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POIssue porting Decryption from Windows CryptoAPI to linux libmcrypt
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2011-05-27T02:20:51.693
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I am trying to port my program from Windows to Linux. The windows program uses Window CryptoAPI and linux is using libmcrypt. Here is the Windows code: <pre><code>#include <windows.h> #include <iostream> #include <iomanip> #include <vector> #include <string> #include <exception> using namespace std; class CryptError:public exception{ public: CryptError(){} }; #define CHECK_RET(x) if(x == FALSE) {retval = GetLastError(); throw CryptError();}; LONG Decrypt(const string &key, std::vector<BYTE> &data){ LONG retval = 0; try{ HCRYPTPROV hCrypt; HCRYPTHASH hHash; HCRYPTKEY hKey; CHECK_RET(CryptAcquireContext(&hCrypt, NULL, NULL, PROV_RSA_FULL, 0)); CHECK_RET(CryptCreateHash(hCrypt, CALG_MD5, 0, 0, &hHash)); CHECK_RET(CryptHashData(hHash, reinterpret_cast<const BYTE *>(key.c_str()), key.size(), 0)); CHECK_RET(CryptDeriveKey(hCrypt, CALG_RC2, hHash, MAKELPARAM(CRYPT_EXPORTABLE, 80), &hKey)); BYTE tempVal[200]; DWORD len = 200; CryptGetKeyParam(hKey, KP_EFFECTIVE_KEYLEN, tempVal, &len, 0); len = 200; CryptGetKeyParam(hKey, KP_MODE, tempVal, &len, 0); len = 200; CryptExportKey(hKey, NULL, PLAINTEXTKEYBLOB, 0, tempVal, &len); len = 200; CryptGetKeyParam(hKey, KP_IV, tempVal, &len, 0); DWORD count = data.size(); CHECK_RET(CryptDecrypt(hKey, 0, TRUE, 0, &(data[0]), &count)); data.resize(count); }catch(CryptError &e){ } return retval; } int main(void){ BYTE data[9] = {0xdc,0x3d,0x96,0x23,0x29,0xdd,0x1b,0x2f, 0}; vector<BYTE> vData(data, data + 8); Decrypt("PNEMAIL", vData); cerr << "vData: "; int len = vData.size(); for(int i = 0; i < len; i++){ if(i > 0) cerr << ','; cerr << hex << setw(2) << setfill('0') << (int)(vData[i]); } cerr << endl; return 0; } </code></pre> When the program is run, it returns: <pre><code>vData: 42,46,30,41,43,34,31 </code></pre> The Q&D linux version looks like this: <pre><code>#include <mcrypt.h> #include <iostream> #include <iomanip> #include <string> #include <openssl/md5.h> #include <stdint.h> #include <stdexcept> #include <vector> #include <valarray> #include <memory.h> using namespace std; class MCrypt{ private: MCRYPT mcrypt; public: MCrypt(char *algorithm, char* algorithm_directory, char *mode, char* mode_directory){ mcrypt = mcrypt_module_open(algorithm, algorithm_directory, mode, mode_directory); if(mcrypt == MCRYPT_FAILED) throw runtime_error("MCrypt init failed"); } int init(void *key, int lenofkey, void *IV){ return mcrypt_generic_init(mcrypt, key, lenofkey, IV); } int enc_get_iv_size(){ return mcrypt_enc_get_iv_size(mcrypt); } int deinit(){ return mcrypt_generic_deinit(mcrypt); } int decrypt(void *data, int len){ mdecrypt_generic(mcrypt, data, len); } ~MCrypt(){ deinit(); mcrypt_module_close(mcrypt); } }; #ifdef DEBUG void inline printArrayFunc(const char *start, const uint8_t *data, int len){ // DEBUG: print value of $key1 cerr << start; for(int i = 0; i < len; i++){ if(i > 0) cerr << ','; cerr << hex << setw(2) << setfill('0') << (int)(data[i]); } cerr << endl; } #define printArray(start, data, len) printArrayFunc(start, data, len) #else #define printArray(start, data, len) #endif int main(void){ uint8_t data[8] = {0xdc,0x3d,0x96,0x23,0x29,0xdd,0x1b,0x2f}; const char *sKey1 = "PNEMAIL"; const int key1Len = 7; uint8_t *dataPtr = &(data[0]); uint8_t key1[17]; key1[16] = 0; // Hash sKey1 MD5(reinterpret_cast<const unsigned char *>(sKey1), key1Len, key1); MCrypt mcrypt(MCRYPT_RC2, NULL, MCRYPT_CBC, NULL); vector<uint8_t> iv(mcrypt.enc_get_iv_size(), 0); // Use the first 80-bits of key1 mcrypt.init(key1, 10, &(iv[0])); mcrypt.decrypt(dataPtr, 8); printArray("vData: ", dataPtr, 8); return 0; } </code></pre> When the program is run, it returns: <pre><code>vData: 4d,3d,82,71,88,d2,d5,4b </code></pre> I've check that both programs are using the same data. <ul> <li>CryptDeriveKey creates a key <code>07,f1,e2,ea,d4,c8,79,74,03,a6</code> (according to CryptExportKey), the same as the first 10 bytes of the md5 generated in Linux (which I shorten to match the requested 80-bit key).</li> <li>Neither are using a salt on the algorithm (or at least are not reporting as such)</li> <li>They are both using an 8-byte IV of {0,0,0,0,0,0,0,0}</li> <li>They are both using the RC2 algorithm</li> <li>They are both using CBC mode</li> </ul> I cannot figure out why they are returning different data. Any assistance would be greatly appreciated.
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<encryption><porting><mcrypt><cryptoapi>
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Issue porting Decryption from Windows CryptoAPI to linux libmcrypt
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