Change signer.Init(forEncryption: to false.
MODIFY
HiddenWallet/Crypto/BlindingRsaKey.cs
HiddenWallet/Crypto/BlindingRsaKey.cs
@@ -65,7 +65,7 @@ namespace HiddenWallet.Crypto
public byte[] SignBlindedData(byte[] blindedData)
{
var signer = new RsaEngine();
- signer.Init(forEncryption: true, parameters: KeyPair.Private);
+ signer.Init(forEncryption: false, parameters: KeyPair.Private);
return signer.ProcessBlock(blindedData, 0, blindedData.Length);
}

Change signer.Init(forEncryption: to false.