public void testEncodeDecodeModQ()
{
int[] coeffs = PolynomialGenerator.GenerateRandom(1000, 2048).coeffs;
byte[] data = ArrayEncoder.EncodeModQ(coeffs, 2048);
int[] coeffs2 = ArrayEncoder.DecodeModQ(data, 1000, 2048);
Assert.True(coeffs.SequenceEqual(coeffs2));
}
private void EncodeDecodeModQ()
{
int[] coeffs = PolynomialGeneratorForTesting.generateRandomPositive(1000, 2048).Coeffs;
byte[] data = ArrayEncoder.EncodeModQ(coeffs, 2048);
int[] coeffs2 = ArrayEncoder.DecodeModQ(data, 1000, 2048);
if (!Compare.AreEqual(coeffs, coeffs2))
{
throw new Exception("ArrayEncoder EncodeDecodeModQ test failed!");
}
}
/**
* Decodes a byte array encoded with {@link #toBinary()} to a ploynomial.
*
* @param is an input stream containing an encoded polynomial
* @param N number of coefficients including zeros
* @param numOnes number of coefficients equal to 1
* @param numNegOnes number of coefficients equal to -1
* @return the decoded polynomial
* @throws IOException
*/
public static SparseTernaryPolynomial FromBinary(Stream stream, int N, int numOnes, int numNegOnes)
{
int maxIndex = 1 << BITS_PER_INDEX;
int bitsPerIndex = 32 - Integers.NumberOfLeadingZeros(maxIndex - 1);
int data1Len = (numOnes * bitsPerIndex + 7) / 8;
byte[] data1 = Util.Util.ReadFullLength(stream, data1Len);
int[] ones = ArrayEncoder.DecodeModQ(data1, numOnes, maxIndex);
int data2Len = (numNegOnes * bitsPerIndex + 7) / 8;
byte[] data2 = Util.Util.ReadFullLength(stream, data2Len);
int[] negOnes = ArrayEncoder.DecodeModQ(data2, numNegOnes, maxIndex);
return(new SparseTernaryPolynomial(N, ones, negOnes));
}
/// <summary>
/// Decodes a polynomial encoded with ToBinary()
/// </summary>
///
/// <param name="InputStream">An input stream containing an encoded polynomial</param>
/// <param name="N">Number of coefficients in the polynomial</param>
///
/// <returns>The decoded polynomial</returns>
public static SparseTernaryPolynomial FromBinary(MemoryStream InputStream, int N)
{
BinaryReader br = new BinaryReader(InputStream);
// number of coefficients equal to 1
int numOnes = IntUtils.ReadShort(InputStream);
// number of coefficients equal to -1
int numNegOnes = IntUtils.ReadShort(InputStream);
int maxIndex = 1 << BITS_PER_INDEX;
int bitsPerIndex = 32 - IntUtils.NumberOfLeadingZeros(maxIndex - 1);
int data1Len = (numOnes * bitsPerIndex + 7) / 8;
byte[] data1 = ArrayEncoder.ReadFullLength(InputStream, data1Len);
int[] ones = ArrayEncoder.DecodeModQ(data1, numOnes, maxIndex);
int data2Len = (numNegOnes * bitsPerIndex + 7) / 8;
byte[] data2 = ArrayEncoder.ReadFullLength(InputStream, data2Len);
int[] negOnes = ArrayEncoder.DecodeModQ(data2, numNegOnes, maxIndex);
return(new SparseTernaryPolynomial(N, ones, negOnes));
}
/**
* Returns a polynomial with N coefficients between <code>0</code> and <code>q-1</code>.<br>
* <code>q</code> must be a power of 2.<br>
* Ignores any excess bytes.
*
* @param is an encoded ternary polynomial
* @param N number of coefficients
* @param q
* @return the decoded polynomial
*/
public static IntegerPolynomial FromBinary(Stream stream, int N, int q)
{
return(new IntegerPolynomial(ArrayEncoder.DecodeModQ(stream, N, q)));
}
/**
* Returns a polynomial with N coefficients between <code>0</code> and <code>q-1</code>.<br>
* <code>q</code> must be a power of 2.<br>
* Ignores any excess bytes.
*
* @param data an encoded ternary polynomial
* @param N number of coefficients
* @param q
* @return the decoded polynomial
*/
public static IntegerPolynomial FromBinary(byte[] data, int N, int q)
{
return(new IntegerPolynomial(ArrayEncoder.DecodeModQ(data, N, q)));
}