CryptographicException: Invalid input block size.

I get this error now on several asset packages that I have purchased.

Here is the full error:

CryptographicException: Invalid input block size.
Mono.Security.Cryptography.SymmetricTransform.FinalDecrypt (System.Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount)
Mono.Security.Cryptography.SymmetricTransform.TransformFinalBlock (System.Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount)
System.Security.Cryptography.CryptoStream.Read (System.Byte[] buffer, Int32 offset, Int32...

CryptographicException: Invalid input block size.