@dwn-protocol/id-sdk/src/crypto/crypto-algorithms/aes-ctr.ts

SDK for accessing the features and capabilities

import { universalTypeOf } from '../../common/index.js';

import type { IDCrypto } from '../types/iddwn-crypto.js';

import { AesCtr } from '../crypto-primitives/index.js';
import { BaseAesCtrAlgorithm, CryptoKey } from '../algorithms-api/index.js';

export class AesCtrAlgorithm extends BaseAesCtrAlgorithm {
  public async decrypt(options: {
    algorithm: IDCrypto.AesCtrOptions,
    key: IDCrypto.CryptoKey,
    data: Uint8Array
  }): Promise<Uint8Array> {
    const { algorithm, key, data } = options;

    this.checkAlgorithmOptions({ algorithm, key });
    // The secret key must be allowed to be used for 'decrypt' operations.
    this.checkKeyUsages({ keyUsages: ['decrypt'], allowedKeyUsages: key.usages });

    const plaintext = AesCtr.decrypt({
      counter : algorithm.counter,
      data    : data,
      key     : key.material,
      length  : algorithm.length
    });

    return plaintext;
  }

  public async encrypt(options: {
    algorithm: IDCrypto.AesCtrOptions,
    key: IDCrypto.CryptoKey,
    data: Uint8Array
  }): Promise<Uint8Array> {
    const { algorithm, key, data } = options;

    this.checkAlgorithmOptions({ algorithm, key });
    // The secret key must be allowed to be used for 'encrypt' operations.
    this.checkKeyUsages({ keyUsages: ['encrypt'], allowedKeyUsages: key.usages });

    const ciphertext = AesCtr.encrypt({
      counter : algorithm.counter,
      data    : data,
      key     : key.material,
      length  : algorithm.length
    });

    return ciphertext;
  }

  public async generateKey(options: {
    algorithm: IDCrypto.AesGenerateKeyOptions,
    extractable: boolean,
    keyUsages: IDCrypto.KeyUsage[]
  }): Promise<IDCrypto.CryptoKey> {
    const { algorithm, extractable, keyUsages } = options;

    this.checkGenerateKey({ algorithm, keyUsages });

    const secretKey = await AesCtr.generateKey({ length: algorithm.length });

    if (universalTypeOf(secretKey) !== 'Uint8Array') {
      throw new Error('Operation failed to generate key.');
    }

    const secretCryptoKey = new CryptoKey(algorithm, extractable, secretKey, 'secret', this.keyUsages);

    return secretCryptoKey;
  }
}