libgocryptfs/Documentation/file-format.md
Jakob Unterwurzacher 1caa925868 Increase GCM IV size from 96 to 128 bits
This pushes back the birthday bound for collisions to make it virtually
irrelevant.
2015-12-19 15:02:29 +01:00

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Markdown

File Format
===========
Header
2 bytes header version (big endian uint16, currently 2)
16 bytes file id
Data block
16 bytes GCM IV (nonce)
1-4096 bytes encrypted data
16 bytes GHASH
Example: 1-byte file
--------------------
Header 18 bytes
Data block 33 bytes
Total: 51 bytes
Example: 5000-byte file
-----------------------
Header 18 bytes
Data block 4128 bytes
Data block 936 bytes
Total: 5082 bytes