//
//crypt-dh.c
//
//Code for making Diffie-Hellman keys
//
//
//-UserX 2001/11/15

#include "base/bignum.h"
#include "crypt/random.h"
#include "crypt/dh.h"

typedef struct DHPrimeEntry {
	int	length;
	int	strength;
	char *key;
} DHPrimeEntry;

DHPrimeEntry primes[] = {
	{
		768, 64, //50
		"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
		"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
		"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
		"E485B576" "625E7EC6" "F44C42E9" "A63A3620" "FFFFFFFF" "FFFFFFFF"
	}, {
		1024, 96, //90
		"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234"	"C4C6628B" "80DC1CD1"
		"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
		"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
		"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED" 
		"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE65381"
		"FFFFFFFF" "FFFFFFFF"
	}, {
		1536, 128, //120
		"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
		"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
		"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
		"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
		"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
		"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
		"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
		"670C354E" "4ABC9804" "F1746C08" "CA237327" "FFFFFFFF" "FFFFFFFF"
	}, {
		2048, 160, //160
		"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
		"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
		"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
		"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
		"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
		"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
		"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
		"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
		"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
		"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
		"15728E5A" "8AACAA68" "FFFFFFFF" "FFFFFFFF"
	}, {
		3072, 224, //210
		"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
		"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
		"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
		"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
		"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
		"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
		"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
		"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
		"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
		"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
		"15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
		"ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
		"ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
		"F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
		"BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
		"43DB5BFC" "E0FD108E" "4B82D120" "A93AD2CA" "FFFFFFFF" "FFFFFFFF"
	}, {
		4096, 256, //240
		"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
		"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
		"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
		"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
		"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
		"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
		"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
		"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
		"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
		"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
		"15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
		"ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
		"ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
		"F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
		"BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
		"43DB5BFC" "E0FD108E" "4B82D120" "A9210801" "1A723C12" "A787E6D7"
		"88719A10" "BDBA5B26" "99C32718" "6AF4E23C" "1A946834" "B6150BDA"
		"2583E9CA" "2AD44CE8" "DBBBC2DB" "04DE8EF9" "2E8EFC14" "1FBECAA6"
		"287C5947" "4E6BC05D" "99B2964F" "A090C3A2" "233BA186" "515BE7ED"
		"1F612970" "CEE2D7AF" "B81BDD76" "2170481C" "D0069127" "D5B05AA9"
		"93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34063199"
		"FFFFFFFF" "FFFFFFFF"
	}, {
		6144, 288, //270
		"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
		"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
		"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
		"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
		"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
		"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
		"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
		"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
		"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
		"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
		"15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
		"ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
		"ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
		"F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
		"BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
		"43DB5BFC" "E0FD108E" "4B82D120" "A9210801" "1A723C12" "A787E6D7"
		"88719A10" "BDBA5B26" "99C32718" "6AF4E23C" "1A946834" "B6150BDA"
		"2583E9CA" "2AD44CE8" "DBBBC2DB" "04DE8EF9" "2E8EFC14" "1FBECAA6"
		"287C5947" "4E6BC05D" "99B2964F" "A090C3A2" "233BA186" "515BE7ED"
		"1F612970" "CEE2D7AF" "B81BDD76" "2170481C" "D0069127" "D5B05AA9"
		"93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34028492"
		"36C3FAB4" "D27C7026" "C1D4DCB2" "602646DE" "C9751E76" "3DBA37BD"
		"F8FF9406" "AD9E530E" "E5DB382F" "413001AE" "B06A53ED" "9027D831"
		"179727B0" "865A8918" "DA3EDBEB" "CF9B14ED" "44CE6CBA" "CED4BB1B"
		"DB7F1447" "E6CC254B" "33205151" "2BD7AF42" "6FB8F401" "378CD2BF"
		"5983CA01" "C64B92EC" "F032EA15" "D1721D03" "F482D7CE" "6E74FEF6"
		"D55E702F" "46980C82" "B5A84031" "900B1C9E" "59E7C97F" "BEC7E8F3"
		"23A97A7E" "36CC88BE" "0F1D45B7" "FF585AC5" "4BD407B2" "2B4154AA"
		"CC8F6D7E" "BF48E1D8" "14CC5ED2" "0F8037E0" "A79715EE" "F29BE328"
		"06A1D58B" "B7C5DA76" "F550AA3D" "8A1FBFF0" "EB19CCB1" "A313D55C"
		"DA56C9EC" "2EF29632" "387FE8D7" "6E3C0468" "043E8F66" "3F4860EE"
		"12BF2D5B" "0B7474D6" "E694F91E" "6DCC4024" "FFFFFFFF" "FFFFFFFF"
	}, {
		8192, 320, //310
		"FFFFFFFF" "FFFFFFFF" "C90FDAA2" "2168C234" "C4C6628B" "80DC1CD1"
		"29024E08" "8A67CC74" "020BBEA6" "3B139B22" "514A0879" "8E3404DD"
		"EF9519B3" "CD3A431B" "302B0A6D" "F25F1437" "4FE1356D" "6D51C245"
		"E485B576" "625E7EC6" "F44C42E9" "A637ED6B" "0BFF5CB6" "F406B7ED"
		"EE386BFB" "5A899FA5" "AE9F2411" "7C4B1FE6" "49286651" "ECE45B3D"
		"C2007CB8" "A163BF05" "98DA4836" "1C55D39A" "69163FA8" "FD24CF5F"
		"83655D23" "DCA3AD96" "1C62F356" "208552BB" "9ED52907" "7096966D"
		"670C354E" "4ABC9804" "F1746C08" "CA18217C" "32905E46" "2E36CE3B"
		"E39E772C" "180E8603" "9B2783A2" "EC07A28F" "B5C55DF0" "6F4C52C9"
		"DE2BCBF6" "95581718" "3995497C" "EA956AE5" "15D22618" "98FA0510"
		"15728E5A" "8AAAC42D" "AD33170D" "04507A33" "A85521AB" "DF1CBA64"
		"ECFB8504" "58DBEF0A" "8AEA7157" "5D060C7D" "B3970F85" "A6E1E4C7"
		"ABF5AE8C" "DB0933D7" "1E8C94E0" "4A25619D" "CEE3D226" "1AD2EE6B"
		"F12FFA06" "D98A0864" "D8760273" "3EC86A64" "521F2B18" "177B200C"
		"BBE11757" "7A615D6C" "770988C0" "BAD946E2" "08E24FA0" "74E5AB31"
		"43DB5BFC" "E0FD108E" "4B82D120" "A9210801" "1A723C12" "A787E6D7"
		"88719A10" "BDBA5B26" "99C32718" "6AF4E23C" "1A946834" "B6150BDA"
		"2583E9CA" "2AD44CE8" "DBBBC2DB" "04DE8EF9" "2E8EFC14" "1FBECAA6"
		"287C5947" "4E6BC05D" "99B2964F" "A090C3A2" "233BA186" "515BE7ED"
		"1F612970" "CEE2D7AF" "B81BDD76" "2170481C" "D0069127" "D5B05AA9"
		"93B4EA98" "8D8FDDC1" "86FFB7DC" "90A6C08F" "4DF435C9" "34028492"
		"36C3FAB4" "D27C7026" "C1D4DCB2" "602646DE" "C9751E76" "3DBA37BD"
		"F8FF9406" "AD9E530E" "E5DB382F" "413001AE" "B06A53ED" "9027D831"
		"179727B0" "865A8918" "DA3EDBEB" "CF9B14ED" "44CE6CBA" "CED4BB1B"
		"DB7F1447" "E6CC254B" "33205151" "2BD7AF42" "6FB8F401" "378CD2BF"
		"5983CA01" "C64B92EC" "F032EA15" "D1721D03" "F482D7CE" "6E74FEF6"
		"D55E702F" "46980C82" "B5A84031" "900B1C9E" "59E7C97F" "BEC7E8F3"
		"23A97A7E" "36CC88BE" "0F1D45B7" "FF585AC5" "4BD407B2" "2B4154AA"
		"CC8F6D7E" "BF48E1D8" "14CC5ED2" "0F8037E0" "A79715EE" "F29BE328"
		"06A1D58B" "B7C5DA76" "F550AA3D" "8A1FBFF0" "EB19CCB1" "A313D55C"
		"DA56C9EC" "2EF29632" "387FE8D7" "6E3C0468" "043E8F66" "3F4860EE"
		"12BF2D5B" "0B7474D6" "E694F91E" "6DBE1159" "74A3926F" "12FEE5E4"
		"38777CB6" "A932DF8C" "D8BEC4D0" "73B931BA" "3BC832B6" "8D9DD300"
		"741FA7BF" "8AFC47ED" "2576F693" "6BA42466" "3AAB639C" "5AE4F568"
		"3423B474" "2BF1C978" "238F16CB" "E39D652D" "E3FDB8BE" "FC848AD9"
		"22222E04" "A4037C07" "13EB57A8" "1A23F0C7" "3473FC64" "6CEA306B"
		"4BCBC886" "2F8385DD" "FA9D4B7F" "A2C087E8" "79683303" "ED5BDD3A"
		"062B3CF5" "B3A278A6" "6D2A13F8" "3F44F82D" "DF310EE0" "74AB6A36"
		"4597E899" "A0255DC1" "64F31CC5" "0846851D" "F9AB4819" "5DED7EA1"
		"B1D510BD" "7EE74D73" "FAF36BC3" "1ECFA268" "359046F4" "EB879F92"
		"4009438B" "481C6CD7" "889A002E" "D5EE382B" "C9190DA6" "FC026E47"
		"9558E447" "5677E9AA" "9E3050E2" "765694DF" "C81F56E8" "80B96E71"
		"60C980DD" "98EDD3DF" "FFFFFFFF" "FFFFFFFF"
	}, {
		0, 0,
		NULL
	}
};

//check for existence of a prime of matching length
//returns length in bytes
int dhCheckPrime(int bitlength) {
	int i;
	for(i = 0; primes[i].length != 0; i++) {
		if(primes[i].length == bitlength) {
			return bitlength / 8;
		}
	}
	return 0;
}

int dhGetPrimeLength(int exponentlength) {
	int i;
	int bitlength = 0;
	for(i = 0; primes[i].length != 0; i++) {
		if(primes[i].strength * 2 >= exponentlength) {
			bitlength = primes[i].length;
			break;
		}
	}
	return bitlength;
}

int dhGetExponentLength(int bitlength) {
	int i;
	for(i = 0; primes[i].length != 0; i++) {
		if(primes[i].length == bitlength) {
			return primes[i].strength * 2;
		}
	}
	return 0;
}

BigNum *dhGetPrime(int bitlength) {
	int i;
	for(i = 0; primes[i].length != 0; i++) {
		if(primes[i].length == bitlength) {
			return bignumFromHex(primes[i].key);
		}
	}
	return NULL;
}

//make a new private key
BigNum *dhGeneratePrivKey(int bitlength) {
	DataBlock *db;
	BigNum *big;
	int bytelength = bitlength / 8;
	/*
	int bytelength = dhCheckPrime(bitlength);
	if(bytelength == 0) {
		return NULL;
	}
	*/
	db = randomDBlock(bytelength);
	big = bignumFromBuffer(db->data, db->size);
	dblockFree(db);
	return big;
}

BigNum *dhGeneratePubKey(int bitlength, BigNum *PrivKey) {
	BigNum *result;
	BigNum *base;
	BigNum *prime = dhGetPrime(bitlength);
	if(prime == NULL) {
		return NULL;
	}
	base = bignumFromInt(DH_GENERATOR_BASE);
	result = bignumExpModKeep(base, PrivKey, prime);
	bignumFree(prime);
	bignumFree(base);
	return result;
}

BigNum *dhGenerateSharedKey(int bitlength, BigNum *PrivKey, BigNum *RemotePubKey) {
	BigNum *result;
	BigNum *prime = dhGetPrime(bitlength);
	if(prime == NULL) {
		return NULL;
	}
	result = bignumExpModKeep(RemotePubKey, PrivKey, prime);
	bignumFree(prime);
	return result;
}