diff --git a/stepmania/src/crypto51/pubkey.h b/stepmania/src/crypto51/pubkey.h
index 5bb3cadbca..3d733d25eb 100644
--- a/stepmania/src/crypto51/pubkey.h
+++ b/stepmania/src/crypto51/pubkey.h
@@ -105,6 +105,22 @@ public:
 
 // ********************************************************
 
+//! .
+class PK_EncryptionMessageEncodingMethod
+{
+public:
+	virtual ~PK_EncryptionMessageEncodingMethod() {}
+
+	//! max size of unpadded message in bytes, given max size of padded message in bits (1 less than size of modulus)
+	virtual unsigned int MaxUnpaddedLength(unsigned int paddedLength) const =0;
+
+	virtual void Pad(RandomNumberGenerator &rng, const byte *raw, unsigned int inputLength, byte *padded, unsigned int paddedBitLength) const =0;
+
+	virtual DecodingResult Unpad(const byte *padded, unsigned int paddedBitLength, byte *raw) const =0;
+};
+
+// ********************************************************
+
 //! .
 template <class TFI, class MEI>
 class TF_Base
@@ -569,6 +585,9 @@ public:
 #endif
 };
 
+//! Base class for public key encryption standard classes. These classes are used to select from variants of algorithms. Note that not all standards apply to all algorithms.
+struct EncryptionStandard {};
+
 //! Base class for public key signature standard classes. These classes are used to select from variants of algorithms. Note that not all standards apply to all algorithms.
 struct SignatureStandard {};