1 files changed, 51 insertions, 0 deletions
diff --git a/metadata/constants.go b/metadata/constants.go
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+/*
+ * constants.go - Some metadata constants used throughout fscrypt
+ *
+ * Copyright 2017 Google Inc.
+ * Author: Joe Richey (joerichey@google.com)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package metadata
+
+import (
+	"crypto/sha256"
+
+	"golang.org/x/sys/unix"
+)
+
+// Lengths for our keys, buffers, and strings used in fscrypt.
+const (
+	// DescriptorLen is the length of all Protector and Policy descriptors.
+	DescriptorLen = 2 * unix.FS_KEY_DESCRIPTOR_SIZE
+	// We always use 256-bit keys internally (compared to 512-bit policy keys).
+	InternalKeyLen = 32
+	IVLen          = 16
+	SaltLen        = 16
+	// We use SHA256 for the HMAC, and len(HMAC) == len(hash size).
+	HMACLen = sha256.Size
+	// PolicyKeyLen is the length of all keys passed directly to the Keyring
+	PolicyKeyLen = unix.FS_MAX_KEY_SIZE
+)
+
+var (
+	// DefaultOptions use the supported encryption modes and max padding.
+	DefaultOptions = &EncryptionOptions{
+		Padding:   32,
+		Contents:  EncryptionOptions_XTS,
+		Filenames: EncryptionOptions_CTS,
+	}
+	// DefaultSource is the source we use if none is specified.
+	DefaultSource = SourceType_custom_passphrase
+)