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