Java Utililty Methods BigInteger is Prime

List of utility methods to do BigInteger is Prime

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Description

The list of methods to do BigInteger is Prime are organized into topic(s).

Method

BigIntegercalculateMPrime(BigInteger n, byte[] message)
Method taken (renamed) from SpongyCastle ECDSASigner class. 
if (n.bitLength() > message.length * 8) {
    return new BigInteger(1, message);
} else {
    int messageBitLength = message.length * 8;
    BigInteger trunc = new BigInteger(1, message);
    if (messageBitLength - n.bitLength() > 0) {
        trunc = trunc.shiftRight(messageBitLength - n.bitLength());
    return trunc;
BigIntegerfnvHash(final byte[] data, final BigInteger fnvOffs, final BigInteger fnvPrime, final BigInteger mod)
fnv Hash 
BigInteger hash = fnvOffs;
for (final byte next : data) {
    final BigInteger bigIntValue = BigInteger.valueOf(next & 0xff);
    hash = hash.xor(bigIntValue);
    hash = hash.multiply(fnvPrime).mod(mod);
return hash;
booleanhasSqrtModPrime(BigInteger r, BigInteger p)
has Sqrt Mod Prime 
BigInteger two = new BigInteger("2");
return r.modPow(p.subtract(BigInteger.ONE).divide(two), p).equals(BigInteger.ONE);
booleanisBigPrime(BigInteger number)
is Big Prime 
BigInteger random = createRandomInteger(number, new Random());
return testPrime(number, random);
booleanisCoprime(BigInteger a, BigInteger b)
Returns true if A and B are coprime. 
return a.gcd(b).equals(BigInteger.ONE);
booleanisFermatPrime(BigInteger f)
Fermat number deterministic primality test (Fermat number is an integer in the form Fn = 22^n + 1). 
if (f.signum() <= 0)
    return false;
if (f.bitLength() <= 31) {
    switch (f.intValue()) {
    case 3:
    case 5:
    case 17:
    case 257:
...
booleanisPrime(BigInteger value)
Checks if value is a prime number, 
if (value.signum() < 0) {
    throw new IllegalArgumentException("Only positive values permitted.");
BigInteger two = new BigInteger("2");
if (value.compareTo(two) < 0) {
    return false;
if (value.equals(two)) {
...
BooleanprimeProcessPart(BigInteger from)
prime Process Part 
return null;
BigIntegersqrtModPrime(BigInteger rSquare, BigInteger p)
sqrt Mod Prime 
BigInteger two = new BigInteger("2");
BigInteger z = two;
while (hasSqrtModPrime(z, p)) {
    z = z.add(BigInteger.ONE);
if (!hasSqrtModPrime(rSquare, p)) {
    throw new UnknownError("r has no square root");
} else {
...