add basic user authentication

internal/jwtauth/jwt.go

@@ -0,0 +1,22 @@
+package jwtauth
+
+import (
+	"encoding/base64"
+	"os"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+func GenerateJwtToken(username string) (string, error) {
+	var s string
+	key, err := base64.URLEncoding.DecodeString(os.Getenv(getKeyVariableName()))
+	if err != nil {
+		return s, err
+	}
+	t := jwt.NewWithClaims(jwt.SigningMethodHS256,
+		jwt.MapClaims{
+			"iss": "PersonalLibraryManager",
+			"sub": username,
+		})
+	return t.SignedString(key)
+}

internal/jwtauth/key.go

@@ -0,0 +1,39 @@
+package jwtauth
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"os"
+)
+
+func generateRandomBytes(n int) ([]byte, error) {
+	b := make([]byte, n)
+	_, err := rand.Read(b)
+	if err != nil {
+		return nil, err
+	}
+	return b, nil
+}
+
+func generateSecureToken(n int) (string, error) {
+	bytes, err := generateRandomBytes(n)
+	if err != nil {
+		return "", err
+	}
+	return base64.URLEncoding.EncodeToString(bytes), nil
+}
+
+func getKeyVariableName() string {
+	return "PLM_JWT_KEY"
+}
+
+func InitKey() error {
+	var err error
+	keyName := getKeyVariableName()
+	key := os.Getenv(keyName)
+	if key == "" {
+		key, err = generateSecureToken(64)
+		os.Setenv(keyName, key)
+	}
+	return err
+}