C AES不解密二进制文件

Question

我创建了两个C函数来加密和解密整个文件夹。

#include "myaes.h"

#define SUFFIX ".crypt" //the file suffix for encrypted files
#define MASTER "6ADAC6D678CF49EEF4BB9C16A61F4"


int aesEncryptDir(const char *d)
//encrypts every file in directory d 
{
    AES_KEY key;
    DIR *dp = opendir(d);
    FILE *fp,*fp_c;
    struct dirent *entry;
    char fullpath[strlen(d) + 300];
    char cryppath[strlen(fullpath) + 20];
    char buffer[10000];
    void *in = malloc(16);
    void *out = malloc(16);
    int sz;
    size_t s_read;

    if(AES_set_encrypt_key(MASTER,256,&key) != 0)
        return -1;

    const AES_KEY *static_key = &key;

    if(!dp) //could not dir file pointer, maybe the folder does not exist
        return -1;

    while(entry = readdir(dp))
    {
        if(strncmp(entry->d_name,".",1) != 0 && strncmp(entry->d_name,"..",2) != 0)
        {
            memset(fullpath,0,sizeof(fullpath));
            memset(cryppath,0,sizeof(cryppath));
            memset(buffer,0,sizeof(buffer));
            snprintf(fullpath,sizeof(fullpath),"%s/%s",d,entry->d_name);
            snprintf(cryppath,sizeof(fullpath),"%s%s",fullpath,SUFFIX);
            if(strstr(fullpath,SUFFIX) != NULL)
                continue;
            fp = fopen(fullpath,"r+");
            fp_c = fopen(cryppath,"w");
            fseek(fp,0L,SEEK_END);
            sz = ftell(fp);
            rewind(fp);
            fwrite(&sz,sizeof(int),1,fp_c);

            while((s_read = fread(buffer,1,1000,fp)))
            {
                for(int v = 0; v < s_read; v+= 16)
                {
                    memcpy(in,buffer+v,16);
                    AES_encrypt(in,out,static_key);
                    fwrite(out,1,16,fp_c);
                }
            }     
        }
            fclose(fp);
            remove(fullpath);
            fclose(fp_c);
    }


    if(closedir(dp) != 0)
        return -1;

    free(in);
    free(out);
    return 0;
}

int aesDecryptDir(const char *d)
//decrypts every file in directory d 
{
    AES_KEY key;
    DIR *dp = opendir(d);
    FILE *fp,*fp_c;
    struct dirent *entry;
    char fullpath[strlen(d) + 300];
    char comppath[strlen(d) + 300];
    char recoverpath[strlen(fullpath)];
    char buffer[10000];
    int sz = 0;

    void *in = malloc(16);
    void *out= malloc(16);

    if(AES_set_decrypt_key(MASTER,256,&key) != 0)
        return -1;

    const AES_KEY *static_key = &key;
    if(!dp) //could not dir file pointer, maybe the folder does not exist
        return -1;

    while(entry = readdir(dp))
    {
        if(strncmp(entry->d_name,".",1) != 0 && strncmp(entry->d_name,"..",2) != 0)
        {
            memset(fullpath,0,sizeof(fullpath));
            memset(recoverpath,0,sizeof(recoverpath));
            snprintf(fullpath,sizeof(fullpath),"%s/%s",d,entry->d_name);
            strcpy(comppath,fullpath);
            if(strstr(comppath,SUFFIX) == NULL)
                continue;
            strcpy(recoverpath,fullpath);
            recoverpath[strlen(fullpath) - strlen(SUFFIX)] = '\0';

            fp = fopen(fullpath,"r+");
            fp_c = fopen(recoverpath,"w");
            fread(&sz,sizeof(int),1,fp);
            while(fread(in,16,1,fp))
            {
                AES_decrypt(in,out,static_key);
                fwrite(out,(sz>=16)?16:sz,1,fp_c);
                sz-=16;
            }
            fclose(fp);
            fclose(fp_c);
        }

    }


    if(closedir(dp) != 0)
        return -1;

    free(in);
    free(out);
    return 0;
}

myaes.h

#ifndef MYAES_H
#define MYAES_H

#include <dirent.h>
#include <openssl/aes.h>
#include <openssl/rand.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>

int aesEncryptDir(const char *d);
int aesDecryptDir(const char *d);

#endif

如果我现在通过aesEncryptDir和aesDecryptDir运行纯文本文件，它将保持不变。差异也表示没有变化。然而，二进制文件（.jpg）在此过程中会被破坏。

为什么会这样？它与二进制文件的编码有关吗？我是否必须以不同的方式处理二进制文件以进行加密/解密？