[转载]借助openssl解析ECC公钥

void GetPubKey(const char* FilePath, char*PubKey)

{

    unsignedchar Cert[4099];

    unsignedchar *pTmp =NULL;

    FILE*fp =NULL;

    fp=fopen(FilePath,“rb”);if( NULL !=fp)

    {

        X509*usrCert = NULL; //X509证书结构体，保存用户证书
        unsigned long Certlen = 0;

        Certlen=fread(Cert,1,4096,fp);

        fclose(fp);//判断是否为DER编码的用户证书，并转化为X509结构体
        pTmp =Cert;//usrCert = d2i_X509(NULL,(const unsigned char ** )&pTmp,Certlen);//if( NULL == usrCert)
{

            BIO b;/ 判断是否为PEM格式的数字证书 */b=BIO_new_file(FilePath,“r”);

            PEM_read_bio_X509(b,&usrCert, NULL, NULL);

            BIO_free(b);if(usrCert==NULL)

            {return;

            }

        }//保存证书公钥
        int derpubkeyLen = 0;

        EVP_PKEY pubKeytemp=NULL;

        pTmp=NULL;char HexKey =NULL;//获取证书公钥
        pubKeytemp =X509_get_pubkey(usrCert);if (!pubKeytemp)return;



        X509_PUBKEY*pubKeytempss;

        pubKeytempss=X509_get_X509_PUBKEY(usrCert);

        derpubkeyLen=i2d_PublicKey(pubKeytemp, NULL);if(derpubkeyLen < 1)return;



        unsignedchar* buf =NULL;

        buf= (unsigned char*)malloc(derpubkeyLen);

        i2d_PublicKey(pubKeytemp,&buf);



        EC_KEY ec_key=EVP_PKEY_get0_EC_KEY(pubKeytemp);if (!ec_key)return;int buflen = EC_KEY_key2buf(ec_key, EC_KEY_get_conv_form(ec_key),(unsigned char)&pTmp, NULL);*BIGNUM*pub_key_BIGNUM;

        pub_key_BIGNUM=BN_new();

        BN_bin2bn(pTmp, buflen, pub_key_BIGNUM);

        HexKey=BN_bn2hex(pub_key_BIGNUM);

        strcpy(PubKey,HexKey);



        EVP_PKEY_free(pubKeytemp);

        X509_free(usrCert);



    }



}