wolfssl之aes加密文件算法

          看了wolfssl－example里面用aes加密文件的c源码，但是他是通过终端命令行编译的，我嫌命令行麻烦，修改了他的代码，然后去掉了一些不需要的部分，能成功加密本地文件。

         代码用xcode编译，对0910－e.rtf文件进行加密生成0910.rtf文件，再对0910.rtf文件进行解密生成0190-de.rtf文件，代码是昨天写的，昨天是教师节祝导师教师节快乐，原文件和解密后的文件截图如下，加密后的文件由于系统字符库的原因在mac下打不开：

以下是代码在xcode运行截图：

      代码只能对文件进行加密和解密以及显示帮助文件，我写的代码附上：

 

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define SALT_SIZE 8

/*
 * Makes a cyptographically secure key by stretching a user entered key
 */
int GenerateKey(RNG* rng, byte* key, int size, byte* salt, int pad)
{
    int ret;
    
    ret = wc_RNG_GenerateBlock(rng, salt, SALT_SIZE);
    if (ret != 0)
        return -1020;
    
    if (pad == 0)
        salt[0] = 0;
    
    /* stretches key */
    ret = wc_PBKDF2(key, key, strlen((const char*)key), salt, SALT_SIZE, 4096,
                    size, SHA256);
    if (ret != 0)
        return -1030;
    
    return 0;
}

/*
 * Encrypts a file using AES
 */
int AesEncrypt(Aes* aes, byte* key, int size, FILE* inFile, FILE* outFile)
{
    RNG     rng;
    byte    iv[AES_BLOCK_SIZE];
    byte*   input;
    byte*   output;
    byte    salt[SALT_SIZE] = {0};
    
    
    
    int     i = 0;
    int     ret = 0;
    int     inputLength;
    int     length;
    int     padCounter = 0;
    
    inFile=fopen("/Users/QY/Desktop/temp09110/temp09110/0910-e.rtf","r");
    outFile=fopen("/Users/QY/Desktop/temp09110/temp09110/0910.rtf","w");
    
    fseek(inFile, 0, SEEK_END);
    inputLength = ftell(inFile);
    fseek(inFile, 0, SEEK_SET);
    
    length = inputLength;
    /* pads the length until it evenly matches a block / increases pad number*/
    while (length % AES_BLOCK_SIZE != 0) {
        length++;
        padCounter++;
    }
    
    input = malloc(length);
    output = malloc(length);
    
    ret = wc_InitRng(&rng);
    if (ret != 0) {
        printf("Failed to initialize random number generator\n");
        return -1030;
    }
    
    /* reads from inFile and wrties whatever is there to the input array */
    ret = fread(input, 1, inputLength, inFile);
    if (ret == 0) {
        printf("Input file does not exist.\n");
        return -1010;
    }
    for (i = inputLength; i < length; i++) {
        /* padds the added characters with the number of pads */
        input[i] = padCounter;
    }
    
    ret = wc_RNG_GenerateBlock(&rng, iv, AES_BLOCK_SIZE);
    if (ret != 0)
        return -1020;
    
    /* stretches key to fit size */
    ret = GenerateKey(&rng, key, size, salt, padCounter);
    if (ret != 0)
        return -1040;
    
    /* sets key */
    ret = wc_AesSetKey(aes, key, AES_BLOCK_SIZE, iv, AES_ENCRYPTION);
    if (ret != 0)
        return -1001;
    
    /* encrypts the message to the ouput based on input length + padding */
    ret = wc_AesCbcEncrypt(aes, output, input, length);
    if (ret != 0)
        return -1005;
    
    /* writes to outFile */
    fwrite(salt, 1, SALT_SIZE, outFile);
    fwrite(iv, 1, AES_BLOCK_SIZE, outFile);
    fwrite(output, 1, length, outFile);
    
    /* closes the opened files and frees the memory*/
    memset(input, 0, length);
    memset(output, 0, length);
    memset(key, 0, size);
    free(input);
    free(output);
    free(key);
    fclose(inFile);
    fclose(outFile);
    
    printf("encrypt success\n");
    
    return ret;
}

/*
 * Decryptsr a file using AES
 */
int AesDecrypt(Aes* aes, byte* key, int size, FILE* inFile, FILE* outFile)
{
    RNG     rng;
    byte    iv[AES_BLOCK_SIZE];
    byte*   input;
    byte*   output;
    byte    salt[SALT_SIZE] = {0};
    
    if((inFile=fopen("/Users/QY/Desktop/temp09110/temp09110/0910.rtf","r"))==NULL)
        printf("Input file does not exist.\n");
    if((outFile=fopen("/Users/QY/Desktop/temp09110/temp09110/0910-de.rtf","w"))==NULL)
        printf("Output file does not exist.\n");
    
    int     i = 0;
    int     ret = 0;
    int     length;
    int     aSize;
    
    fseek(inFile, 0, SEEK_END);
    length = ftell(inFile);
    fseek(inFile, 0, SEEK_SET);
    aSize = length;
    
    input = malloc(aSize);
    output = malloc(aSize);
    
    wc_InitRng(&rng);
    
    
    /* reads from inFile and wrties whatever is there to the input array */
    ret = fread(input, 1, length, inFile);
    if (ret == 0) {
        printf("Data does not exist.\n");
        return -1010;
    }
    for (i = 0; i < SALT_SIZE; i++) {
        /* finds salt from input message */
        salt[i] = input[i];
    }
    for (i = SALT_SIZE; i < AES_BLOCK_SIZE + SALT_SIZE; i++) {
        /* finds iv from input message */
        iv[i - SALT_SIZE] = input[i];
    }
    
    /* replicates old key if keys match */
    ret = wc_PBKDF2(key, key, strlen((const char*)key), salt, SALT_SIZE, 4096,
                    size, SHA256);
    if (ret != 0)
        return -1050;
    
    /* sets key */
    ret = wc_AesSetKey(aes, key, AES_BLOCK_SIZE, iv, AES_DECRYPTION);
    if (ret != 0)
        return -1002;
    
    /* change length to remove salt/iv block from being decrypted */
    length -= (AES_BLOCK_SIZE + SALT_SIZE);
    for (i = 0; i < length; i++) {
        /* shifts message: ignores salt/iv on message*/
        input[i] = input[i + (AES_BLOCK_SIZE + SALT_SIZE)];
    }
    /* decrypts the message to output based on input length + padding*/
    ret = wc_AesCbcDecrypt(aes, output, input, length);
    if (ret != 0)
        return -1006;
    
    if (salt[0] != 0) {
        /* reduces length based on number of padded elements */
        length -= output[length-1];
    }
    /* writes output to the outFile based on shortened length */
    fwrite(output, 1, length, outFile);
    
    /* closes the opened files and frees the memory*/
    memset(input, 0, aSize);
    memset(output, 0, aSize);
    memset(key, 0, size);
    free(input);
    free(output);
    free(key);
    fclose(inFile);
    fclose(outFile);
    
    printf("dencrypt success\n");
    
    return 0;
}

/*
 * help message
 */
void help()
{
    printf("\n~~~~~~~~~~~~~~~~~~~~|Help|~~~~~~~~~~~~~~~~~~~~~\n\n");
    printf("Usage: ./aes-file-encrypt <-option>  <-i file.in> "
           "<-o file.out>\n\n");
    printf("Options\n");
    printf("-d    Decryption\n-e    Encryption\n-h    Help\n");
}

int main(int argc, char** argv)
{
    Aes    aes;
    byte*  key;       /* user entered key */
    FILE*  inFile ;
    FILE*  outFile ;
    
    const char* in;
    const char* out;
    
    char    option;    /* choice of how to run program */
    int    ret = 0;   /* return value */
    int    size = 128;
    int    inCheck = 0;
    int    outCheck = 0;
  //  char   choice = 'n';
    
    inFile=fopen("/Users/QY/Desktop/temp09110/temp09110/0910-e.rtf ","r");
    outFile=fopen("/Users/QY/Desktop/temp09110/temp09110/0910.rtf","w");
    printf("\n\nd:if entered decrypt\n");
    printf("e:if entered encrypt\n");
    printf("h:if entered 'help'\n");
    printf("?:Ending Session\n");
    printf("Please make your choice:\n");
    scanf("%c",&option);
    
    
    while (option != '?') {
        
        key = malloc(size);    /* sets size memory of key */
        switch (option) {
            case 'd': /* if entered decrypt */
            
                AesDecrypt(&aes, key, size, inFile , outFile );
                break;
            case 'e': /* if entered encrypt */
                
                AesEncrypt(&aes, key, size, inFile, outFile);
                break;
            case 'h': /* if entered 'help' */
                help();
                break;
          
            case '?':
                if (optopt) {
                    printf("Ending Session\n");
                    exit(0);
                }
            default:
                break;
        }
        printf("\n\nd:if entered decrypt\n");
        printf("e:if entered encrypt\n");
        printf("h:if entered 'help'\n");
        printf("?:Ending Session\n");
        printf("Please make your choice:\n");
        getchar();
        scanf("%c",&option);
 
    }
    return 0;
}