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hydrogen-web/prototypes/derive-keys.js

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import {base58} from "../src/utils/base-encoding.js";
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function subtleCryptoResult(promiseOrOp, method) {
if (promiseOrOp instanceof Promise) {
return promiseOrOp;
} else {
return new Promise((resolve, reject) => {
promiseOrOp.oncomplete = e => resolve(e.target.result);
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promiseOrOp.onerror = e => reject(new Error("Crypto error on " + method));
});
}
}
class CryptoHMACDriver {
constructor(subtleCrypto) {
this._subtleCrypto = subtleCrypto;
}
/**
* [hmac description]
* @param {BufferSource} key
* @param {BufferSource} mac
* @param {BufferSource} data
* @param {HashName} hash
* @return {boolean}
*/
async verify(key, mac, data, hash) {
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const opts = {
name: 'HMAC',
hash: {name: hashName(hash)},
};
const hmacKey = await subtleCryptoResult(this._subtleCrypto.importKey(
'raw',
key,
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opts,
false,
['verify'],
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), "importKey");
const isVerified = await subtleCryptoResult(this._subtleCrypto.verify(
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opts,
hmacKey,
mac,
data,
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), "verify");
return isVerified;
}
async compute(key, data, hash) {
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const opts = {
name: 'HMAC',
hash: {name: hashName(hash)},
};
const hmacKey = await subtleCryptoResult(this._subtleCrypto.importKey(
'raw',
key,
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opts,
false,
['sign'],
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), "importKey");
const buffer = await subtleCryptoResult(this._subtleCrypto.sign(
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opts,
hmacKey,
data,
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), "sign");
return new Uint8Array(buffer);
}
}
const nwbo = (num, len) => {
const arr = new Uint8Array(len);
for(let i=0; i<len; i++) arr[i] = 0xFF && (num >> ((len - i - 1)*8));
return arr;
};
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class CryptoLegacyHMACDriver {
constructor(hmacDriver) {
this._hmacDriver = hmacDriver;
}
async verify(key, mac, data, hash) {
if (hash === "SHA-512") {
throw new Error("SHA-512 HMAC verification is not implemented yet");
} else {
return this._hmacDriver.verify(key, mac, data, hash)
}
}
async compute(key, data, hash) {
if (hash === "SHA-256") {
return await this._hmacDriver.compute(key, data, hash);
} else {
const shaObj = new window.jsSHA(hash, "UINT8ARRAY", {
"hmacKey": {
"value": key,
"format": "UINT8ARRAY"
}
});
shaObj.update(data);
return shaObj.getHash("UINT8ARRAY");
}
}
}
class CryptoLegacyDeriveDriver {
constructor(cryptoDriver) {
this._cryptoDriver = cryptoDriver;
}
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// adapted from https://github.com/junkurihara/jscu/blob/develop/packages/js-crypto-pbkdf/src/pbkdf.ts#L21
// could also consider https://github.com/brix/crypto-js/blob/develop/src/pbkdf2.js although not async
async pbkdf2(password, iterations, salt, hash, length) {
const dkLen = length / 8;
if (iterations <= 0) {
throw new Error('InvalidIterationCount');
}
if (dkLen <= 0) {
throw new Error('InvalidDerivedKeyLength');
}
const hLen = this._cryptoDriver.digestSize(hash);
if(dkLen > (Math.pow(2, 32) - 1) * hLen) throw new Error('DerivedKeyTooLong');
const l = Math.ceil(dkLen/hLen);
const r = dkLen - (l-1)*hLen;
const funcF = async (i) => {
const seed = new Uint8Array(salt.length + 4);
seed.set(salt);
seed.set(nwbo(i+1, 4), salt.length);
let u = await this._cryptoDriver.hmac.compute(password, seed, hash);
let outputF = new Uint8Array(u);
for(let j = 1; j < iterations; j++){
if ((j % 1000) === 0) {
console.log(j, j/iterations);
}
u = await this._cryptoDriver.hmac.compute(password, u, hash);
outputF = u.map( (elem, idx) => elem ^ outputF[idx]);
}
return {index: i, value: outputF};
};
const Tis = [];
const DK = new Uint8Array(dkLen);
for(let i = 0; i < l; i++) {
Tis.push(funcF(i));
}
const TisResolved = await Promise.all(Tis);
TisResolved.forEach(elem => {
if (elem.index !== l - 1) {
DK.set(elem.value, elem.index*hLen);
}
else {
DK.set(elem.value.slice(0, r), elem.index*hLen);
}
});
return DK;
}
// based on https://github.com/junkurihara/jscu/blob/develop/packages/js-crypto-hkdf/src/hkdf.ts
async hkdf(key, salt, info, hash, length) {
length = length / 8;
const len = this._cryptoDriver.digestSize(hash);
// RFC5869 Step 1 (Extract)
const prk = await this._cryptoDriver.hmac.compute(salt, key, hash);
// RFC5869 Step 2 (Expand)
let t = new Uint8Array([]);
const okm = new Uint8Array(Math.ceil(length / len) * len);
for(let i = 0; i < Math.ceil(length / len); i++){
const concat = new Uint8Array(t.length + info.length + 1);
concat.set(t);
concat.set(info, t.length);
concat.set(new Uint8Array([i+1]), t.length + info.length);
t = await this._cryptoDriver.hmac.compute(prk, concat, hash);
okm.set(t, len * i);
}
return okm.slice(0, length);
}
}
class CryptoDeriveDriver {
constructor(subtleCrypto) {
this._subtleCrypto = subtleCrypto;
}
/**
* [pbkdf2 description]
* @param {BufferSource} password
* @param {Number} iterations
* @param {BufferSource} salt
* @param {HashName} hash
* @param {Number} length the desired length of the generated key, in bits (not bytes!)
* @return {BufferSource}
*/
async pbkdf2(password, iterations, salt, hash, length) {
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// check for existance of deriveBits, which IE11 does not have
const key = await subtleCryptoResult(this._subtleCrypto.importKey(
'raw',
password,
{name: 'PBKDF2'},
false,
['deriveBits'],
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), "importKey");
const keybits = await subtleCryptoResult(this._subtleCrypto.deriveBits(
{
name: 'PBKDF2',
salt,
iterations,
hash: hashName(hash),
},
key,
length,
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), "deriveBits");
return new Uint8Array(keybits);
}
/**
* [hkdf description]
* @param {BufferSource} key [description]
* @param {BufferSource} salt [description]
* @param {BufferSource} info [description]
* @param {HashName} hash the hash to use
* @param {Number} length desired length of the generated key in bits (not bytes!)
* @return {[type]} [description]
*/
async hkdf(key, salt, info, hash, length) {
const hkdfkey = await subtleCryptoResult(this._subtleCrypto.importKey(
'raw',
key,
{name: "HKDF"},
false,
["deriveBits"],
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), "importKey");
const keybits = await subtleCryptoResult(this._subtleCrypto.deriveBits({
name: "HKDF",
salt,
info,
hash: hashName(hash),
},
hkdfkey,
length,
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), "deriveBits");
return new Uint8Array(keybits);
}
}
class CryptoAESDriver {
constructor(subtleCrypto) {
this._subtleCrypto = subtleCrypto;
}
/**
* [decrypt description]
* @param {BufferSource} key [description]
* @param {BufferSource} iv [description]
* @param {BufferSource} ciphertext [description]
* @return {BufferSource} [description]
*/
async decrypt(key, iv, ciphertext) {
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const opts = {
name: "AES-CTR",
counter: iv,
length: 64,
};
let aesKey;
try {
aesKey = await subtleCryptoResult(this._subtleCrypto.importKey(
'raw',
key,
opts,
false,
['decrypt'],
), "importKey");
} catch (err) {
throw new Error(`Could not import key for AES-CTR decryption: ${err.message}`);
}
try {
const plaintext = await subtleCryptoResult(this._subtleCrypto.decrypt(
// see https://developer.mozilla.org/en-US/docs/Web/API/AesCtrParams
opts,
aesKey,
ciphertext,
), "decrypt");
return new Uint8Array(plaintext);
} catch (err) {
throw new Error(`Could not decrypt with AES-CTR: ${err.message}`);
}
}
}
class CryptoLegacyAESDriver {
/**
* [decrypt description]
* @param {BufferSource} key [description]
* @param {BufferSource} iv [description]
* @param {BufferSource} ciphertext [description]
* @return {BufferSource} [description]
*/
async decrypt(key, iv, ciphertext) {
const aesjs = window.aesjs;
var aesCtr = new aesjs.ModeOfOperation.ctr(key, new aesjs.Counter(iv));
return aesCtr.decrypt(ciphertext);
}
}
function hashName(name) {
if (name !== "SHA-256" && name !== "SHA-512") {
throw new Error(`Invalid hash name: ${name}`);
}
return name;
}
export class CryptoDriver {
constructor(subtleCrypto) {
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this.aes = new CryptoLegacyAESDriver();
// this.aes = new CryptoAESDriver(subtleCrypto);
//this.derive = new CryptoDeriveDriver(subtleCrypto);
this.derive = new CryptoLegacyDeriveDriver(this);
// subtleCrypto.deriveBits ?
// new CryptoDeriveDriver(subtleCrypto) :
// new CryptoLegacyDeriveDriver(this);
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this.hmac = new CryptoLegacyHMACDriver(new CryptoHMACDriver(subtleCrypto));
this._subtleCrypto = subtleCrypto;
}
/**
* [digest description]
* @param {HashName} hash
* @param {BufferSource} data
* @return {BufferSource}
*/
async digest(hash, data) {
return await subtleCryptoResult(this._subtleCrypto.digest(hashName(hash), data));
}
digestSize(hash) {
switch (hashName(hash)) {
case "SHA-512": return 64;
case "SHA-256": return 32;
default: throw new Error(`Not implemented for ${hashName(hash)}`);
}
}
}
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export function decodeBase64(base64) {
const binStr = window.atob(base64);
const len = binStr.length;
const bytes = new Uint8Array(len);
for (let i = 0; i < len; i++) {
bytes[i] = binStr.charCodeAt(i);
}
return bytes;
}
const DEFAULT_ITERATIONS = 500000;
const DEFAULT_BITSIZE = 256;
export async function deriveSSSSKey(cryptoDriver, passphrase, ssssKey) {
const textEncoder = new TextEncoder();
return await cryptoDriver.derive.pbkdf2(
textEncoder.encode(passphrase),
ssssKey.content.passphrase.iterations || DEFAULT_ITERATIONS,
textEncoder.encode(ssssKey.content.passphrase.salt),
"SHA-512",
ssssKey.content.passphrase.bits || DEFAULT_BITSIZE);
}
export async function decryptSecret(cryptoDriver, keyId, ssssKey, event) {
const textEncoder = new TextEncoder();
const textDecoder = new TextDecoder();
// now derive the aes and mac key from the 4s key
const hkdfKey = await cryptoDriver.derive.hkdf(
ssssKey,
new Uint8Array(8).buffer, //salt
textEncoder.encode(event.type), // info
"SHA-256",
512 // 512 bits or 64 bytes
);
const aesKey = hkdfKey.slice(0, 32);
const hmacKey = hkdfKey.slice(32);
const data = event.content.encrypted[keyId];
const ciphertextBytes = decodeBase64(data.ciphertext);
const isVerified = await cryptoDriver.hmac.verify(
hmacKey, decodeBase64(data.mac),
ciphertextBytes, "SHA-256");
if (!isVerified) {
throw new Error("Bad MAC");
}
const plaintext = await cryptoDriver.aes.decrypt(aesKey, decodeBase64(data.iv), ciphertextBytes);
return textDecoder.decode(new Uint8Array(plaintext));
}
export async function decryptSession(backupKeyBase64, backupInfo, sessionResponse) {
const privKey = decodeBase64(backupKeyBase64);
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console.log("privKey", privKey);
const decryption = new window.Olm.PkDecryption();
let backupPubKey;
try {
backupPubKey = decryption.init_with_private_key(privKey);
} catch (e) {
decryption.free();
throw e;
}
// If the pubkey computed from the private data we've been given
// doesn't match the one in the auth_data, the user has enetered
// a different recovery key / the wrong passphrase.
if (backupPubKey !== backupInfo.auth_data.public_key) {
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console.log("backupPubKey", backupPubKey.length, backupPubKey);
throw new Error("bad backup key");
}
const sessionInfo = decryption.decrypt(
sessionResponse.session_data.ephemeral,
sessionResponse.session_data.mac,
sessionResponse.session_data.ciphertext,
);
return JSON.parse(sessionInfo);
}
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const OLM_RECOVERY_KEY_PREFIX = [0x8B, 0x01];
export async function deserializeSSSSKey(recoverykey) {
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const result = base58.decode(recoverykey.replace(/ /g, ''));
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let parity = 0;
for (const b of result) {
parity ^= b;
}
if (parity !== 0) {
throw new Error("Incorrect parity");
}
for (let i = 0; i < OLM_RECOVERY_KEY_PREFIX.length; ++i) {
if (result[i] !== OLM_RECOVERY_KEY_PREFIX[i]) {
throw new Error("Incorrect prefix");
}
}
if (
result.length !==
OLM_RECOVERY_KEY_PREFIX.length + window.Olm.PRIVATE_KEY_LENGTH + 1
) {
throw new Error("Incorrect length");
}
return Uint8Array.from(result.slice(
OLM_RECOVERY_KEY_PREFIX.length,
OLM_RECOVERY_KEY_PREFIX.length + window.Olm.PRIVATE_KEY_LENGTH,
));
}