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Code Issues Releases Wiki Activity

clarify some bits I missed

This commit is contained in:
Antoine Beaupré 2014-12-16 10:03:20 -05:00
parent a8ab9c3445
commit 9f0ed2a8c0
3 changed files with 14 additions and 11 deletions
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1
docs/global.rst.inc
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@ -15,6 +15,7 @@
.. _PBKDF2: https://en.wikipedia.org/wiki/PBKDF2
.. _SHA256: https://en.wikipedia.org/wiki/SHA-256
.. _HMAC: https://en.wikipedia.org/wiki/HMAC
.. _AES: https://en.wikipedia.org/wiki/AES
.. _msgpack: http://msgpack.org/
.. _`msgpack-python`: https://pypi.python.org/pypi/msgpack-python/
.. _llfuse: https://pypi.python.org/pypi/llfuse/

1
docs/index.rst
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@ -50,6 +50,7 @@ User's Guide
quickstart
usage
faq
internals
Getting help
============

23
docs/internals.rst
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@ -24,21 +24,22 @@ repository_id
the ``id`` field in the ``config`` ``INI`` file of the repository.
enc_key
the AES encryption key
the key used to encrypt data with AES (256 bits)
enc_hmac_key
the HMAC key (32 bytes)
the key used to HMAC the resulting AES-encrypted data (256 bits)
id_key
another HMAC key? unclear.
the key used to HMAC the above chunks, the resulting hash is
stored out of band (256 bits)
chunk_seed
unknown
the seed for the buzhash chunking table (signed 32 bit integer)
Those fields are encoded using msgpack_. The utf-8-encoded phassphrase
is encrypted with a PBKDF2_ and SHA256_ using 100000 iterations and a
random 32 bytes salt to give us a derived key. The derived key is 32
bytes long. A HMAC_ SHA256_ checksum of the above fields is generated
random 256 bits salt to give us a derived key. The derived key is 256
bits long. A HMAC_ SHA256_ checksum of the above fields is generated
with the derived key, then the derived key is also used to encrypt the
above pack of fields. Then the result is stored in a another msgpack_
formatted as follows:
@ -47,20 +48,20 @@ version
currently always an integer, 1
salt
random 32 bytes salt used to encrypt the passphrase
random 256 bits salt used to encrypt the passphrase
iterations
number of iterations used to encrypt the passphrase
number of iterations used to encrypt the passphrase (currently 100000)
algorithm
the hashing algorithm used to encrypt the passphrase and do the HMAC
checksum
checksum (currently the string ``sha256``)
hash
the HMAC checksum of the encrypted passphrase key
the HMAC checksum of the encrypted derived key
data
the passphrase key, encrypted with AES over a PBKDF2_ SHA256 hash
the derived key, encrypted with AES over a PBKDF2_ SHA256 hash
described above
The resulting msgpack_ is then encoded using base64 and written to the