diff options
author | Roberto Tyley <roberto.tyley@gmail.com> | 2014-07-15 01:38:01 +0400 |
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committer | Roberto Tyley <roberto.tyley@gmail.com> | 2014-07-26 11:23:17 +0400 |
commit | 7cb752aaf746dc0b473afeb9e892b7fbc12666c5 (patch) | |
tree | cc4f91ddc18332b5adbe82e3fcb040d976c90105 /core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java | |
parent | 551830f8ea5177042af2c7dd1fc90888bc67387d (diff) |
Execute become-spongy.sh
https://github.com/rtyley/spongycastle/blob/3040af/become-spongy.sh
Diffstat (limited to 'core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java')
-rw-r--r-- | core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java | 365 |
1 files changed, 0 insertions, 365 deletions
diff --git a/core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java b/core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java deleted file mode 100644 index 37298a1e..00000000 --- a/core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java +++ /dev/null @@ -1,365 +0,0 @@ -package org.bouncycastle.pqc.math.linearalgebra; - -import java.security.SecureRandom; - -/** - * This class describes operations with elements from the finite field F = - * GF(2^m). ( GF(2^m)= GF(2)[A] where A is a root of irreducible polynomial with - * degree m, each field element B has a polynomial basis representation, i.e. it - * is represented by a different binary polynomial of degree less than m, B = - * poly(A) ) All operations are defined only for field with 1< m <32. For the - * representation of field elements the map f: F->Z, poly(A)->poly(2) is used, - * where integers have the binary representation. For example: A^7+A^3+A+1 -> - * (00...0010001011)=139 Also for elements type Integer is used. - * - * @see PolynomialRingGF2 - */ -public class GF2mField -{ - - /* - * degree - degree of the field polynomial - the field polynomial ring - - * polynomial ring over the finite field GF(2) - */ - - private int degree = 0; - - private int polynomial; - - /** - * create a finite field GF(2^m) - * - * @param degree the degree of the field - */ - public GF2mField(int degree) - { - if (degree >= 32) - { - throw new IllegalArgumentException( - " Error: the degree of field is too large "); - } - if (degree < 1) - { - throw new IllegalArgumentException( - " Error: the degree of field is non-positive "); - } - this.degree = degree; - polynomial = PolynomialRingGF2.getIrreduciblePolynomial(degree); - } - - /** - * create a finite field GF(2^m) with the fixed field polynomial - * - * @param degree the degree of the field - * @param poly the field polynomial - */ - public GF2mField(int degree, int poly) - { - if (degree != PolynomialRingGF2.degree(poly)) - { - throw new IllegalArgumentException( - " Error: the degree is not correct"); - } - if (!PolynomialRingGF2.isIrreducible(poly)) - { - throw new IllegalArgumentException( - " Error: given polynomial is reducible"); - } - this.degree = degree; - polynomial = poly; - - } - - public GF2mField(byte[] enc) - { - if (enc.length != 4) - { - throw new IllegalArgumentException( - "byte array is not an encoded finite field"); - } - polynomial = LittleEndianConversions.OS2IP(enc); - if (!PolynomialRingGF2.isIrreducible(polynomial)) - { - throw new IllegalArgumentException( - "byte array is not an encoded finite field"); - } - - degree = PolynomialRingGF2.degree(polynomial); - } - - public GF2mField(GF2mField field) - { - degree = field.degree; - polynomial = field.polynomial; - } - - /** - * return degree of the field - * - * @return degree of the field - */ - public int getDegree() - { - return degree; - } - - /** - * return the field polynomial - * - * @return the field polynomial - */ - public int getPolynomial() - { - return polynomial; - } - - /** - * return the encoded form of this field - * - * @return the field in byte array form - */ - public byte[] getEncoded() - { - return LittleEndianConversions.I2OSP(polynomial); - } - - /** - * Return sum of two elements - * - * @param a - * @param b - * @return a+b - */ - public int add(int a, int b) - { - return a ^ b; - } - - /** - * Return product of two elements - * - * @param a - * @param b - * @return a*b - */ - public int mult(int a, int b) - { - return PolynomialRingGF2.modMultiply(a, b, polynomial); - } - - /** - * compute exponentiation a^k - * - * @param a a field element a - * @param k k degree - * @return a^k - */ - public int exp(int a, int k) - { - if (a == 0) - { - return 0; - } - if (a == 1) - { - return 1; - } - int result = 1; - if (k < 0) - { - a = inverse(a); - k = -k; - } - while (k != 0) - { - if ((k & 1) == 1) - { - result = mult(result, a); - } - a = mult(a, a); - k >>>= 1; - } - return result; - } - - /** - * compute the multiplicative inverse of a - * - * @param a a field element a - * @return a<sup>-1</sup> - */ - public int inverse(int a) - { - int d = (1 << degree) - 2; - - return exp(a, d); - } - - /** - * compute the square root of an integer - * - * @param a a field element a - * @return a<sup>1/2</sup> - */ - public int sqRoot(int a) - { - for (int i = 1; i < degree; i++) - { - a = mult(a, a); - } - return a; - } - - /** - * create a random field element using PRNG sr - * - * @param sr SecureRandom - * @return a random element - */ - public int getRandomElement(SecureRandom sr) - { - int result = RandUtils.nextInt(sr, 1 << degree); - return result; - } - - /** - * create a random non-zero field element - * - * @return a random element - */ - public int getRandomNonZeroElement() - { - return getRandomNonZeroElement(new SecureRandom()); - } - - /** - * create a random non-zero field element using PRNG sr - * - * @param sr SecureRandom - * @return a random non-zero element - */ - public int getRandomNonZeroElement(SecureRandom sr) - { - int controltime = 1 << 20; - int count = 0; - int result = RandUtils.nextInt(sr, 1 << degree); - while ((result == 0) && (count < controltime)) - { - result = RandUtils.nextInt(sr, 1 << degree); - count++; - } - if (count == controltime) - { - result = 1; - } - return result; - } - - /** - * @return true if e is encoded element of this field and false otherwise - */ - public boolean isElementOfThisField(int e) - { - // e is encoded element of this field iff 0<= e < |2^m| - if (degree == 31) - { - return e >= 0; - } - return e >= 0 && e < (1 << degree); - } - - /* - * help method for visual control - */ - public String elementToStr(int a) - { - String s = ""; - for (int i = 0; i < degree; i++) - { - if (((byte)a & 0x01) == 0) - { - s = "0" + s; - } - else - { - s = "1" + s; - } - a >>>= 1; - } - return s; - } - - /** - * checks if given object is equal to this field. - * <p> - * The method returns false whenever the given object is not GF2m. - * - * @param other object - * @return true or false - */ - public boolean equals(Object other) - { - if ((other == null) || !(other instanceof GF2mField)) - { - return false; - } - - GF2mField otherField = (GF2mField)other; - - if ((degree == otherField.degree) - && (polynomial == otherField.polynomial)) - { - return true; - } - - return false; - } - - public int hashCode() - { - return polynomial; - } - - /** - * Returns a human readable form of this field. - * - * @return a human readable form of this field. - */ - public String toString() - { - String str = "Finite Field GF(2^" + degree + ") = " + "GF(2)[X]/<" - + polyToString(polynomial) + "> "; - return str; - } - - private static String polyToString(int p) - { - String str = ""; - if (p == 0) - { - str = "0"; - } - else - { - byte b = (byte)(p & 0x01); - if (b == 1) - { - str = "1"; - } - p >>>= 1; - int i = 1; - while (p != 0) - { - b = (byte)(p & 0x01); - if (b == 1) - { - str = str + "+x^" + i; - } - p >>>= 1; - i++; - } - } - return str; - } - -} |