Preserve data across the Straywild transition

network/network_identity_crypto.gd

@@ -6,6 +6,7 @@ const FINGERPRINT_LENGTH: int = 64
 const MAX_PUBLIC_KEY_BYTES: int = 8192
 const MAX_SIGNATURE_BYTES: int = 1024
 const DOMAIN_PREFIX: String = "straywild"
+const LEGACY_DOMAIN_PREFIX: String = "NETFISHING"
 const IDENTITY_VERSION: String = "identity_v1"
 
 
@@ -50,8 +51,16 @@ static func secure_id(byte_count: int = 16) -> String:
 
 
 static func canonical_bytes(domain: String, fields: Array) -> PackedByteArray:
+	return canonical_bytes_for_prefix(DOMAIN_PREFIX, domain, fields)
+
+
+static func canonical_bytes_for_prefix(
+	prefix: String,
+	domain: String,
+	fields: Array,
+) -> PackedByteArray:
 	var output := PackedByteArray()
-	_append_string(output, DOMAIN_PREFIX)
+	_append_string(output, prefix)
 	_append_string(output, IDENTITY_VERSION)
 	_append_string(output, domain)
 	for value: Variant in fields:
@@ -117,6 +126,37 @@ static func verify_fields(
 	)
 
 
+static func verify_legacy_fields(
+	public_key: CryptoKey,
+	domain: String,
+	fields: Array,
+	signature: PackedByteArray,
+) -> bool:
+	if (
+		public_key == null
+		or signature.is_empty()
+		or signature.size() > MAX_SIGNATURE_BYTES
+	):
+		return false
+	var bytes: PackedByteArray = canonical_bytes_for_prefix(
+		LEGACY_DOMAIN_PREFIX,
+		domain,
+		fields,
+	)
+	if bytes.is_empty():
+		return false
+	var context := HashingContext.new()
+	if context.start(HashingContext.HASH_SHA256) != OK:
+		return false
+	context.update(bytes)
+	return Crypto.new().verify(
+		HashingContext.HASH_SHA256,
+		context.finish(),
+		signature,
+		public_key,
+	)
+
+
 static func load_public_key(public_pem: String) -> CryptoKey:
 	var normalized := normalize_public_pem(public_pem)
 	if normalized.is_empty() or normalized.to_utf8_buffer().size() > MAX_PUBLIC_KEY_BYTES: