public byte[] Secp256K1Encrypt(Span <byte> recipientPublicKey, ReadOnlySpan <byte> plaintext)
{
var ephemeralPrivateKey = GeneratePrivateKey();
var ephemeralPublicKey = new byte[64];
var recipientPublicKeyParsed = new byte[64];
if (!Secp256K1.PublicKeyCreate(ephemeralPublicKey, ephemeralPrivateKey))
{
throw new Exception("Corrupted private key");
}
if (!Secp256K1.PublicKeyParse(recipientPublicKeyParsed, recipientPublicKey))
{
throw new Exception("Corrupted recipient public key");
}
var sessionKey = new byte[32];
if (!Secp256K1.Ecdh(sessionKey, recipientPublicKeyParsed, ephemeralPrivateKey))
{
throw new Exception("Ecdh failed");
}
var ephemeralPublicKeySerialized = new byte[33];
if (!Secp256K1.PublicKeySerialize(ephemeralPublicKeySerialized, ephemeralPublicKey,
Flags.SECP256K1_EC_COMPRESSED))
{
throw new Exception("Corrupted public key");
}
return(ephemeralPublicKeySerialized.Concat(AesGcmEncrypt(sessionKey, plaintext)).ToArray());
}
public static byte[] Ecdh(byte[] privateKey, byte[] publicKey)
{
try
{
Lock.AcquireWriterLock(Timeout.Infinite);
var usablePublicKey = new byte[Secp256k1.SERIALIZED_UNCOMPRESSED_PUBKEY_LENGTH];
Secp256K1.PublicKeyParse(usablePublicKey, publicKey);
var ecdhKey = new byte[Secp256k1.SERIALIZED_COMPRESSED_PUBKEY_LENGTH];
Secp256K1.Ecdh(ecdhKey, usablePublicKey, privateKey);
return(ecdhKey);
}
finally
{
Lock.ReleaseWriterLock();
}
}
public static byte[] Ecdh(byte[] privateKey, byte[] publicKey)
{
try
{
Lock.AcquireWriterLock(Timeout.Infinite);
var usablePublicKey = new byte[Secp256k1.SERIALIZED_UNCOMPRESSED_PUBKEY_LENGTH];
if (!Secp256K1.PublicKeyParse(usablePublicKey, publicKey))
{
throw new PublicKeyOperationException("Parse public key failed.");
}
var ecdhKey = new byte[Secp256k1.SERIALIZED_COMPRESSED_PUBKEY_LENGTH];
if (!Secp256K1.Ecdh(ecdhKey, usablePublicKey, privateKey))
{
throw new EcdhOperationException("Compute EC Diffie- secret failed.");
}
return(ecdhKey);
}
finally
{
Lock.ReleaseWriterLock();
}
}