这里不做签名，只验签
应用办法：
openssl版本：1.0.2g 其余的自行验证
编译：g++ test.cpp -o test -lssl -lcrypto -std=c++11
执行：./test
签名过程：随机数进行SHA256哈希后再应用私钥对其签名
验签过程：用随机数的SHA256和公钥来验证签名
以下代码是验证签名
#include <iostream>#include <memory>#include <string>#include <sstream>#include <stdio.h>#include <string.h>#include <openssl/ecdsa.h>#include <openssl/pem.h>#include <openssl/err.h>#include <openssl/conf.h>#include <openssl/evp.h>#include <openssl/err.h>#include <openssl/ec.h>#include <openssl/bn.h>bool verify_signature(const unsigned char* hash, const ECDSA_SIG* signature, EC_KEY* eckey){ int verify_status = ECDSA_do_verify(hash, SHA256_DIGEST_LENGTH, signature, eckey); if (1 != verify_status) { printf("Failed to verify EC Signature\n"); return false; } printf("Verifed EC Signature\n"); return true;}void SetOpensslSignature(const std::string& sSignatureInHex, ECDSA_SIG* pSign){ // std::unique_ptr< BIGNUM, std::function<void(BIGNUM*)>> rr(NULL, [](BIGNUM* b) { BN_free(b); }); // BIGNUM* r_ptr = rr.get(); // std::unique_ptr< BIGNUM, std::function<void(BIGNUM*)>> ss(NULL, [](BIGNUM* b) { BN_free(b); }); // BIGNUM* s_ptr = ss.get(); std::string sSignatureR = sSignatureInHex.substr(0, sSignatureInHex.size() / 2); std::string sSignatureS = sSignatureInHex.substr(sSignatureInHex.size() / 2); pSign->r = BN_new(); pSign->s = BN_new(); BN_hex2bn(&pSign->r, sSignatureR.c_str()); BN_hex2bn(&pSign->s, sSignatureS.c_str()); return;}bool SetOpensslPublicKey(const std::string& sPublicKeyInHex, EC_KEY* pKey){ const char* sPubKeyString = sPublicKeyInHex.c_str(); char cx[65]; std::unique_ptr< BIGNUM, std::function<void(BIGNUM*)>> gx(NULL, [](BIGNUM* b) { BN_free(b); }); std::unique_ptr< BIGNUM, std::function<void(BIGNUM*)>> gy(NULL, [](BIGNUM* b) { BN_free(b); }); BIGNUM* gx_ptr = gx.get(); BIGNUM* gy_ptr = gy.get(); EC_KEY_set_asn1_flag(pKey, OPENSSL_EC_NAMED_CURVE); memcpy(cx, sPubKeyString, 64); cx[64] = 0; if (!BN_hex2bn(&gx_ptr, cx)) { std::cout << "Error getting to binary format" << std::endl; } if (!BN_hex2bn(&gy_ptr, &sPubKeyString[64])) { std::cout << "Error getting to binary format" << std::endl; } if (!EC_KEY_set_public_key_affine_coordinates(pKey, gx_ptr, gy_ptr)) { std::cout << "setting public key attributes" << std::endl; } if (EC_KEY_check_key(pKey) == 1) { printf("EC Key valid.\n"); return true; } else { printf("EC Key Invalid!\n"); return false; }}std::string sha256(const std::string str){ unsigned char hash[SHA256_DIGEST_LENGTH]; SHA256_CTX sha256; SHA256_Init(&sha256); SHA256_Update(&sha256, str.c_str(), str.size()); SHA256_Final(hash, &sha256); std::stringstream ss; for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) { ss << hash[i]; } return ss.str();}bool Verify(const std::string& sRandomNumber, const std::string& sSignature, const std::string& sDevicePubKeyInHex){ std::unique_ptr< ECDSA_SIG, std::function<void(ECDSA_SIG*)>> zSignature(ECDSA_SIG_new(), [](ECDSA_SIG* b) { ECDSA_SIG_free(b); }); // Set up the signature... SetOpensslSignature(sSignature, zSignature.get()); std::unique_ptr< EC_KEY, std::function<void(EC_KEY*)>> zPublicKey(EC_KEY_new_by_curve_name(NID_X9_62_prime256v1), [](EC_KEY* b) { EC_KEY_free(b); }); if (!SetOpensslPublicKey(sDevicePubKeyInHex, zPublicKey.get())) std::cout << "Failed to get the public key from the hex input" << std::endl; std::string sHash = sha256(sRandomNumber); return verify_signature((const unsigned char*)sHash.c_str(), zSignature.get(), zPublicKey.get());}int main(int argc, char* argv[]){ std::string sSignatureInHex = "D506D976EC17DD3717C40329E28FD8DB4F32D6A3773454A6427FD12E69728157508086B661D91E07ADF5B57E787EA1EEA526A84500436E430E89B1C1F8532A41"; std::string sPublicKeyInHex = "94E62E0C77A2955B1FB3EE98AEAA99AACAD742F20E45B727EACDD10487C2F7D0D8257C6102921880ABE953245D573D7E33EC88A67E2BA930980CB9C3D6722F8A"; std::string sRandomNumber = "65560886818773090201885807838738706912015073749623293202319529"; if (!Verify(sRandomNumber, sSignatureInHex, sPublicKeyInHex)) std::cout << "Verification failed." << std::endl; else std::cout << "Verification succeeded" << std::endl;}