OpenSSL对称加密算法中怎么样添加新算法

{

des_key_schedule ks1;/* key schedule */

des_key_schedule ks2;/* key schedule (for ede) */

des_key_schedule ks3;/* key schedule (for ede3) */

} des_ede;

#endif

#ifndef NO_IDEA

IDEA_KEY_SCHEDULE idea_ks;/* key schedule */

#endif

#ifndef NO_RC2

struct {

int key_bits; /* effective key bits */

RC2_KEY ks;/* key schedule */

} rc2;

#endif

#ifndef NO_RC5

struct {

int rounds; /* number of rounds */

RC5_32_KEY ks;/* key schedule */

} rc5;

#endif

#ifndef NO_BF

BF_KEY bf_ks;/* key schedule */

#endif

#ifndef NO_CAST

CAST_KEY cast_ks;/* key schedule */

#endif

} c;

};

下面的函数用来实现设定加密密钥和解密密钥。

void set_encrypt_key(const unsigned char *key, KEY_SCHEDULE *ks)

void set_decrypt_key(const unsigned char *key, KEY_SCHEDULE *ks)

在这两个函数的基础上实现EVP_CIPHER中密钥初始化函数。

static int init_key(EVP_CIPHER_CTX *ctx, const unsigned char *key,

const unsigned char *iv, int enc)

{

if(!enc)

{

if (EVP_CIPHER_CTX_mode(ctx) == EVP_CIPH_OFB_MODE) enc = 1;

else if (EVP_CIPHER_CTX_mode(ctx) == EVP_CIPH_CFB_MODE) enc = 1;

}

if (enc)

set_encrypt_key(key,&(ctx->c. ks));

else

{

set_decrypt_key(key,&(ctx->c. ks));

}

return 1;

}

/* 清除保留在内存中的密码 */

static int clean_key(EVP_CIPHER_CTX *ctx)

{

if(ctx)

memset(&(ctx-c.ks),0,sizeof(ctx->c.ks));

return 1;

}

如果加密算法结构EVP_CIPHER是通过BLOCK_CIPHER_defs宏定义的，则四种模式的算法接口必须何处理宏之后的接口一样:

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

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

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