在OpenSSL中添加自定义加密算法

一、简介

本文以添加自定义算法EVP_ssf33为例，介绍在OpenSSL中添加自定义加密算法的方法

二、步骤

1、修改crypto/object/objects.txt，注册算法OID，如下：

rsadsi 3 255    : SSF33     : ssf33

2、进入目录：crypto/object/，执行如下命令，生成算法的声明

perl objects.pl objects.txt obj_mac.num obj_mac.h

3、在crypto/evp/下添加e_ssf33.c，内容如下

#include <stdio.h>
#include "cryptlib.h"
#ifndef OPENSSL_NO_RC4
    #include <openssl/evp.h>
    #include <openssl/objects.h>
    #include <openssl/rc4.h>

    /* FIXME: surely this is available elsewhere? */
    #define EVP_SSF33_KEY_SIZE      16

    typedef struct
    {
        RC4_KEY ks; /* working key */
    } EVP_SSF33_KEY;

    #define data(ctx) ((EVP_SSF33_KEY *)(ctx)->cipher_data)

    static int ssf33_init_key(EVP_CIPHER_CTX *ctx, const unsigned char *key, const unsigned char *iv,int enc);

    static int ssf33_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out, const unsigned char *in, unsigned int inl);

    static const EVP_CIPHER ssf33_evp_cipher=
    {
        NID_ssf33,
        1,
        EVP_SSF33_KEY_SIZE,
        0,
        EVP_CIPH_VARIABLE_LENGTH,
        ssf33_init_key,
        ssf33_cipher,
        NULL,
        sizeof(EVP_SSF33_KEY),
        NULL,
        NULL,
        NULL,
        NULL
    };

    const EVP_CIPHER *EVP_ssf33(void)
    {
        return(&ssf33_evp_cipher);
    }

    static int ssf33_init_key(EVP_CIPHER_CTX *ctx, const unsigned char *key, const unsigned char *iv, int enc)
    {
        RC4_set_key(&data(ctx)->ks,EVP_CIPHER_CTX_key_length(ctx), key);

        return 1;
    }

    static int ssf33_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out, const unsigned char *in, unsigned int inl)
    {
        RC4(&data(ctx)->ks,inl,in,out);

        return 1;
    }

#endif

4、修改crypto/evp/evp.h，添加对算法的声明，如下

const EVP_CIPHER *EVP_ssf33(void);

5、修改crypto/evp/c_allc.c，在OpenSSL_add_all_ciphers函数中使用EVP_add_cipher注册加密函数，如下

EVP_add_cipher(EVP_ssf33());

6、修改crypto/evp/Makefile，如下

7、完成

参考：http://blog.csdn.net/force_eagle/article/details/794856