R4R: Make gaiacli keys show multisig-ready

PENDING.md

@@ -128,6 +128,7 @@ FEATURES
   * [stake][cli] [\#1672](https://github.com/cosmos/cosmos-sdk/issues/1672) Introduced
   new commission flags for validator commands `create-validator` and `edit-validator`.
   * [stake][cli] [\#1890](https://github.com/cosmos/cosmos-sdk/issues/1890) Add `--genesis-format` flag to `gaiacli tx create-validator` to produce transactions in genesis-friendly format.
+  * [cli][\#2554](https://github.com/cosmos/cosmos-sdk/issues/2554) Make `gaiacli keys show` multisig ready.
 
 * Gaia
   * [cli] #2170 added ability to show the node's address via `gaiad tendermint show-address`

client/keys/show.go

@@ -2,12 +2,16 @@ package keys
 
 import (
 	"fmt"
+	"github.com/cosmos/cosmos-sdk/crypto/keys"
+	"github.com/tendermint/tendermint/crypto"
 	"net/http"
 
+	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/gorilla/mux"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
+	"github.com/tendermint/tendermint/crypto/multisig"
 	"github.com/tendermint/tendermint/libs/cli"
 )
 
@@ -18,30 +22,68 @@ const (
 	FlagPublicKey = "pubkey"
 	// FlagBechPrefix defines a desired Bech32 prefix encoding for a key.
 	FlagBechPrefix = "bech"
+
+	flagMultiSigThreshold  = "multisig-threshold"
+	defaultMultiSigKeyName = "multi"
 )
 
+var _ keys.Info = (*multiSigKey)(nil)
+
+type multiSigKey struct {
+	name string
+	key  crypto.PubKey
+}
+
+func (m multiSigKey) GetName() string            { return m.name }
+func (m multiSigKey) GetType() keys.KeyType      { return keys.TypeLocal }
+func (m multiSigKey) GetPubKey() crypto.PubKey   { return m.key }
+func (m multiSigKey) GetAddress() sdk.AccAddress { return sdk.AccAddress(m.key.Address()) }
+
 func showKeysCmd() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "show [name]",
 		Short: "Show key info for the given name",
 		Long:  `Return public details of one local key.`,
-		Args:  cobra.ExactArgs(1),
+		Args:  cobra.MinimumNArgs(1),
 		RunE:  runShowCmd,
 	}
 
 	cmd.Flags().String(FlagBechPrefix, "acc", "The Bech32 prefix encoding for a key (acc|val|cons)")
 	cmd.Flags().Bool(FlagAddress, false, "output the address only (overrides --output)")
 	cmd.Flags().Bool(FlagPublicKey, false, "output the public key only (overrides --output)")
+	cmd.Flags().Uint(flagMultiSigThreshold, 1, "K out of N required signatures")
 
 	return cmd
 }
 
-func runShowCmd(cmd *cobra.Command, args []string) error {
-	name := args[0]
+func runShowCmd(cmd *cobra.Command, args []string) (err error) {
+	var info keys.Info
 
-	info, err := GetKeyInfo(name)
-	if err != nil {
-		return err
+	if len(args) == 1 {
+		info, err = GetKeyInfo(args[0])
+		if err != nil {
+			return err
+		}
+	} else {
+		pks := make([]crypto.PubKey, len(args))
+		for i, keyName := range args {
+			info, err := GetKeyInfo(keyName)
+			if err != nil {
+				return err
+			}
+			pks[i] = info.GetPubKey()
+		}
+
+		multisigThreshold := viper.GetInt(flagMultiSigThreshold)
+		err = validateMultisigThreshold(multisigThreshold, len(args))
+		if err != nil {
+			return err
+		}
+		multikey := multisig.NewPubKeyMultisigThreshold(multisigThreshold, pks)
+		info = multiSigKey{
+			name: defaultMultiSigKeyName,
+			key:  multikey,
+		}
 	}
 
 	isShowAddr := viper.GetBool(FlagAddress)
@@ -73,6 +115,17 @@ func runShowCmd(cmd *cobra.Command, args []string) error {
 	return nil
 }
 
+func validateMultisigThreshold(k, nKeys int) error {
+	if k <= 0 {
+		return fmt.Errorf("threshold must be a positive integer")
+	}
+	if nKeys < k {
+		return fmt.Errorf(
+			"threshold k of n multisignature: %d < %d", nKeys, k)
+	}
+	return nil
+}
+
 func getBechKeyOut(bechPrefix string) (bechKeyOutFn, error) {
 	switch bechPrefix {
 	case "acc":

docs/sdk/clients.md

@@ -74,6 +74,16 @@ gaiad tendermint show-validator
 We strongly recommend _NOT_ using the same passphrase for multiple keys. The Tendermint team and the Interchain Foundation will not be responsible for the loss of funds.
 :::
 
+#### Multisig public keys
+
+You can generate and print a multisig public key by typing:
+
+```bash
+gaiacli show -m K key1 key2...keyK
+```
+
+`K` is the minimum weight, e.g. minimum number of private keys that must have signed the transactions that carry the generated public key.
+
 ### Account
 
 #### Get Tokens