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1# 使用SM2非对称密钥加解密
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4对应的算法规格请查看[非对称密钥加解密算法规格：SM2](crypto-asym-encrypt-decrypt-spec.md#sm2)。
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7**加密**
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101. 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)，生成RSA密钥类型为SM2_256的非对称密钥对（KeyPair）。KeyPair对象中包括公钥PubKey、私钥PriKey。
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12   如何生成SM2非对称密钥对，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：SM2](crypto-asym-key-generation-conversion-spec.md#sm2)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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142. 调用[cryptoFramework.createCipher](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreatecipher)，指定字符串参数'SM2_256|SM3'，创建非对称密钥类型为SM2_256、摘要算法为SM3的Cipher实例，用于完成加解密操作。
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163. 调用[Cipher.init](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#init-1)，设置模式为加密（CryptoMode.ENCRYPT_MODE），指定加密密钥（KeyPair.PubKey），初始化加密Cipher实例。
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18   非对称密钥无加密参数，直接传入null。
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204. 调用[Cipher.doFinal](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#dofinal-1)，传入明文，获取加密后的数据。
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22   - doFinal输出结果可能为null，在访问具体数据前，需要先判断结果是否为null，避免产生异常。
23   - 当数据量较大时，可以多次调用doFinal，即[分段加解密](crypto-rsa-asym-encrypt-decrypt-by-segment.md)。
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26**解密**
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291. 由于SM2算法的Cipher实例不支持重复init操作，需要调用[cryptoFramework.createCipher](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#cryptoframeworkcreatecipher)，重新生成Cipher实例。
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312. 调用[Cipher.init](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#init-1)，设置模式为解密（CryptoMode.DECRYPT_MODE），指定解密密钥（KeyPair.PriKey）初始化解密Cipher实例。SM2无加密参数，直接传入null。
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333. 调用[Cipher.doFinal](../../reference/apis-crypto-architecture-kit/js-apis-cryptoFramework.md#dofinal-1)，传入密文，获取解密后的数据。
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35
36```ts
37import cryptoFramework from '@ohos.security.cryptoFramework';
38import buffer from '@ohos.buffer';
39
40// 加密消息
41async function encryptMessagePromise(publicKey: cryptoFramework.PubKey, plainText: cryptoFramework.DataBlob) {
42  let cipher = cryptoFramework.createCipher('SM2_256|SM3');
43  await cipher.init(cryptoFramework.CryptoMode.ENCRYPT_MODE, publicKey, null);
44  let encryptData = await cipher.doFinal(plainText);
45  return encryptData;
46}
47// 解密消息
48async function decryptMessagePromise(privateKey: cryptoFramework.PriKey, cipherText: cryptoFramework.DataBlob) {
49  let decoder = cryptoFramework.createCipher('SM2_256|SM3');
50  await decoder.init(cryptoFramework.CryptoMode.DECRYPT_MODE, privateKey, null);
51  let decryptData = await decoder.doFinal(cipherText);
52  return decryptData;
53}
54// 生成SM2密钥对
55async function genKeyPairByData(pubKeyData: Uint8Array, priKeyData: Uint8Array) {
56  let pubKeyBlob: cryptoFramework.DataBlob = { data: pubKeyData };
57  let priKeyBlob: cryptoFramework.DataBlob = { data: priKeyData };
58  let sm2Generator = cryptoFramework.createAsyKeyGenerator('SM2_256');
59  let keyPair = await sm2Generator.convertKey(pubKeyBlob, priKeyBlob);
60  console.info('convertKey success');
61  return keyPair;
62}
63async function main() {
64  let pkData = new Uint8Array([48, 89, 48, 19, 6, 7, 42, 134, 72, 206, 61, 2, 1, 6, 8, 42, 129, 28, 207, 85, 1, 130, 45, 3, 66, 0, 4, 90, 3, 58, 157, 190, 248, 76, 7, 132, 200, 151, 208, 112, 230, 96, 140, 90, 238, 211, 155, 128, 109, 248, 40, 83, 214, 78, 42, 104, 106, 55, 148, 249, 35, 61, 32, 221, 135, 143, 100, 45, 97, 194, 176, 52, 73, 136, 174, 40, 70, 70, 34, 103, 103, 161, 99, 27, 187, 13, 187, 109, 244, 13, 7]);
65  let skData = new Uint8Array([48, 49, 2, 1, 1, 4, 32, 54, 41, 239, 240, 63, 188, 134, 113, 31, 102, 149, 203, 245, 89, 15, 15, 47, 202, 170, 60, 38, 154, 28, 169, 189, 100, 251, 76, 112, 223, 156, 159, 160, 10, 6, 8, 42, 129, 28, 207, 85, 1, 130, 45]);
66  let keyPair = await genKeyPairByData(pkData, skData);
67  let pubKey = keyPair.pubKey;
68  let priKey = keyPair.priKey;
69  let message = 'This is a test';
70  // 把字符串按utf-8解码为Uint8Array
71  let plainText: cryptoFramework.DataBlob = { data: new Uint8Array(buffer.from(message, 'utf-8').buffer) };
72  let encryptText = await encryptMessagePromise(pubKey, plainText);
73  let decryptText = await decryptMessagePromise(priKey, encryptText);
74  if (plainText.data.toString() === decryptText.data.toString()) {
75    console.info('decrypt ok');
76    // 把Uint8Array按utf-8编码为字符串
77    let messageDecrypted = buffer.from(decryptText.data).toString('utf-8');
78    console.info('decrypted result string:' + messageDecrypted);
79  } else {
80    console.error('decrypt failed');
81  }
82}
83```
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