Phase 1

user/util.go

@@ -1,7 +1,9 @@
 package user
 
 import (
+	"crypto/sha256"
 	"database/sql"
+	"encoding/hex"
 	"regexp"
 	"strings"
 
@@ -9,6 +11,11 @@ import (
 	"heckel.io/ntfy/v2/util"
 )
 
+// linkTokenLength is the length of a raw magic-link token. At 48 base62 characters
+// it carries ~285 bits of entropy, well above the ~256-bit target, so the tokens
+// need no brute-force cap -- just expiry and single-use.
+const linkTokenLength = 48
+
 var (
 	allowedUsernameRegex     = regexp.MustCompile(`^[-_.+@a-zA-Z0-9]+$`)    // Does not include Everyone (*)
 	allowedTopicRegex        = regexp.MustCompile(`^[-_A-Za-z0-9]{1,64}$`)  // No '*'
@@ -67,6 +74,21 @@ func GenerateToken() string {
 	return util.RandomLowerStringPrefix(tokenPrefix, tokenLength)
 }
 
+// generateLinkToken returns a fresh high-entropy raw token for a magic link
+// (email verification or password reset). The raw token is carried in the emailed
+// link; only its hashToken digest is persisted.
+func generateLinkToken() string {
+	return util.RandomString(linkTokenLength)
+}
+
+// hashToken returns the hex-encoded SHA-256 digest of a raw magic-link token.
+// Tokens are stored hashed so a database read cannot yield working links; a high-entropy
+// token makes a fast (unsalted) hash sufficient, unlike a password.
+func hashToken(raw string) string {
+	sum := sha256.Sum256([]byte(raw))
+	return hex.EncodeToString(sum[:])
+}
+
 // HashPassword hashes the given password using bcrypt with the configured cost
 func HashPassword(password string) (string, error) {
 	return hashPassword(password, DefaultUserPasswordBcryptCost)