1.源码实现

#include

#include

#include

#include

#include

struct DSA_SIG_st {

BIGNUM *r;

BIGNUM *s;

};

//公钥验证签名

int my_verify(const char *input, int input_len, DSA_SIG *signret, const char *pub_key_fn)

{

DSA *p_dsa = NULL;

FILE *file = NULL;

int ret = 0;

if((file = fopen(pub_key_fn, "rb")) == NULL)

{

ret = -1;

return ret;

}

if((p_dsa = PEM_read_DSA_PUBKEY(file, NULL,NULL,NULL )) == NULL)

{

ret = -2;

fclose(file);

return ret;

}

fclose(file);

ret = DSA_do_verify(input, input_len, signret, p_dsa);

if(ret != 1)

{

ret = -3;

printf("DSA_verify err!\n");

DSA_free(p_dsa);

return ret;

}

printf("verify is ok!\n");

DSA_free(p_dsa);

return 0;

}

//私钥签名

int my_sign(const char *input, int input_len, const char *pri_key_fn)

{

DSA *p_dsa = NULL;

DSA_SIG *s;

FILE *file = NULL;

unsigned char *data[2];

int nid;

int signlen = 0;

int i = 0;

int ret = 0;

memset(data, 0x00, sizeof(data));

nid = 0;

file = fopen(pri_key_fn, "rb");

if(!file)

{

ret = -1;

return ret;

}

if((p_dsa = PEM_read_DSAPrivateKey(file, NULL, NULL, NULL)) == NULL)

{

ret = -2;

fclose(file);

return ret;

}

fclose(file);

s = DSA_do_sign(input, input_len, p_dsa);

if(s == NULL)

{

ret = -3;

DSA_free(p_dsa);

return ret;

}

data[0] = BN_bn2hex(s->r);

data[1] = BN_bn2hex(s->s);

DSA_free(p_dsa);

DSA_SIG_free(s);

printf("%s\n", data[0]);

printf("%s\n", data[1]);

free(data[0]);

free(data[1]);

return 0;

}

int main(int argc, char**argv)

{

char src[512+1];

char dst_str[2][512+1];

int src_len;

int ret;

FILE *f;

memset(src, 0x00, sizeof(src));

//memset(dst, 0x00, sizeof(dst));

if(argv[1][0] == 's')

{

strcpy(src, "aedewderdfercfrtvgfrtfgrtgfrtgvtrgtrvgtyebtybytbnybyuyubndrybrfgswdhyewhde");

src_len = strlen(src) ;

ret = my_sign(src, src_len, argv[2]);

if(ret)

{

fprintf(stderr, "Error\n");

}

}

else

{

DSA_SIG *s = (DSA_SIG *)malloc(sizeof(DSA_SIG));

strcpy(src, "aedewderdfercfrtvgfrtfgrtgfrtgvtrgtrvgtyebtybytbnybyuyubndrybrfgswdhyewhde");

strncpy(dst_str[0], argv[2], 512);

strncpy(dst_str[1], argv[3], 512);

src_len = strlen(src);

s->r = BN_new();

s->s = BN_new();

BN_hex2bn(&(s->r), dst_str[0]);

BN_hex2bn(&(s->s), dst_str[1]);

ret = my_verify(src, src_len, s, argv[1]);

if(ret)

{

fprintf(stderr, "Error\n");

}

BN_free(s->r);

BN_free(s->s);

free(s);

}

return 0;

}

2.编译源码

$ gcc -I$HOME/local/include -o example example.c -L$HOME/local/lib -lssl

3.生成私钥和公钥

$ openssl dsaparam -out dsa_param.pem 2048

$ openssl gendsa -out dsapri2048.pem dsa_param.pem

$ openssl dsa -in dsapri2048.pem -pubout -out dsapub2048.pem

4.运行结果

$ ./example s dsapri2048.pem

2B3BB6C33239C738AF186ADCAFB0A2704B1A4DC2

0D33CC1A97773BB607252A058E7B9F87E7B885E1

$ ./example dsapub2048.pem 2B3BB6C33239C738AF186ADCAFB0A2704B1A4DC2 0D33CC1A97773BB607252A058E7B9F87E7B885E1

verify is ok!