Rewrite identity and access management

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/securetoken/securetoken.go

@@ -0,0 +1,91 @@
+// Copyright (c) 2025 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package securetoken
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"go.probo.inc/probo/pkg/bearertoken"
+)
+
+var (
+	ErrInvalidToken     = errors.New("invalid token")
+	ErrTokenNotFound    = errors.New("token not found")
+	ErrInvalidSignature = errors.New("invalid signature")
+)
+
+func Get(req *http.Request, secret string) (string, error) {
+	v := req.Header.Get("Authorization")
+	if v == "" {
+		return "", ErrTokenNotFound
+	}
+
+	token, err := bearertoken.Parse(v)
+	if err != nil {
+		return "", ErrInvalidToken
+	}
+
+	value, err := Verify(token, secret)
+	if err != nil {
+		return "", ErrInvalidToken
+	}
+
+	return value, nil
+}
+
+// Sign creates a signed value using HMAC-SHA256
+func Sign(value, secret string) (string, error) {
+	if secret == "" {
+		return "", fmt.Errorf("secret cannot be empty")
+	}
+
+	h := hmac.New(sha256.New, []byte(secret))
+	h.Write([]byte(value))
+
+	signature := base64.RawURLEncoding.EncodeToString(h.Sum(nil))
+
+	return value + "." + signature, nil
+}
+
+// Verify checks if a signed value is valid
+func Verify(signedValue, secret string) (string, error) {
+	if secret == "" {
+		return "", fmt.Errorf("secret cannot be empty")
+	}
+
+	parts := strings.Split(signedValue, ".")
+	if len(parts) != 2 {
+		return "", fmt.Errorf("invalid signed value format")
+	}
+
+	value := parts[0]
+
+	expectedSignedValue, err := Sign(value, secret)
+	if err != nil {
+		return "", fmt.Errorf("cannot sign value: %w", err)
+	}
+
+	if signedValue != expectedSignedValue {
+		return "", ErrInvalidSignature
+	}
+
+	return value, nil
+}