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/*
This is where the magic happens
*/
var WidevineCrypto = {};
(function() {
// The public 2048-bit RSA key Widevine uses for Chrome devices in L3
WidevineCrypto.chromeRSAPublicKey =
`-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtdHcRBiDWWxdJyKDLTPO9OTapumVnW+9g6k3RSflM0CESFEufZUJGC73UKe9e+u789HVZT04pB5or3WB0XOx
aOibJklLBkd7Yfn1OndVrenMKTE1F4/6jg5rmwyv4qFQ1u8M/ThZUrAgb8pTmKfb9vrv1V8AApwVzcQg3s48eESnKjBU99Vk8alPTjPSfOgoTDluGxQONWiwCaMwftNs
YrOzlde+V3UOb5FVzPcrOmaERfyujV3h4sHGRbTCsqYVwMalO7hmNmtemwt0xBuf5Juia7t1scuJypQ8lI1iEsB+JZVo3Uovfa9nNX0gl5TAq1tAh6M55/ttpWAirWHv
CQIDAQAB
-----END PUBLIC KEY-----`;
// The private 2048-bit RSA key Widevine uses for authenticating Chrome devices in L3
// Extracted by applying some mathematical tricks to Arxan's white-box algorithm
WidevineCrypto.chromeRSAPrivateKey =
`-----BEGIN PRIVATE KEY-----
MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQC10dxEGINZbF0nIoMtM8705Nqm6ZWdb72DqTdFJ+UzQIRIUS59lQkYLvdQp71767vz0dVlPTikHmiv
dYHRc7Fo6JsmSUsGR3th+fU6d1Wt6cwpMTUXj/qODmubDK/ioVDW7wz9OFlSsCBvylOYp9v2+u/VXwACnBXNxCDezjx4RKcqMFT31WTxqU9OM9J86ChMOW4bFA41aLAJ
ozB+02xis7OV175XdQ5vkVXM9ys6ZoRF/K6NXeHiwcZFtMKyphXAxqU7uGY2a16bC3TEG5/km6Jru3Wxy4nKlDyUjWISwH4llWjdSi99r2c1fSCXlMCrW0CHoznn+22l
YCKtYe8JAgMBAAECggEAGOPDJvFCHd43PFG9qlTyylR/2CSWzigLRfhGsClfd24oDaxLVHav+YcIZRqpVkr1flGlyEeittjQ1OAdptoTGbzp7EpRQmlLqyRoHRpT+MxO
Hf91+KVFk+fGdEG+3CPgKKQt34Y0uByTPCpy2i10b7F3Xnq0Sicq1vG33DhYT9A/DRIjYr8Y0AVovq0VDjWqA1FW5OO9p7vky6e+PDMjSHucQ+uaLzVZSc7vWOh0tH5M
0GVk17YpBiB/iTpw4zBUIcaneQX3eaIfSCDHK0SCD6IRF7kl+uORzvWqiWlGzpdG2B96uyP4hd3WoPcZntM79PKm4dAotdgmalbueFJfpwKBgQDUy0EyA9Fq0aPF4LID
HqDPduIm4hEAZf6sQLd8Fe6ywM4p9KOEVx7YPaFxQHFSgIiWXswildPJl8Cg5cM2EyMU1tdn5xaR4VIDk8e2JEDfhPtaWskpJp2rU2wHvAXOeAES7UFMrkhKVqqVOdbo
IhlLdcYp5KxiJ3mwINSSO94ShwKBgQDavJvF+c8AINfCaMocUX0knXz+xCwdP430GoPQCHa1rUj5bZ3qn3XMwSWa57J4x3pVhYmgJv4jpEK+LBULFezNLV5N4C7vH63a
Zo4OF7IUedFBS5B508yAq7RiPhN2VOC8LRdDh5oqnFufjafF82y9d+/czCrVIG43D+KO2j4F7wKBgDg/HZWF0tYEYeDNGuCeOO19xBt5B/tt+lo3pQhkl7qiIhyO8KXr
jVilOcZAvXOMTA5LMnQ13ExeE2m0MdxaRJyeiUOKnrmisFYHuvNXM9qhQPtKIgABmA2QOG728SX5LHd/RRJqwur7a42UQ00Krlr235F1Q2eSfaTjmKyqrHGDAoGAOTrd
2ueoZFUzfnciYlRj1L+r45B6JlDpmDOTx0tfm9sx26j1h1yfWqoyZ5w1kupGNLgSsSdimPqyR8WK3/KlmW1EXkXIoeH8/8aTZlaGzlqtCFN4ApgKyqOiN44cU3qTrkhx
7MY+7OUqB83tVpqBGfWWeYOltUud6qQqV8v8LFsCgYEAnOq+Ls83CaHIWCjpVfiWC+R7mqW+ql1OGtoaajtA4AzhXzX8HIXpYjupPBlXlQ1FFfPem6jwa1UTZf8CpIb8
pPULAN9ZRrxG8V+bvkZWVREPTZj7xPCwPaZHNKoAmi3Dbv7S5SEYDbBX/NyPCLE4sj/AgTPbUsUtaiw5TvrPsFE=
-----END PRIVATE KEY-----`;
WidevineCrypto.initializeKeys = async function()
{
// load the device RSA keys for various purposes
this.publicKeyEncrypt = await crypto.subtle.importKey('spki', PEM2Binary(this.chromeRSAPublicKey), {name: 'RSA-OAEP', hash: { name: 'SHA-1' },}, true, ['encrypt']);
this.publicKeyVerify = await crypto.subtle.importKey('spki', PEM2Binary(this.chromeRSAPublicKey), {name: 'RSA-PSS', hash: { name: 'SHA-1' },}, true, ['verify']);
this.privateKeyDecrypt = await crypto.subtle.importKey('pkcs8', PEM2Binary(this.chromeRSAPrivateKey), {name: 'RSA-OAEP', hash: { name: 'SHA-1' },}, true, ['decrypt']);
var isRSAGood = await isRSAConsistent(this.publicKeyEncrypt, this.privateKeyDecrypt);
if (!isRSAGood)
{
throw "Can't verify RSA keys consistency; This means the public key does not match the private key!";
}
this.keysInitialized = true;
}
WidevineCrypto.decryptContentKey = async function(licenseRequest, licenseResponse)
{
licenseRequest = SignedMessage.read(new Pbf(licenseRequest));
licenseResponse = SignedMessage.read(new Pbf(licenseResponse));
if (licenseRequest.type != SignedMessage.MessageType.LICENSE_REQUEST.value) return;
license = License.read(new Pbf(licenseResponse.msg));
if (!this.keysInitialized) await this.initializeKeys();
// make sure the signature in the license request validates under the private key
var signatureVerified = await window.crypto.subtle.verify({name: "RSA-PSS", saltLength: 20,}, this.publicKeyVerify,
licenseRequest.signature, licenseRequest.msg)
if (!signatureVerified)
{
console.log("Can't verify license request signature; either the platform is wrong or the key has changed!");
return null;
}
// decrypt the session key
var sessionKey = await crypto.subtle.decrypt({name: "RSA-OAEP"}, this.privateKeyDecrypt, licenseResponse.session_key);
// calculate context_enc
var encoder = new TextEncoder();
var keySize = 128;
var context_enc = concatBuffers([[0x01], encoder.encode("ENCRYPTION"), [0x00], licenseRequest.msg, intToBuffer(keySize)]);
// calculate encrypt_key using CMAC
var encryptKey = wordToByteArray(
CryptoJS.CMAC(arrayToWordArray(new Uint8Array(sessionKey)),
arrayToWordArray(new Uint8Array(context_enc))).words);
// iterate the keys we got to find those we want to decrypt (the content key(s))
var contentKeys = []
for (currentKey of license.key)
{
if (currentKey.type != License.KeyContainer.KeyType.CONTENT.value) continue;
var keyId = currentKey.id;
var keyData = currentKey.key.slice(0, 16);
var keyIv = currentKey.iv.slice(0, 16);
// finally decrypt the content key
var decryptedKey = wordToByteArray(
CryptoJS.AES.decrypt({ ciphertext: arrayToWordArray(keyData) }, arrayToWordArray(encryptKey), { iv: arrayToWordArray(keyIv) }).words);
contentKeys.push(decryptedKey);
console.log("WidevineDecryptor: Found key: " + toHexString(decryptedKey) + " (KID=" + toHexString(keyId) + ")");
}
return contentKeys[0];
}
//
// Helper functions
//
async function isRSAConsistent(publicKey, privateKey)
{
// See if the data is correctly decrypted after encryption
var testData = new Uint8Array([0x41, 0x42, 0x43, 0x44]);
var encryptedData = await crypto.subtle.encrypt({name: "RSA-OAEP"}, publicKey, testData);
var testDecryptedData = await crypto.subtle.decrypt({name: "RSA-OAEP"}, privateKey, encryptedData);
return areBuffersEqual(testData, testDecryptedData);
}
function areBuffersEqual(buf1, buf2)
{
if (buf1.byteLength != buf2.byteLength) return false;
var dv1 = new Int8Array(buf1);
var dv2 = new Int8Array(buf2);
for (var i = 0 ; i != buf1.byteLength ; i++)
{
if (dv1[i] != dv2[i]) return false;
}
return true;
}
function concatBuffers(arrays)
{
// Get the total length of all arrays.
let length = 0;
arrays.forEach(item => {
length += item.length;
});
// Create a new array with total length and merge all source arrays.
let mergedArray = new Uint8Array(length);
let offset = 0;
arrays.forEach(item => {
mergedArray.set(new Uint8Array(item), offset);
offset += item.length;
});
return mergedArray;
}
// CryptoJS format to byte array
function wordToByteArray(wordArray)
{
var byteArray = [], word, i, j;
for (i = 0; i < wordArray.length; ++i) {
word = wordArray[i];
for (j = 3; j >= 0; --j) {
byteArray.push((word >> 8 * j) & 0xFF);
}
}
return byteArray;
}
// byte array to CryptoJS format
function arrayToWordArray(u8Array)
{
var words = [], i = 0, len = u8Array.length;
while (i < len) {
words.push(
(u8Array[i++] << 24) |
(u8Array[i++] << 16) |
(u8Array[i++] << 8) |
(u8Array[i++])
);
}
return {
sigBytes: len,
words: words
};
}
const toHexString = bytes => bytes.reduce((str, byte) => str + byte.toString(16).padStart(2, '0'), '');
const intToBuffer = num =>
{
let b = new ArrayBuffer(4);
new DataView(b).setUint32(0, num);
return Array.from(new Uint8Array(b));
}
function PEM2Binary(pem)
{
var encoded = '';
var lines = pem.split('\n');
for (var i = 0; i < lines.length; i++) {
if (lines[i].indexOf('-----') < 0) {
encoded += lines[i];
}
}
var byteStr = atob(encoded);
var bytes = new Uint8Array(byteStr.length);
for (var i = 0; i < byteStr.length; i++) {
bytes[i] = byteStr.charCodeAt(i);
}
return bytes.buffer;
}
}());
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