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Diffstat (limited to 'core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2Polynomial.java')
-rw-r--r-- | core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2Polynomial.java | 2039 |
1 files changed, 0 insertions, 2039 deletions
diff --git a/core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2Polynomial.java b/core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2Polynomial.java deleted file mode 100644 index 3ef1fbbc..00000000 --- a/core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2Polynomial.java +++ /dev/null @@ -1,2039 +0,0 @@ -package org.bouncycastle.pqc.math.linearalgebra; - - -import java.math.BigInteger; -import java.util.Random; - - -/** - * This class stores very long strings of bits and does some basic arithmetics. - * It is used by <tt>GF2nField</tt>, <tt>GF2nPolynomialField</tt> and - * <tt>GFnPolynomialElement</tt>. - * - * @see GF2nPolynomialElement - * @see GF2nField - */ -public class GF2Polynomial -{ - - // number of bits stored in this GF2Polynomial - private int len; - - // number of int used in value - private int blocks; - - // storage - private int[] value; - - // Random source - private static Random rand = new Random(); - - // Lookup-Table for vectorMult: parity[a]= #1(a) mod 2 == 1 - private static final boolean[] parity = {false, true, true, false, true, - false, false, true, true, false, false, true, false, true, true, - false, true, false, false, true, false, true, true, false, false, - true, true, false, true, false, false, true, true, false, false, - true, false, true, true, false, false, true, true, false, true, - false, false, true, false, true, true, false, true, false, false, - true, true, false, false, true, false, true, true, false, true, - false, false, true, false, true, true, false, false, true, true, - false, true, false, false, true, false, true, true, false, true, - false, false, true, true, false, false, true, false, true, true, - false, false, true, true, false, true, false, false, true, true, - false, false, true, false, true, true, false, true, false, false, - true, false, true, true, false, false, true, true, false, true, - false, false, true, true, false, false, true, false, true, true, - false, false, true, true, false, true, false, false, true, false, - true, true, false, true, false, false, true, true, false, false, - true, false, true, true, false, false, true, true, false, true, - false, false, true, true, false, false, true, false, true, true, - false, true, false, false, true, false, true, true, false, false, - true, true, false, true, false, false, true, false, true, true, - false, true, false, false, true, true, false, false, true, false, - true, true, false, true, false, false, true, false, true, true, - false, false, true, true, false, true, false, false, true, true, - false, false, true, false, true, true, false, false, true, true, - false, true, false, false, true, false, true, true, false, true, - false, false, true, true, false, false, true, false, true, true, - false}; - - // Lookup-Table for Squaring: squaringTable[a]=a^2 - private static final short[] squaringTable = {0x0000, 0x0001, 0x0004, - 0x0005, 0x0010, 0x0011, 0x0014, 0x0015, 0x0040, 0x0041, 0x0044, - 0x0045, 0x0050, 0x0051, 0x0054, 0x0055, 0x0100, 0x0101, 0x0104, - 0x0105, 0x0110, 0x0111, 0x0114, 0x0115, 0x0140, 0x0141, 0x0144, - 0x0145, 0x0150, 0x0151, 0x0154, 0x0155, 0x0400, 0x0401, 0x0404, - 0x0405, 0x0410, 0x0411, 0x0414, 0x0415, 0x0440, 0x0441, 0x0444, - 0x0445, 0x0450, 0x0451, 0x0454, 0x0455, 0x0500, 0x0501, 0x0504, - 0x0505, 0x0510, 0x0511, 0x0514, 0x0515, 0x0540, 0x0541, 0x0544, - 0x0545, 0x0550, 0x0551, 0x0554, 0x0555, 0x1000, 0x1001, 0x1004, - 0x1005, 0x1010, 0x1011, 0x1014, 0x1015, 0x1040, 0x1041, 0x1044, - 0x1045, 0x1050, 0x1051, 0x1054, 0x1055, 0x1100, 0x1101, 0x1104, - 0x1105, 0x1110, 0x1111, 0x1114, 0x1115, 0x1140, 0x1141, 0x1144, - 0x1145, 0x1150, 0x1151, 0x1154, 0x1155, 0x1400, 0x1401, 0x1404, - 0x1405, 0x1410, 0x1411, 0x1414, 0x1415, 0x1440, 0x1441, 0x1444, - 0x1445, 0x1450, 0x1451, 0x1454, 0x1455, 0x1500, 0x1501, 0x1504, - 0x1505, 0x1510, 0x1511, 0x1514, 0x1515, 0x1540, 0x1541, 0x1544, - 0x1545, 0x1550, 0x1551, 0x1554, 0x1555, 0x4000, 0x4001, 0x4004, - 0x4005, 0x4010, 0x4011, 0x4014, 0x4015, 0x4040, 0x4041, 0x4044, - 0x4045, 0x4050, 0x4051, 0x4054, 0x4055, 0x4100, 0x4101, 0x4104, - 0x4105, 0x4110, 0x4111, 0x4114, 0x4115, 0x4140, 0x4141, 0x4144, - 0x4145, 0x4150, 0x4151, 0x4154, 0x4155, 0x4400, 0x4401, 0x4404, - 0x4405, 0x4410, 0x4411, 0x4414, 0x4415, 0x4440, 0x4441, 0x4444, - 0x4445, 0x4450, 0x4451, 0x4454, 0x4455, 0x4500, 0x4501, 0x4504, - 0x4505, 0x4510, 0x4511, 0x4514, 0x4515, 0x4540, 0x4541, 0x4544, - 0x4545, 0x4550, 0x4551, 0x4554, 0x4555, 0x5000, 0x5001, 0x5004, - 0x5005, 0x5010, 0x5011, 0x5014, 0x5015, 0x5040, 0x5041, 0x5044, - 0x5045, 0x5050, 0x5051, 0x5054, 0x5055, 0x5100, 0x5101, 0x5104, - 0x5105, 0x5110, 0x5111, 0x5114, 0x5115, 0x5140, 0x5141, 0x5144, - 0x5145, 0x5150, 0x5151, 0x5154, 0x5155, 0x5400, 0x5401, 0x5404, - 0x5405, 0x5410, 0x5411, 0x5414, 0x5415, 0x5440, 0x5441, 0x5444, - 0x5445, 0x5450, 0x5451, 0x5454, 0x5455, 0x5500, 0x5501, 0x5504, - 0x5505, 0x5510, 0x5511, 0x5514, 0x5515, 0x5540, 0x5541, 0x5544, - 0x5545, 0x5550, 0x5551, 0x5554, 0x5555}; - - // pre-computed Bitmask for fast masking, bitMask[a]=0x1 << a - private static final int[] bitMask = {0x00000001, 0x00000002, 0x00000004, - 0x00000008, 0x00000010, 0x00000020, 0x00000040, 0x00000080, - 0x00000100, 0x00000200, 0x00000400, 0x00000800, 0x00001000, - 0x00002000, 0x00004000, 0x00008000, 0x00010000, 0x00020000, - 0x00040000, 0x00080000, 0x00100000, 0x00200000, 0x00400000, - 0x00800000, 0x01000000, 0x02000000, 0x04000000, 0x08000000, - 0x10000000, 0x20000000, 0x40000000, 0x80000000, 0x00000000}; - - // pre-computed Bitmask for fast masking, rightMask[a]=0xffffffff >>> (32-a) - private static final int[] reverseRightMask = {0x00000000, 0x00000001, - 0x00000003, 0x00000007, 0x0000000f, 0x0000001f, 0x0000003f, - 0x0000007f, 0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff, - 0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff, 0x0000ffff, - 0x0001ffff, 0x0003ffff, 0x0007ffff, 0x000fffff, 0x001fffff, - 0x003fffff, 0x007fffff, 0x00ffffff, 0x01ffffff, 0x03ffffff, - 0x07ffffff, 0x0fffffff, 0x1fffffff, 0x3fffffff, 0x7fffffff, - 0xffffffff}; - - /** - * Creates a new GF2Polynomial of the given <i>length</i> and value zero. - * - * @param length the desired number of bits to store - */ - public GF2Polynomial(int length) - { - int l = length; - if (l < 1) - { - l = 1; - } - blocks = ((l - 1) >> 5) + 1; - value = new int[blocks]; - len = l; - } - - /** - * Creates a new GF2Polynomial of the given <i>length</i> and random value. - * - * @param length the desired number of bits to store - * @param rand SecureRandom to use for randomization - */ - public GF2Polynomial(int length, Random rand) - { - int l = length; - if (l < 1) - { - l = 1; - } - blocks = ((l - 1) >> 5) + 1; - value = new int[blocks]; - len = l; - randomize(rand); - } - - /** - * Creates a new GF2Polynomial of the given <i>length</i> and value - * selected by <i>value</i>: - * <UL> - * <LI>ZERO</LI> - * <LI>ONE</LI> - * <LI>RANDOM</LI> - * <LI>X</LI> - * <LI>ALL</LI> - * </UL> - * - * @param length the desired number of bits to store - * @param value the value described by a String - */ - public GF2Polynomial(int length, String value) - { - int l = length; - if (l < 1) - { - l = 1; - } - blocks = ((l - 1) >> 5) + 1; - this.value = new int[blocks]; - len = l; - if (value.equalsIgnoreCase("ZERO")) - { - assignZero(); - } - else if (value.equalsIgnoreCase("ONE")) - { - assignOne(); - } - else if (value.equalsIgnoreCase("RANDOM")) - { - randomize(); - } - else if (value.equalsIgnoreCase("X")) - { - assignX(); - } - else if (value.equalsIgnoreCase("ALL")) - { - assignAll(); - } - else - { - throw new IllegalArgumentException( - "Error: GF2Polynomial was called using " + value - + " as value!"); - } - - } - - /** - * Creates a new GF2Polynomial of the given <i>length</i> using the given - * int[]. LSB is contained in bs[0]. - * - * @param length the desired number of bits to store - * @param bs contains the desired value, LSB in bs[0] - */ - public GF2Polynomial(int length, int[] bs) - { - int leng = length; - if (leng < 1) - { - leng = 1; - } - blocks = ((leng - 1) >> 5) + 1; - value = new int[blocks]; - len = leng; - int l = Math.min(blocks, bs.length); - System.arraycopy(bs, 0, value, 0, l); - zeroUnusedBits(); - } - - /** - * Creates a new GF2Polynomial by converting the given byte[] <i>os</i> - * according to 1363 and using the given <i>length</i>. - * - * @param length the intended length of this polynomial - * @param os the octet string to assign to this polynomial - * @see "P1363 5.5.2 p22f, OS2BSP" - */ - public GF2Polynomial(int length, byte[] os) - { - int l = length; - if (l < 1) - { - l = 1; - } - blocks = ((l - 1) >> 5) + 1; - value = new int[blocks]; - len = l; - int i, m; - int k = Math.min(((os.length - 1) >> 2) + 1, blocks); - for (i = 0; i < k - 1; i++) - { - m = os.length - (i << 2) - 1; - value[i] = (os[m]) & 0x000000ff; - value[i] |= (os[m - 1] << 8) & 0x0000ff00; - value[i] |= (os[m - 2] << 16) & 0x00ff0000; - value[i] |= (os[m - 3] << 24) & 0xff000000; - } - i = k - 1; - m = os.length - (i << 2) - 1; - value[i] = os[m] & 0x000000ff; - if (m > 0) - { - value[i] |= (os[m - 1] << 8) & 0x0000ff00; - } - if (m > 1) - { - value[i] |= (os[m - 2] << 16) & 0x00ff0000; - } - if (m > 2) - { - value[i] |= (os[m - 3] << 24) & 0xff000000; - } - zeroUnusedBits(); - reduceN(); - } - - /** - * Creates a new GF2Polynomial by converting the given FlexiBigInt <i>bi</i> - * according to 1363 and using the given <i>length</i>. - * - * @param length the intended length of this polynomial - * @param bi the FlexiBigInt to assign to this polynomial - * @see "P1363 5.5.1 p22, I2BSP" - */ - public GF2Polynomial(int length, BigInteger bi) - { - int l = length; - if (l < 1) - { - l = 1; - } - blocks = ((l - 1) >> 5) + 1; - value = new int[blocks]; - len = l; - int i; - byte[] val = bi.toByteArray(); - if (val[0] == 0) - { - byte[] dummy = new byte[val.length - 1]; - System.arraycopy(val, 1, dummy, 0, dummy.length); - val = dummy; - } - int ov = val.length & 0x03; - int k = ((val.length - 1) >> 2) + 1; - for (i = 0; i < ov; i++) - { - value[k - 1] |= (val[i] & 0x000000ff) << ((ov - 1 - i) << 3); - } - int m = 0; - for (i = 0; i <= (val.length - 4) >> 2; i++) - { - m = val.length - 1 - (i << 2); - value[i] = (val[m]) & 0x000000ff; - value[i] |= ((val[m - 1]) << 8) & 0x0000ff00; - value[i] |= ((val[m - 2]) << 16) & 0x00ff0000; - value[i] |= ((val[m - 3]) << 24) & 0xff000000; - } - if ((len & 0x1f) != 0) - { - value[blocks - 1] &= reverseRightMask[len & 0x1f]; - } - reduceN(); - } - - /** - * Creates a new GF2Polynomial by cloneing the given GF2Polynomial <i>b</i>. - * - * @param b the GF2Polynomial to clone - */ - public GF2Polynomial(GF2Polynomial b) - { - len = b.len; - blocks = b.blocks; - value = IntUtils.clone(b.value); - } - - /** - * @return a copy of this GF2Polynomial - */ - public Object clone() - { - return new GF2Polynomial(this); - } - - /** - * Returns the length of this GF2Polynomial. The length can be greater than - * the degree. To get the degree call reduceN() before calling getLength(). - * - * @return the length of this GF2Polynomial - */ - public int getLength() - { - return len; - } - - /** - * Returns the value of this GF2Polynomial in an int[]. - * - * @return the value of this GF2Polynomial in a new int[], LSB in int[0] - */ - public int[] toIntegerArray() - { - int[] result; - result = new int[blocks]; - System.arraycopy(value, 0, result, 0, blocks); - return result; - } - - /** - * Returns a string representing this GF2Polynomials value using hexadecimal - * or binary radix in MSB-first order. - * - * @param radix the radix to use (2 or 16, otherwise 2 is used) - * @return a String representing this GF2Polynomials value. - */ - public String toString(int radix) - { - final char[] HEX_CHARS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', - '9', 'a', 'b', 'c', 'd', 'e', 'f'}; - final String[] BIN_CHARS = {"0000", "0001", "0010", "0011", "0100", - "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", - "1101", "1110", "1111"}; - String res; - int i; - res = new String(); - if (radix == 16) - { - for (i = blocks - 1; i >= 0; i--) - { - res += HEX_CHARS[(value[i] >>> 28) & 0x0f]; - res += HEX_CHARS[(value[i] >>> 24) & 0x0f]; - res += HEX_CHARS[(value[i] >>> 20) & 0x0f]; - res += HEX_CHARS[(value[i] >>> 16) & 0x0f]; - res += HEX_CHARS[(value[i] >>> 12) & 0x0f]; - res += HEX_CHARS[(value[i] >>> 8) & 0x0f]; - res += HEX_CHARS[(value[i] >>> 4) & 0x0f]; - res += HEX_CHARS[(value[i]) & 0x0f]; - res += " "; - } - } - else - { - for (i = blocks - 1; i >= 0; i--) - { - res += BIN_CHARS[(value[i] >>> 28) & 0x0f]; - res += BIN_CHARS[(value[i] >>> 24) & 0x0f]; - res += BIN_CHARS[(value[i] >>> 20) & 0x0f]; - res += BIN_CHARS[(value[i] >>> 16) & 0x0f]; - res += BIN_CHARS[(value[i] >>> 12) & 0x0f]; - res += BIN_CHARS[(value[i] >>> 8) & 0x0f]; - res += BIN_CHARS[(value[i] >>> 4) & 0x0f]; - res += BIN_CHARS[(value[i]) & 0x0f]; - res += " "; - } - } - return res; - } - - /** - * Converts this polynomial to a byte[] (octet string) according to 1363. - * - * @return a byte[] representing the value of this polynomial - * @see "P1363 5.5.2 p22f, BS2OSP" - */ - public byte[] toByteArray() - { - int k = ((len - 1) >> 3) + 1; - int ov = k & 0x03; - int m; - byte[] res = new byte[k]; - int i; - for (i = 0; i < (k >> 2); i++) - { - m = k - (i << 2) - 1; - res[m] = (byte)((value[i] & 0x000000ff)); - res[m - 1] = (byte)((value[i] & 0x0000ff00) >>> 8); - res[m - 2] = (byte)((value[i] & 0x00ff0000) >>> 16); - res[m - 3] = (byte)((value[i] & 0xff000000) >>> 24); - } - for (i = 0; i < ov; i++) - { - m = (ov - i - 1) << 3; - res[i] = (byte)((value[blocks - 1] & (0x000000ff << m)) >>> m); - } - return res; - } - - /** - * Converts this polynomial to an integer according to 1363. - * - * @return a FlexiBigInt representing the value of this polynomial - * @see "P1363 5.5.1 p22, BS2IP" - */ - public BigInteger toFlexiBigInt() - { - if (len == 0 || isZero()) - { - return new BigInteger(0, new byte[0]); - } - return new BigInteger(1, toByteArray()); - } - - /** - * Sets the LSB to 1 and all other to 0, assigning 'one' to this - * GF2Polynomial. - */ - public void assignOne() - { - int i; - for (i = 1; i < blocks; i++) - { - value[i] = 0x00; - } - value[0] = 0x01; - } - - /** - * Sets Bit 1 to 1 and all other to 0, assigning 'x' to this GF2Polynomial. - */ - public void assignX() - { - int i; - for (i = 1; i < blocks; i++) - { - value[i] = 0x00; - } - value[0] = 0x02; - } - - /** - * Sets all Bits to 1. - */ - public void assignAll() - { - int i; - for (i = 0; i < blocks; i++) - { - value[i] = 0xffffffff; - } - zeroUnusedBits(); - } - - /** - * Resets all bits to zero. - */ - public void assignZero() - { - int i; - for (i = 0; i < blocks; i++) - { - value[i] = 0x00; - } - } - - /** - * Fills all len bits of this GF2Polynomial with random values. - */ - public void randomize() - { - int i; - for (i = 0; i < blocks; i++) - { - value[i] = rand.nextInt(); - } - zeroUnusedBits(); - } - - /** - * Fills all len bits of this GF2Polynomial with random values using the - * specified source of randomness. - * - * @param rand the source of randomness - */ - public void randomize(Random rand) - { - int i; - for (i = 0; i < blocks; i++) - { - value[i] = rand.nextInt(); - } - zeroUnusedBits(); - } - - /** - * Returns true if two GF2Polynomials have the same size and value and thus - * are equal. - * - * @param other the other GF2Polynomial - * @return true if this GF2Polynomial equals <i>b</i> (<i>this</i> == - * <i>b</i>) - */ - public boolean equals(Object other) - { - if (other == null || !(other instanceof GF2Polynomial)) - { - return false; - } - - GF2Polynomial otherPol = (GF2Polynomial)other; - - if (len != otherPol.len) - { - return false; - } - for (int i = 0; i < blocks; i++) - { - if (value[i] != otherPol.value[i]) - { - return false; - } - } - return true; - } - - /** - * @return the hash code of this polynomial - */ - public int hashCode() - { - return len + value.hashCode(); - } - - /** - * Tests if all bits equal zero. - * - * @return true if this GF2Polynomial equals 'zero' (<i>this</i> == 0) - */ - public boolean isZero() - { - int i; - if (len == 0) - { - return true; - } - for (i = 0; i < blocks; i++) - { - if (value[i] != 0) - { - return false; - } - } - return true; - } - - /** - * Tests if all bits are reset to 0 and LSB is set to 1. - * - * @return true if this GF2Polynomial equals 'one' (<i>this</i> == 1) - */ - public boolean isOne() - { - int i; - for (i = 1; i < blocks; i++) - { - if (value[i] != 0) - { - return false; - } - } - if (value[0] != 0x01) - { - return false; - } - return true; - } - - /** - * Adds <i>b</i> to this GF2Polynomial and assigns the result to this - * GF2Polynomial. <i>b</i> can be of different size. - * - * @param b GF2Polynomial to add to this GF2Polynomial - */ - public void addToThis(GF2Polynomial b) - { - expandN(b.len); - xorThisBy(b); - } - - /** - * Adds two GF2Polynomials, <i>this</i> and <i>b</i>, and returns the - * result. <i>this</i> and <i>b</i> can be of different size. - * - * @param b a GF2Polynomial - * @return a new GF2Polynomial (<i>this</i> + <i>b</i>) - */ - public GF2Polynomial add(GF2Polynomial b) - { - return xor(b); - } - - /** - * Subtracts <i>b</i> from this GF2Polynomial and assigns the result to - * this GF2Polynomial. <i>b</i> can be of different size. - * - * @param b a GF2Polynomial - */ - public void subtractFromThis(GF2Polynomial b) - { - expandN(b.len); - xorThisBy(b); - } - - /** - * Subtracts two GF2Polynomials, <i>this</i> and <i>b</i>, and returns the - * result in a new GF2Polynomial. <i>this</i> and <i>b</i> can be of - * different size. - * - * @param b a GF2Polynomial - * @return a new GF2Polynomial (<i>this</i> - <i>b</i>) - */ - public GF2Polynomial subtract(GF2Polynomial b) - { - return xor(b); - } - - /** - * Toggles the LSB of this GF2Polynomial, increasing its value by 'one'. - */ - public void increaseThis() - { - xorBit(0); - } - - /** - * Toggles the LSB of this GF2Polynomial, increasing the value by 'one' and - * returns the result in a new GF2Polynomial. - * - * @return <tt>this + 1</tt> - */ - public GF2Polynomial increase() - { - GF2Polynomial result = new GF2Polynomial(this); - result.increaseThis(); - return result; - } - - /** - * Multiplies this GF2Polynomial with <i>b</i> and returns the result in a - * new GF2Polynomial. This method does not reduce the result in GF(2^N). - * This method uses classic multiplication (schoolbook). - * - * @param b a GF2Polynomial - * @return a new GF2Polynomial (<i>this</i> * <i>b</i>) - */ - public GF2Polynomial multiplyClassic(GF2Polynomial b) - { - GF2Polynomial result = new GF2Polynomial(Math.max(len, b.len) << 1); - GF2Polynomial[] m = new GF2Polynomial[32]; - int i, j; - m[0] = new GF2Polynomial(this); - for (i = 1; i <= 31; i++) - { - m[i] = m[i - 1].shiftLeft(); - } - for (i = 0; i < b.blocks; i++) - { - for (j = 0; j <= 31; j++) - { - if ((b.value[i] & bitMask[j]) != 0) - { - result.xorThisBy(m[j]); - } - } - for (j = 0; j <= 31; j++) - { - m[j].shiftBlocksLeft(); - } - } - return result; - } - - /** - * Multiplies this GF2Polynomial with <i>b</i> and returns the result in a - * new GF2Polynomial. This method does not reduce the result in GF(2^N). - * This method uses Karatzuba multiplication. - * - * @param b a GF2Polynomial - * @return a new GF2Polynomial (<i>this</i> * <i>b</i>) - */ - public GF2Polynomial multiply(GF2Polynomial b) - { - int n = Math.max(len, b.len); - expandN(n); - b.expandN(n); - return karaMult(b); - } - - /** - * Does the recursion for Karatzuba multiplication. - */ - private GF2Polynomial karaMult(GF2Polynomial b) - { - GF2Polynomial result = new GF2Polynomial(len << 1); - if (len <= 32) - { - result.value = mult32(value[0], b.value[0]); - return result; - } - if (len <= 64) - { - result.value = mult64(value, b.value); - return result; - } - if (len <= 128) - { - result.value = mult128(value, b.value); - return result; - } - if (len <= 256) - { - result.value = mult256(value, b.value); - return result; - } - if (len <= 512) - { - result.value = mult512(value, b.value); - return result; - } - - int n = IntegerFunctions.floorLog(len - 1); - n = bitMask[n]; - - GF2Polynomial a0 = lower(((n - 1) >> 5) + 1); - GF2Polynomial a1 = upper(((n - 1) >> 5) + 1); - GF2Polynomial b0 = b.lower(((n - 1) >> 5) + 1); - GF2Polynomial b1 = b.upper(((n - 1) >> 5) + 1); - - GF2Polynomial c = a1.karaMult(b1); // c = a1*b1 - GF2Polynomial e = a0.karaMult(b0); // e = a0*b0 - a0.addToThis(a1); // a0 = a0 + a1 - b0.addToThis(b1); // b0 = b0 + b1 - GF2Polynomial d = a0.karaMult(b0); // d = (a0+a1)*(b0+b1) - - result.shiftLeftAddThis(c, n << 1); - result.shiftLeftAddThis(c, n); - result.shiftLeftAddThis(d, n); - result.shiftLeftAddThis(e, n); - result.addToThis(e); - return result; - } - - /** - * 16-Integer Version of Karatzuba multiplication. - */ - private static int[] mult512(int[] a, int[] b) - { - int[] result = new int[32]; - int[] a0 = new int[8]; - System.arraycopy(a, 0, a0, 0, Math.min(8, a.length)); - int[] a1 = new int[8]; - if (a.length > 8) - { - System.arraycopy(a, 8, a1, 0, Math.min(8, a.length - 8)); - } - int[] b0 = new int[8]; - System.arraycopy(b, 0, b0, 0, Math.min(8, b.length)); - int[] b1 = new int[8]; - if (b.length > 8) - { - System.arraycopy(b, 8, b1, 0, Math.min(8, b.length - 8)); - } - int[] c = mult256(a1, b1); - result[31] ^= c[15]; - result[30] ^= c[14]; - result[29] ^= c[13]; - result[28] ^= c[12]; - result[27] ^= c[11]; - result[26] ^= c[10]; - result[25] ^= c[9]; - result[24] ^= c[8]; - result[23] ^= c[7] ^ c[15]; - result[22] ^= c[6] ^ c[14]; - result[21] ^= c[5] ^ c[13]; - result[20] ^= c[4] ^ c[12]; - result[19] ^= c[3] ^ c[11]; - result[18] ^= c[2] ^ c[10]; - result[17] ^= c[1] ^ c[9]; - result[16] ^= c[0] ^ c[8]; - result[15] ^= c[7]; - result[14] ^= c[6]; - result[13] ^= c[5]; - result[12] ^= c[4]; - result[11] ^= c[3]; - result[10] ^= c[2]; - result[9] ^= c[1]; - result[8] ^= c[0]; - a1[0] ^= a0[0]; - a1[1] ^= a0[1]; - a1[2] ^= a0[2]; - a1[3] ^= a0[3]; - a1[4] ^= a0[4]; - a1[5] ^= a0[5]; - a1[6] ^= a0[6]; - a1[7] ^= a0[7]; - b1[0] ^= b0[0]; - b1[1] ^= b0[1]; - b1[2] ^= b0[2]; - b1[3] ^= b0[3]; - b1[4] ^= b0[4]; - b1[5] ^= b0[5]; - b1[6] ^= b0[6]; - b1[7] ^= b0[7]; - int[] d = mult256(a1, b1); - result[23] ^= d[15]; - result[22] ^= d[14]; - result[21] ^= d[13]; - result[20] ^= d[12]; - result[19] ^= d[11]; - result[18] ^= d[10]; - result[17] ^= d[9]; - result[16] ^= d[8]; - result[15] ^= d[7]; - result[14] ^= d[6]; - result[13] ^= d[5]; - result[12] ^= d[4]; - result[11] ^= d[3]; - result[10] ^= d[2]; - result[9] ^= d[1]; - result[8] ^= d[0]; - int[] e = mult256(a0, b0); - result[23] ^= e[15]; - result[22] ^= e[14]; - result[21] ^= e[13]; - result[20] ^= e[12]; - result[19] ^= e[11]; - result[18] ^= e[10]; - result[17] ^= e[9]; - result[16] ^= e[8]; - result[15] ^= e[7] ^ e[15]; - result[14] ^= e[6] ^ e[14]; - result[13] ^= e[5] ^ e[13]; - result[12] ^= e[4] ^ e[12]; - result[11] ^= e[3] ^ e[11]; - result[10] ^= e[2] ^ e[10]; - result[9] ^= e[1] ^ e[9]; - result[8] ^= e[0] ^ e[8]; - result[7] ^= e[7]; - result[6] ^= e[6]; - result[5] ^= e[5]; - result[4] ^= e[4]; - result[3] ^= e[3]; - result[2] ^= e[2]; - result[1] ^= e[1]; - result[0] ^= e[0]; - return result; - } - - /** - * 8-Integer Version of Karatzuba multiplication. - */ - private static int[] mult256(int[] a, int[] b) - { - int[] result = new int[16]; - int[] a0 = new int[4]; - System.arraycopy(a, 0, a0, 0, Math.min(4, a.length)); - int[] a1 = new int[4]; - if (a.length > 4) - { - System.arraycopy(a, 4, a1, 0, Math.min(4, a.length - 4)); - } - int[] b0 = new int[4]; - System.arraycopy(b, 0, b0, 0, Math.min(4, b.length)); - int[] b1 = new int[4]; - if (b.length > 4) - { - System.arraycopy(b, 4, b1, 0, Math.min(4, b.length - 4)); - } - if (a1[3] == 0 && a1[2] == 0 && b1[3] == 0 && b1[2] == 0) - { - if (a1[1] == 0 && b1[1] == 0) - { - if (a1[0] != 0 || b1[0] != 0) - { // [3]=[2]=[1]=0, [0]!=0 - int[] c = mult32(a1[0], b1[0]); - result[9] ^= c[1]; - result[8] ^= c[0]; - result[5] ^= c[1]; - result[4] ^= c[0]; - } - } - else - { // [3]=[2]=0 [1]!=0, [0]!=0 - int[] c = mult64(a1, b1); - result[11] ^= c[3]; - result[10] ^= c[2]; - result[9] ^= c[1]; - result[8] ^= c[0]; - result[7] ^= c[3]; - result[6] ^= c[2]; - result[5] ^= c[1]; - result[4] ^= c[0]; - } - } - else - { // [3]!=0 [2]!=0 [1]!=0, [0]!=0 - int[] c = mult128(a1, b1); - result[15] ^= c[7]; - result[14] ^= c[6]; - result[13] ^= c[5]; - result[12] ^= c[4]; - result[11] ^= c[3] ^ c[7]; - result[10] ^= c[2] ^ c[6]; - result[9] ^= c[1] ^ c[5]; - result[8] ^= c[0] ^ c[4]; - result[7] ^= c[3]; - result[6] ^= c[2]; - result[5] ^= c[1]; - result[4] ^= c[0]; - } - a1[0] ^= a0[0]; - a1[1] ^= a0[1]; - a1[2] ^= a0[2]; - a1[3] ^= a0[3]; - b1[0] ^= b0[0]; - b1[1] ^= b0[1]; - b1[2] ^= b0[2]; - b1[3] ^= b0[3]; - int[] d = mult128(a1, b1); - result[11] ^= d[7]; - result[10] ^= d[6]; - result[9] ^= d[5]; - result[8] ^= d[4]; - result[7] ^= d[3]; - result[6] ^= d[2]; - result[5] ^= d[1]; - result[4] ^= d[0]; - int[] e = mult128(a0, b0); - result[11] ^= e[7]; - result[10] ^= e[6]; - result[9] ^= e[5]; - result[8] ^= e[4]; - result[7] ^= e[3] ^ e[7]; - result[6] ^= e[2] ^ e[6]; - result[5] ^= e[1] ^ e[5]; - result[4] ^= e[0] ^ e[4]; - result[3] ^= e[3]; - result[2] ^= e[2]; - result[1] ^= e[1]; - result[0] ^= e[0]; - return result; - } - - /** - * 4-Integer Version of Karatzuba multiplication. - */ - private static int[] mult128(int[] a, int[] b) - { - int[] result = new int[8]; - int[] a0 = new int[2]; - System.arraycopy(a, 0, a0, 0, Math.min(2, a.length)); - int[] a1 = new int[2]; - if (a.length > 2) - { - System.arraycopy(a, 2, a1, 0, Math.min(2, a.length - 2)); - } - int[] b0 = new int[2]; - System.arraycopy(b, 0, b0, 0, Math.min(2, b.length)); - int[] b1 = new int[2]; - if (b.length > 2) - { - System.arraycopy(b, 2, b1, 0, Math.min(2, b.length - 2)); - } - if (a1[1] == 0 && b1[1] == 0) - { - if (a1[0] != 0 || b1[0] != 0) - { - int[] c = mult32(a1[0], b1[0]); - result[5] ^= c[1]; - result[4] ^= c[0]; - result[3] ^= c[1]; - result[2] ^= c[0]; - } - } - else - { - int[] c = mult64(a1, b1); - result[7] ^= c[3]; - result[6] ^= c[2]; - result[5] ^= c[1] ^ c[3]; - result[4] ^= c[0] ^ c[2]; - result[3] ^= c[1]; - result[2] ^= c[0]; - } - a1[0] ^= a0[0]; - a1[1] ^= a0[1]; - b1[0] ^= b0[0]; - b1[1] ^= b0[1]; - if (a1[1] == 0 && b1[1] == 0) - { - int[] d = mult32(a1[0], b1[0]); - result[3] ^= d[1]; - result[2] ^= d[0]; - } - else - { - int[] d = mult64(a1, b1); - result[5] ^= d[3]; - result[4] ^= d[2]; - result[3] ^= d[1]; - result[2] ^= d[0]; - } - if (a0[1] == 0 && b0[1] == 0) - { - int[] e = mult32(a0[0], b0[0]); - result[3] ^= e[1]; - result[2] ^= e[0]; - result[1] ^= e[1]; - result[0] ^= e[0]; - } - else - { - int[] e = mult64(a0, b0); - result[5] ^= e[3]; - result[4] ^= e[2]; - result[3] ^= e[1] ^ e[3]; - result[2] ^= e[0] ^ e[2]; - result[1] ^= e[1]; - result[0] ^= e[0]; - } - return result; - } - - /** - * 2-Integer Version of Karatzuba multiplication. - */ - private static int[] mult64(int[] a, int[] b) - { - int[] result = new int[4]; - int a0 = a[0]; - int a1 = 0; - if (a.length > 1) - { - a1 = a[1]; - } - int b0 = b[0]; - int b1 = 0; - if (b.length > 1) - { - b1 = b[1]; - } - if (a1 != 0 || b1 != 0) - { - int[] c = mult32(a1, b1); - result[3] ^= c[1]; - result[2] ^= c[0] ^ c[1]; - result[1] ^= c[0]; - } - int[] d = mult32(a0 ^ a1, b0 ^ b1); - result[2] ^= d[1]; - result[1] ^= d[0]; - int[] e = mult32(a0, b0); - result[2] ^= e[1]; - result[1] ^= e[0] ^ e[1]; - result[0] ^= e[0]; - return result; - } - - /** - * 4-Byte Version of Karatzuba multiplication. Here the actual work is done. - */ - private static int[] mult32(int a, int b) - { - int[] result = new int[2]; - if (a == 0 || b == 0) - { - return result; - } - long b2 = b; - b2 &= 0x00000000ffffffffL; - int i; - long h = 0; - for (i = 1; i <= 32; i++) - { - if ((a & bitMask[i - 1]) != 0) - { - h ^= b2; - } - b2 <<= 1; - } - result[1] = (int)(h >>> 32); - result[0] = (int)(h & 0x00000000ffffffffL); - return result; - } - - /** - * Returns a new GF2Polynomial containing the upper <i>k</i> bytes of this - * GF2Polynomial. - * - * @param k - * @return a new GF2Polynomial containing the upper <i>k</i> bytes of this - * GF2Polynomial - * @see GF2Polynomial#karaMult - */ - private GF2Polynomial upper(int k) - { - int j = Math.min(k, blocks - k); - GF2Polynomial result = new GF2Polynomial(j << 5); - if (blocks >= k) - { - System.arraycopy(value, k, result.value, 0, j); - } - return result; - } - - /** - * Returns a new GF2Polynomial containing the lower <i>k</i> bytes of this - * GF2Polynomial. - * - * @param k - * @return a new GF2Polynomial containing the lower <i>k</i> bytes of this - * GF2Polynomial - * @see GF2Polynomial#karaMult - */ - private GF2Polynomial lower(int k) - { - GF2Polynomial result = new GF2Polynomial(k << 5); - System.arraycopy(value, 0, result.value, 0, Math.min(k, blocks)); - return result; - } - - /** - * Returns the remainder of <i>this</i> divided by <i>g</i> in a new - * GF2Polynomial. - * - * @param g GF2Polynomial != 0 - * @return a new GF2Polynomial (<i>this</i> % <i>g</i>) - * @throws PolynomialIsZeroException if <i>g</i> equals zero - */ - public GF2Polynomial remainder(GF2Polynomial g) - throws RuntimeException - { - /* a div b = q / r */ - GF2Polynomial a = new GF2Polynomial(this); - GF2Polynomial b = new GF2Polynomial(g); - GF2Polynomial j; - int i; - if (b.isZero()) - { - throw new RuntimeException(); - } - a.reduceN(); - b.reduceN(); - if (a.len < b.len) - { - return a; - } - i = a.len - b.len; - while (i >= 0) - { - j = b.shiftLeft(i); - a.subtractFromThis(j); - a.reduceN(); - i = a.len - b.len; - } - return a; - } - - /** - * Returns the absolute quotient of <i>this</i> divided by <i>g</i> in a - * new GF2Polynomial. - * - * @param g GF2Polynomial != 0 - * @return a new GF2Polynomial |_ <i>this</i> / <i>g</i> _| - * @throws PolynomialIsZeroException if <i>g</i> equals zero - */ - public GF2Polynomial quotient(GF2Polynomial g) - throws RuntimeException - { - /* a div b = q / r */ - GF2Polynomial q = new GF2Polynomial(len); - GF2Polynomial a = new GF2Polynomial(this); - GF2Polynomial b = new GF2Polynomial(g); - GF2Polynomial j; - int i; - if (b.isZero()) - { - throw new RuntimeException(); - } - a.reduceN(); - b.reduceN(); - if (a.len < b.len) - { - return new GF2Polynomial(0); - } - i = a.len - b.len; - q.expandN(i + 1); - - while (i >= 0) - { - j = b.shiftLeft(i); - a.subtractFromThis(j); - a.reduceN(); - q.xorBit(i); - i = a.len - b.len; - } - - return q; - } - - /** - * Divides <i>this</i> by <i>g</i> and returns the quotient and remainder - * in a new GF2Polynomial[2], quotient in [0], remainder in [1]. - * - * @param g GF2Polynomial != 0 - * @return a new GF2Polynomial[2] containing quotient and remainder - * @throws PolynomialIsZeroException if <i>g</i> equals zero - */ - public GF2Polynomial[] divide(GF2Polynomial g) - throws RuntimeException - { - /* a div b = q / r */ - GF2Polynomial[] result = new GF2Polynomial[2]; - GF2Polynomial q = new GF2Polynomial(len); - GF2Polynomial a = new GF2Polynomial(this); - GF2Polynomial b = new GF2Polynomial(g); - GF2Polynomial j; - int i; - if (b.isZero()) - { - throw new RuntimeException(); - } - a.reduceN(); - b.reduceN(); - if (a.len < b.len) - { - result[0] = new GF2Polynomial(0); - result[1] = a; - return result; - } - i = a.len - b.len; - q.expandN(i + 1); - - while (i >= 0) - { - j = b.shiftLeft(i); - a.subtractFromThis(j); - a.reduceN(); - q.xorBit(i); - i = a.len - b.len; - } - - result[0] = q; - result[1] = a; - return result; - } - - /** - * Returns the greatest common divisor of <i>this</i> and <i>g</i> in a - * new GF2Polynomial. - * - * @param g GF2Polynomial != 0 - * @return a new GF2Polynomial gcd(<i>this</i>,<i>g</i>) - * @throws ArithmeticException if <i>this</i> and <i>g</i> both are equal to zero - * @throws PolynomialIsZeroException to be API-compliant (should never be thrown). - */ - public GF2Polynomial gcd(GF2Polynomial g) - throws RuntimeException - { - if (isZero() && g.isZero()) - { - throw new ArithmeticException("Both operands of gcd equal zero."); - } - if (isZero()) - { - return new GF2Polynomial(g); - } - if (g.isZero()) - { - return new GF2Polynomial(this); - } - GF2Polynomial a = new GF2Polynomial(this); - GF2Polynomial b = new GF2Polynomial(g); - GF2Polynomial c; - - while (!b.isZero()) - { - c = a.remainder(b); - a = b; - b = c; - } - - return a; - } - - /** - * Checks if <i>this</i> is irreducible, according to IEEE P1363, A.5.5, - * p103.<br> - * Note: The algorithm from IEEE P1363, A5.5 can be used to check a - * polynomial with coefficients in GF(2^r) for irreducibility. As this class - * only represents polynomials with coefficients in GF(2), the algorithm is - * adapted to the case r=1. - * - * @return true if <i>this</i> is irreducible - * @see "P1363, A.5.5, p103" - */ - public boolean isIrreducible() - { - if (isZero()) - { - return false; - } - GF2Polynomial f = new GF2Polynomial(this); - int d, i; - GF2Polynomial u, g; - GF2Polynomial dummy; - f.reduceN(); - d = f.len - 1; - u = new GF2Polynomial(f.len, "X"); - - for (i = 1; i <= (d >> 1); i++) - { - u.squareThisPreCalc(); - u = u.remainder(f); - dummy = u.add(new GF2Polynomial(32, "X")); - if (!dummy.isZero()) - { - g = f.gcd(dummy); - if (!g.isOne()) - { - return false; - } - } - else - { - return false; - } - } - - return true; - } - - /** - * Reduces this GF2Polynomial using the trinomial x^<i>m</i> + x^<i>tc</i> + - * 1. - * - * @param m the degree of the used field - * @param tc degree of the middle x in the trinomial - */ - void reduceTrinomial(int m, int tc) - { - int i; - int p0, p1; - int q0, q1; - long t; - p0 = m >>> 5; // block which contains 2^m - q0 = 32 - (m & 0x1f); // (32-index) of 2^m within block p0 - p1 = (m - tc) >>> 5; // block which contains 2^tc - q1 = 32 - ((m - tc) & 0x1f); // (32-index) of 2^tc within block q1 - int max = ((m << 1) - 2) >>> 5; // block which contains 2^(2m-2) - int min = p0; // block which contains 2^m - for (i = max; i > min; i--) - { // for i = maxBlock to minBlock - // reduce coefficients contained in t - // t = block[i] - t = value[i] & 0x00000000ffffffffL; - // block[i-p0-1] ^= t << q0 - value[i - p0 - 1] ^= (int)(t << q0); - // block[i-p0] ^= t >>> (32-q0) - value[i - p0] ^= t >>> (32 - q0); - // block[i-p1-1] ^= << q1 - value[i - p1 - 1] ^= (int)(t << q1); - // block[i-p1] ^= t >>> (32-q1) - value[i - p1] ^= t >>> (32 - q1); - value[i] = 0x00; - } - // reduce last coefficients in block containing 2^m - t = value[min] & 0x00000000ffffffffL & (0xffffffffL << (m & 0x1f)); // t - // contains the last coefficients > m - value[0] ^= t >>> (32 - q0); - if (min - p1 - 1 >= 0) - { - value[min - p1 - 1] ^= (int)(t << q1); - } - value[min - p1] ^= t >>> (32 - q1); - - value[min] &= reverseRightMask[m & 0x1f]; - blocks = ((m - 1) >>> 5) + 1; - len = m; - } - - /** - * Reduces this GF2Polynomial using the pentanomial x^<i>m</i> + x^<i>pc[2]</i> + - * x^<i>pc[1]</i> + x^<i>pc[0]</i> + 1. - * - * @param m the degree of the used field - * @param pc degrees of the middle x's in the pentanomial - */ - void reducePentanomial(int m, int[] pc) - { - int i; - int p0, p1, p2, p3; - int q0, q1, q2, q3; - long t; - p0 = m >>> 5; - q0 = 32 - (m & 0x1f); - p1 = (m - pc[0]) >>> 5; - q1 = 32 - ((m - pc[0]) & 0x1f); - p2 = (m - pc[1]) >>> 5; - q2 = 32 - ((m - pc[1]) & 0x1f); - p3 = (m - pc[2]) >>> 5; - q3 = 32 - ((m - pc[2]) & 0x1f); - int max = ((m << 1) - 2) >>> 5; - int min = p0; - for (i = max; i > min; i--) - { - t = value[i] & 0x00000000ffffffffL; - value[i - p0 - 1] ^= (int)(t << q0); - value[i - p0] ^= t >>> (32 - q0); - value[i - p1 - 1] ^= (int)(t << q1); - value[i - p1] ^= t >>> (32 - q1); - value[i - p2 - 1] ^= (int)(t << q2); - value[i - p2] ^= t >>> (32 - q2); - value[i - p3 - 1] ^= (int)(t << q3); - value[i - p3] ^= t >>> (32 - q3); - value[i] = 0; - } - t = value[min] & 0x00000000ffffffffL & (0xffffffffL << (m & 0x1f)); - value[0] ^= t >>> (32 - q0); - if (min - p1 - 1 >= 0) - { - value[min - p1 - 1] ^= (int)(t << q1); - } - value[min - p1] ^= t >>> (32 - q1); - if (min - p2 - 1 >= 0) - { - value[min - p2 - 1] ^= (int)(t << q2); - } - value[min - p2] ^= t >>> (32 - q2); - if (min - p3 - 1 >= 0) - { - value[min - p3 - 1] ^= (int)(t << q3); - } - value[min - p3] ^= t >>> (32 - q3); - value[min] &= reverseRightMask[m & 0x1f]; - - blocks = ((m - 1) >>> 5) + 1; - len = m; - } - - /** - * Reduces len by finding the most significant bit set to one and reducing - * len and blocks. - */ - public void reduceN() - { - int i, j, h; - i = blocks - 1; - while ((value[i] == 0) && (i > 0)) - { - i--; - } - h = value[i]; - j = 0; - while (h != 0) - { - h >>>= 1; - j++; - } - len = (i << 5) + j; - blocks = i + 1; - } - - /** - * Expands len and int[] value to <i>i</i>. This is useful before adding - * two GF2Polynomials of different size. - * - * @param i the intended length - */ - public void expandN(int i) - { - int k; - int[] bs; - if (len >= i) - { - return; - } - len = i; - k = ((i - 1) >>> 5) + 1; - if (blocks >= k) - { - return; - } - if (value.length >= k) - { - int j; - for (j = blocks; j < k; j++) - { - value[j] = 0; - } - blocks = k; - return; - } - bs = new int[k]; - System.arraycopy(value, 0, bs, 0, blocks); - blocks = k; - value = null; - value = bs; - } - - /** - * Squares this GF2Polynomial and expands it accordingly. This method does - * not reduce the result in GF(2^N). There exists a faster method for - * squaring in GF(2^N). - * - * @see GF2nPolynomialElement#square - */ - public void squareThisBitwise() - { - int i, h, j, k; - if (isZero()) - { - return; - } - int[] result = new int[blocks << 1]; - for (i = blocks - 1; i >= 0; i--) - { - h = value[i]; - j = 0x00000001; - for (k = 0; k < 16; k++) - { - if ((h & 0x01) != 0) - { - result[i << 1] |= j; - } - if ((h & 0x00010000) != 0) - { - result[(i << 1) + 1] |= j; - } - j <<= 2; - h >>>= 1; - } - } - value = null; - value = result; - blocks = result.length; - len = (len << 1) - 1; - } - - /** - * Squares this GF2Polynomial by using precomputed values of squaringTable. - * This method does not reduce the result in GF(2^N). - */ - public void squareThisPreCalc() - { - int i; - if (isZero()) - { - return; - } - if (value.length >= (blocks << 1)) - { - for (i = blocks - 1; i >= 0; i--) - { - value[(i << 1) + 1] = GF2Polynomial.squaringTable[(value[i] & 0x00ff0000) >>> 16] - | (GF2Polynomial.squaringTable[(value[i] & 0xff000000) >>> 24] << 16); - value[i << 1] = GF2Polynomial.squaringTable[value[i] & 0x000000ff] - | (GF2Polynomial.squaringTable[(value[i] & 0x0000ff00) >>> 8] << 16); - } - blocks <<= 1; - len = (len << 1) - 1; - } - else - { - int[] result = new int[blocks << 1]; - for (i = 0; i < blocks; i++) - { - result[i << 1] = GF2Polynomial.squaringTable[value[i] & 0x000000ff] - | (GF2Polynomial.squaringTable[(value[i] & 0x0000ff00) >>> 8] << 16); - result[(i << 1) + 1] = GF2Polynomial.squaringTable[(value[i] & 0x00ff0000) >>> 16] - | (GF2Polynomial.squaringTable[(value[i] & 0xff000000) >>> 24] << 16); - } - value = null; - value = result; - blocks <<= 1; - len = (len << 1) - 1; - } - } - - /** - * Does a vector-multiplication modulo 2 and returns the result as boolean. - * - * @param b GF2Polynomial - * @return this x <i>b</i> as boolean (1->true, 0->false) - * @throws PolynomialsHaveDifferentLengthException if <i>this</i> and <i>b</i> have a different length and - * thus cannot be vector-multiplied - */ - public boolean vectorMult(GF2Polynomial b) - throws RuntimeException - { - int i; - int h; - boolean result = false; - if (len != b.len) - { - throw new RuntimeException(); - } - for (i = 0; i < blocks; i++) - { - h = value[i] & b.value[i]; - result ^= parity[h & 0x000000ff]; - result ^= parity[(h >>> 8) & 0x000000ff]; - result ^= parity[(h >>> 16) & 0x000000ff]; - result ^= parity[(h >>> 24) & 0x000000ff]; - } - return result; - } - - /** - * Returns the bitwise exclusive-or of <i>this</i> and <i>b</i> in a new - * GF2Polynomial. <i>this</i> and <i>b</i> can be of different size. - * - * @param b GF2Polynomial - * @return a new GF2Polynomial (<i>this</i> ^ <i>b</i>) - */ - public GF2Polynomial xor(GF2Polynomial b) - { - int i; - GF2Polynomial result; - int k = Math.min(blocks, b.blocks); - if (len >= b.len) - { - result = new GF2Polynomial(this); - for (i = 0; i < k; i++) - { - result.value[i] ^= b.value[i]; - } - } - else - { - result = new GF2Polynomial(b); - for (i = 0; i < k; i++) - { - result.value[i] ^= value[i]; - } - } - // If we xor'ed some bits too many by proceeding blockwise, - // restore them to zero: - result.zeroUnusedBits(); - return result; - } - - /** - * Computes the bitwise exclusive-or of this GF2Polynomial and <i>b</i> and - * stores the result in this GF2Polynomial. <i>b</i> can be of different - * size. - * - * @param b GF2Polynomial - */ - public void xorThisBy(GF2Polynomial b) - { - int i; - for (i = 0; i < Math.min(blocks, b.blocks); i++) - { - value[i] ^= b.value[i]; - } - // If we xor'ed some bits too many by proceeding blockwise, - // restore them to zero: - zeroUnusedBits(); - } - - /** - * If {@link #len} is not a multiple of the block size (32), some extra bits - * of the last block might have been modified during a blockwise operation. - * This method compensates for that by restoring these "extra" bits to zero. - */ - private void zeroUnusedBits() - { - if ((len & 0x1f) != 0) - { - value[blocks - 1] &= reverseRightMask[len & 0x1f]; - } - } - - /** - * Sets the bit at position <i>i</i>. - * - * @param i int - * @throws BitDoesNotExistException if (<i>i</i> < 0) || (<i>i</i> > (len - 1)) - */ - public void setBit(int i) - throws RuntimeException - { - if (i < 0 || i > (len - 1)) - { - throw new RuntimeException(); - } - if (i > (len - 1)) - { - return; - } - value[i >>> 5] |= bitMask[i & 0x1f]; - return; - } - - /** - * Returns the bit at position <i>i</i>. - * - * @param i int - * @return the bit at position <i>i</i> if <i>i</i> is a valid position, 0 - * otherwise. - */ - public int getBit(int i) - { - if (i < 0 || i > (len - 1)) - { - return 0; - } - return ((value[i >>> 5] & bitMask[i & 0x1f]) != 0) ? 1 : 0; - } - - /** - * Resets the bit at position <i>i</i>. - * - * @param i int - * @throws BitDoesNotExistException if (<i>i</i> < 0) || (<i>i</i> > (len - 1)) - */ - public void resetBit(int i) - throws RuntimeException - { - if (i < 0 || i > (len - 1)) - { - throw new RuntimeException(); - } - if (i > (len - 1)) - { - return; - } - value[i >>> 5] &= ~bitMask[i & 0x1f]; - } - - /** - * Xors the bit at position <i>i</i>. - * - * @param i int - * @throws BitDoesNotExistException if (<i>i</i> < 0) || (<i>i</i> > (len - 1)) - */ - public void xorBit(int i) - throws RuntimeException - { - if (i < 0 || i > (len - 1)) - { - throw new RuntimeException(); - } - if (i > (len - 1)) - { - return; - } - value[i >>> 5] ^= bitMask[i & 0x1f]; - } - - /** - * Tests the bit at position <i>i</i>. - * - * @param i the position of the bit to be tested - * @return true if the bit at position <i>i</i> is set (a(<i>i</i>) == - * 1). False if (<i>i</i> < 0) || (<i>i</i> > (len - 1)) - */ - public boolean testBit(int i) - { - if (i < 0 || i > (len - 1)) - { - return false; - } - return (value[i >>> 5] & bitMask[i & 0x1f]) != 0; - } - - /** - * Returns this GF2Polynomial shift-left by 1 in a new GF2Polynomial. - * - * @return a new GF2Polynomial (this << 1) - */ - public GF2Polynomial shiftLeft() - { - GF2Polynomial result = new GF2Polynomial(len + 1, value); - int i; - for (i = result.blocks - 1; i >= 1; i--) - { - result.value[i] <<= 1; - result.value[i] |= result.value[i - 1] >>> 31; - } - result.value[0] <<= 1; - return result; - } - - /** - * Shifts-left this by one and enlarges the size of value if necesary. - */ - public void shiftLeftThis() - { - /** @todo This is untested. */ - int i; - if ((len & 0x1f) == 0) - { // check if blocks increases - len += 1; - blocks += 1; - if (blocks > value.length) - { // enlarge value - int[] bs = new int[blocks]; - System.arraycopy(value, 0, bs, 0, value.length); - value = null; - value = bs; - } - for (i = blocks - 1; i >= 1; i--) - { - value[i] |= value[i - 1] >>> 31; - value[i - 1] <<= 1; - } - } - else - { - len += 1; - for (i = blocks - 1; i >= 1; i--) - { - value[i] <<= 1; - value[i] |= value[i - 1] >>> 31; - } - value[0] <<= 1; - } - } - - /** - * Returns this GF2Polynomial shift-left by <i>k</i> in a new - * GF2Polynomial. - * - * @param k int - * @return a new GF2Polynomial (this << <i>k</i>) - */ - public GF2Polynomial shiftLeft(int k) - { - // Variant 2, requiring a modified shiftBlocksLeft(k) - // In case of modification, consider a rename to doShiftBlocksLeft() - // with an explicit note that this method assumes that the polynomial - // has already been resized. Or consider doing things inline. - // Construct the resulting polynomial of appropriate length: - GF2Polynomial result = new GF2Polynomial(len + k, value); - // Shift left as many multiples of the block size as possible: - if (k >= 32) - { - result.doShiftBlocksLeft(k >>> 5); - } - // Shift left by the remaining (<32) amount: - final int remaining = k & 0x1f; - if (remaining != 0) - { - for (int i = result.blocks - 1; i >= 1; i--) - { - result.value[i] <<= remaining; - result.value[i] |= result.value[i - 1] >>> (32 - remaining); - } - result.value[0] <<= remaining; - } - return result; - } - - /** - * Shifts left b and adds the result to Its a fast version of - * <tt>this = add(b.shl(k));</tt> - * - * @param b GF2Polynomial to shift and add to this - * @param k the amount to shift - * @see GF2nPolynomialElement#invertEEA - */ - public void shiftLeftAddThis(GF2Polynomial b, int k) - { - if (k == 0) - { - addToThis(b); - return; - } - int i; - expandN(b.len + k); - int d = k >>> 5; - for (i = b.blocks - 1; i >= 0; i--) - { - if ((i + d + 1 < blocks) && ((k & 0x1f) != 0)) - { - value[i + d + 1] ^= b.value[i] >>> (32 - (k & 0x1f)); - } - value[i + d] ^= b.value[i] << (k & 0x1f); - } - } - - /** - * Shifts-left this GF2Polynomial's value blockwise 1 block resulting in a - * shift-left by 32. - * - * @see GF2Polynomial#multiply - */ - void shiftBlocksLeft() - { - blocks += 1; - len += 32; - if (blocks <= value.length) - { - int i; - for (i = blocks - 1; i >= 1; i--) - { - value[i] = value[i - 1]; - } - value[0] = 0x00; - } - else - { - int[] result = new int[blocks]; - System.arraycopy(value, 0, result, 1, blocks - 1); - value = null; - value = result; - } - } - - /** - * Shifts left this GF2Polynomial's value blockwise <i>b</i> blocks - * resulting in a shift-left by b*32. This method assumes that {@link #len} - * and {@link #blocks} have already been updated to reflect the final state. - * - * @param b shift amount (in blocks) - */ - private void doShiftBlocksLeft(int b) - { - if (blocks <= value.length) - { - int i; - for (i = blocks - 1; i >= b; i--) - { - value[i] = value[i - b]; - } - for (i = 0; i < b; i++) - { - value[i] = 0x00; - } - } - else - { - int[] result = new int[blocks]; - System.arraycopy(value, 0, result, b, blocks - b); - value = null; - value = result; - } - } - - /** - * Returns this GF2Polynomial shift-right by 1 in a new GF2Polynomial. - * - * @return a new GF2Polynomial (this << 1) - */ - public GF2Polynomial shiftRight() - { - GF2Polynomial result = new GF2Polynomial(len - 1); - int i; - System.arraycopy(value, 0, result.value, 0, result.blocks); - for (i = 0; i <= result.blocks - 2; i++) - { - result.value[i] >>>= 1; - result.value[i] |= result.value[i + 1] << 31; - } - result.value[result.blocks - 1] >>>= 1; - if (result.blocks < blocks) - { - result.value[result.blocks - 1] |= value[result.blocks] << 31; - } - return result; - } - - /** - * Shifts-right this GF2Polynomial by 1. - */ - public void shiftRightThis() - { - int i; - len -= 1; - blocks = ((len - 1) >>> 5) + 1; - for (i = 0; i <= blocks - 2; i++) - { - value[i] >>>= 1; - value[i] |= value[i + 1] << 31; - } - value[blocks - 1] >>>= 1; - if ((len & 0x1f) == 0) - { - value[blocks - 1] |= value[blocks] << 31; - } - } - -} |