refactoring: more precise types for ProofTreeLeaf + Hint.image

common/shared/src/test/scala/scalan/BaseTests.scala

@@ -34,7 +34,8 @@ abstract class BaseShouldTests extends AnyFlatSpec with TestUtils {
     }
   }
 
-  protected implicit def convertToInAndIgnoreMethods2(resultOfStringPassedToVerb: ResultOfStringPassedToVerb) =
+  protected implicit def convertToInAndIgnoreMethods2(
+      resultOfStringPassedToVerb: ResultOfStringPassedToVerb): InAndIgnoreMethods2 =
     new InAndIgnoreMethods2(resultOfStringPassedToVerb)
 
 }

interpreter/shared/src/main/scala/sigmastate/UncheckedTree.scala

@@ -16,23 +16,21 @@ sealed trait UncheckedSigmaTree extends UncheckedTree {
 
 trait UncheckedConjecture extends UncheckedSigmaTree with ProofTreeConjecture
 
-trait UncheckedLeaf[SP <: SigmaBoolean] extends UncheckedSigmaTree with ProofTreeLeaf {
-  val proposition: SigmaBoolean
-}
+trait UncheckedLeaf extends UncheckedSigmaTree with ProofTreeLeaf
 
 case class UncheckedSchnorr(
     override val proposition: ProveDlog,
     override val commitmentOpt: Option[FirstDLogProverMessage],
     override val challenge: Challenge,
     secondMessage: SecondDLogProverMessage
-) extends UncheckedLeaf[ProveDlog]
+) extends UncheckedLeaf
 
 case class UncheckedDiffieHellmanTuple(
     override val proposition: ProveDHTuple,
     override val commitmentOpt: Option[FirstDHTupleProverMessage],
     override val challenge: Challenge,
     secondMessage: SecondDHTupleProverMessage
-) extends UncheckedLeaf[ProveDHTuple]
+) extends UncheckedLeaf
 
 case class CAndUncheckedNode(
     override val challenge: Challenge,

interpreter/shared/src/main/scala/sigmastate/UnprovenTree.scala

@@ -25,7 +25,7 @@ object ConjectureType extends Enumeration {
 trait ProofTree extends Product
 
 trait ProofTreeLeaf extends ProofTree {
-  val proposition: SigmaBoolean
+  val proposition: SigmaLeaf
   val commitmentOpt: Option[FirstProverMessage]
 }
 

interpreter/shared/src/main/scala/sigmastate/interpreter/Hint.scala

@@ -1,8 +1,7 @@
 package sigmastate.interpreter
 
 import java.math.BigInteger
-
-import sigmastate.{NodePosition, UncheckedTree}
+import sigmastate.{NodePosition, SigmaLeaf, UncheckedTree}
 import sigmastate.Values.SigmaBoolean
 import sigmastate.basics.FirstProverMessage
 import sigmastate.basics.VerifierMessage.Challenge
@@ -13,6 +12,10 @@ import sigmastate.basics.VerifierMessage.Challenge
   * prover knows that pk2 is known to another party, the prover may prove the statement (with an empty proof for "pk2").
   */
 trait Hint {
+  /**
+    * Public image of a secret
+    */
+  def image: SigmaLeaf
 
   /**
     * A hint is related to a subtree (or a leaf) of a tree. This field encodes a position in the tree.
@@ -25,12 +28,6 @@ trait Hint {
   * A hint which is indicating that a secret associated with its public image "image" is already proven.
   */
 abstract class SecretProven extends Hint {
-
-  /**
-    * Public image of a secret which is proven
-    */
-  def image: SigmaBoolean
-
   /**
     * Challenge used for a proof
     */
@@ -46,16 +43,16 @@ abstract class SecretProven extends Hint {
   * A hint which contains a proof-of-knowledge for a secret associated with its public image "image",
   * with also the mark that the proof is real.
   */
-case class RealSecretProof(image: SigmaBoolean,
+case class RealSecretProof(image: SigmaLeaf,
                            challenge: Challenge,
                            uncheckedTree: UncheckedTree,
                            override val position: NodePosition) extends SecretProven
 
 /**
   * A hint which contains a proof-of-knowledge for a secret associated with its public image "image",
-  * with also the mark that the proof is real.
+  * with also the mark that the proof is simulated (not real).
   */
-case class SimulatedSecretProof(image: SigmaBoolean,
+case class SimulatedSecretProof(image: SigmaLeaf,
                                 challenge: Challenge,
                                 uncheckedTree: UncheckedTree,
                                 override val position: NodePosition) extends SecretProven
@@ -66,7 +63,7 @@ case class SimulatedSecretProof(image: SigmaBoolean,
   * to randomness ("a" in a sigma protocol).
   */
 abstract class CommitmentHint extends Hint {
-  def image: SigmaBoolean
+  /** Commitment to randomness (first message in a sigma protocol) */
   def commitment: FirstProverMessage
 }
 
@@ -78,7 +75,7 @@ abstract class CommitmentHint extends Hint {
   * @param secretRandomness - randomness
   * @param commitment - commitment to randomness used while proving knowledge of the secret
   */
-case class OwnCommitment(override val image: SigmaBoolean,
+case class OwnCommitment(override val image: SigmaLeaf,
                          secretRandomness: BigInteger,
                          commitment: FirstProverMessage,
                          override val position: NodePosition) extends CommitmentHint
@@ -89,7 +86,7 @@ case class OwnCommitment(override val image: SigmaBoolean,
   * @param image      - image of a secret
   * @param commitment - commitment to randomness used while proving knowledge of the secret
   */
-case class RealCommitment(override val image: SigmaBoolean,
+case class RealCommitment(override val image: SigmaLeaf,
                           commitment: FirstProverMessage,
                           override val position: NodePosition) extends CommitmentHint
 
@@ -99,7 +96,7 @@ case class RealCommitment(override val image: SigmaBoolean,
   * @param image      - image of a secret
   * @param commitment - commitment to randomness used while proving knowledge of the secret
   */
-case class SimulatedCommitment(override val image: SigmaBoolean,
+case class SimulatedCommitment(override val image: SigmaLeaf,
                                commitment: FirstProverMessage,
                                override val position: NodePosition) extends CommitmentHint
 

interpreter/shared/src/main/scala/sigmastate/interpreter/ProverUtils.scala

@@ -115,7 +115,7 @@ trait ProverUtils extends Interpreter {
           inner.children.zipWithIndex.foldLeft(hintsBag) { case (hb, (c, idx)) =>
             traverseNode(c, realPropositions, simulatedPropositions, hb, position.child(idx))
           }
-        case leaf: UncheckedLeaf[_] =>
+        case leaf: UncheckedLeaf =>
           val realFound = realPropositions.contains(leaf.proposition)
           val simulatedFound = simulatedPropositions.contains(leaf.proposition)
           if (realFound || simulatedFound) {