2 files changed, 110 insertions, 0 deletions
diff --git a/modules/generate/generate.go b/modules/generate/generate.go
new file mode 100644
index 0000000..41a6aa2
--- /dev/null
+++ b/modules/generate/generate.go
@@ -0,0 +1,75 @@
+// Copyright 2016 The Gogs Authors. All rights reserved.
+// Copyright 2016 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package generate
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"time"
+
+	"code.gitea.io/gitea/modules/util"
+
+	"github.com/golang-jwt/jwt/v5"
+)
+
+// NewInternalToken generate a new value intended to be used by INTERNAL_TOKEN.
+func NewInternalToken() (string, error) {
+	secretBytes := make([]byte, 32)
+	_, err := io.ReadFull(rand.Reader, secretBytes)
+	if err != nil {
+		return "", err
+	}
+
+	secretKey := base64.RawURLEncoding.EncodeToString(secretBytes)
+
+	now := time.Now()
+
+	var internalToken string
+	internalToken, err = jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
+		"nbf": now.Unix(),
+	}).SignedString([]byte(secretKey))
+	if err != nil {
+		return "", err
+	}
+
+	return internalToken, nil
+}
+
+const defaultJwtSecretLen = 32
+
+// DecodeJwtSecret decodes a base64 encoded jwt secret into bytes, and check its length
+func DecodeJwtSecret(src string) ([]byte, error) {
+	encoding := base64.RawURLEncoding
+	decoded := make([]byte, encoding.DecodedLen(len(src))+3)
+	if n, err := encoding.Decode(decoded, []byte(src)); err != nil {
+		return nil, err
+	} else if n != defaultJwtSecretLen {
+		return nil, fmt.Errorf("invalid base64 decoded length: %d, expects: %d", n, defaultJwtSecretLen)
+	}
+	return decoded[:defaultJwtSecretLen], nil
+}
+
+// NewJwtSecret generates a new base64 encoded value intended to be used for JWT secrets.
+func NewJwtSecret() ([]byte, string, error) {
+	bytes := make([]byte, 32)
+	_, err := rand.Read(bytes)
+	if err != nil {
+		return nil, "", err
+	}
+
+	return bytes, base64.RawURLEncoding.EncodeToString(bytes), nil
+}
+
+// NewSecretKey generate a new value intended to be used by SECRET_KEY.
+func NewSecretKey() (string, error) {
+	secretKey, err := util.CryptoRandomString(64)
+	if err != nil {
+		return "", err
+	}
+
+	return secretKey, nil
+}
diff --git a/modules/generate/generate_test.go b/modules/generate/generate_test.go
new file mode 100644
index 0000000..eb7178a
--- /dev/null
+++ b/modules/generate/generate_test.go
@@ -0,0 +1,35 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package generate
+
+import (
+	"encoding/base64"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDecodeJwtSecret(t *testing.T) {
+	_, err := DecodeJwtSecret("abcd")
+	require.ErrorContains(t, err, "invalid base64 decoded length")
+	_, err = DecodeJwtSecret(strings.Repeat("a", 64))
+	require.ErrorContains(t, err, "invalid base64 decoded length")
+
+	str32 := strings.Repeat("x", 32)
+	encoded32 := base64.RawURLEncoding.EncodeToString([]byte(str32))
+	decoded32, err := DecodeJwtSecret(encoded32)
+	require.NoError(t, err)
+	assert.Equal(t, str32, string(decoded32))
+}
+
+func TestNewJwtSecret(t *testing.T) {
+	secret, encoded, err := NewJwtSecret()
+	require.NoError(t, err)
+	assert.Len(t, secret, 32)
+	decoded, err := DecodeJwtSecret(encoded)
+	require.NoError(t, err)
+	assert.Equal(t, secret, decoded)
+}