#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/des.h>
/************************************************************************
** 本例采用：
** 3des-ecb加密方式；
** 24位密钥，不足24位的右补0x00；
** 加密内容8位补齐，补齐方式为：少1位补一个0x01,少2位补两个0x02,...
** 本身已8位对齐的，后面补八个0x08。
************************************************************************/
int main(void)
{ int docontinue = 1; char *data = "hello world!"; /* 明文 */ int data_len; int data_rest; unsigned char ch; unsigned char *src = NULL; /* 补齐后的明文 */ unsigned char *dst = NULL; /* 解密后的明文 */ int len; unsigned char tmp[8]; unsigned char in[8]; unsigned char out[8]; char *k = "01234567899876543210"; /* 原始密钥 */ int key_len; #define LEN_OF_KEY 24 unsigned char key[LEN_OF_KEY]; /* 补齐后的密钥 */ unsigned char block_key[9]; DES_key_schedule ks,ks2,ks3; /* 构造补齐后的密钥 */ key_len = strlen(k); memcpy(key, k, key_len); memset(key + key_len, 0x00, LEN_OF_KEY - key_len); /* 分析补齐明文所需空间及补齐填充数据 */ data_len = strlen(data); data_rest = data_len % 8; len = data_len + (8 - data_rest); ch = 8 - data_rest; src = (unsigned char *)malloc(len); dst = (unsigned char *)malloc(len); if (NULL == src || NULL == dst) { docontinue = 0; } if (docontinue) { int count; int i; /* 构造补齐后的加密内容 */ memset(src, 0, len); memcpy(src, data, data_len); memset(src + data_len, ch, 8 - data_rest); /* 密钥置换 */ memset(block_key, 0, sizeof(block_key)); memcpy(block_key, key + 0, 8); DES_set_key_unchecked((const_DES_cblock*)block_key, &ks); memcpy(block_key, key + 8, 8); DES_set_key_unchecked((const_DES_cblock*)block_key, &ks2); memcpy(block_key, key + 16, 8); DES_set_key_unchecked((const_DES_cblock*)block_key, &ks3); printf("before encrypt:\n"); for (i = 0; i < len; i++) { printf("0x%.2X ", *(src + i)); } printf("\n"); /* 循环加密/解密，每8字节一次 */ count = len / 8; for (i = 0; i < count; i++) { memset(tmp, 0, 8); memset(in, 0, 8); memset(out, 0, 8); memcpy(tmp, src + 8 * i, 8); /* 加密 */ DES_ecb3_encrypt((const_DES_cblock*)tmp, (DES_cblock*)in, &ks, &ks2, &ks3, DES_ENCRYPT); /* 解密 */ DES_ecb3_encrypt((const_DES_cblock*)in, (DES_cblock*)out, &ks, &ks2, &ks3, DES_DECRYPT);/* 将解密的内容拷贝到解密后的明文 */ memcpy(dst + 8 * i, out, 8); } printf("after decrypt :\n"); for (i = 0; i < len; i++) { printf("0x%.2X ", *(dst + i)); } printf("\n"); } if (NULL != src) { free(src);src = NULL; } if (NULL != dst) { free(dst); dst = NULL; } return 0;
}