NTRU_IoT/legacy-code/sample/sample_NTRUEncrypt.c

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include "ntru_crypto.h"
#include "ntru_crypto_drbg.h"

//typedef uint32_t (*urnd)(uint8_t *out, uint32_t num_bytes);
static uint8_t const aes_key[] = "Decr";
uint32_t get_rand(uint8_t *out, uint32_t num_bytes)
{
	int rng = 50;
	int urnd = open("/dev/random", O_RDONLY);
	read(urnd, &rng, sizeof(int));
	*out = urnd;
	close(urnd);
	return 0;
}

int main(void) {


	//uint8_t public_key[557];
	double cpu_time_used;
    	uint8_t public_key[557];          /* sized for EES401EP2 */
    	uint16_t public_key_len;          /* no. of octets in public key */
    	uint8_t private_key[607];         /* sized for EES401EP2 */
    	uint16_t private_key_len;         /* no. of octets in private key */
    	uint16_t expected_private_key_len;
    	uint16_t expected_encoded_public_key_len;
    	uint8_t encoded_public_key[593];  /* sized for EES401EP2 */
    	uint16_t encoded_public_key_len;  /* no. of octets in encoded public key */
    	uint8_t ciphertext[552];          /* sized fof EES401EP2 */
    	uint16_t ciphertext_len;          /* no. of octets in ciphertext */
    	uint8_t plaintext[16];            /* size of AES-128 key */
    	uint16_t plaintext_len;           /* no. of octets in plaintext */
    	uint8_t *next = NULL;             /* points to next cert field to parse */
    	uint32_t next_len;                /* no. of octets it next */
    	DRBG_HANDLE drbg;                 /* handle for instantiated DRBG */
    	uint32_t rc;                      /* return code */
    	bool error = FALSE;               /* records if error occurred */
    	FILE *Handle=NULL;                /* File Handle for writing NTRU key to file */
	clock_t time_s, time_e;

	rc = ntru_crypto_drbg_external_instantiate(&get_rand, &drbg);

	if (rc != DRBG_OK)
		goto error;

	rc = ntru_crypto_ntru_encrypt_keygen(drbg, NTRU_EES401EP2, &public_key_len, NULL, &private_key_len, NULL);

	if (rc != NTRU_OK)
	{
		error = TRUE;
	}

	expected_private_key_len=private_key_len;
	time_s = clock();
	rc = ntru_crypto_ntru_encrypt_keygen(drbg, NTRU_EES401EP2, &public_key_len, public_key, &private_key_len, private_key);
	time_e = clock();

	if (rc != NTRU_OK)
		error = TRUE;

	if (expected_private_key_len!=private_key_len)
	{
		fprintf(stderr, "PRivate key length is different\n");
		error  = TRUE;
	}

	printf("Key sucessfully generated. \n");

	rc = ntru_crypto_drbg_uninstantiate(drbg);
	if ((rc != DRBG_OK) || error)
	{
		error = TRUE;
	}

	printf("KEY DRBG Success. \n");

	Handle=fopen("Nino-ntru-key.raw","wb");
	if (Handle!=NULL){
		printf("Writing Pirvatkey\n");
		fwrite(private_key, private_key_len, 1, Handle);
		fclose(Handle);
	}
	Handle=fopen("Nino-ntru-pubkey.raw","wb");
	if(Handle!=NULL){
		printf("Writing Publickey\n");
		printf("Public Key : \n %s\n", public_key);
		fwrite(public_key, public_key_len, 1, Handle);
		fclose(Handle);
	}

	rc = ntru_crypto_ntru_encrypt_publicKey2SubjectPublicKeyInfo(public_key_len, public_key, &encoded_public_key_len, NULL);
	if (rc != NTRU_OK)
		goto error;
	printf("DER encoded, sized requierd %d . \n", encoded_public_key_len);
	expected_encoded_public_key_len = encoded_public_key_len;
	rc = ntru_crypto_ntru_encrypt_publicKey2SubjectPublicKeyInfo(public_key_len, public_key, &encoded_public_key_len, encoded_public_key);

	if (expected_encoded_public_key_len!=encoded_public_key_len)
	{
		fprintf(stderr, "Different encoded pub key detected\n");
		error = TRUE;
	}

	next = encoded_public_key;
	next_len = encoded_public_key_len;
	rc = ntru_crypto_ntru_encrypt_subjectPublicKeyInfo2PublicKey(next, &public_key_len, NULL, &next, &next_len);

	if (rc != NTRU_OK)
		goto error;
	printf("Pub key buffer must %d\n", public_key_len);

	rc = ntru_crypto_ntru_encrypt_subjectPublicKeyInfo2PublicKey(next, &public_key_len, public_key, &next, &next_len);

	if (rc != NTRU_OK)
		goto error;

	printf("Pub DER Encoding success\n");

	printf("Encryption Phase \n");
	rc = ntru_crypto_drbg_external_instantiate(&get_rand, &drbg);

	if (rc != DRBG_OK)
		goto error;
	printf("Sucess encrypt\n");
	rc = ntru_crypto_ntru_encrypt(drbg, public_key_len, public_key, sizeof(aes_key), aes_key, &ciphertext_len, NULL);

	if (rc != NTRU_OK)
		goto error;
	printf("String to be encrypted: %s\n", aes_key);
	
	rc = ntru_crypto_ntru_encrypt(drbg, public_key_len, public_key, sizeof(aes_key), aes_key, &ciphertext_len, ciphertext);

	if (rc != NTRU_OK)
		goto error;
	//printf("Ciphertext : %s\n", ciphertext);
	rc = ntru_crypto_drbg_uninstantiate(drbg);
	printf("Done BLyat!!!!\n");
	
	if (rc != NTRU_OK)
		goto error;

    	rc = ntru_crypto_ntru_decrypt(private_key_len, private_key, ciphertext_len,
    	                              ciphertext, &plaintext_len, NULL);
    	if (rc != NTRU_OK)
    	    /* An error occurred requesting the buffer size needed. */
    	    goto error;
    	printf("Maximum plaintext buffer size required: %d octets.\n",
    	        plaintext_len);

    	/* Now we could allocate a buffer of length plaintext_len to hold the
    	 * plaintext, but note that plaintext_len has the maximum plaintext
    	 * size for the EES401EP2 parameter set.  Since we know that we've
    	 * received an encrypted AES-128 key in this example, and since we
    	 * already have a plaintext buffer as a local variable, we'll just
    	 * supply the length of that plaintext buffer for decryption.
    	 */
    	plaintext_len = sizeof(plaintext);
    	rc = ntru_crypto_ntru_decrypt(private_key_len, private_key, ciphertext_len,
    	                              ciphertext, &plaintext_len, plaintext);
    	if (rc != NTRU_OK)
    	{
    	    fprintf(stderr,"Error: An error occurred decrypting the AES-128 key.\n");
    	    return 1;
    	}
    	printf("AES-128 key decrypted successfully.\n");
    	printf("Decoded plaintext length: %d octets\n",plaintext_len);

    	if(plaintext_len!=sizeof(aes_key))
    	{
    	    fprintf(stderr,"Error: Decrypted length does not match original plaintext length\n");
    	    return 1;
    	}
    	if(memcmp(plaintext,aes_key,sizeof(aes_key)))
    	{
    	    fprintf(stderr,"Error: Decrypted plaintext does not match original plaintext\n");
    	    return 1;
    	}


    	Handle=fopen("sample-decoded-plaintext.bin","wb");
    	if(Handle!=NULL)
    	{
    	  printf("Writing decoded plaintext to decoded-plaintext.bin\n");
    	  printf("Plain text : %s", plaintext);
    	  fwrite(plaintext,plaintext_len,1,Handle);
    	  fclose(Handle);
    	}

	cpu_time_used = (float)(time_e - time_s) / CLOCKS_PER_SEC;
	printf("Time Keygen NTRU : %lf\n", cpu_time_used);

	



    	/* And now the plaintext buffer holds the decrypted AES-128 key. */
    	printf("Sample code completed successfully.\n");
error:
	printf("ERROR %x\n", rc);
	return 1;
	
}