Example usage for java.math BigInteger mod

Introduction

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

Prototype

public BigInteger mod(BigInteger m) 

Source Link

Document

Returns a BigInteger whose value is (this mod m ).

Usage

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

private static void elGamalString(WeierStrassCurve curve) {
    // Droulement de El Gamal
    // Cryptage/*from ww w. ja  va2s .c  o  m*/
    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

static BigInteger inverseMod(BigInteger a, BigInteger b) {
    BigInteger b0 = b, t, q;//w  ww  .j  av  a 2 s  .co  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:org.mozilla.gecko.sync.Utils.java

public static BigInteger generateBigIntegerLessThan(BigInteger r) {
    int maxBytes = (int) Math.ceil(((double) r.bitLength()) / 8);
    BigInteger randInt = new BigInteger(generateRandomBytes(maxBytes));
    return randInt.mod(r);
}

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From source file:com.amazonaws.services.kinesis.log4j.helpers.AmazonKinesisPutRecordsHelper.java

public static int calculateShardBucket(String partitionKey, int totalNumOfShards) {
    MessageDigest m = null;/*  ww  w  .ja  v a  2  s  .  c  o m*/
    int shardBucket = 1;
    try {
        m = MessageDigest.getInstance("MD5");
        m.reset();
        m.update(partitionKey.getBytes());
        byte[] digest = m.digest();
        BigInteger bigInt = new BigInteger(1, digest);
        shardBucket = bigInt.mod(BigInteger.valueOf(totalNumOfShards)).intValue() + 1;
    } catch (NoSuchAlgorithmException e) {
        //ignore
    }
    return shardBucket;
}

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From source file:burstcoin.jminer.core.round.Round.java

private static int calcScoopNumber(long blockNumber, byte[] generationSignature) {
    if (blockNumber > 0 && generationSignature != null) {
        ByteBuffer buf = ByteBuffer.allocate(32 + 8);
        buf.put(generationSignature);//from   ww w . j  a  v  a  2 s .  co  m
        buf.putLong(blockNumber);

        // generate new scoop number
        Shabal256 md = new Shabal256();
        md.update(buf.array());

        BigInteger hashnum = new BigInteger(1, md.digest());
        return hashnum.mod(BigInteger.valueOf(MiningPlot.SCOOPS_PER_PLOT)).intValue();
    }
    return 0;
}

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From source file:Main.java

public static BigInteger getZ(ArrayList<byte[]> c1, ArrayList<byte[]> c2, BigInteger p) {
    BigInteger z = BigInteger.ZERO;

    //TODO: make sure c1 and c2 are of the same size
    int size = c1.size();
    if (size > c2.size()) {
        size = c2.size();/*from   w w  w  .  j  a v  a  2 s  .co  m*/
    }

    for (int i = 0; i < size; i++) {
        BigInteger c1BI = new BigInteger(1, c1.get(i));
        BigInteger c2BI = new BigInteger(1, c2.get(i));
        BigInteger exp = new BigInteger(1, ByteBuffer.allocate(8).putLong((long) Math.pow(2, i)).array());

        z = z.add((c1BI.multiply(c2BI)).modPow(exp, p));
        Log.d("CeCk", "z calculation " + i + "/" + size + " round");
    }
    return z.mod(p);
}

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From source file:org.apache.pdfbox.pdmodel.encryption.StandardSecurityHandler.java

private static byte[] computeHash2B(byte[] input, byte[] password, byte[] userKey) throws IOException {
    try {//from   w  ww.  j av a 2 s  .  c o  m
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        byte[] k = md.digest(input);

        byte[] e = null;
        for (int round = 0; round < 64 || ((int) e[e.length - 1] & 0xFF) > round - 32; round++) {
            byte[] k1;
            if (userKey != null && userKey.length >= 48) {
                k1 = new byte[64 * (password.length + k.length + 48)];
            } else {
                k1 = new byte[64 * (password.length + k.length)];
            }

            int pos = 0;
            for (int i = 0; i < 64; i++) {
                System.arraycopy(password, 0, k1, pos, password.length);
                pos += password.length;
                System.arraycopy(k, 0, k1, pos, k.length);
                pos += k.length;
                if (userKey != null && userKey.length >= 48) {
                    System.arraycopy(userKey, 0, k1, pos, 48);
                    pos += 48;
                }
            }

            byte[] kFirst = new byte[16];
            byte[] kSecond = new byte[16];
            System.arraycopy(k, 0, kFirst, 0, 16);
            System.arraycopy(k, 16, kSecond, 0, 16);

            Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
            SecretKeySpec keySpec = new SecretKeySpec(kFirst, "AES");
            IvParameterSpec ivSpec = new IvParameterSpec(kSecond);
            cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);
            e = cipher.doFinal(k1);

            byte[] eFirst = new byte[16];
            System.arraycopy(e, 0, eFirst, 0, 16);
            BigInteger bi = new BigInteger(1, eFirst);
            BigInteger remainder = bi.mod(new BigInteger("3"));
            String nextHash = HASHES_2B[remainder.intValue()];

            md = MessageDigest.getInstance(nextHash);
            k = md.digest(e);
        }

        if (k.length > 32) {
            byte[] kTrunc = new byte[32];
            System.arraycopy(k, 0, kTrunc, 0, 32);
            return kTrunc;
        } else {
            return k;
        }
    } catch (GeneralSecurityException e) {
        logIfStrongEncryptionMissing();
        throw new IOException(e);
    }
}

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

/**
 * Generates a {@link Id}.// w  w  w  .j  a v a 2 s.  c om
 * @return a {@link Id} between {@code 0} and {@code limit}
 * @throws NullPointerException if any arguments are {@code null}
 */
public Id generate() {
    try {
        int rawLen = limit.length;
        byte[] raw = new byte[rawLen];
        random.nextBytes(raw);

        BigInteger rawBd = new BigInteger(1, raw);
        BigInteger limitBd = new BigInteger(1, limit);

        rawBd = rawBd.mod(limitBd);

        return new Id(rawBd.toByteArray(), limit);
    } catch (Exception e) {
        throw new IllegalStateException(e);
    }
}

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From source file:org.stem.domain.DHT.java

public int getSection(byte[] keyBytes) {
    BigInteger token = new BigInteger(new String(Hex.encodeHex(keyBytes)), 16);
    BigInteger sectionSize = capacity.divide(BigInteger.valueOf(sections));

    int quotient = token.divide(sectionSize).intValue();
    BigInteger mod = token.mod(sectionSize);
    int index;//from   w  ww  .j a  va2s.  c o  m
    if (quotient == 0)
        index = 0;
    else if (mod.equals(BigInteger.ZERO))
        index = Math.max(quotient - 1, 0);
    else
        index = Math.max(quotient, 0);

    if (index >= sections) {
        return sections - 1;
    }

    return index;
}

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From source file:org.trnltk.numeral.DigitsToTextConverter.java

private int getNthGroupNumber(BigInteger naturalNumber, int n) {
    naturalNumber = naturalNumber.divide(ONE_THOUSAND.pow(n));
    naturalNumber = naturalNumber.mod(ONE_THOUSAND);
    return naturalNumber.intValue();
}

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