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-rw-r--r--bcprov/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java369
1 files changed, 0 insertions, 369 deletions
diff --git a/bcprov/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java b/bcprov/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java
deleted file mode 100644
index f5f7b64..0000000
--- a/bcprov/src/main/java/org/bouncycastle/pqc/math/linearalgebra/GF2mField.java
+++ /dev/null
@@ -1,369 +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 (k == 0)
- {
- return 1;
- }
- 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;
- }
-
-}
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