Files
frontend/src/utils/crypto_polyfill.ts
2026-02-01 21:13:15 -08:00

136 lines
4.0 KiB
TypeScript

import * as ExpoCrypto from 'expo-crypto';
import { Buffer } from 'buffer';
import { pbkdf2 as noblePbkdf2 } from '@noble/hashes/pbkdf2';
import { sha1 } from '@noble/hashes/sha1';
import { sha256 } from '@noble/hashes/sha256';
import { sha512 } from '@noble/hashes/sha512';
import { gcm } from '@noble/ciphers/aes';
/**
* Node.js Crypto Polyfill for React Native
*/
export function randomBytes(size: number): Buffer {
const bytes = new Uint8Array(size);
ExpoCrypto.getRandomValues(bytes);
return Buffer.from(bytes);
}
const hashMap: Record<string, any> = {
sha1,
sha256,
sha512,
};
export function pbkdf2(
password: string | Buffer,
salt: string | Buffer,
iterations: number,
keylen: number,
digest: string,
callback: (err: Error | null, derivedKey: Buffer) => void
): void {
try {
const passwordBytes = typeof password === 'string' ? Buffer.from(password) : password;
const saltBytes = typeof salt === 'string' ? Buffer.from(salt) : salt;
const hasher = hashMap[digest.toLowerCase()];
if (!hasher) {
throw new Error(`Unsupported digest: ${digest}`);
}
const result = noblePbkdf2(hasher, passwordBytes, saltBytes, {
c: iterations,
dkLen: keylen,
});
callback(null, Buffer.from(result));
} catch (err) {
callback(err as Error, Buffer.alloc(0));
}
}
// AES-GCM Implementation
class Cipher {
private key: Uint8Array;
private iv: Uint8Array;
private authTag: Buffer | null = null;
private aesGcm: any;
private buffer: Buffer = Buffer.alloc(0);
constructor(key: Buffer, iv: Buffer) {
this.key = new Uint8Array(key);
this.iv = new Uint8Array(iv);
// @noble/ciphers/aes gcm takes (key, nonce)
this.aesGcm = gcm(this.key, this.iv);
}
update(data: string | Buffer, inputEncoding?: string): Buffer {
const input = typeof data === 'string' ? Buffer.from(data, inputEncoding as any) : data;
this.buffer = Buffer.concat([this.buffer, input]);
return Buffer.alloc(0);
}
final(): Buffer {
const result = this.aesGcm.encrypt(this.buffer);
// @noble/ciphers returns ciphertext + tag (16 bytes)
const tag = result.slice(-16);
const ciphertext = result.slice(0, -16);
this.authTag = Buffer.from(tag);
return Buffer.from(ciphertext);
}
getAuthTag(): Buffer {
if (!this.authTag) throw new Error('Ciphers: TAG not available before final()');
return this.authTag;
}
}
class Decipher {
private key: Uint8Array;
private iv: Uint8Array;
private tag: Uint8Array | null = null;
private aesGcm: any;
private buffer: Buffer = Buffer.alloc(0);
constructor(key: Buffer, iv: Buffer) {
this.key = new Uint8Array(key);
this.iv = new Uint8Array(iv);
this.aesGcm = gcm(this.key, this.iv);
}
setAuthTag(tag: Buffer): void {
this.tag = new Uint8Array(tag);
}
update(data: Buffer): Buffer {
this.buffer = Buffer.concat([this.buffer, data]);
return Buffer.alloc(0);
}
final(): Buffer {
if (!this.tag) throw new Error('Decipher: Auth tag not set');
// @noble/ciphers expects ciphertext then tag
const full = new Uint8Array(this.buffer.length + this.tag.length);
full.set(this.buffer);
full.set(this.tag, this.buffer.length);
const decrypted = this.aesGcm.decrypt(full);
return Buffer.from(decrypted);
}
}
export function createCipheriv(algorithm: string, key: Buffer, iv: Buffer): Cipher {
if (algorithm !== 'aes-256-gcm') {
throw new Error(`Polyfill only supports aes-256-gcm, got ${algorithm}`);
}
return new Cipher(key, iv);
}
export function createDecipheriv(algorithm: string, key: Buffer, iv: Buffer): Decipher {
if (algorithm !== 'aes-256-gcm') {
throw new Error(`Polyfill only supports aes-256-gcm, got ${algorithm}`);
}
return new Decipher(key, iv);
}