diff options
Diffstat (limited to 'node_modules/diffie-hellman/lib/generatePrime.js')
-rw-r--r-- | node_modules/diffie-hellman/lib/generatePrime.js | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/node_modules/diffie-hellman/lib/generatePrime.js b/node_modules/diffie-hellman/lib/generatePrime.js new file mode 100644 index 0000000..32e053c --- /dev/null +++ b/node_modules/diffie-hellman/lib/generatePrime.js @@ -0,0 +1,105 @@ +var randomBytes = require('randombytes'); +module.exports = findPrime; +findPrime.simpleSieve = simpleSieve; +findPrime.fermatTest = fermatTest; +var BN = require('bn.js'); +var TWENTYFOUR = new BN(24); +var MillerRabin = require('miller-rabin'); +var millerRabin = new MillerRabin(); +var ONE = new BN(1); +var TWO = new BN(2); +var FIVE = new BN(5); +var SIXTEEN = new BN(16); +var EIGHT = new BN(8); +var TEN = new BN(10); +var THREE = new BN(3); +var SEVEN = new BN(7); +var ELEVEN = new BN(11); +var FOUR = new BN(4); +var TWELVE = new BN(12); +var primes = null; + +function _getPrimes() { + if (primes !== null) + return primes; + + var limit = 0x100000; + var res = []; + res[0] = 2; + for (var i = 1, k = 3; k < limit; k += 2) { + var sqrt = Math.ceil(Math.sqrt(k)); + for (var j = 0; j < i && res[j] <= sqrt; j++) + if (k % res[j] === 0) + break; + + if (i !== j && res[j] <= sqrt) + continue; + + res[i++] = k; + } + primes = res; + return res; +} + +function simpleSieve(p) { + var primes = _getPrimes(); + + for (var i = 0; i < primes.length; i++) + if (p.modn(primes[i]) === 0) { + if (p.cmpn(primes[i]) === 0) { + return true; + } else { + return false; + } + } + + return true; +} + +function fermatTest(p) { + var red = BN.mont(p); + return TWO.toRed(red).redPow(p.subn(1)).fromRed().cmpn(1) === 0; +} + +function findPrime(bits, gen) { + if (bits < 16) { + // this is what openssl does + if (gen === 2 || gen === 5) { + return new BN([0x8c, 0x7b]); + } else { + return new BN([0x8c, 0x27]); + } + } + gen = new BN(gen); + + var num, n2; + + while (true) { + num = new BN(randomBytes(Math.ceil(bits / 8))); + while (num.bitLength() > bits) { + num.ishrn(1); + } + if (num.isEven()) { + num.iadd(ONE); + } + if (!num.testn(1)) { + num.iadd(TWO); + } + if (!gen.cmp(TWO)) { + while (num.mod(TWENTYFOUR).cmp(ELEVEN)) { + num.iadd(FOUR); + } + } else if (!gen.cmp(FIVE)) { + while (num.mod(TEN).cmp(THREE)) { + num.iadd(FOUR); + } + } + n2 = num.shrn(1); + if (simpleSieve(n2) && simpleSieve(num) && + fermatTest(n2) && fermatTest(num) && + millerRabin.test(n2) && millerRabin.test(num)) { + return num; + } + } + +} |