git-annex/doc/special_remotes/Amazon_S3.mdwn

This special remote type stores file contents in a bucket in Amazon S3
or a similar service.

See [[walkthrough/using_Amazon_S3]] for usage examples.

## bucket names

When `git annex s3bucket` is used to create a new bucket, it generates a
UUID, and the name of the bucket includes that UUID, as well as the name
specified by the user. This makes for some unweidly bucket names, but
since S3 requires that bucket names be globally unique, it avoids needing
to hunt for a unused bucket name.

## data security

When `git annex s3bucket` is used to create an unencrypted bucket,
there is **no** protection against your data being read as it is sent
to/from S3, or by Amazon when it is stored in S3. This should only be used
for public data.

** Encryption is not yet supported. **

When an encrypted bucket is created, all files stored in the bucket are
encrypted with gpg. Additionally, the filenames themselves are hashed
to obfuscate them. The size of the encrypted files, and access patterns of
the data, should be the only clues to what type of data you are storing in
S3.

[[!template id=note text="""
This scheme was originally developed by Lars Wirzenius at al
[for Obnam](http://braawi.org/obnam/encryption/).
"""]]
The data stored in S3 is encrypted by gpg with a symmetric cipher. The
passphrase of the cipher is itself checked into your git repository,
encrypted using one or more gpg public keys. This scheme allows new private
keys to be given access to a bucket's content, after the bucket is created
and is in use. The symmetric cipher is also hashed together with filenames
used in the bucket, in order to obfuscate the filenames.

To add a new gpg key to an existing bucket, just re-run `git annex
s3bucket`, specifying the new key id. For example:

	# git annex s3bucket mybucket 16D0B8EF
	s3bucket (adding gpg key 16D0B8EF) ok