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Code Issues Releases Wiki Activity

hkdf crypto functions (#190)

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* hkdf crypto functions

* comment to spec
This commit is contained in:
Kyle Spearrin
2020-10-29 15:52:12 -04:00
committed by GitHub
parent 76c09641ba
commit 8cb5a9f505
6 changed files with 283 additions and 23 deletions
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27
src/services/crypto.service.ts
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@@ -182,8 +182,8 @@ export class CryptoService implements CryptoServiceAbstraction {
throw new Error('No public key available.');
}
const keyFingerprint = await this.cryptoFunctionService.hash(publicKey, 'sha256');
const userFingerprint = await this.hkdfExpand(keyFingerprint, Utils.fromUtf8ToArray(userId), 32);
return this.hashPhrase(userFingerprint.buffer);
const userFingerprint = await this.cryptoFunctionService.hkdfExpand(keyFingerprint, userId, 32, 'sha256');
return this.hashPhrase(userFingerprint);
}
@sequentialize(() => 'getOrgKeys')
@@ -679,28 +679,13 @@ export class CryptoService implements CryptoServiceAbstraction {
private async stretchKey(key: SymmetricCryptoKey): Promise<SymmetricCryptoKey> {
const newKey = new Uint8Array(64);
newKey.set(await this.hkdfExpand(key.key, Utils.fromUtf8ToArray('enc'), 32));
newKey.set(await this.hkdfExpand(key.key, Utils.fromUtf8ToArray('mac'), 32), 32);
const encKey = await this.cryptoFunctionService.hkdfExpand(key.key, 'enc', 32, 'sha256');
const macKey = await this.cryptoFunctionService.hkdfExpand(key.key, 'mac', 32, 'sha256');
newKey.set(new Uint8Array(encKey));
newKey.set(new Uint8Array(macKey), 32);
return new SymmetricCryptoKey(newKey.buffer);
}
// ref: https://tools.ietf.org/html/rfc5869
private async hkdfExpand(prk: ArrayBuffer, info: Uint8Array, size: number) {
const hashLen = 32; // sha256
const okm = new Uint8Array(size);
let previousT = new Uint8Array(0);
const n = Math.ceil(size / hashLen);
for (let i = 0; i < n; i++) {
const t = new Uint8Array(previousT.length + info.length + 1);
t.set(previousT);
t.set(info, previousT.length);
t.set([i + 1], t.length - 1);
previousT = new Uint8Array(await this.cryptoFunctionService.hmac(t.buffer, prk, 'sha256'));
okm.set(previousT, i * hashLen);
}
return okm;
}
private async hashPhrase(hash: ArrayBuffer, minimumEntropy: number = 64) {
const entropyPerWord = Math.log(EEFLongWordList.length) / Math.log(2);
let numWords = Math.ceil(minimumEntropy / entropyPerWord);