#include "lib4.h"
#include "lib3.h"
#include "lib2.h"
#include "lib.h"
/**
  * encrypt always with the same key, same nonce?
  *
  **/
int aes_ctr_edit(char *ciphertext, int ciphertext_length, int offset, char *newtext)
{
	// do not allow greater ciphertexts
	if((strlen(newtext)+offset) > ciphertext_length)
		return 1;
		
	// insert newtext at offset and reencrpyt
	char *plaintext = malloc(ciphertext_length);
	aes_ctr(ciphertext, ciphertext_length, plaintext, key, nonce);
	memcpy(&plaintext[offset], newtext, strlen(newtext));

	aes_ctr(plaintext, ciphertext_length, ciphertext, key, nonce);
	return 0;
}

void sha1_hmac(unsigned int *mac, unsigned char *message, unsigned int msg_len, unsigned char *key,
		unsigned int key_len)
{
	char *res = malloc(msg_len + key_len);

	memcpy(res, key, key_len);
	memcpy(&res[key_len], message, msg_len);

	SHA1Context sh;

	SHA1Reset(&sh);
	SHA1Input(&sh, res, (msg_len + key_len));
	SHA1Result(&sh);

	memcpy(mac, &(sh.Message_Digest), 20);
}

int sha1_hmac_verify(unsigned int *mac, unsigned char *msg, unsigned int msg_len,
		unsigned char *key, unsigned int key_len)
{
	unsigned int com_mac[5];

	sha1_hmac(com_mac, msg, msg_len, key, key_len);

	return !memcmp(com_mac, mac, 20);

}