Java Code Examples for java.math.BigInteger#clearBit()

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if {@code rp} is null.
 * @exception IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if {@code rp} is null.
 * @exception IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if {@code rp} is null.
 * @exception IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

private BigInteger getMaskedAddress(boolean one) {
    BigInteger numAddress = netAddress;

    int numBits;
    if (isV4) {
        numBits = 32 - networkMask;
    } else {
        numBits = 128 - networkMask;
    }

    for (int i = 0; i < numBits; i++) {
        if (one)
            numAddress = numAddress.setBit(i);
        else
            numAddress = numAddress.clearBit(i);
    }
    return numAddress;
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if {@code rp} is null.
 * @exception IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if {@code rp} is null.
 * @exception IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

private BigInteger getMaskedAddress(boolean one) {
    BigInteger numAddress = netAddress;

    int numBits;
    if (isV4) {
        numBits = 32 - networkMask;
    } else {
        numBits = 128 - networkMask;
    }

    for (int i = 0; i < numBits; i++) {
        if (one)
            numAddress = numAddress.setBit(i);
        else
            numAddress = numAddress.clearBit(i);
    }
    return numAddress;
}
 

private BigInteger getMaskedAddress(boolean one) {
    BigInteger numAddress = netAddress;

    int numBits;
    if (isV4) {
        numBits = 32 - networkMask;
    } else {
        numBits = 128 - networkMask;
    }

    for (int i = 0; i < numBits; i++) {
        if (one)
            numAddress = numAddress.setBit(i);
        else
            numAddress = numAddress.clearBit(i);
    }
    return numAddress;
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if {@code rp} is null.
 * @exception IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if {@code rp} is null.
 * @exception IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^<code>m</code> elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on <code>rp</code> whose i-th bit correspondes to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^<code>m</code> + X^<code>k</code> + 1
 * with <code>m</code> > <code>k</code> >= 1) or a
 * pentanomial (X^<code>m</code> + X^<code>k3</code>
 * + X^<code>k2</code> + X^<code>k1</code> + 1 with
 * <code>m</code> > <code>k3</code> > <code>k2</code>
 * > <code>k1</code> >= 1).
 * @param m with 2^<code>m</code> being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if <code>rp</code> is null.
 * @exception IllegalArgumentException if <code>m</code>
 * is not positive, or <code>rp</code> does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if {@code rp} is null.
 * @exception IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @exception NullPointerException if {@code rp} is null.
 * @exception IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

/**
 * Creates an elliptic curve characteristic 2 finite
 * field which has 2^{@code m} elements with
 * polynomial basis.
 * The reduction polynomial for this field is based
 * on {@code rp} whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.<p>
 * Note: A valid reduction polynomial is either a
 * trinomial (X^{@code m} + X^{@code k} + 1
 * with {@code m} &gt; {@code k} &gt;= 1) or a
 * pentanomial (X^{@code m} + X^{@code k3}
 * + X^{@code k2} + X^{@code k1} + 1 with
 * {@code m} &gt; {@code k3} &gt; {@code k2}
 * &gt; {@code k1} &gt;= 1).
 * @param m with 2^{@code m} being the number of elements.
 * @param rp the BigInteger whose i-th bit corresponds to
 * the i-th coefficient of the reduction polynomial.
 * @throws    NullPointerException if {@code rp} is null.
 * @throws    IllegalArgumentException if {@code m}
 * is not positive, or {@code rp} does not represent
 * a valid reduction polynomial.
 */
public ECFieldF2m(int m, BigInteger rp) {
    // check m and rp
    this.m = m;
    this.rp = rp;
    if (m <= 0) {
        throw new IllegalArgumentException("m is not positive");
    }
    int bitCount = this.rp.bitCount();
    if (!this.rp.testBit(0) || !this.rp.testBit(m) ||
        ((bitCount != 3) && (bitCount != 5))) {
        throw new IllegalArgumentException
            ("rp does not represent a valid reduction polynomial");
    }
    // convert rp into ks
    BigInteger temp = this.rp.clearBit(0).clearBit(m);
    this.ks = new int[bitCount-2];
    for (int i = this.ks.length-1; i >= 0; i--) {
        int index = temp.getLowestSetBit();
        this.ks[i] = index;
        temp = temp.clearBit(index);
    }
}
 

/**
 * clearBit(int n) inside a positive number
 */
public void testClearBitPositiveInside4 () {
    byte aBytes[] = {1, -128, 56, 100, -2, -76, 89, 45, 91, 3, -15, 35, 26};
    int aSign = 1;
    int number = 50;
    byte rBytes[] = {1, -128, 56, 100, -2, -76, 89, 45, 91, 3, -15, 35, 26};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger result = aNumber.clearBit(number);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for(int i = 0; i < resBytes.length; i++) {
        assertTrue(resBytes[i] == rBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
}
 

/**
 * clearBit(int n) outside a positive number
 */
public void testClearBitPositiveOutside1() {
    byte aBytes[] = {1, -128, 56, 100, -2, -76, 89, 45, 91, 3, -15, 35, 26};
    int aSign = 1;
    int number = 150;
    byte rBytes[] = {1, -128, 56, 100, -2, -76, 89, 45, 91, 3, -15, 35, 26};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger result = aNumber.clearBit(number);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for(int i = 0; i < resBytes.length; i++) {
        assertTrue(resBytes[i] == rBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
}
 

/**
 * clearBit(int n) outside a positive number
 */
public void testClearBitPositiveOutside2() {
    byte aBytes[] = {1, -128, 56, 100, -2, -76, 89, 45, 91, 3, -15, 35, 26};
    int aSign = 1;
    int number = 191;
    byte rBytes[] = {1, -128, 56, 100, -2, -76, 89, 45, 91, 3, -15, 35, 26};
    BigInteger aNumber = new BigInteger(aSign, aBytes);
    BigInteger result = aNumber.clearBit(number);
    byte resBytes[] = new byte[rBytes.length];
    resBytes = result.toByteArray();
    for(int i = 0; i < resBytes.length; i++) {
        assertTrue(resBytes[i] == rBytes[i]);
    }
    assertEquals("incorrect sign", 1, result.signum());
}
 

/**
 * clearBit(2) in the negative number with all ones in bit representation
 */
public void testClearBitNegativeInside3() {
    String as = "-18446744073709551615";
    int number = 2;
    BigInteger aNumber = new BigInteger(as);
    BigInteger result = aNumber.clearBit(number);
    assertEquals(as, result.toString());
}
 

/**
 * Computes the <code>&tau;</code>-adic NAF (non-adjacent form) of an
 * element <code>&lambda;</code> of <code><b>Z</b>[&tau;]</code>.
 * @param mu The parameter <code>&mu;</code> of the elliptic curve.
 * @param lambda The element <code>&lambda;</code> of
 * <code><b>Z</b>[&tau;]</code>.
 * @return The <code>&tau;</code>-adic NAF of <code>&lambda;</code>.
 */
public static byte[] tauAdicNaf(byte mu, ZTauElement lambda)
{
    if (!((mu == 1) || (mu == -1)))
    {
        throw new IllegalArgumentException("mu must be 1 or -1");
    }
    
    BigInteger norm = norm(mu, lambda);

    // Ceiling of log2 of the norm 
    int log2Norm = norm.bitLength();

    // If length(TNAF) > 30, then length(TNAF) < log2Norm + 3.52
    int maxLength = log2Norm > 30 ? log2Norm + 4 : 34;

    // The array holding the TNAF
    byte[] u = new byte[maxLength];
    int i = 0;

    // The actual length of the TNAF
    int length = 0;

    BigInteger r0 = lambda.u;
    BigInteger r1 = lambda.v;

    while(!((r0.equals(ECConstants.ZERO)) && (r1.equals(ECConstants.ZERO))))
    {
        // If r0 is odd
        if (r0.testBit(0))
        {
            u[i] = (byte) ECConstants.TWO.subtract((r0.subtract(r1.shiftLeft(1))).mod(ECConstants.FOUR)).intValue();

            // r0 = r0 - u[i]
            if (u[i] == 1)
            {
                r0 = r0.clearBit(0);
            }
            else
            {
                // u[i] == -1
                r0 = r0.add(ECConstants.ONE);
            }
            length = i;
        }
        else
        {
            u[i] = 0;
        }

        BigInteger t = r0;
        BigInteger s = r0.shiftRight(1);
        if (mu == 1)
        {
            r0 = r1.add(s);
        }
        else
        {
            // mu == -1
            r0 = r1.subtract(s);
        }

        r1 = t.shiftRight(1).negate();
        i++;
    }

    length++;

    // Reduce the TNAF array to its actual length
    byte[] tnaf = new byte[length];
    System.arraycopy(u, 0, tnaf, 0, length);
    return tnaf;
}
 

@Override
BigInteger apply(BigInteger left, BigInteger right) {
  return left.clearBit(right.intValue());
}