Initial DDC release

internal/auth/credentials.go

@@ -0,0 +1,18 @@
+package auth
+
+import (
+	"crypto/sha256"
+	"crypto/subtle"
+)
+
+func CredentialsMatch(expectedUsername, expectedPassword, username, password string) bool {
+	usernameMatches := constantTimeEqual(expectedUsername, username)
+	passwordMatches := constantTimeEqual(expectedPassword, password)
+	return usernameMatches && passwordMatches
+}
+
+func constantTimeEqual(expected, actual string) bool {
+	expectedHash := sha256.Sum256([]byte(expected))
+	actualHash := sha256.Sum256([]byte(actual))
+	return subtle.ConstantTimeCompare(expectedHash[:], actualHash[:]) == 1
+}