Example usage for java.math BigInteger subtract

Introduction

In this page you can find the example usage for java.math BigInteger subtract.

Prototype

public BigInteger subtract(BigInteger val) 

Source Link

Document

Returns a BigInteger whose value is (this - val) .

Usage

From source file:Main.java

public static BigInteger sqrt(final BigInteger val) {
    final BigInteger two = BigInteger.valueOf(2);
    BigInteger a = BigInteger.ONE.shiftLeft(val.bitLength() / 2);
    BigInteger b;//from w  ww  .  j a va2  s  . c  o m
    do {
        b = val.divide(a);
        a = (a.add(b)).divide(two);
    } while (a.subtract(b).abs().compareTo(two) >= 0);
    return a;
}

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From source file:jp.co.ntts.vhut.util.MacConversionUtil.java

/**
 * ????????.//from  w  w w .j a  v  a 2 s .  c  o m
 * @param macStart ()
 * @param macEnd ()
 * @return 
 */
public static int getCount(String macStart, String macEnd) {
    BigInteger biMacStart = new BigInteger(addrToByte(macStart));
    BigInteger biMacEnd = new BigInteger(addrToByte(macEnd));
    return biMacEnd.subtract(biMacStart).intValue() + 1;
}

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From source file:Main.java

static BigInteger inverseMod(BigInteger a, BigInteger b) {
    BigInteger b0 = b, t, q;/*w  ww .j  a va  2 s.c o m*/
    BigInteger x0 = BigInteger.ZERO, x1 = BigInteger.ONE;
    if (b.equals(BigInteger.ONE))
        return BigInteger.ONE;
    while (a.subtract(BigInteger.ONE).signum() > 0) {
        q = a.divide(b);
        t = b;
        b = a.mod(b);
        a = t;
        t = x0;
        x0 = x1.subtract(q.multiply(x0));
        x1 = t;
    }
    if (x1.signum() < 0)
        x1 = x1.add(b0);
    return x1;
}

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From source file:jp.co.ntts.vhut.util.MacConversionUtil.java

/**
 * ??????./*from ww w . jav a 2s. c  o m*/
 * @param mac 
 * @param macStart 
 * @return ?
 */
public static int getMacAddressOrder(String mac, String macStart) {
    BigInteger biMacTarget = new BigInteger(addrToByte(mac));
    BigInteger biMacStart = new BigInteger(addrToByte(macStart));
    return biMacTarget.subtract(biMacStart).intValue();
}

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From source file:Main.java

private static boolean passesMillerRabin(BigInteger us, int iterations, Random rnd) {
    final BigInteger ONE = BigInteger.ONE;
    final BigInteger TWO = BigInteger.valueOf(2);
    // Find a and m such that m is odd and this == 1 + 2**a * m
    BigInteger thisMinusOne = us.subtract(ONE);
    BigInteger m = thisMinusOne;/*from   ww  w. j  av  a  2s.  c o m*/
    int a = m.getLowestSetBit();
    m = m.shiftRight(a);

    // Do the tests
    if (rnd == null) {
        rnd = new SecureRandom();
    }
    for (int i = 0; i < iterations; i++) {
        // Generate a uniform random on (1, this)
        BigInteger b;
        do {
            b = new BigInteger(us.bitLength(), rnd);
        } while (b.compareTo(ONE) <= 0 || b.compareTo(us) >= 0);

        int j = 0;
        BigInteger z = b.modPow(m, us);
        while (!((j == 0 && z.equals(ONE)) || z.equals(thisMinusOne))) {
            if (j > 0 && z.equals(ONE) || ++j == a)
                return false;
            z = z.modPow(TWO, us);
        }
    }
    return true;
}

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From source file:com.offbynull.peernetic.common.identification.Id.java

/**
 * Adds two IDs together. The limit of the IDs must match.
 * @param lhs right-hand side/*from ww w  .  j a  v a2  s.  co m*/
 * @param rhs right-hand side
 * @return {@code lhs + rhs}, wrapped if it exceeds the limit
 * @throws NullPointerException if any argument is {@code null}
 * @throws IllegalArgumentException if the limit from {@code lhs} doesn't match the limit from {@code rhs}
 */
public static Id add(Id lhs, Id rhs) {
    Validate.notNull(lhs);
    Validate.notNull(rhs);
    Validate.isTrue(lhs.limit.equals(rhs.limit));

    BigInteger added = lhs.data.add(rhs.data);
    if (added.compareTo(lhs.limit) > 0) {
        added = added.subtract(lhs.limit).subtract(BigInteger.ONE);
    }

    Id addedId = new Id(added, lhs.limit);

    return addedId;
}

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From source file:com.og.elliptic.sdk.main.java

private static void elGamalString(WeierStrassCurve curve) {
    // Droulement de El Gamal
    // Cryptage/*  ww w  .j a  va2  s  .  c  om*/
    PointGMP generateur = new PointGMP(curve.getGx(), curve.getGy(), curve);// le point gnrateur qui servira  calculer notre clef
    // secrte
    Random rnd = new Random();

    BigInteger clefSecrete = BigInteger.probablePrime(7, rnd);
    PointGMP publicKey = generateur.mult(clefSecrete);// on calcule notre clef secrte, qui nous servira  crypter les messages (h)

    BigInteger m = new BigInteger(Base64.decodeBase64("bonjour lesil"));

    BigInteger k = BigInteger.probablePrime(7, rnd);// on choisit un k random

    PointGMP C1 = generateur.mult(k);// on multiplie le gnrateur par k
    PointGMP tmp = publicKey.mult(k);
    BigInteger C2 = m.add(tmp.getX());// on multiplie notre clef secrte par k

    // Dcryptage
    PointGMP temp = C1.mult(clefSecrete);// on multiplie C1 par notre clef secrte
    BigInteger messageTraduit = C2.subtract(temp.getX());// et on obtient le message en ajoutant m2 avec l'oppos de temp
    messageTraduit = messageTraduit.mod(curve.getP());

    if (m == messageTraduit)
        System.out.println("El Gamal fonctionnel");
    else
        System.out.println("El Gamal non fonctionnel");

    System.out.println("Message a retrouver " + m + " " + Base64.encodeBase64String(m.toByteArray()) + "\n");
    System.out.println("Resultat El gamal " + messageTraduit + " "
            + Base64.encodeBase64String(messageTraduit.toByteArray()) + "\n");

}

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From source file:Main.java

private static BigInteger findSquareRoot(BigInteger alpha, BigInteger p) {
    BigInteger beta = null;//from  w  w  w.ja  v  a  2 s  .c  o m
    if (p.mod(BigInteger.valueOf(4)).compareTo(BigInteger.valueOf(3)) == 0) {
        BigInteger k = p.shiftRight(2).add(ONE);
        beta = alpha.modPow(k, p);
    } else if (p.mod(BigInteger.valueOf(8)).compareTo(BigInteger.valueOf(5)) == 0) {
        System.out.println("p = 8 mod 5");
        BigInteger k = p.subtract(BigInteger.valueOf(5)).divide(BigInteger.valueOf(8));
        BigInteger gamma = alpha.multiply(BigInteger.valueOf(2)).modPow(k, p);
        BigInteger i = alpha.multiply(BigInteger.valueOf(2)).multiply(gamma.pow(2)).mod(p);
        beta = alpha.multiply(gamma).multiply(i.subtract(ONE)).mod(p);
    } else if (p.mod(BigInteger.valueOf(8)).compareTo(BigInteger.valueOf(1)) == 0) {
        beta = null;
        //TODO
        System.out.println("finding square root not fully implemented yet");
    }
    return beta;
}

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From source file:jp.co.ntts.vhut.util.Ipv4ConversionUtil.java

/**
 * ??IP???.//from  w  w w .  ja  va2  s . c o  m
 * @param startIpaddr (HEX/)
 * @param endIpaddr (HEX/)
 * @return IP?
 */
public static int getHostAddressCount(String startIpaddr, String endIpaddr) {
    BigInteger startBI = new BigInteger(addrTobyte(startIpaddr));
    BigInteger endBI = new BigInteger(addrTobyte(endIpaddr));
    return (int) Math.min(endBI.subtract(startBI).longValue() + 1, Integer.MAX_VALUE);
}

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From source file:jp.co.ntts.vhut.util.Ipv4ConversionUtil.java

/**
 * IP(HEX)????.//from w  w w . j  a  va  2s . c  o  m
 * ????int????????????.
 * @param startIpaddr (HEX/)
 * @param endIpaddr (HEX/)
 * @return IP(HEX)??
 */
public static Set<String> getIpAddressSetBetween(String startIpaddr, String endIpaddr) {
    BigInteger startBI = new BigInteger(addrTobyte(startIpaddr));
    BigInteger endBI = new BigInteger(addrTobyte(endIpaddr));
    int length = (int) Math.min(endBI.subtract(startBI).longValue(), Integer.MAX_VALUE);

    Set<String> resultSet = new HashSet<String>();

    BigInteger currentBI = startBI;

    for (int i = 0; i <= length; i++) {
        resultSet.add(byteToAddr(currentBI.toByteArray()));
        currentBI = currentBI.add(BigInteger.ONE);
    }

    return resultSet;
}

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