openssl 中的 AES 加密

Love_for_Live

（LZ 一直没找到 所以自己看了资料，然后自己写了一下，用的是 VS 2010 ）
// demo.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <openssl/aes.h>
#include <openssl\err.h>
#include <openssl\rand.h>

using namespace std;

#pragma comment(lib, "libeay32.lib")
#pragma comment(lib, "ssleay32.lib")

#define BIG_TEXT_SIZE 10240
int _tmain(int argc, _TCHAR* argv[])
{

       
        //char source[] = {"qiaoshaoyi12345671213 sdafdsaf asdf asdf asdf"};

        char source[BIG_TEXT_SIZE] = {'\0'};
        printf("please input an string:\n");
        cin.getline(source,BIG_TEXT_SIZE);
        AES_KEY aes;
    unsigned char key[AES_BLOCK_SIZE];        // AES_BLOCK_SIZE = 16
    unsigned char iv[AES_BLOCK_SIZE];        // init vector
    unsigned char* input_string;
    unsigned char* encrypt_string;
    unsigned char* decrypt_string;
    unsigned int len;        // encrypt length (in multiple of AES_BLOCK_SIZE)
    unsigned int i;

    // check usage
    //if (argc != 2) {
       // fprintf(stderr, "%s <plain text>\n", argv[0]);
        //exit(-1);
    //}

    // set the encryption length
    len = 0;
    if ((strlen(source) + 1) % AES_BLOCK_SIZE == 0) {
        len = strlen(source) + 1;
    } else {
        len = ((strlen(source) + 1) / AES_BLOCK_SIZE + 1) * AES_BLOCK_SIZE;
    }

    // set the input string
    input_string = (unsigned char*)calloc(len, sizeof(unsigned char));
    if (input_string == NULL) {
        fprintf(stderr, "Unable to allocate memory for input_string\n");
        exit(-1);
    }
    strncpy((char*)input_string, source, strlen(source));

    // Generate AES 128-bit key
    for (i=0; i<16; ++i) {
        key[i] = 32 + i;
    }

    // Set encryption key
    for (i=0; i<AES_BLOCK_SIZE; ++i) {
        iv[i] = 0;
    }
    if (AES_set_encrypt_key(key, 128, &aes) < 0) {
        fprintf(stderr, "Unable to set encryption key in AES\n");
        exit(-1);
    }

    // alloc encrypt_string
    encrypt_string = (unsigned char*)calloc(len, sizeof(unsigned char));   
    if (encrypt_string == NULL) {
        fprintf(stderr, "Unable to allocate memory for encrypt_string\n");
        exit(-1);
    }

    // encrypt (iv will change)
    AES_cbc_encrypt(input_string, encrypt_string, len, &aes, iv, AES_ENCRYPT);

    // alloc decrypt_string
    decrypt_string = (unsigned char*)calloc(len, sizeof(unsigned char));
    if (decrypt_string == NULL) {
        fprintf(stderr, "Unable to allocate memory for decrypt_string\n");
        exit(-1);
    }

    // Set decryption key
    for (i=0; i<AES_BLOCK_SIZE; ++i) {
        iv[i] = 0;
    }
    if (AES_set_decrypt_key(key, 128, &aes) < 0) {
        fprintf(stderr, "Unable to set decryption key in AES\n");
        exit(-1);
    }

    // decrypt
    AES_cbc_encrypt(encrypt_string, decrypt_string, len, &aes, iv,
            AES_DECRYPT);

    // print
    printf("input_string:\n%s\n", input_string);
    printf("encrypted string:\n ");
    for (i=0; i<len; ++i) {
        printf("%x%x", (encrypt_string[i] >> 4) & 0xf,
                encrypt_string[i] & 0xf);   
    }
    printf("\n");
    printf("decrypted string:\n%s\n", decrypt_string);

    return 0;
}