#include <stdio.h>
#include <string.h>
#include <openssl/conf.h>
#include <openssl/evp.h>
#include <openssl/err.h>


unsigned char *cheie;
unsigned char *iv = "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f";

unsigned char *buff = NULL, *buff2 = NULL, decryptedtext[500];

int lungimeaTextuluiDecriptat, lungimeaTextuluiCriptat;


FILE *fisierTextCriptat, *fisierTextSimplu, *fisierDictionar;
size_t len = 0;
ssize_t read;

char line[128];
int flen, flen2;

int decriptareECB(unsigned char *textCriptat, int lungimeaTextuluiCriptat
, unsigned char *cheie,
           unsigned char *textSimplu)
{
	EVP_CIPHER_CTX *context;

	int lungime;

	int lungimeaTextuluiSimplu;

	/* Create and initialise the context */
	context = EVP_CIPHER_CTX_new();

	EVP_DecryptInit_ex(context, EVP_aes_128_ecb(), NULL, cheie, NULL);

	EVP_DecryptUpdate(context, textSimplu, &lungime, textCriptat, lungimeaTextuluiCriptat);
	lungimeaTextuluiSimplu = lungime;

	EVP_DecryptFinal_ex(context, textSimplu + lungime, &lungime);

	lungimeaTextuluiSimplu += lungime;


	EVP_CIPHER_CTX_free(context);

	return lungimeaTextuluiSimplu;
}

int decriptareCBC(unsigned char *textCriptat, int lungimeaTextuluiCriptat, unsigned char *cheie,
           unsigned char *iv, unsigned char *textSimplu)
{
	EVP_CIPHER_CTX *context;

	int lungime;

	int lungimeaTextuluiSimplu;

	/* Create and initialise the context */
	context = EVP_CIPHER_CTX_new();

	EVP_DecryptInit_ex(context, EVP_aes_128_cbc(), NULL, cheie, iv);

	EVP_DecryptUpdate(context, textSimplu, &lungime, textCriptat, lungimeaTextuluiCriptat);

	lungimeaTextuluiSimplu = lungime;

	EVP_DecryptFinal_ex(context, textSimplu + lungime, &lungime);

	lungimeaTextuluiSimplu += lungime;


	EVP_CIPHER_CTX_free(context);

	return lungimeaTextuluiSimplu;
}


void logicaDeImpartire(unsigned char* tip)
{

if (strcmp(tip, "ECB") ==0)
			{
				lungimeaTextuluiDecriptat = decriptareECB(buff, flen, cheie, decryptedtext);
				decryptedtext[lungimeaTextuluiDecriptat] = '\0';
			}
		else if (strcmp(tip, "CBC") ==0)
			{
				lungimeaTextuluiDecriptat = decriptareCBC(buff, flen, cheie, iv, decryptedtext);
				decryptedtext[lungimeaTextuluiDecriptat] = '\0';

			}
		else
		{
			printf("%s", "Nu este un algoritm cunoscut");
			break;
		}

}

int main( int argc, char *argv[] )
{
	if(argc !=4)
	{
		printf("%s", "Numar invalid de argumente");
		exit(0);
	}


	fisierTextSimplu = fopen(argv[1], "r");
	fisierTextCriptat = fopen(argv[2], "r");

	fisierDictionar = fopen("dictionar.txt", "r");


	fseek (fisierTextCriptat, 0, SEEK_END);
	flen = ftell (fisierTextCriptat);
	rewind (fisierTextCriptat);

	fseek (fisierTextSimplu, 0, SEEK_END);
	flen2 = ftell (fisierTextSimplu);
	rewind (fisierTextSimplu);

	buff = (unsigned char *)malloc(flen2+4);
	buff2 = (unsigned char *)malloc(flen2+4);

	fread (buff, sizeof(char), flen, fisierTextCriptat);
	fread (buff2, sizeof(char), flen2, fisierTextSimplu);





	while (fgets(line, sizeof(line) - 4, fisierDictionar))
	{

		line[strlen(line) - 1] = '\0';
		int i;


		for (i = strlen(line) + 1; i <= 30; i++)
			strcat(line, " ");
		cheie = line;

        logicaDeImpartire(argv[3]);

		printf("%s \n", decryptedtext);

		if (strcmp(buff2, decryptedtext) == 0)
		{
			printf("%s", cheie);

			break;
		}


	}





	return 0;
}