From d059767e7946545c2ddad56c267e7639c8bf2a5e Mon Sep 17 00:00:00 2001
From: Evgeniy Kulikov <kim@nspcc.ru>
Date: Thu, 21 Nov 2019 17:24:36 +0300
Subject: [PATCH 1/3] Add method to load PrivateKey

- from hex string
- from wif format
- from file path
---
 load.go      | 21 +++++++++++++
 load_test.go | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 107 insertions(+)
 create mode 100644 load.go
 create mode 100644 load_test.go

diff --git a/load.go b/load.go
new file mode 100644
index 0000000..601e89e
--- /dev/null
+++ b/load.go
@@ -0,0 +1,21 @@
+package crypto
+
+import (
+	"crypto/ecdsa"
+	"encoding/hex"
+	"io/ioutil"
+
+	"github.com/pkg/errors"
+)
+
+func LoadPrivateKey(val string) (*ecdsa.PrivateKey, error) {
+	if data, err := ioutil.ReadFile(val); err == nil {
+		return UnmarshalPrivateKey(data)
+	} else if data, err = hex.DecodeString(val); err == nil {
+		return UnmarshalPrivateKey(data)
+	} else if key, err := WIFDecode(val); err == nil {
+		return key, nil
+	}
+
+	return nil, errors.Errorf("unknown key format (%q), expect: hex-string, wif or file-path", val)
+}
diff --git a/load_test.go b/load_test.go
new file mode 100644
index 0000000..b7c3fd4
--- /dev/null
+++ b/load_test.go
@@ -0,0 +1,86 @@
+package crypto
+
+import (
+	"crypto/x509"
+	"encoding/hex"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/nspcc-dev/neofs-crypto/test"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_LoadPrivateKey_FromWIF(t *testing.T) {
+	for i := 0; i < 10; i++ {
+		expected := test.DecodeKey(i)
+
+		wif, err := WIFEncode(expected)
+		require.NoError(t, err)
+
+		actual, err := LoadPrivateKey(wif)
+		require.NoError(t, err)
+
+		require.Equal(t, expected, actual)
+	}
+}
+
+func Test_LoadPrivateKey_FromHexString(t *testing.T) {
+	for i := 0; i < 10; i++ {
+		expected := test.DecodeKey(i)
+
+		hs := hex.EncodeToString(expected.D.Bytes())
+
+		actual, err := LoadPrivateKey(hs)
+		require.NoError(t, err)
+
+		require.Equal(t, expected, actual)
+	}
+}
+
+func Test_LoadPrivateKey_FromFile(t *testing.T) {
+	for i := 0; i < 10; i++ {
+		expected := test.DecodeKey(i)
+
+		file, err := ioutil.TempFile("", "_marshaled.key")
+		require.NoError(t, err)
+
+		defer func() {
+			require.NoError(t, file.Close())
+			require.NoError(t, os.Remove(file.Name()))
+		}()
+
+		data, err := x509.MarshalECPrivateKey(expected)
+		require.NoError(t, err)
+
+		_, err = file.Write(data)
+		require.NoError(t, err)
+
+		actual, err := LoadPrivateKey(file.Name())
+		require.NoError(t, err)
+
+		require.Equal(t, expected, actual)
+	}
+}
+
+func Test_LoadPrivateKey_FromCompressedFormatFile(t *testing.T) {
+	for i := 0; i < 10; i++ {
+		expected := test.DecodeKey(i)
+
+		file, err := ioutil.TempFile("", "_compressed.key")
+		require.NoError(t, err)
+
+		defer func() {
+			require.NoError(t, file.Close())
+			require.NoError(t, os.Remove(file.Name()))
+		}()
+
+		_, err = file.Write(expected.D.Bytes())
+		require.NoError(t, err)
+
+		actual, err := LoadPrivateKey(file.Name())
+		require.NoError(t, err)
+
+		require.Equal(t, expected, actual)
+	}
+}

From f707f6449cc2205903ea02f4c260b0e017b17855 Mon Sep 17 00:00:00 2001
From: Evgeniy Kulikov <kim@nspcc.ru>
Date: Thu, 21 Nov 2019 17:29:34 +0300
Subject: [PATCH 2/3] docs: describe LoadPrivateKey in readme

---
 README.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/README.md b/README.md
index 2fa03b6..de6b3de 100644
--- a/README.md
+++ b/README.md
@@ -60,3 +60,16 @@ wif, err := crypto.WIFEncode(sk)
 // if something went wrong, returns error:
 skFromWIF, err := crypto.WIFDecode(wif)
 ```
+
+### LoadPrivateKey
+
+```
+// Load private key from wif format
+sk, err := crypto.LoadPrivateKey(wif_string)
+
+// Load private key from hex string
+sk, err := crypto.LoadPrivateKey(hex_string)
+
+// Load private key from file
+sk, err := crypto.LoadPrivateKey(file_path)
+```

From 9f21fbbfd52c2bd819d737938720976e9f3dc9e0 Mon Sep 17 00:00:00 2001
From: Evgeniy Kulikov <kim@nspcc.ru>
Date: Thu, 21 Nov 2019 17:32:08 +0300
Subject: [PATCH 3/3] docs: add doc comment for LoadPrivateKey

---
 load.go | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/load.go b/load.go
index 601e89e..7c61277 100644
--- a/load.go
+++ b/load.go
@@ -8,6 +8,10 @@ import (
 	"github.com/pkg/errors"
 )
 
+// LoadPrivateKey allows to load private key from various formats:
+// - wif string
+// - hex string
+// - file path (D-bytes or SEC 1 / ASN.1 DER form)
 func LoadPrivateKey(val string) (*ecdsa.PrivateKey, error) {
 	if data, err := ioutil.ReadFile(val); err == nil {
 		return UnmarshalPrivateKey(data)