do no use legacy marshaling on key exports (#567)

## Describe your changes and provide context
When we export the private keys, an extra prefix `e1b0f79b20` is being
prepended to all of the keys e.g:
```
seid keys export ta9 --unarmored-hex --unsafe
WARNING: The private key will be exported as an unarmored hexadecimal string. USE AT YOUR OWN RISK. Continue? [y/N]: y
e1b0f79b20ae7f662971f762e3d594f03a5386c440023e04899a4fe155622301245d0b64ce
```
This change removes some of the older marshalling, that is responsible
for the extra prefix.

## Testing performed to validate your change
- unit tests
- local seid

Author: dssei

client/keys/import_test.go

@@ -63,12 +63,13 @@ func Test_runImportCmd(t *testing.T) {
 	}
 
 	armoredKey := `-----BEGIN TENDERMINT PRIVATE KEY-----
-salt: A790BB721D1C094260EA84F5E5B72289
 kdf: bcrypt
+salt: 0A2203634D31B7BAFD938564E19A173A
+type: secp256k1
 
-HbP+c6JmeJy9JXe2rbbF1QtCX1gLqGcDQPBXiCtFvP7/8wTZtVOPj8vREzhZ9ElO
-3P7YnrzPQThG0Q+ZnRSbl9MAS8uFAM4mqm5r/Ys=
-=f3l4
+OqpHBjYDPl5/jfm3LqzatY1Re19JvYvZ5fCAKGj/VUk1PZFj0bDjdYfr7CLDqduS
+mBtElE9j21pFaLf9gt8hVPTMDXWPtbIL
+=ctQV
 -----END TENDERMINT PRIVATE KEY-----
 `
 

crypto/keyring/keyring.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"encoding/hex"
 	"fmt"
+	"github.com/cosmos/cosmos-sdk/crypto/keys/secp256k1"
 	"io"
 	"io/ioutil"
 	"os"
@@ -249,7 +250,7 @@ func (ks keystore) ExportPrivateKeyObject(uid string) ([]byte, error) {
 			if err != nil {
 				return nil, err
 			}
-			priv = legacy.Cdc.MustMarshal(privKeys)
+			priv = privKeys.Bytes()
 		}
 
 	case ledgerInfo, offlineInfo, multiInfo:
@@ -286,10 +287,11 @@ func (ks keystore) ImportPrivKey(uid, armor, passphrase string) error {
 		}
 		privKey = typedKey
 	} else {
-		privKey, err = legacy.PrivKeyFromBytes(privKeyBytes)
-		if err != nil {
+		secpKey := &secp256k1.PrivKey{}
+		if err := secpKey.UnmarshalAmino(privKeyBytes); err != nil {
 			return err
 		}
+		privKey = secpKey
 	}
 
 	_, err = ks.writeLocalKey(uid, privKey, hd.PubKeyType(algo))

crypto/keyring/keyring_test.go

@@ -895,7 +895,7 @@ func TestAltKeyring_UnsafeExportPrivKeyHex(t *testing.T) {
 	privKey, err := unsafeKeyring.UnsafeExportPrivKeyHex(uid)
 
 	require.NoError(t, err)
-	require.Equal(t, 74, len(privKey))
+	require.Equal(t, 64, len(privKey))
 
 	_, err = hex.DecodeString(privKey)
 	require.NoError(t, err)