/// <summary>
/// Generate an encryption Key pair
/// </summary>
///
/// <returns>A McElieceKeyPair containing public and private keys</returns>
public IAsymmetricKeyPair GenerateKeyPair()
{
// finite field GF(2^m)
GF2mField field = new GF2mField(_M, _fieldPoly);
// irreducible Goppa polynomial
PolynomialGF2mSmallM gp = new PolynomialGF2mSmallM(field, _T, PolynomialGF2mSmallM.RANDOM_IRREDUCIBLE_POLYNOMIAL, _rngEngine);
PolynomialRingGF2m ring = new PolynomialRingGF2m(field, gp);
// matrix for computing square roots in (GF(2^m))^t
PolynomialGF2mSmallM[] qInv = ring.SquareRootMatrix;
// generate canonical check matrix
GF2Matrix h = GoppaCode.CreateCanonicalCheckMatrix(field, gp);
// compute short systematic form of check matrix
GoppaCode.MaMaPe mmp = GoppaCode.ComputeSystematicForm(h, _rngEngine);
GF2Matrix shortH = mmp.SecondMatrix;
Permutation p = mmp.Permutation;
// compute short systematic form of generator matrix
GF2Matrix shortG = (GF2Matrix)shortH.ComputeTranspose();
// obtain number of rows of G (= dimension of the code)
int k = shortG.RowCount;
// generate keys
IAsymmetricKey pubKey = new MPKCPublicKey(_N, _T, shortG);
IAsymmetricKey privKey = new MPKCPrivateKey(_N, k, field, gp, p, h, qInv);
// return key pair
return(new MPKCKeyPair(pubKey, privKey));
}
/// <summary>
/// Read a Public key from a stream
/// </summary>
///
/// <param name="KeyStream">The stream containing the key</param>
///
/// <returns>An initialized MPKCPublicKey class</returns>
///
/// <exception cref="MPKCException">Thrown if the stream can not be read</exception>
public static MPKCPublicKey From(Stream KeyStream)
{
try
{
BinaryReader reader = new BinaryReader(KeyStream);
int n = reader.ReadInt32();
int t = reader.ReadInt32();
byte[] encG = reader.ReadBytes((int)(reader.BaseStream.Length - reader.BaseStream.Position));
MPKCPublicKey pubKey = new MPKCPublicKey(t, n, encG);
return(pubKey);
}
catch (Exception ex)
{
throw new MPKCException("MPKCPublicKey:Ctor", ex.Message, ex);
}
}
/// <summary>
/// Initialize the cipher.
/// <para>Requires a <see cref="MPKCPublicKey"/> for encryption, or a <see cref="MPKCPrivateKey"/> for decryption</para>
/// </summary>
///
/// <param name="Encryption">When true cipher is for encryption, if false, decryption</param>
/// <param name="KeyPair">The <see cref="IAsymmetricKeyPair"/> containing the McEliece public or private key</param>
///
/// <exception cref="MPKCException">Thrown if the cipher is not initialized or the key is invalid</exception>
public void Initialize(bool Encryption, IAsymmetricKeyPair KeyPair)
{
if (!(KeyPair is MPKCKeyPair))
{
throw new MPKCException("MPKCEncrypt:Initialize", "Not a valid McEliece key pair!", new InvalidOperationException());
}
// init implementation engine
_encEngine.Initialize(Encryption, KeyPair);
// get the sizes
if (Encryption)
{
if (KeyPair.PublicKey == null)
{
throw new MPKCException("MPKCEncrypt:Initialize", "Encryption requires a public key!", new InvalidOperationException());
}
if (!(KeyPair.PublicKey is MPKCPublicKey))
{
throw new MPKCException("MPKCEncrypt:Initialize", "The public key is invalid!", new ArgumentException());
}
MPKCPublicKey pub = (MPKCPublicKey)KeyPair.PublicKey;
_maxCipherText = pub.N >> 3;
_maxPlainText = pub.K >> 3;
}
else
{
if (KeyPair.PrivateKey == null)
{
throw new MPKCException("MPKCEncrypt:Initialize", "Decryption requires a private key!", new InvalidOperationException());
}
if (!(KeyPair.PrivateKey is MPKCPrivateKey))
{
throw new MPKCException("MPKCEncrypt:Initialize", "The private key is invalid!", new ArgumentException());
}
MPKCPrivateKey pri = (MPKCPrivateKey)KeyPair.PrivateKey;
_maxPlainText = pri.K >> 3;
_maxCipherText = pri.N >> 3;
}
_isInitialized = true;
}
/// <summary>
/// Decides whether the given object <c>other</c> is the same as this field
/// </summary>
///
/// <param name="Obj">The object for comparison</param>
///
/// <returns>Returns <c>(this == other)</c></returns>
public override bool Equals(Object Obj)
{
if (Obj == null || !(Obj is MPKCPublicKey))
{
return(false);
}
MPKCPublicKey key = (MPKCPublicKey)Obj;
if (N != key.N)
{
return(false);
}
if (T != key.T)
{
return(false);
}
if (!G.Equals(key.G))
{
return(false);
}
return(true);
}
/// <summary>
/// Read a Public key from a stream
/// </summary>
///
/// <param name="KeyStream">The stream containing the key</param>
///
/// <returns>An initialized MPKCPublicKey class</returns>
///
/// <exception cref="MPKCException">Thrown if the stream can not be read</exception>
public static MPKCPublicKey From(Stream KeyStream)
{
try
{
BinaryReader reader = new BinaryReader(KeyStream);
int n = reader.ReadInt32();
int t = reader.ReadInt32();
byte[] encG = reader.ReadBytes((int)(reader.BaseStream.Length - reader.BaseStream.Position));
MPKCPublicKey pubKey = new MPKCPublicKey(t, n, encG);
return pubKey;
}
catch (Exception ex)
{
throw new MPKCException("MPKCPublicKey:Ctor", ex.Message, ex);
}
}
/// <summary>
/// Generate an encryption Key pair
/// </summary>
///
/// <returns>A McElieceKeyPair containing public and private keys</returns>
public IAsymmetricKeyPair GenerateKeyPair()
{
// finite field GF(2^m)
GF2mField field = new GF2mField(_M, _fieldPoly);
// irreducible Goppa polynomial
PolynomialGF2mSmallM gp = new PolynomialGF2mSmallM(field, _T, PolynomialGF2mSmallM.RANDOM_IRREDUCIBLE_POLYNOMIAL, _rngEngine);
PolynomialRingGF2m ring = new PolynomialRingGF2m(field, gp);
// matrix for computing square roots in (GF(2^m))^t
PolynomialGF2mSmallM[] qInv = ring.SquareRootMatrix;
// generate canonical check matrix
GF2Matrix h = GoppaCode.CreateCanonicalCheckMatrix(field, gp);
// compute short systematic form of check matrix
GoppaCode.MaMaPe mmp = GoppaCode.ComputeSystematicForm(h, _rngEngine);
GF2Matrix shortH = mmp.SecondMatrix;
Permutation p = mmp.Permutation;
// compute short systematic form of generator matrix
GF2Matrix shortG = (GF2Matrix)shortH.ComputeTranspose();
// obtain number of rows of G (= dimension of the code)
int k = shortG.RowCount;
// generate keys
IAsymmetricKey pubKey = new MPKCPublicKey(_N, _T, shortG);
IAsymmetricKey privKey = new MPKCPrivateKey(_N, k, field, gp, p, h, qInv);
// return key pair
return new MPKCKeyPair(pubKey, privKey);
}
