# 使用ECDH进行密钥协商


对应的算法规格请查看[密钥协商算法规格：ECDH](crypto-key-agreement-overview.md#ecdh)。


## 开发步骤

1. 调用[cryptoFramework.createAsyKeyGenerator](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreateasykeygenerator)、[AsyKeyGenerator.generateKeyPair](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#generatekeypair-1)、[AsyKeyGenerator.convertKey](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#convertkey-3)生成密钥算法为ECC、密钥长度为256位的非对称密钥（KeyPair）。
   
   如何生成ECC非对称密钥，开发者可参考下文示例，并结合[非对称密钥生成和转换规格：ECC](crypto-asym-key-generation-conversion-spec.md#ecc)和[随机生成非对称密钥对](crypto-generate-asym-key-pair-randomly.md)理解，参考文档与当前示例可能存在入参差异，请在阅读时注意区分。

2. 调用[cryptoFramework.createKeyAgreement](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreatekeyagreement)，指定字符串参数'ECC256'，创建密钥算法为ECC、密钥长度为256位的密钥协议生成器（KeyAgreement）。

3. 调用[KeyAgreement.generateSecret](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#generatesecret-1)，基于传入的私钥（KeyPair.priKey）与公钥（KeyPair.pubKey）进行密钥协商，返回共享秘密。

- 以使用await方式，完成密钥协商为例：

  ```ts
  import { cryptoFramework } from '@kit.CryptoArchitectureKit';

  async function ecdhAwait() {
    // 假设此公私钥对数据为外部传入
    let pubKeyArray = new Uint8Array([48, 89, 48, 19, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 8, 42, 134, 72, 206, 61, 3, 1, 7, 3, 66, 0, 4, 83, 96, 142, 9, 86, 214, 126, 106, 247, 233, 92, 125, 4, 128, 138, 105, 246, 162, 215, 71, 81, 58, 202, 121, 26, 105, 211, 55, 130, 45, 236, 143, 55, 16, 248, 75, 167, 160, 167, 106, 2, 152, 243, 44, 68, 66, 0, 167, 99, 92, 235, 215, 159, 239, 28, 106, 124, 171, 34, 145, 124, 174, 57, 92]);
    let priKeyArray = new Uint8Array([48, 49, 2, 1, 1, 4, 32, 115, 56, 137, 35, 207, 0, 60, 191, 90, 61, 136, 105, 210, 16, 27, 4, 171, 57, 10, 61, 123, 40, 189, 28, 34, 207, 236, 22, 45, 223, 10, 189, 160, 10, 6, 8, 42, 134, 72, 206, 61, 3, 1, 7]);
    let eccGen = cryptoFramework.createAsyKeyGenerator('ECC256');
    // 外部传入的公私钥对A
    let keyPairA = await eccGen.convertKey({ data: pubKeyArray }, { data: priKeyArray });
    // 内部生成的公私钥对B
    let keyPairB = await eccGen.generateKeyPair();
    let eccKeyAgreement = cryptoFramework.createKeyAgreement('ECC256');
    // 使用A的公钥和B的私钥进行密钥协商
    let secret1 = await eccKeyAgreement.generateSecret(keyPairB.priKey, keyPairA.pubKey);
    // 使用A的私钥和B的公钥进行密钥协商
    let secret2 = await eccKeyAgreement.generateSecret(keyPairA.priKey, keyPairB.pubKey);
    // 两种协商的结果应当一致
    if (secret1.data.toString() == secret2.data.toString()) {
      console.info('ecdh success');
      console.info('ecdh output is ' + secret1.data);
    } else {
      console.error('ecdh result is not equal');
    }
  }
  ```

- 同步方法示例：

  ```ts
  import { cryptoFramework } from '@kit.CryptoArchitectureKit';

  function ecdhAwait() {
    // 假设此公私钥对数据为外部传入
    let pubKeyArray = new Uint8Array([48, 89, 48, 19, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 8, 42, 134, 72, 206, 61, 3, 1, 7, 3, 66, 0, 4, 83, 96, 142, 9, 86, 214, 126, 106, 247, 233, 92, 125, 4, 128, 138, 105, 246, 162, 215, 71, 81, 58, 202, 121, 26, 105, 211, 55, 130, 45, 236, 143, 55, 16, 248, 75, 167, 160, 167, 106, 2, 152, 243, 44, 68, 66, 0, 167, 99, 92, 235, 215, 159, 239, 28, 106, 124, 171, 34, 145, 124, 174, 57, 92]);
    let priKeyArray = new Uint8Array([48, 49, 2, 1, 1, 4, 32, 115, 56, 137, 35, 207, 0, 60, 191, 90, 61, 136, 105, 210, 16, 27, 4, 171, 57, 10, 61, 123, 40, 189, 28, 34, 207, 236, 22, 45, 223, 10, 189, 160, 10, 6, 8, 42, 134, 72, 206, 61, 3, 1, 7]);
    let eccGen = cryptoFramework.createAsyKeyGenerator('ECC256');
    // 外部传入的公私钥对A
    let keyPairA = eccGen.convertKeySync({ data: pubKeyArray }, { data: priKeyArray });
    // 内部生成的公私钥对B
    let keyPairB = eccGen.generateKeyPairSync();
    let eccKeyAgreement = cryptoFramework.createKeyAgreement('ECC256');
    // 使用A的公钥和B的私钥进行密钥协商
    let secret1 = eccKeyAgreement.generateSecretSync(keyPairB.priKey, keyPairA.pubKey);
    // 使用A的私钥和B的公钥进行密钥协商
    let secret2 = eccKeyAgreement.generateSecretSync(keyPairA.priKey, keyPairB.pubKey);
    // 两种协商的结果应当一致
    if (secret1.data.toString() == secret2.data.toString()) {
      console.info('ecdh success');
      console.info('ecdh output is ' + secret1.data);
    } else {
      console.error('ecdh result is not equal');
    }
  }
  ```