fix: unmarshalling issue with multisig keys in master (backport #10061)

CHANGELOG.md

@@ -36,9 +36,13 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## Unreleased
 
+### Bug Fixes
+
++ [\#10061](https://github.com/cosmos/cosmos-sdk/pull/10061) Ensure that `LegacyAminoPubKey` struct correctly unmarshals from JSON
+
 ### API Breaking Changes
 
-* [\#10077](https://github.com/cosmos/cosmos-sdk/pull/10077) Remove telemetry on `GasKV` and `CacheKV` store Get/Set operations, significantly improving their performance.
++ [\#10077](https://github.com/cosmos/cosmos-sdk/pull/10077) Remove telemetry on `GasKV` and `CacheKV` store Get/Set operations, significantly improving their performance.
 
 ## [v0.42.9](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.42.9) - 2021-08-04
 

crypto/keys/multisig/amino.go

@@ -78,7 +78,9 @@ func (m *LegacyAminoPubKey) UnmarshalAminoJSON(tmPk tmMultisig) error {
 	// Instead of just doing `*m = *protoPk`, we prefer to modify in-place the
 	// existing Anys inside `m` (instead of allocating new Anys), as so not to
 	// break the `.compat` fields in the existing Anys.
+	m.PubKeys = make([]*types.Any, len(protoPk.PubKeys))
 	for i := range m.PubKeys {
+		m.PubKeys[i] = &types.Any{}
 		m.PubKeys[i].TypeUrl = protoPk.PubKeys[i].TypeUrl
 		m.PubKeys[i].Value = protoPk.PubKeys[i].Value
 	}

crypto/keys/multisig/multisig_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec/legacy"
 	"github.com/cosmos/cosmos-sdk/codec/types"
 	cryptocodec "github.com/cosmos/cosmos-sdk/crypto/codec"
+	"github.com/cosmos/cosmos-sdk/crypto/keyring"
 	kmultisig "github.com/cosmos/cosmos-sdk/crypto/keys/multisig"
 	"github.com/cosmos/cosmos-sdk/crypto/keys/secp256k1"
 	cryptotypes "github.com/cosmos/cosmos-sdk/crypto/types"
@@ -17,6 +18,15 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/auth/legacy/legacytx"
 )
 
+func generatePubKeys(n int) []cryptotypes.PubKey {
+	pks := make([]cryptotypes.PubKey, n)
+	for i := 0; i < n; i++ {
+		pks[i] = secp256k1.GenPrivKey().PubKey()
+	}
+
+	return pks
+}
+
 func TestAddress(t *testing.T) {
 	msg := []byte{1, 2, 3, 4}
 	pubKeys, _ := generatePubKeysAndSignatures(5, msg)
@@ -379,5 +389,41 @@ func TestAminoUnmarshalJSON(t *testing.T) {
 	var pk cryptotypes.PubKey
 	err := cdc.UnmarshalJSON([]byte(pkJSON), &pk)
 	require.NoError(t, err)
-	require.Equal(t, uint32(3), pk.(*kmultisig.LegacyAminoPubKey).Threshold)
+	lpk := pk.(*kmultisig.LegacyAminoPubKey)
+	require.Equal(t, uint32(3), lpk.Threshold)
+	require.Equal(t, 5, len(pk.(*kmultisig.LegacyAminoPubKey).PubKeys))
+
+	for _, key := range pk.(*kmultisig.LegacyAminoPubKey).PubKeys {
+		require.NotNil(t, key)
+		pk := secp256k1.PubKey{}
+		err := pk.Unmarshal(key.Value)
+		require.NoError(t, err)
+	}
+}
+
+func TestProtoMarshalJSON(t *testing.T) {
+	require := require.New(t)
+	pubkeys := generatePubKeys(3)
+	msig := kmultisig.NewLegacyAminoPubKey(2, pubkeys)
+
+	registry := types.NewInterfaceRegistry()
+	cryptocodec.RegisterInterfaces(registry)
+	cdc := codec.NewProtoCodec(registry)
+
+	bz, err := cdc.MarshalInterfaceJSON(msig)
+	require.NoError(err)
+
+	var pk2 cryptotypes.PubKey
+	err = cdc.UnmarshalInterfaceJSON(bz, &pk2)
+	require.NoError(err)
+	require.True(pk2.Equals(msig))
+
+	// Test that we can correctly unmarshal key from keyring output
+	info, err := keyring.NewMultiInfo("my multisig", msig)
+	require.NoError(err)
+
+	ko, err := keyring.MkAccKeyOutput(info)
+	require.NoError(err)
+	require.Equal(ko.Address, sdk.AccAddress(pk2.Address()).String())
+	require.Equal(ko.PubKey, string(bz))
 }