| 1 | import { modPow, bigIntToU8Array, u8ArrayToBigInt } from "./bigint.js"; |
| 2 | |
| 3 | class DHPublicKey { |
| 4 | constructor(key) { |
| 5 | this._key = key; |
| 6 | } |
| 7 | |
| 8 | get algorithm() { |
| 9 | return { name: "DH" }; |
| 10 | } |
| 11 | |
| 12 | exportKey() { |
| 13 | return this._key; |
| 14 | } |
| 15 | } |
| 16 | |
| 17 | export class DHCipher { |
| 18 | constructor() { |
| 19 | this._g = null; |
| 20 | this._p = null; |
| 21 | this._gBigInt = null; |
| 22 | this._pBigInt = null; |
| 23 | this._privateKey = null; |
| 24 | } |
| 25 | |
| 26 | get algorithm() { |
| 27 | return { name: "DH" }; |
| 28 | } |
| 29 | |
| 30 | static generateKey(algorithm, _extractable) { |
| 31 | const cipher = new DHCipher; |
| 32 | cipher._generateKey(algorithm); |
| 33 | return { privateKey: cipher, publicKey: new DHPublicKey(cipher._publicKey) }; |
| 34 | } |
| 35 | |
| 36 | _generateKey(algorithm) { |
| 37 | const g = algorithm.g; |
| 38 | const p = algorithm.p; |
| 39 | this._keyBytes = p.length; |
| 40 | this._gBigInt = u8ArrayToBigInt(g); |
| 41 | this._pBigInt = u8ArrayToBigInt(p); |
| 42 | this._privateKey = window.crypto.getRandomValues(new Uint8Array(this._keyBytes)); |
| 43 | this._privateKeyBigInt = u8ArrayToBigInt(this._privateKey); |
| 44 | this._publicKey = bigIntToU8Array(modPow( |
| 45 | this._gBigInt, this._privateKeyBigInt, this._pBigInt), this._keyBytes); |
| 46 | } |
| 47 | |
| 48 | deriveBits(algorithm, length) { |
| 49 | const bytes = Math.ceil(length / 8); |
| 50 | const pkey = new Uint8Array(algorithm.public); |
| 51 | const len = bytes > this._keyBytes ? bytes : this._keyBytes; |
| 52 | const secret = modPow(u8ArrayToBigInt(pkey), this._privateKeyBigInt, this._pBigInt); |
| 53 | return bigIntToU8Array(secret, len).slice(0, len); |
| 54 | } |
| 55 | } |