1# 使用X25519进行密钥协商(C/C++) 2 3<!--Kit: Crypto Architecture Kit--> 4<!--Subsystem: Security--> 5<!--Owner: @zxz--3--> 6<!--Designer: @lanming--> 7<!--Tester: @PAFT--> 8<!--Adviser: @zengyawen--> 9 10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)。 11 12## 开发步骤 13 141. 调用[OH_CryptoAsymKeyGenerator_Create](../../reference/apis-crypto-architecture-kit/capi-crypto-asym-key-h.md#oh_cryptoasymkeygenerator_create)、[OH_CryptoAsymKeyGenerator_Generate](../../reference/apis-crypto-architecture-kit/capi-crypto-asym-key-h.md#oh_cryptoasymkeygenerator_generate)、[OH_CryptoAsymKeyGenerator_Convert](../../reference/apis-crypto-architecture-kit/capi-crypto-asym-key-h.md#oh_cryptoasymkeygenerator_convert)生成密钥算法为X25519的非对称密钥（keyPair）。 15 16 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-ndk.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。 17 182. 调用[OH_CryptoKeyAgreement_Create](../../reference/apis-crypto-architecture-kit/capi-crypto-key-agreement-h.md#oh_cryptokeyagreement_create)，指定字符串参数'X25519'，创建密钥算法为X25519的密钥协议生成器。 19 203. 调用[OH_CryptoKeyAgreement_GenerateSecret](../../reference/apis-crypto-architecture-kit/capi-crypto-key-agreement-h.md#oh_cryptokeyagreement_generatesecret)，基于传入的私钥（keyPair.priKey）与公钥（keyPair.pubKey）进行密钥协商，返回共享秘钥。 21 22```C++ 23#include "CryptoArchitectureKit/crypto_architecture_kit.h" 24#include "CryptoArchitectureKit/crypto_key_agreement.h" 25#include <stdio.h> 26#include <cstring> 27 28static OH_Crypto_ErrCode doTestX25519KeyAgreement() 29{ 30 uint8_t pubKeyArray[] = {48, 42, 48, 5, 6, 3, 43, 101, 110, 3, 33, 0, 36, 98, 216, 106, 74, 99, 179, 203, 81, 145, 31 147, 101, 139, 57, 74, 225, 119, 196, 207, 0, 50, 232, 93, 147, 188, 21, 225, 228, 54, 251, 32 230, 52}; 33 uint8_t priKeyArray[] = {48, 46, 2, 1, 0, 48, 5, 6, 3, 43, 101, 110, 4, 34, 4, 32, 112, 65, 156, 73, 65, 89, 183, 34 39, 119, 229, 110, 12, 192, 237, 186, 153, 21, 122, 28, 176, 248, 108, 22, 242, 239, 179, 35 106, 175, 85, 65, 214, 90}; 36 // 创建X25519密钥生成器。 37 OH_CryptoAsymKeyGenerator *x25519Gen = nullptr; 38 OH_Crypto_ErrCode ret = OH_CryptoAsymKeyGenerator_Create("X25519", &x25519Gen); 39 if (ret != CRYPTO_SUCCESS) { 40 return ret; 41 } 42 43 // 外部传入的公私钥对A。 44 Crypto_DataBlob pubKeyBlob = {pubKeyArray, sizeof(pubKeyArray)}; 45 Crypto_DataBlob priKeyBlob = {priKeyArray, sizeof(priKeyArray)}; 46 OH_CryptoKeyPair *keyPairA = nullptr; 47 ret = OH_CryptoAsymKeyGenerator_Convert(x25519Gen, CRYPTO_DER, &pubKeyBlob, &priKeyBlob, &keyPairA); 48 if (ret != CRYPTO_SUCCESS) { 49 OH_CryptoAsymKeyGenerator_Destroy(x25519Gen); 50 return ret; 51 } 52 53 // 内部生成的公私钥对B。 54 OH_CryptoKeyPair *keyPairB = nullptr; 55 ret = OH_CryptoAsymKeyGenerator_Generate(x25519Gen, &keyPairB); 56 if (ret != CRYPTO_SUCCESS) { 57 OH_CryptoKeyPair_Destroy(keyPairA); 58 OH_CryptoAsymKeyGenerator_Destroy(x25519Gen); 59 return ret; 60 } 61 62 // 创建密钥协议生成器。 63 OH_CryptoKeyAgreement *x25519KeyAgreement = nullptr; 64 ret = OH_CryptoKeyAgreement_Create("X25519", &x25519KeyAgreement); 65 if (ret != CRYPTO_SUCCESS) { 66 OH_CryptoKeyPair_Destroy(keyPairA); 67 OH_CryptoKeyPair_Destroy(keyPairB); 68 OH_CryptoAsymKeyGenerator_Destroy(x25519Gen); 69 return ret; 70 } 71 72 // 使用A的公钥和B的私钥进行密钥协商。 73 OH_CryptoPrivKey *privKeyB = OH_CryptoKeyPair_GetPrivKey(keyPairB); 74 OH_CryptoPubKey *pubKeyA = OH_CryptoKeyPair_GetPubKey(keyPairA); 75 Crypto_DataBlob secret1 = {0}; 76 ret = OH_CryptoKeyAgreement_GenerateSecret(x25519KeyAgreement, privKeyB, pubKeyA, &secret1); 77 if (ret != CRYPTO_SUCCESS) { 78 OH_CryptoKeyAgreement_Destroy(x25519KeyAgreement); 79 OH_CryptoKeyPair_Destroy(keyPairA); 80 OH_CryptoKeyPair_Destroy(keyPairB); 81 OH_CryptoAsymKeyGenerator_Destroy(x25519Gen); 82 return ret; 83 } 84 85 // 使用A的私钥和B的公钥进行密钥协商。 86 OH_CryptoPrivKey *privKeyA = OH_CryptoKeyPair_GetPrivKey(keyPairA); 87 OH_CryptoPubKey *pubKeyB = OH_CryptoKeyPair_GetPubKey(keyPairB); 88 Crypto_DataBlob secret2 = {0}; 89 ret = OH_CryptoKeyAgreement_GenerateSecret(x25519KeyAgreement, privKeyA, pubKeyB, &secret2); 90 if (ret != CRYPTO_SUCCESS) { 91 OH_Crypto_FreeDataBlob(&secret1); 92 OH_CryptoKeyAgreement_Destroy(x25519KeyAgreement); 93 OH_CryptoKeyPair_Destroy(keyPairA); 94 OH_CryptoKeyPair_Destroy(keyPairB); 95 OH_CryptoAsymKeyGenerator_Destroy(x25519Gen); 96 return ret; 97 } 98 99 // 比较两次协商的结果。 100 if ((secret1.len == secret2.len) && (memcmp(secret1.data, secret2.data, secret1.len) == 0)) { 101 printf("x25519 success\n"); 102 } else { 103 printf("x25519 result is not equal\n"); 104 ret = CRYPTO_OPERTION_ERROR; 105 } 106 107 // 清理资源。 108 OH_Crypto_FreeDataBlob(&secret1); 109 OH_Crypto_FreeDataBlob(&secret2); 110 OH_CryptoKeyAgreement_Destroy(x25519KeyAgreement); 111 OH_CryptoKeyPair_Destroy(keyPairA); 112 OH_CryptoKeyPair_Destroy(keyPairB); 113 OH_CryptoAsymKeyGenerator_Destroy(x25519Gen); 114 return ret; 115} 116``` 117