78 lines
1.5 KiB
C++
78 lines
1.5 KiB
C++
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#include <fstream>
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#include "decrypt_image.h"
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#include "log.h"
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#define HEADER_PNG1 0x89
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#define HEADER_PNG2 0x50
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#define HEADER_JPG1 0xFF
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#define HEADER_JPG2 0xD8
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#define HEADER_GIF1 0x47
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#define HEADER_GIF2 0x49
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using namespace std;
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static string get_key(uint8_t header1, uint8_t header2, uint8_t *key)
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{
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// PNG?
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*key = HEADER_PNG1 ^ header1;
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if ((HEADER_PNG2 ^ *key) == header2) {
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return ".png";
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}
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// JPG?
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*key = HEADER_JPG1 ^ header1;
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if ((HEADER_JPG2 ^ *key) == header2) {
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return ".jpg";
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}
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// GIF?
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*key = HEADER_GIF1 ^ header1;
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if ((HEADER_GIF2 ^ *key) == header2) {
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return ".gif";
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}
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return ""; // 错误
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}
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bool DecryptImage(string src, string dst)
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{
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ifstream in(src.c_str(), ios::binary);
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if (!in.is_open()) {
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LOG_ERROR("Failed to open file {}", src);
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return false;
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}
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filebuf *pfb = in.rdbuf();
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size_t size = pfb->pubseekoff(0, ios::end, ios::in);
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pfb->pubseekpos(0, ios::in);
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char *pBuf = new char[size];
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pfb->sgetn(pBuf, size);
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in.close();
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uint8_t key = 0x00;
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string ext = get_key(pBuf[0], pBuf[1], &key);
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if (ext.empty()) {
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LOG_ERROR("Failed to get key.");
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return false;
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}
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for (size_t i = 0; i < size; i++) {
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pBuf[i] ^= key;
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}
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ofstream out((dst + ext).c_str(), ios::binary);
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if (!out.is_open()) {
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LOG_ERROR("Failed to open file {}", dst);
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return false;
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}
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out.write(pBuf, size);
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out.close();
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delete[] pBuf;
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return true;
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}
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