int decrypt_file()

in reversing/SOMBRERO_ROJO/crypto/rc4block.c [822:897]

• 53 lines of code
• 7 McCabe index (conditional complexity)

int decrypt_file(char *infile, char *outfile) //unsigned char key[RC4_KEY_BYTES])
{
	struct stat st;
	unsigned int fsize = 0;
	unsigned char *input = NULL;
	unsigned char *output;
	rc4ctx decrypted_ctx;

	//memset(&encrypted_ctx.key, 0x20, RC4_KEY_BYTES);


	FILE *fp = fopen(infile, "rb");
	FILE *fo = fopen(outfile, "wb");

	if(fp == 0 || fo == 0){

		return -1;
	}



	stat(infile, &st);
	fsize = st.st_size;

	if(fread(&decrypted_ctx, 1, sizeof(rc4ctx), fp) < 0)
	{

		fclose(fp);
		fclose(fo);
		return -1;
	}

	if((decrypted_ctx.encrypted_size + sizeof(rc4ctx)) != fsize)
	{
		#ifdef DEBUG
			fprintf(stderr, "Stat file size: %d Encrypted file size: %d\n", fsize, decrypted_ctx.encrypted_size);
			fprintf(stderr, "Decrypted context error esize %d dsize %d padding %d, bool_encrypted %d\n",
			decrypted_ctx.encrypted_size, 
			decrypted_ctx.decrypted_size,
			decrypted_ctx.padding, 
			decrypted_ctx.encrypted);
		#endif

		fclose(fp);
		fclose(fo);
		return -1;
	}

	input = (unsigned char *) calloc(decrypted_ctx.encrypted_size, sizeof(unsigned char));

	if(input == NULL)
	{

		fclose(fp);
		fclose(fo);
		return -1;
	}

	if(fread(input, sizeof(unsigned char), decrypted_ctx.encrypted_size, fp) < 0)
	{
		fclose(fp);
		fclose(fo);
		return -1;
	}
	

	output = rc4_block_decrypt(&decrypted_ctx, input);

	fwrite(output, sizeof(unsigned char), decrypted_ctx.decrypted_size, fo);

	fclose(fo);
	fclose(fp);

return 0;

}