1# 使用X25519进行密钥协商
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4对应的算法规格请查看[密钥协商算法规格：X25519](crypto-key-agreement-overview.md#x25519)。
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6
7## 开发步骤
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91. 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X25519的非对称密钥（KeyPair）。
10   如何生成X25519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：X25519](crypto-asym-key-generation-conversion-spec.md#x25519)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。
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122. 调用[cryptoFramework.createKeyAgreement](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreatekeyagreement)，指定字符串参数'X25519'，创建密钥算法为X25519的密钥协议生成器（KeyAgreement）。
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143. 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。
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16- 以使用await方式，完成密钥协商为例：
17
18  ```ts
19  import { cryptoFramework } from '@kit.CryptoArchitectureKit';
20
21  async function x25519Await() {
22    // 假设此公私钥对数据为外部传入
23    let pubKeyArray = new Uint8Array([48, 42, 48, 5, 6, 3, 43, 101, 110, 3, 33, 0, 36, 98, 216, 106, 74, 99, 179, 203, 81, 145, 147, 101, 139, 57, 74, 225, 119, 196, 207, 0, 50, 232, 93, 147, 188, 21, 225, 228, 54, 251, 230, 52]);
24    let priKeyArray = new Uint8Array([48, 46, 2, 1, 0, 48, 5, 6, 3, 43, 101, 110, 4, 34, 4, 32, 112, 65, 156, 73, 65, 89, 183, 39, 119, 229, 110, 12, 192, 237, 186, 153, 21, 122, 28, 176, 248, 108, 22, 242, 239, 179, 106, 175, 85, 65, 214, 90]);
25    let keyGen = cryptoFramework.createAsyKeyGenerator('X25519');
26    // 外部传入的公私钥对A
27    let keyPairA = await keyGen.convertKey({ data: pubKeyArray }, { data: priKeyArray });
28    // 内部生成的公私钥对B
29    let keyPairB = await keyGen.generateKeyPair();
30    let keyAgreement = cryptoFramework.createKeyAgreement('X25519');
31    // 使用A的公钥和B的私钥进行密钥协商
32    let secret1 = await keyAgreement.generateSecret(keyPairB.priKey, keyPairA.pubKey);
33    // 使用A的私钥和B的公钥进行密钥协商
34    let secret2 = await keyAgreement.generateSecret(keyPairA.priKey, keyPairB.pubKey);
35    // 两种协商的结果应当一致
36    if (secret1.data.toString() == secret2.data.toString()) {
37      console.info('x25519 success');
38      console.info('x25519 output is ' + secret1.data);
39    } else {
40      console.error('x25519 result is not equal');
41    }
42  }
43  ```
44
45- 同步方法示例：
46
47  ```ts
48  import { cryptoFramework } from '@kit.CryptoArchitectureKit';
49
50  function x25519Await() {
51    // 假设此公私钥对数据为外部传入
52    let pubKeyArray = new Uint8Array([48, 42, 48, 5, 6, 3, 43, 101, 110, 3, 33, 0, 36, 98, 216, 106, 74, 99, 179, 203, 81, 145, 147, 101, 139, 57, 74, 225, 119, 196, 207, 0, 50, 232, 93, 147, 188, 21, 225, 228, 54, 251, 230, 52]);
53    let priKeyArray = new Uint8Array([48, 46, 2, 1, 0, 48, 5, 6, 3, 43, 101, 110, 4, 34, 4, 32, 112, 65, 156, 73, 65, 89, 183, 39, 119, 229, 110, 12, 192, 237, 186, 153, 21, 122, 28, 176, 248, 108, 22, 242, 239, 179, 106, 175, 85, 65, 214, 90]);
54    let keyGen = cryptoFramework.createAsyKeyGenerator('X25519');
55    // 外部传入的公私钥对A
56    let keyPairA = keyGen.convertKeySync({ data: pubKeyArray }, { data: priKeyArray });
57    // 内部生成的公私钥对B
58    let keyPairB = keyGen.generateKeyPairSync();
59    let keyAgreement = cryptoFramework.createKeyAgreement('X25519');
60    // 使用A的公钥和B的私钥进行密钥协商
61    let secret1 = keyAgreement.generateSecretSync(keyPairB.priKey, keyPairA.pubKey);
62    // 使用A的私钥和B的公钥进行密钥协商
63    let secret2 = keyAgreement.generateSecretSync(keyPairA.priKey, keyPairB.pubKey);
64    // 两种协商的结果应当一致
65    if (secret1.data.toString() == secret2.data.toString()) {
66      console.info('x25519 success');
67      console.info('x25519 output is ' + secret1.data);
68    } else {
69      console.error('x25519 result is not equal');
70    }
71  }
72  ```
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