From 4a08497b52159cae277aa72261054ed0696634be Mon Sep 17 00:00:00 2001
From: Camille Meulien <camille.meulien@gmail.com>
Date: Mon, 7 Dec 2020 22:42:16 +0200
Subject: [PATCH] Add the support of OpenDAX HMAC authentication method

---
 go.sum                |  1 +
 pkg/auth/hmac.go      | 47 +++++++++++++++++++++++++++++++++++++++++++
 pkg/auth/hmac_test.go | 34 +++++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+)
 create mode 100644 pkg/auth/hmac.go
 create mode 100644 pkg/auth/hmac_test.go

diff --git a/go.sum b/go.sum
index a4d830a..221f52a 100644
--- a/go.sum
+++ b/go.sum
@@ -55,6 +55,7 @@ github.com/modern-go/reflect2 v0.0.0-20180701023420-4b7aa43c6742/go.mod h1:bx2lN
 github.com/modern-go/reflect2 v1.0.1/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
 github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
diff --git a/pkg/auth/hmac.go b/pkg/auth/hmac.go
new file mode 100644
index 0000000..ad8895e
--- /dev/null
+++ b/pkg/auth/hmac.go
@@ -0,0 +1,47 @@
+package auth
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"net/http"
+	"time"
+)
+
+// APIKeyHMAC contains API keys credential to authenticate to HTTP API using HMAC
+type APIKeyHMAC struct {
+	AccessKey string
+	SecretKey string
+}
+
+// NewAPIKeyHMAC creates an instance of APIKeyHMAC
+func NewAPIKeyHMAC(accessKey, secretKey string) *APIKeyHMAC {
+	return &APIKeyHMAC{
+		AccessKey: accessKey,
+		SecretKey: secretKey,
+	}
+}
+
+// GetSignature return a signature for the given nonce, if nonce is zero it use the current time in millisecond
+func (key *APIKeyHMAC) GetSignature(nonce int64) string {
+	if nonce == 0 {
+		nonce = int64(time.Now().UnixNano() * 1000000)
+	}
+	mac := hmac.New(sha256.New, []byte(key.SecretKey))
+	mac.Write([]byte(fmt.Sprintf("%d%s", nonce, key.AccessKey)))
+	return hex.EncodeToString(mac.Sum(nil))
+}
+
+// GetSignedHeader returns a header with valid HMAC authorization fields
+func (key *APIKeyHMAC) GetSignedHeader(nonce int64) http.Header {
+	if nonce == 0 {
+		nonce = int64(time.Now().UnixNano() * 1000000)
+	}
+
+	return http.Header{
+		"X-Auth-Apikey":    {key.AccessKey},
+		"X-Auth-Nonce":     {fmt.Sprintf("%d", nonce)},
+		"X-Auth-Signature": {key.GetSignature(nonce)},
+	}
+}
diff --git a/pkg/auth/hmac_test.go b/pkg/auth/hmac_test.go
new file mode 100644
index 0000000..546d741
--- /dev/null
+++ b/pkg/auth/hmac_test.go
@@ -0,0 +1,34 @@
+package auth
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAPIKeyHMACGetSignature(t *testing.T) {
+	accessKey := "61d025b8573501c2"
+	secretKey := "2d0b4979c7fe6986daa8e21d1dc0644f"
+
+	k := NewAPIKeyHMAC(accessKey, secretKey)
+	nonce := int64(1584524005143)
+	signature := k.GetSignature(nonce)
+	assert.Equal(t, "bd42b945e095880e28d046846dbecf655fdf09d95a396a24fe6fe1df42f15d13", signature)
+}
+
+func TestAPIKeyHMACGetSignedHeader(t *testing.T) {
+	accessKey := "61d025b8573501c2"
+	secretKey := "2d0b4979c7fe6986daa8e21d1dc0644f"
+
+	k := NewAPIKeyHMAC(accessKey, secretKey)
+	nonce := int64(1584524005143)
+	headers := k.GetSignedHeader(nonce)
+
+	assert.Equal(t,
+		http.Header{
+			"X-Auth-Apikey":    {accessKey},
+			"X-Auth-Nonce":     {"1584524005143"},
+			"X-Auth-Signature": {"bd42b945e095880e28d046846dbecf655fdf09d95a396a24fe6fe1df42f15d13"},
+		}, headers)
+}