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[CRYPTO] doc: Update api-intro.txt
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This patch updates the list of transforms we support and clarifies that
the Block Ciphers interface in fact supports all ciphers including stream
ciphers.

It also removes the obsolete Configuration Notes section and adds the
linux-crypto mailing list as the primary bug reporting address.

Finally it documents the fact that setkey should only be called from
user context.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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herbertx committed Jan 10, 2008
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41 changes: 16 additions & 25 deletions Documentation/crypto/api-intro.txt
Original file line number Diff line number Diff line change
Expand Up @@ -33,9 +33,16 @@ The idea is to make the user interface and algorithm registration API
very simple, while hiding the core logic from both. Many good ideas
from existing APIs such as Cryptoapi and Nettle have been adapted for this.

The API currently supports three types of transforms: Ciphers, Digests and
Compressors. The compression algorithms especially seem to be performing
very well so far.
The API currently supports five main types of transforms: AEAD (Authenticated
Encryption with Associated Data), Block Ciphers, Ciphers, Compressors and
Hashes.

Please note that Block Ciphers is somewhat of a misnomer. It is in fact
meant to support all ciphers including stream ciphers. The difference
between Block Ciphers and Ciphers is that the latter operates on exactly
one block while the former can operate on an arbitrary amount of data,
subject to block size requirements (i.e., non-stream ciphers can only
process multiples of blocks).

Support for hardware crypto devices via an asynchronous interface is
under development.
Expand Down Expand Up @@ -69,29 +76,12 @@ Here's an example of how to use the API:
Many real examples are available in the regression test module (tcrypt.c).


CONFIGURATION NOTES

As Triple DES is part of the DES module, for those using modular builds,
add the following line to /etc/modprobe.conf:

alias des3_ede des

The Null algorithms reside in the crypto_null module, so these lines
should also be added:

alias cipher_null crypto_null
alias digest_null crypto_null
alias compress_null crypto_null

The SHA384 algorithm shares code within the SHA512 module, so you'll
also need:
alias sha384 sha512


DEVELOPER NOTES

Transforms may only be allocated in user context, and cryptographic
methods may only be called from softirq and user contexts.
methods may only be called from softirq and user contexts. For
transforms with a setkey method it too should only be called from
user context.

When using the API for ciphers, performance will be optimal if each
scatterlist contains data which is a multiple of the cipher's block
Expand Down Expand Up @@ -130,8 +120,9 @@ might already be working on.
BUGS

Send bug reports to:
Herbert Xu <herbert@gondor.apana.org.au>
Cc: David S. Miller <davem@redhat.com>
linux-crypto@vger.kernel.org
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
David S. Miller <davem@redhat.com>


FURTHER INFORMATION
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