// New Diffie-Hellman 1080bit Key-exchange

/* For Diffie-Hellman key-exchange a 1080bit germain prime is used, the
generator g=2 renders a field Fp from 1 to p-1. Therefore breaking it
means to solve a discrete logarithm problem with no less than 1080bit.

Base64 format is used to send the public keys over IRC.

The calculated secret key is hashed with SHA-256, the result is converted
to base64 for final use with blowfish. */



#include <stdio.h>
#include <time.h>
#include "DH1080.h"

// ### new sophie-germain 1080bit prime number ###
char *prime1080="++ECLiPSE+is+proud+to+present+latest+FiSH+release+featuring+even+more+security+for+you+++shouts+go+out+to+TMG+for+helping+to+generate+this+cool+sophie+germain+prime+number++++/C32L";
// Base16: FBE1022E23D213E8ACFA9AE8B9DFADA3EA6B7AC7A7B7E95AB5EB2DF858921FEADE95E6AC7BE7DE6ADBAB8A783E7AF7A7FA6A2B7BEB1E72EAE2B72F9FA2BFB2A2EFBEFAC868BADB3E828FA8BADFADA3E4CC1BE7E8AFE85E9698A783EB68FA07A77AB6AD7BEB618ACF9CA2897EB28A6189EFA07AB99A8A7FA9AE299EFA7BA66DEAFEFBEFBF0B7D8B
// Base10: 12745216229761186769575009943944198619149164746831579719941140425076456621824834322853258804883232842877311723249782818608677050956745409379781245497526069657222703636504651898833151008222772087491045206203033063108075098874712912417029101508315117935752962862335062591404043092163187352352197487303798807791605274487594646923


// Input:  priv_key = buffer of 200 bytes
//         pub_key  = buffer of 200 bytes
// Output: priv_key = Your private key
//         pub_key  = Your public key
int DH1080_gen(char *priv_key, char *pub_key)
{
	unsigned char raw_buf[160], iniHash[33];
	unsigned long seed;
	int len;

	big b_privkey, b_prime, b_pubkey;
	csprng myRNG;
	miracl *mip;

	FILE *hRnd;

	priv_key[0]='0';
	priv_key[1]='\0';
	pub_key[0]='0';
	pub_key[1]='\0';
	hRnd = fopen("/dev/urandom", "r");	// don't use /dev/random, it's a blocking device
	if(!hRnd) return 0;

	initb64();
	mip=mirsys(500, 16);

	b_privkey=mirvar(0);
	b_pubkey=mirvar(0);
	b_prime=mirvar(0);

	len=b64toh(prime1080, raw_buf);
	bytes_to_big(len, raw_buf, b_prime);

	// #*#*#*#*#* RNG START #*#*#*#*#*
	time((time_t *)&seed);

	seed ^= (long)hRnd << 16;
	if(fread(raw_buf, 1, sizeof(raw_buf), hRnd) < 32)
	{
		ZeroMemory(raw_buf, sizeof(raw_buf));
		fclose(hRnd);
		mirkill(b_privkey);
		mirkill(b_pubkey);
		mirkill(b_prime);
		mirexit();
		return 0;
	}
	fclose(hRnd);

	sha_file(iniPath, iniHash);
	memXOR(raw_buf+128, iniHash, 32);
	sha_file((unsigned char *)get_irssi_config(), iniHash);
	memXOR(raw_buf+128, iniHash, 32);
	ZeroMemory(iniHash, sizeof(iniHash));
	// first 128 byte in raw_buf: output from /dev/urandom
	// last 32 byte in raw_buf: SHA-256 digest from blow.ini and irssi.conf

	seed *= (unsigned long)mip;
	strong_init(&myRNG, sizeof(raw_buf), raw_buf, (unsigned int)seed);
	strong_rng(&myRNG);
	strong_bigdig(&myRNG, 1080, 2, b_privkey);
	strong_kill(&myRNG);
	seed=0;
	// #*#*#*#*#* RNG END #*#*#*#*#*

	powltr(2, b_privkey, b_prime, b_pubkey);

	len=big_to_bytes(sizeof(raw_buf), b_privkey, raw_buf, FALSE);
	mirkill(b_privkey);
	htob64(raw_buf, priv_key, len);

	len=big_to_bytes(sizeof(raw_buf), b_pubkey, raw_buf, FALSE);
	htob64(raw_buf, pub_key, len);
	ZeroMemory(raw_buf, sizeof(raw_buf));

	mirkill(b_pubkey);
	mirkill(b_prime);
	mirexit();

	return 1;
}



// Input:  MyPrivKey = Your private key
//         HisPubKey = Someones public key
// Output: MyPrivKey has been destroyed for security reasons
//         HisPubKey = the secret key
int DH1080_comp(char *MyPrivKey, char *HisPubKey)
{
	int i=0, len;
	unsigned char SHA256digest[35], base64_tmp[160];
	big b_myPrivkey, b_HisPubkey, b_prime, b_theKey;
	miracl *mip;

	// Verify base64 strings
	if((strspn(MyPrivKey, B64ABC) != strlen(MyPrivKey)) || (strspn(HisPubKey, B64ABC) != strlen(HisPubKey)))
	{
		memset(MyPrivKey, 0x20, strlen(MyPrivKey));
		memset(HisPubKey, 0x20, strlen(HisPubKey));
		return 0;
	}

	mip=mirsys(500, 16);

	b_myPrivkey=mirvar(0);
	b_HisPubkey=mirvar(0);
	b_theKey=mirvar(0);
	b_prime=mirvar(0);

	len=b64toh(prime1080, base64_tmp);
	bytes_to_big(len, base64_tmp, b_prime);

	len=b64toh(MyPrivKey, base64_tmp);
	bytes_to_big(len, base64_tmp, b_myPrivkey);
	memset(MyPrivKey, 0x20, strlen(MyPrivKey));

	len=b64toh(HisPubKey, base64_tmp);
	bytes_to_big(len, base64_tmp, b_HisPubkey);

	powmod(b_HisPubkey, b_myPrivkey, b_prime, b_theKey);
	mirkill(b_myPrivkey);

	len=big_to_bytes(sizeof(base64_tmp), b_theKey, base64_tmp, FALSE);
	mirkill(b_theKey);
	SHA256_memory(base64_tmp, len, SHA256digest);
	htob64(SHA256digest, HisPubKey, 32);
	ZeroMemory(base64_tmp, sizeof(base64_tmp));
	ZeroMemory(SHA256digest, sizeof(SHA256digest));

	mirkill(b_HisPubkey);
	mirkill(b_prime);
	mirexit();
	return 1;
}