openssl关于RSA算法

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rsa为非对称算法，加密和解密的密钥是不同的，一个密钥进行加密，另一个密钥进行解密。这个过程是相互的，用私钥加密，公钥解密，被称为签名。用公钥加密，用私钥解密，就是通常说的加密。

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/time.h>#include <openssl/rsa.h>#include <openssl/pem.h>#include <openssl/err.h>#define OPENSSLKEY "test.key"#define PUBLICKEY "test_pub.key"#define BUFFSIZE 1024char* STR = "abcdefghigklm";char* my_encrypt(char *str,char *path_key);//加密char* my_decrypt(char *str,char *path_key);//解密long get_mesl() {    struct timeval tv;    gettimeofday(&tv,NULL);    return tv.tv_sec*1000 + tv.tv_usec/1000;}long get_trick() {    struct timeval tv;    gettimeofday(&tv,NULL);    return tv.tv_sec*1000000 + tv.tv_usec;}int main(void){    char *source = STR;     char *ptr_en,*ptr_de;    printf("source is:%s, len:%d\n",source, strlen(source));    long start = get_trick();    ptr_en=my_encrypt(source,PUBLICKEY);    long spend = get_trick() - start;    printf("spend:%ld\n", spend);    printf("after encrypt len:%d\n", strlen(ptr_en));    start = get_trick();    ptr_de=my_decrypt(ptr_en,OPENSSLKEY);    spend = get_trick() - start;    printf("spend:%ld\n", spend);    printf("after decrypt:%s, len:%d\n",ptr_de, strlen(ptr_de));    if(ptr_en!=NULL){        free(ptr_en);    }       if(ptr_de!=NULL){        free(ptr_de);    }       return 0;}char *my_encrypt(char *str,char *path_key){    char *p_en;    RSA *p_rsa;    FILE *file;    int flen,rsa_len;    if((file=fopen(path_key,"r"))==NULL){        perror("open key file error");        return NULL;        }       if((p_rsa=PEM_read_RSA_PUBKEY(file,NULL,NULL,NULL))==NULL){        ERR_print_errors_fp(stdout);        return NULL;    }       flen=strlen(str);    rsa_len=RSA_size(p_rsa);    p_en=(unsigned char *)malloc(rsa_len+1);    memset(p_en,0,rsa_len+1);    if(RSA_public_encrypt(rsa_len,(unsigned char *)str,(unsigned char*)p_en,p_rsa,RSA_NO_PADDING)<0){        return NULL;    }    RSA_free(p_rsa);    fclose(file);    return p_en;}char *my_decrypt(char *str,char *path_key){    char *p_de;    RSA *p_rsa;    FILE *file;    int rsa_len;    if((file=fopen(path_key,"r"))==NULL){        perror("open key file error");        return NULL;    }    if((p_rsa=PEM_read_RSAPrivateKey(file,NULL,NULL,NULL))==NULL){        ERR_print_errors_fp(stdout);        return NULL;    }    rsa_len=RSA_size(p_rsa);    p_de=(unsigned char *)malloc(rsa_len+1);    memset(p_de,0,rsa_len+1);    if(RSA_private_decrypt(rsa_len,(unsigned char *)str,(unsigned char*)p_de,p_rsa,RSA_NO_PADDING)<0){        return NULL;    }    RSA_free(p_rsa);    fclose(file);    return p_de;}

测算的数据显示无论加密还是解密都耗时了1000微妙以上，详细数据调用指令也可以，openssl speed rsa ，这指令的输出很直观，不再赘述。

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