SSL - Simple of RSA

最新推荐文章于 2025-04-14 08:53:32 发布

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#ssl #加密 #null #hex #callback #解密

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本文介绍RSA非对称加密算法的基本概念，并通过一个具体的C语言实现案例展示如何生成RSA密钥对，进行数据的加密与解密过程。此外，还提供了RSA签名和验证的相关函数说明。

RSA属于不对称加密算法

特点: 加密和解密使用完全不同又完全匹配的一对公钥和私钥

-- RSA密钥产生
RSA * RSA_generate_key(int bits, unsigned long e, void (*callback) (int,int,void *),void *cb_arg);

-- RSA加密和解密
int RSA_public_encrypt(int flen, const unsigned char *from,unsigned char *to, RSA *rsa,int padding);
int RSA_private_decrypt(int flen, const unsigned char *from,unsigned char *to, RSA *rsa,int padding);

-- RSA签名和验证
RSA签名操作是把被签署消息的散列值编码后用私钥加密
int RSA_sign(int type, const unsigned char *m, unsigned int m_length, unsigned char *sigret, unsigned int *siglen, RSA *rsa);
int RSA_verify(int type, const unsigned char *m, unsigned int m_length, unsigned char *sigbuf, unsigned int siglen, RSA *rsa);

/**
 * OPEN SSL Guide
 * http://www.openssl.org/docs/crypto//rsa.html
 */
#include <strings.h>
#include <openssl/rsa.h>
#include <openssl/err.h>
// #define RSA_F4  0x10001L/65537
#define MODULUS "C8FBCF21"
#define PUBLIC_EXPONENT RSA_F4
#define PRIVATE_EXPONENT "97B55D7D"
RSA * MY_generate_key()
{
    BIGNUM *bnn, *bne, *bnd;
    bnn = BN_new();
    bne = BN_new();
    bnd = BN_new();
    BN_hex2bn(&bnn, MODULUS);
    BN_set_word(bne, PUBLIC_EXPONENT);
    BN_hex2bn(&bnd, PRIVATE_EXPONENT);
    RSA *r = RSA_new();
    r->n = bnn;
    r->e = bne;
    r->d = bnd;
    return r;
}
int main()
{
    int ret, flen;
    unsigned char *cleartext = (unsigned char *)"text";
    unsigned char *ciphertext;
    //RSA *r = MY_generate_key();
    //RSA *r = RSA_generate_key(512,RSA_F4,NULL,NULL);
    RSA *r = RSA_generate_key(1024,RSA_F4,NULL,NULL);
    //RSA * r_public = RSAPublicKey_dup(r);
    //RSA * r_private = RSAPrivateKey_dup(r);
    flen = RSA_size(r);
    RSA_print_fp(stdout, r, flen);
    ciphertext = (unsigned char *)malloc(flen);
    bzero(ciphertext, flen);
    printf("Begin encrypt.../n");
    ret = RSA_public_encrypt(flen, cleartext, ciphertext, r,  RSA_NO_PADDING);
    if (ret < 0)
    {
        printf("Encrypt failed! ");
        return 1;
    }
    printf("Size:%d/n", ret);
    printf("ClearText :%s/n", cleartext);
    printf("CipherText:");
    for (int i=0; i<ret; i++)
    {
        printf("%02x", ciphertext[i]);
    }
    printf("/n");

printf("/nBegin decrypt.../n");
    ret = RSA_private_decrypt(flen, ciphertext, cleartext, r, RSA_NO_PADDING);
    if (ret < 0)
    {
        printf("Decrypt failed! ");
        return 1;
    }
    printf("Size:%d/n", ret);
    printf("ClearText :%s/n", cleartext);
    printf("CipherText:");
    for (int i=0; i<ret; i++)
    {
        printf("%02x", ciphertext[i]);
    }
    printf("/n");
    free(ciphertext);
    RSA_free(r);
    return 0;
}