public static void HashToEllipticCurve(ge_p3 res, byte[] key)
{
ge_p2 point = new ge_p2();
ge_p1p1 point2 = new ge_p1p1();
byte[] h = Keccak.Keccak1600(key);
ge_fromfe_frombytes_vartime(point, h);
ge_mul8(point2, point);
ge_p1p1_to_p3(res, point2);
}
public static byte[] ScalarmultKey(byte[] KeyImageA, byte[] KeyImageB)
{
ge_p3 A = new ge_p3();
ge_p2 R = new ge_p2();
ge_frombytes_vartime(A, KeyImageA);
ge_scalarmult(R, KeyImageB, A);
byte[] aP = new byte[32];
ge_tobytes(ref aP, R);
return(aP);
}
public static byte[] GenerateKeyImage(byte[] PublicKey, byte[] PrivateKey)
{
ge_p3 point = new ge_p3();
ge_p2 point2 = new ge_p2();
if (sc_check(PrivateKey) != 0)
{
return(null);
}
HashToEllipticCurve(point, PublicKey);
ge_scalarmult(point2, PrivateKey, point);
byte[] image = new byte[32];
ge_tobytes(ref image, point2);
return(image);
}
public static bool CheckSignature(byte[] PrefixHash, byte[] PublicKey, byte[] Signature)
{
// Create some ED25519 points
ge_p2 tmp2 = new ge_p2();
ge_p3 tmp3 = new ge_p3();
// Declare a few more variables
byte[] Comm = new byte[32];
byte[] SigBytes = new byte[64];
// Verify public key
if (ge_frombytes_vartime(tmp3, PublicKey) != 0)
{
return(false);
}
// Create a signature buffer from the given signature
HashBuffer Buffer = new HashBuffer(Signature);
// Verify signature bytes
if (sc_check(Buffer.A) != 0 || sc_check(Buffer.B) != 0)
{
return(false);
}
// Signature Part A
ge_double_scalarmult_base_vartime(tmp2, Buffer.A, tmp3, Buffer.B);
ge_tobytes(ref Comm, tmp2);
// Combine hashes and convert to a scalar
HashToScalar(ref SigBytes, PrefixHash.AppendBytes(PublicKey).AppendBytes(Comm));
// Perform final math
sc_sub(ref SigBytes, SigBytes, Signature);
// Return result
return(sc_isnonzero(SigBytes) == 0);
}
public static bool CheckRingSignatures(byte[] PrefixHash, byte[] KeyImage, byte[][] PublicKeys, byte[][] Signatures)
{
// Convert signature list to signature buffer array
HashBuffer[] SignaturesBuffer = new HashBuffer[Signatures.Length];
for (int i = 0; i < SignaturesBuffer.Length; i++)
{
SignaturesBuffer[i] = new HashBuffer(Signatures[i]);
}
// Create some ED25519 points
ge_p3 Image_Unp = new ge_p3();
ge_dsmp Image_Pre = new ge_dsmp();
// Declare a few more variables
byte[] Sum = new byte[32];
byte[] Hash = new byte[32];
// Create a signature buffer array
HashBuffer[] Buffer = new HashBuffer[PublicKeys.Length];
// Verify key image
if (ge_frombytes_vartime(Image_Unp, KeyImage) != 0)
{
return(false);
}
// Precomp
ge_dsm_precomp(ref Image_Pre, Image_Unp);
// Another check
if (ge_check_subgroup_precomp_vartime(Image_Pre) != 0)
{
return(false);
}
// Loop through all given signatures
for (int i = 0; i < PublicKeys.Length; i++)
{
// Assign a new signature buffer
Buffer[i] = new HashBuffer();
// Create temporary points
ge_p2 tmp2 = new ge_p2();
ge_p3 tmp3 = new ge_p3();
// Verify information
if (sc_check(SignaturesBuffer[i].A) != 0 || sc_check(SignaturesBuffer[i].B) != 0)
{
return(false);
}
if (ge_frombytes_vartime(tmp3, PublicKeys[i]) != 0)
{
return(false);
}
// Signature Part A
ge_double_scalarmult_base_vartime(tmp2, SignaturesBuffer[i].A, tmp3, SignaturesBuffer[i].B);
ge_tobytes(ref Buffer[i].A, tmp2);
// Convert public key to elliptic curve point
HashToEllipticCurve(tmp3, PublicKeys[i]);
// Signature Part B
ge_double_scalarmult_precomp_vartime(tmp2, SignaturesBuffer[i].B, tmp3, SignaturesBuffer[i].A, Image_Pre);
ge_tobytes(ref Buffer[i].B, tmp2);
// Add to sum
sc_add(ref Sum, Sum, SignaturesBuffer[i].A);
}
// Combine buffer and convert to a scalar
byte[] SigHash = PrefixHash;
for (int i = 0; i < Buffer.Length; i++)
{
SigHash = SigHash.AppendBytes(Buffer[i].Output);
}
HashToScalar(ref Hash, SigHash);
// Perform final math
sc_sub(ref Hash, Hash, Sum);
// Return result of final check
return(sc_isnonzero(Hash) == 0);
}
public static byte[][] GenerateRingSignatures(byte[] PrefixHash, byte[] KeyImage, byte[][] PublicKeys, byte[] TransactionSecretKey, ulong RealOutput)
{
// Create some ED25519 points
ge_p3 Image_Unp = new ge_p3();
ge_dsmp Image_Pre = new ge_dsmp();
// Declare a few more variables
byte[] Sum = new byte[32];
byte[] Scalar = new byte[32];
byte[] Hash = new byte[32];
// Create a signature buffer array and output array
HashBuffer[] Buffer = new HashBuffer[PublicKeys.Length];
HashBuffer[] Signatures = new HashBuffer[PublicKeys.Length];
// Verify key image
if (ge_frombytes_vartime(Image_Unp, KeyImage) != 0)
{
return(null);
}
// Precomp
ge_dsm_precomp(ref Image_Pre, Image_Unp);
// Loop through all given keys
for (ulong i = 0; i < (ulong)PublicKeys.Length; i++)
{
// Assign a new signature buffers
Buffer[i] = new HashBuffer();
Signatures[i] = new HashBuffer();
// Create temporary points
ge_p2 tmp2 = new ge_p2();
ge_p3 tmp3 = new ge_p3();
// This is the real output index
if (i == RealOutput)
{
// Generate a random scalar
random_scalar(ref Scalar);
//random_scalar(k);
ge_scalarmult_base(tmp3, Scalar);
//ge_scalarmult_base(tmp3, k);
// Signature Part A
ge_p3_tobytes(ref Buffer[i].A, tmp3);
//ge_p3_tobytes(reinterpret_cast < unsigned char *> (&buf->ab[i].a), &tmp3);
// Turn public key at this index into an elliptic curve, then multiply
HashToEllipticCurve(tmp3, PublicKeys[i]);
//hash_to_ec(publicKeys[i], tmp3);
ge_scalarmult(tmp2, Scalar, tmp3);
//ge_scalarmult(&tmp2, reinterpret_cast < unsigned char *> (&k), &tmp3);
// Signature Part B
ge_tobytes(ref Buffer[i].B, tmp2);
// ge_tobytes(reinterpret_cast < unsigned char *> (&buf->ab[i].b), &tmp2);
}
// This is a generated signature index
else
{
// Create a random scalar for both signature parts
random_scalar(ref Signatures[i].A);
random_scalar(ref Signatures[i].B);
// Get bytes from this public key (also verifies it)
if (ge_frombytes_vartime(tmp3, PublicKeys[i]) != 0)
{
return(null);
}
// Signature Part A
ge_double_scalarmult_base_vartime(tmp2, Signatures[i].A, tmp3, Signatures[i].B);
ge_tobytes(ref Buffer[i].A, tmp2);
// Convert public key to elliptic curve point
HashToEllipticCurve(tmp3, PublicKeys[i]);
// Signature Part B
ge_double_scalarmult_precomp_vartime(tmp2, Signatures[i].B, tmp3, Signatures[i].A, Image_Pre);
ge_tobytes(ref Buffer[i].B, tmp2);
// Add to sum
sc_add(ref Sum, Sum, Signatures[i].A);
}
}
// Combine buffer and convert to a scalar
byte[] SigHash = PrefixHash;
for (int i = 0; i < Buffer.Length; i++)
{
SigHash = SigHash.AppendBytes(Buffer[i].Output);
}
HashToScalar(ref Hash, SigHash);
// Perform final math
sc_sub(ref Signatures[RealOutput].A, Hash, Sum);
sc_mulsub(ref Signatures[RealOutput].B, Signatures[RealOutput].A, TransactionSecretKey, Scalar);
// Create an output array and return it
byte[][] Output = new byte[Signatures.Length][];
for (int i = 0; i < Signatures.Length; i++)
{
Output[i] = Signatures[i].Output;
}
return(Output);
}
