From a92ec86ca74594755547818a7ae9e95617222624 Mon Sep 17 00:00:00 2001
From: Benjamin DENEUX <b.deneux@okp4.com>
Date: Thu, 5 Oct 2023 15:15:15 +0200
Subject: [PATCH] feat(logic): implement crypto signature verification

---
 x/logic/predicate/crypto.go | 36 ++++++++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/x/logic/predicate/crypto.go b/x/logic/predicate/crypto.go
index 0f9bfa3c..7359cc86 100644
--- a/x/logic/predicate/crypto.go
+++ b/x/logic/predicate/crypto.go
@@ -2,13 +2,15 @@ package predicate
 
 import (
 	"context"
+	"crypto"
+	"crypto/ed25519"
 	"encoding/hex"
 	"fmt"
 
+	"github.com/cometbft/cometbft/crypto/secp256k1"
+	"github.com/cosmos/cosmos-sdk/crypto/keys/secp256r1"
 	"github.com/ichiban/prolog/engine"
 
-	"github.com/cometbft/cometbft/crypto"
-
 	"github.com/okp4/okp4d/x/logic/util"
 )
 
@@ -97,3 +99,33 @@ func HexBytes(vm *engine.VM, hexa, bts engine.Term, cont engine.Cont, env *engin
 		}
 	})
 }
+
+type Alg string
+
+const (
+	Secp256k1 Alg = "secp256k1"
+	Secp256r1 Alg = "secp256r1"
+	Ed25519   Alg = "ed25519"
+)
+
+func verifySignature(alg Alg, pubKey crypto.PublicKey, msg, sig []byte) (bool, error) {
+	switch alg {
+	case Ed25519:
+		if key, ok := pubKey.(ed25519.PublicKey); ok {
+			return ed25519.Verify(key, msg, sig), nil
+		}
+		return false, fmt.Errorf("public key is not ed25519 compatible")
+	case Secp256r1:
+		if key, ok := pubKey.(secp256r1.PubKey); ok {
+			return key.VerifySignature(msg, sig), nil
+		}
+		return false, fmt.Errorf("public key is not secp256r1 compatible")
+	case Secp256k1:
+		if key, ok := pubKey.(secp256k1.PubKey); ok {
+			return key.VerifySignature(msg, sig), nil
+		}
+		return false, fmt.Errorf("public key is not secp256k1 compatible")
+	default:
+		return false, fmt.Errorf("pub key format not implemented")
+	}
+}