Add support for TM secp256k1 (#7838)

* Add secp256k1 support

* Fix test

* Add test in handler_test

* Use table tests

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

crypto/keys/secp256k1/secp256k1_test.go

@@ -12,6 +12,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/tendermint/tendermint/crypto"
+	tmsecp256k1 "github.com/tendermint/tendermint/crypto/secp256k1"
 
 	"github.com/cosmos/cosmos-sdk/codec"
 	"github.com/cosmos/cosmos-sdk/crypto/keys/ed25519"
@@ -267,3 +268,56 @@ func TestMarshalAmino(t *testing.T) {
 		})
 	}
 }
+
+func TestMarshalAmino_BackwardsCompatibility(t *testing.T) {
+	aminoCdc := codec.NewLegacyAmino()
+	// Create Tendermint keys.
+	tmPrivKey := tmsecp256k1.GenPrivKey()
+	tmPubKey := tmPrivKey.PubKey()
+	// Create our own keys, with the same private key as Tendermint's.
+	privKey := &secp256k1.PrivKey{Key: []byte(tmPrivKey)}
+	pubKey := privKey.PubKey().(*secp256k1.PubKey)
+
+	testCases := []struct {
+		desc      string
+		tmKey     interface{}
+		ourKey    interface{}
+		marshalFn func(o interface{}) ([]byte, error)
+	}{
+		{
+			"secp256k1 private key, binary",
+			tmPrivKey,
+			privKey,
+			aminoCdc.MarshalBinaryBare,
+		},
+		{
+			"secp256k1 private key, JSON",
+			tmPrivKey,
+			privKey,
+			aminoCdc.MarshalJSON,
+		},
+		{
+			"secp256k1 public key, binary",
+			tmPubKey,
+			pubKey,
+			aminoCdc.MarshalBinaryBare,
+		},
+		{
+			"secp256k1 public key, JSON",
+			tmPubKey,
+			pubKey,
+			aminoCdc.MarshalJSON,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			// Make sure Amino encoding override is not breaking backwards compatibility.
+			bz1, err := tc.marshalFn(tc.tmKey)
+			require.NoError(t, err)
+			bz2, err := tc.marshalFn(tc.ourKey)
+			require.NoError(t, err)
+			require.Equal(t, bz1, bz2)
+		})
+	}
+}