Initial commit

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)},
+	}
+}