From 8c18fb5db9544486412c697a90ad55710639b36a Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Fri, 4 Jan 2019 19:31:41 +0100
Subject: file-format.md: document AES-SIV block layout

Fixes https://github.com/rfjakob/gocryptfs/issues/299
---
 Documentation/file-format.md | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/Documentation/file-format.md b/Documentation/file-format.md
index ad1fb3f..5699f9e 100644
--- a/Documentation/file-format.md
+++ b/Documentation/file-format.md
@@ -6,12 +6,18 @@ Header
 	 2 bytes header version (big endian uint16, currently 2)
 	16 bytes file id
 
-Data block
+Data block, default AES-GCM mode
 
 	16 bytes GCM IV (nonce)
 	1-4096 bytes encrypted data
 	16 bytes GHASH
 
+Data block, AES-SIV mode (used in reverse mode, or when explicitely enabled with `-init -aessiv`)
+
+	16 bytes nonce
+	16 bytes SIV
+	1-4096 bytes encrypted data
+
 Full block overhead = 32/4096 = 1/128 = 0.78125 %
 
 Example: 1-byte file
-- 
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