EncodePoint function moved to Hashing interface

EncodePoint is important for hashing, especially H2. It is not
important for the signature verification calls (in our current model) or
for the curve operations.

frost/ciphersuite.go

@@ -14,18 +14,6 @@ type Ciphersuite interface {
 	Hashing
 	Curve() Curve
 
-	// EncodePoint encodes the given elliptic curve point to a byte slice in
-	// a way that is *specific* to the given ciphersuite needs. This is
-	// especially important when calculating a signature challenge in [FROST].
-	//
-	// This function may yield a different result than SerializePoint function
-	// from the Curve interface. While the SerializePoint result should be
-	// considered an internal serialization that may be optimized for speed or
-	// data consistency, the EncodePoint result should be considered an external
-	// serialization, always reflecting the given ciphersuite's specification
-	// requirements.
-	EncodePoint(point *Point) []byte
-
 	// VerifySignature verifies the provided signature for the message against
 	// the group public key. The function returns true and nil error when the
 	// signature is valid. The function returns false and an error when the
@@ -55,6 +43,18 @@ type Hashing interface {
 	H3(m []byte, ms ...[]byte) *big.Int
 	H4(m []byte) []byte
 	H5(m []byte) []byte
+
+	// EncodePoint encodes the given elliptic curve point to a byte slice in
+	// a way that is *specific* to the given ciphersuite needs. This is
+	// especially important when calculating a signature challenge in [FROST].
+	//
+	// This function may yield a different result than SerializePoint function
+	// from the Curve interface. While the SerializePoint result should be
+	// considered an internal serialization that may be optimized for speed or
+	// data consistency, the EncodePoint result should be considered an external
+	// serialization, always reflecting the given ciphersuite's specification
+	// requirements.
+	EncodePoint(point *Point) []byte
 }
 
 // Curve interface abstracts out the particular elliptic curve implementation