SM2算法第十五篇：ECDSA数字签名算法的C语言实现

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代码
#include <string.h>#include <stdio.h>#include <openssl/ec.h>#include <openssl/ssl.h>#include <openssl/ecdsa.h>#include <openssl/objects.h>#include <openssl/err.h> int    main(){       EC_KEY              *key1,*key2;       EC_POINT            *pubkey1,*pubkey2;       EC_GROUP            *group1,*group2;       int                 ret,nid,size,i,sig_len;       unsigned char*      signature,digest[20];       BIO                 *berr;       EC_builtin_curve    *curves;       int                 crv_len;       char                shareKey1[128],shareKey2[128];       int                 len1,len2;        /* 构造EC_KEY数据结构 */       key1=EC_KEY_new();       if(key1==NULL)       {              printf("EC_KEY_new err!\n");              return -1;       }       key2=EC_KEY_new();       if(key2==NULL)       {              printf("EC_KEY_new err!\n");              return -1;       }       /* 获取实现的椭圆曲线个数 */       crv_len = EC_get_builtin_curves(NULL, 0);       curves = (EC_builtin_curve *)malloc(sizeof(EC_builtin_curve) * crv_len);       /* 获取椭圆曲线列表 */       EC_get_builtin_curves(curves, crv_len);       /*        nid=curves[0].nid;会有错误，原因是密钥太短       */       /* 选取一种椭圆曲线 */       nid=curves[25].nid;       /* 根据选择的椭圆曲线生成密钥参数group */       group1=EC_GROUP_new_by_curve_name(nid);       if(group1==NULL)       {              printf("EC_GROUP_new_by_curve_name err!\n");              return -1;       }       group2=EC_GROUP_new_by_curve_name(nid);       if(group1==NULL)       {              printf("EC_GROUP_new_by_curve_name err!\n");              return -1;       }       /* 设置密钥参数 */       ret=EC_KEY_set_group(key1,group1);       if(ret!=1)       {              printf("EC_KEY_set_group err.\n");              return -1;       }       ret=EC_KEY_set_group(key2,group2);       if(ret!=1)       {              printf("EC_KEY_set_group err.\n");              return -1;       }       /* 生成密钥 */       ret=EC_KEY_generate_key(key1);       if(ret!=1)       {              printf("EC_KEY_generate_key err.\n");              return -1;       }       ret=EC_KEY_generate_key(key2);       if(ret!=1)       {              printf("EC_KEY_generate_key err.\n");              return -1;       }       /* 检查密钥 */       ret=EC_KEY_check_key(key1);       if(ret!=1)       {              printf("check key err.\n");              return -1;       }       /* 获取密钥大小 */       size=ECDSA_size(key1);       printf("size %d \n",size);       for(i=0;i<20;i++)              memset(&digest[i],i+1,1);       signature=(unsigned char *)malloc(size);       ERR_load_crypto_strings();       berr=BIO_new(BIO_s_file());       BIO_set_fp(berr,stdout,BIO_NOCLOSE);       /* 签名数据，本例未做摘要，可将digest中的数据看作是sha1摘要结果 */       ret=ECDSA_sign(0,digest,20,signature,(unsigned int *)&sig_len,key1);       if(ret!=1)       {              ERR_print_errors(berr);              printf("sign err!\n");              return -1;       }       /* 验证签名 */       ret=ECDSA_verify(0,digest,20,signature,sig_len,key1);       if(ret!=1)       {              ERR_print_errors(berr);              printf("ECDSA_verify err!\n");              return -1;       }       /* 获取对方公钥，不能直接引用 */       pubkey2 = (struct ec_point_st *)EC_KEY_get0_public_key(key2);       /* 生成一方的共享密钥 */       len1=ECDH_compute_key(shareKey1, 128, pubkey2, key1, NULL);       pubkey1 = (struct ec_point_st *)EC_KEY_get0_public_key(key1);       /* 生成另一方共享密钥 */       len2=ECDH_compute_key(shareKey2, 128, pubkey1, key2, NULL);       if(len1!=len2)       {              printf("err\n");       }       else       {              ret=memcmp(shareKey1,shareKey2,len1);              if(ret==0)                     printf("生成共享密钥成功\n");              else                     printf("生成共享密钥失败\n");       }       printf("test ok!\n");       BIO_free(berr);       EC_KEY_free(key1);       EC_KEY_free(key2);       free(signature);       free(curves);       return 0;}
运行结果
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