet.
var mdc = new Uint8Array([0xD3, 0x14]);
// This could probably be cleaned up to use less memory
var tohash = util.concatUint8Array([bytes, mdc]);
var hash = crypto.hash.sha1(util.concatUint8Array([prefix, tohash]));
let tohash = util.concatUint8Array([bytes, mdc]);
const hash = crypto.hash.sha1(util.concatUint8Array([prefix, tohash]));
tohash = util.concatUint8Array([tohash, hash]);
if(sessionKeyAlgorithm.substr(0,3) === 'aes') { // AES optimizations. Native code for node, asmCrypto for browser.
var blockSize = crypto.cipher[sessionKeyAlgorithm].blockSize;
if(nodeCrypto) { // Node crypto library. Only loaded if config.use_native === true
var cipherObj = new nodeCrypto.createCipheriv('aes-' + sessionKeyAlgorithm.substr(3,3) + '-cfb',
new Buffer(key), new Buffer(new Uint8Array(blockSize)));
this.encrypted = new Uint8Array(cipherObj.update(new Buffer(util.concatUint8Array([prefix, tohash]))));
} else { // asm.js fallback
this.encrypted = asmCrypto.AES_CFB.encrypt(util.concatUint8Array([prefix, tohash]), key);
}
this.encrypted = aesEncrypt(sessionKeyAlgorithm, prefix, tohash, key);
} else {
this.encrypted = crypto.cfb.encrypt(prefixrandom, sessionKeyAlgorithm, tohash, key, false)
.subarray(0, prefix.length + tohash.length);
this.encrypted = crypto.cfb.encrypt(prefixrandom, sessionKeyAlgorithm, tohash, key, false);
this.encrypted = this.encrypted.subarray(0, prefix.length + tohash.length);
}
return Promise.resolve();
};
/**
* Decrypts the encrypted data contained in this object read_packet must
* have been called before
*
* @param {module:enums.symmetric} sessionKeyAlgorithm
* The selected symmetric encryption algorithm to be used
* @param {Uint8Array} key The key of cipher blocksize length to be used
* @return {String} The decrypted data of this packet
* Decrypts the encrypted data contained in the packet.
* @param {String} sessionKeyAlgorithm The selected symmetric encryption algorithm to be used e.g. 'aes128'
* @param {Uint8Array} key The key of cipher blocksize length to be used
* @return {Promise}
*/
SymEncryptedIntegrityProtected.prototype.decrypt = function (sessionKeyAlgorithm, key) {
var decrypted;
let decrypted;
if(sessionKeyAlgorithm.substr(0,3) === 'aes') { // AES optimizations. Native code for node, asmCrypto for browser.
var blockSize = crypto.cipher[sessionKeyAlgorithm].blockSize;
if(nodeCrypto) { // Node crypto library. Only loaded if config.use_native === true
var decipherObj = new nodeCrypto.createDecipheriv('aes-' + sessionKeyAlgorithm.substr(3,3) + '-cfb',
new Buffer(key), new Buffer(new Uint8Array(blockSize)));
decrypted = new Uint8Array(decipherObj.update(new Buffer(this.encrypted)));
} else { // asm.js fallback
decrypted = asmCrypto.AES_CFB.decrypt(this.encrypted, key);
}
// Remove random prefix
decrypted = decrypted.subarray(blockSize + 2, decrypted.length);
decrypted = aesDecrypt(sessionKeyAlgorithm, this.encrypted, key);
} else {
decrypted = crypto.cfb.decrypt(sessionKeyAlgorithm, key, this.encrypted, false);
}
// there must be a modification detection code packet as the
// last packet and everything gets hashed except the hash itself
this.hash = util.Uint8Array2str(crypto.hash.sha1(util.concatUint8Array([crypto.cfb.mdc(sessionKeyAlgorithm, key, this.encrypted),
decrypted.subarray(0, decrypted.length - 20)])));
var mdc = util.Uint8Array2str(decrypted.subarray(decrypted.length - 20, decrypted.length));
const prefix = crypto.cfb.mdc(sessionKeyAlgorithm, key, this.encrypted);
const bytes = decrypted.subarray(0, decrypted.length - 20);
const tohash = util.concatUint8Array([prefix, bytes]);
this.hash = util.Uint8Array2str(crypto.hash.sha1(tohash));
const mdc = util.Uint8Array2str(decrypted.subarray(decrypted.length - 20, decrypted.length));
if (this.hash !== mdc) {
throw new Error('Modification detected.');
@ -158,3 +134,46 @@ SymEncryptedIntegrityProtected.prototype.decrypt = function (sessionKeyAlgorithm
return Promise.resolve();
};
//////////////////////////
// //
// Helper functions //
// //
//////////////////////////
function aesEncrypt(algo, prefix, pt, key) {
if(nodeCrypto) { // Node crypto library.
return nodeEncrypt(algo, prefix, pt, key);
} else { // asm.js fallback
return asmCrypto.AES_CFB.encrypt(util.concatUint8Array([prefix, pt]), key);
}
}
function aesDecrypt(algo, ct, key) {
let pt;
if(nodeCrypto) { // Node crypto library.
pt = nodeDecrypt(algo, ct, key);
} else { // asm.js fallback
pt = asmCrypto.AES_CFB.decrypt(ct, key);
}
return pt.subarray(crypto.cipher[algo].blockSize + 2, pt.length); // Remove random prefix
}
function nodeEncrypt(algo, prefix, pt, key) {
key = new Buffer(key);
const iv = new Buffer(new Uint8Array(crypto.cipher[algo].blockSize));
const cipherObj = new nodeCrypto.createCipheriv('aes-' + algo.substr(3,3) + '-cfb', key, iv);
const ct = cipherObj.update(new Buffer(util.concatUint8Array([prefix, pt])));
return new Uint8Array(ct);
}
function nodeDecrypt(algo, ct, key) {
ct = new Buffer(ct);
key = new Buffer(key);
const iv = new Buffer(new Uint8Array(crypto.cipher[algo].blockSize));
const decipherObj = new nodeCrypto.createDecipheriv('aes-' + algo.substr(3,3) + '-cfb', key, iv);
const pt = decipherObj.update(ct);
return new Uint8Array(pt);
}