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/*!
* algorithms/aes-kw.js - AES-KW Key-Wrapping
*
* Copyright (c) 2015 Cisco Systems, Inc. See LICENSE file.
*/
"use strict";
var helpers = require("./helpers.js"),
forge = require("../deps/forge.js"),
DataBuffer = require("../util/databuffer.js");
var A0 = Buffer.from("a6a6a6a6a6a6a6a6", "hex");
// ### helpers
function xor(a, b) {
var len = Math.max(a.length, b.length);
var result = Buffer.alloc(len);
for (var idx = 0; len > idx; idx++) {
result[idx] = (a[idx] || 0) ^ (b[idx] || 0);
}
return result;
}
function split(input, size) {
var output = [];
for (var idx = 0; input.length > idx; idx += size) {
output.push(input.slice(idx, idx + size));
}
return output;
}
function longToBigEndian(input) {
var hi = Math.floor(input / 4294967296),
lo = input % 4294967296;
var output = Buffer.alloc(8);
output[0] = 0xff & (hi >>> 24);
output[1] = 0xff & (hi >>> 16);
output[2] = 0xff & (hi >>> 8);
output[3] = 0xff & (hi >>> 0);
output[4] = 0xff & (lo >>> 24);
output[5] = 0xff & (lo >>> 16);
output[6] = 0xff & (lo >>> 8);
output[7] = 0xff & (lo >>> 0);
return output;
}
function kwEncryptFN(size) {
function commonChecks(key, data) {
if (size !== (key.length << 3)) {
throw new Error("invalid key size");
}
if (0 < data.length && 0 !== (data.length % 8)) {
throw new Error("invalid data length");
}
}
// ### 'fallback' implementation -- uses forge
var fallback = function(key, pdata) {
try {
commonChecks(key, pdata);
} catch (err) {
return Promise.reject(err);
}
// setup cipher
var cipher = forge.cipher.createCipher("AES", new DataBuffer(key));
// split input into chunks
var R = split(pdata, 8);
var A,
B,
count;
A = A0;
for (var jdx = 0; 6 > jdx; jdx++) {
for (var idx = 0; R.length > idx; idx++) {
count = (R.length * jdx) + idx + 1;
B = Buffer.concat([A, R[idx]]);
cipher.start();
cipher.update(new DataBuffer(B));
cipher.finish();
B = cipher.output.native();
A = xor(B.slice(0, 8),
longToBigEndian(count));
R[idx] = B.slice(8, 16);
}
}
R = [A].concat(R);
var cdata = Buffer.concat(R);
return Promise.resolve({
data: cdata
});
};
// ### WebCryptoAPI implementation
var webcrypto = function(key, pdata) {
try {
commonChecks(key, pdata);
} catch (err) {
return Promise.reject(err);
}
var alg = {
name: "AES-KW"
};
var promise = [
helpers.subtleCrypto.importKey("raw", pdata, { name: "HMAC", hash: "SHA-256" }, true, ["sign"]),
helpers.subtleCrypto.importKey("raw", key, alg, true, ["wrapKey"])
];
promise = Promise.all(promise);
promise = promise.then(function(keys) {
return helpers.subtleCrypto.wrapKey("raw",
keys[0], // key
keys[1], // wrappingKey
alg);
});
promise = promise.then(function(result) {
result = Buffer.from(result);
return {
data: result
};
});
return promise;
};
var node = function(key, pdata) {
try {
commonChecks(key, pdata);
} catch (err) {
return Promise.reject(err);
}
// split input into chunks
var R = split(pdata, 8),
iv = Buffer.alloc(16);
var A,
B,
count;
A = A0;
for (var jdx = 0; 6 > jdx; jdx++) {
for (var idx = 0; R.length > idx; idx++) {
count = (R.length * jdx) + idx + 1;
B = Buffer.concat([A, R[idx]]);
var cipher = helpers.nodeCrypto.createCipheriv("AES" + size, key, iv);
B = cipher.update(B);
A = xor(B.slice(0, 8),
longToBigEndian(count));
R[idx] = B.slice(8, 16);
}
}
R = [A].concat(R);
var cdata = Buffer.concat(R);
return Promise.resolve({
data: cdata
});
};
return helpers.setupFallback(node, webcrypto, fallback);
}
function kwDecryptFN(size) {
function commonChecks(key, data) {
if (size !== (key.length << 3)) {
throw new Error("invalid key size");
}
if (0 < (data.length - 8) && 0 !== (data.length % 8)) {
throw new Error("invalid data length");
}
}
// ### 'fallback' implementation -- uses forge
var fallback = function(key, cdata) {
try {
commonChecks(key, cdata);
} catch (err) {
return Promise.reject(err);
}
// setup cipher
var cipher = forge.cipher.createDecipher("AES", new DataBuffer(key));
// prepare inputs
var R = split(cdata, 8),
A,
B,
count;
A = R[0];
R = R.slice(1);
for (var jdx = 5; 0 <= jdx; --jdx) {
for (var idx = R.length - 1; 0 <= idx; --idx) {
count = (R.length * jdx) + idx + 1;
B = xor(A,
longToBigEndian(count));
B = Buffer.concat([B, R[idx]]);
cipher.start();
cipher.update(new DataBuffer(B));
cipher.finish();
B = cipher.output.native();
A = B.slice(0, 8);
R[idx] = B.slice(8, 16);
}
}
if (A.toString() !== A0.toString()) {
return Promise.reject(new Error("decryption failed"));
}
var pdata = Buffer.concat(R);
return Promise.resolve(pdata);
};
// ### WebCryptoAPI implementation
var webcrypto = function(key, cdata) {
try {
commonChecks(key, cdata);
} catch (err) {
return Promise.reject(err);
}
var alg = {
name: "AES-KW"
};
var promise = helpers.subtleCrypto.importKey("raw", key, alg, true, ["unwrapKey"]);
promise = promise.then(function(key) {
return helpers.subtleCrypto.unwrapKey("raw", cdata, key, alg, {name: "HMAC", hash: "SHA-256"}, true, ["sign"]);
});
promise = promise.then(function(result) {
// unwrapped CryptoKey -- extract raw
return helpers.subtleCrypto.exportKey("raw", result);
});
promise = promise.then(function(result) {
result = Buffer.from(result);
return result;
});
return promise;
};
var node = function(key, cdata) {
try {
commonChecks(key, cdata);
} catch (err) {
return Promise.reject(err);
}
// prepare inputs
var R = split(cdata, 8),
iv = Buffer.alloc(16),
A,
B,
count;
A = R[0];
R = R.slice(1);
for (var jdx = 5; 0 <= jdx; --jdx) {
for (var idx = R.length - 1; 0 <= idx; --idx) {
count = (R.length * jdx) + idx + 1;
B = xor(A,
longToBigEndian(count));
B = Buffer.concat([B, R[idx], iv]);
var cipher = helpers.nodeCrypto.createDecipheriv("AES" + size, key, iv);
B = cipher.update(B);
A = B.slice(0, 8);
R[idx] = B.slice(8, 16);
}
}
if (A.toString() !== A0.toString()) {
return Promise.reject(new Error("decryption failed"));
}
var pdata = Buffer.concat(R);
return Promise.resolve(pdata);
};
return helpers.setupFallback(node, webcrypto, fallback);
}
// ### Public API
// * [name].encrypt
// * [name].decrypt
var aesKw = {};
[
"A128KW",
"A192KW",
"A256KW"
].forEach(function(alg) {
var size = parseInt(/A(\d+)KW/g.exec(alg)[1]);
aesKw[alg] = {
encrypt: kwEncryptFN(size),
decrypt: kwDecryptFN(size)
};
});
module.exports = aesKw;