--- /dev/null
+.. SPDX-License-Identifier: GPL-2.0
+
+=============================
+Scatterlist Cryptographic API
+=============================
+
+Introduction
+============
+
+The Scatterlist Crypto API takes page vectors (scatterlists) as
+arguments, and works directly on pages. In some cases (e.g. ECB
+mode ciphers), this will allow for pages to be encrypted in-place
+with no copying.
+
+One of the initial goals of this design was to readily support IPsec,
+so that processing can be applied to paged skb's without the need
+for linearization.
+
+
+Details
+=======
+
+At the lowest level are algorithms, which register dynamically with the
+API.
+
+'Transforms' are user-instantiated objects, which maintain state, handle all
+of the implementation logic (e.g. manipulating page vectors) and provide an
+abstraction to the underlying algorithms. However, at the user
+level they are very simple.
+
+Conceptually, the API layering looks like this::
+
+ [transform api] (user interface)
+ [transform ops] (per-type logic glue e.g. cipher.c, compress.c)
+ [algorithm api] (for registering algorithms)
+
+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 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).
+
+Here's an example of how to use the API::
+
+ #include <crypto/hash.h>
+ #include <linux/err.h>
+ #include <linux/scatterlist.h>
+
+ struct scatterlist sg[2];
+ char result[128];
+ struct crypto_ahash *tfm;
+ struct ahash_request *req;
+
+ tfm = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
+ if (IS_ERR(tfm))
+ fail();
+
+ /* ... set up the scatterlists ... */
+
+ req = ahash_request_alloc(tfm, GFP_ATOMIC);
+ if (!req)
+ fail();
+
+ ahash_request_set_callback(req, 0, NULL, NULL);
+ ahash_request_set_crypt(req, sg, result, 2);
+
+ if (crypto_ahash_digest(req))
+ fail();
+
+ ahash_request_free(req);
+ crypto_free_ahash(tfm);
+
+
+Many real examples are available in the regression test module (tcrypt.c).
+
+
+Developer Notes
+===============
+
+Transforms may only be allocated in user context, and cryptographic
+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
+size (typically 8 bytes). This prevents having to do any copying
+across non-aligned page fragment boundaries.
+
+
+Adding New Algorithms
+=====================
+
+When submitting a new algorithm for inclusion, a mandatory requirement
+is that at least a few test vectors from known sources (preferably
+standards) be included.
+
+Converting existing well known code is preferred, as it is more likely
+to have been reviewed and widely tested. If submitting code from LGPL
+sources, please consider changing the license to GPL (see section 3 of
+the LGPL).
+
+Algorithms submitted must also be generally patent-free (e.g. IDEA
+will not be included in the mainline until around 2011), and be based
+on a recognized standard and/or have been subjected to appropriate
+peer review.
+
+Also check for any RFCs which may relate to the use of specific algorithms,
+as well as general application notes such as RFC2451 ("The ESP CBC-Mode
+Cipher Algorithms").
+
+It's a good idea to avoid using lots of macros and use inlined functions
+instead, as gcc does a good job with inlining, while excessive use of
+macros can cause compilation problems on some platforms.
+
+Also check the TODO list at the web site listed below to see what people
+might already be working on.
+
+
+Bugs
+====
+
+Send bug reports to:
+ linux-crypto@vger.kernel.org
+
+Cc:
+ Herbert Xu <herbert@gondor.apana.org.au>,
+ David S. Miller <davem@redhat.com>
+
+
+Further Information
+===================
+
+For further patches and various updates, including the current TODO
+list, see:
+http://gondor.apana.org.au/~herbert/crypto/
+
+
+Authors
+=======
+
+- James Morris
+- David S. Miller
+- Herbert Xu
+
+
+Credits
+=======
+
+The following people provided invaluable feedback during the development
+of the API:
+
+ - Alexey Kuznetzov
+ - Rusty Russell
+ - Herbert Valerio Riedel
+ - Jeff Garzik
+ - Michael Richardson
+ - Andrew Morton
+ - Ingo Oeser
+ - Christoph Hellwig
+
+Portions of this API were derived from the following projects:
+
+ Kerneli Cryptoapi (http://www.kerneli.org/)
+ - Alexander Kjeldaas
+ - Herbert Valerio Riedel
+ - Kyle McMartin
+ - Jean-Luc Cooke
+ - David Bryson
+ - Clemens Fruhwirth
+ - Tobias Ringstrom
+ - Harald Welte
+
+and;
+
+ Nettle (http://www.lysator.liu.se/~nisse/nettle/)
+ - Niels Möller
+
+Original developers of the crypto algorithms:
+
+ - Dana L. How (DES)
+ - Andrew Tridgell and Steve French (MD4)
+ - Colin Plumb (MD5)
+ - Steve Reid (SHA1)
+ - Jean-Luc Cooke (SHA256, SHA384, SHA512)
+ - Kazunori Miyazawa / USAGI (HMAC)
+ - Matthew Skala (Twofish)
+ - Dag Arne Osvik (Serpent)
+ - Brian Gladman (AES)
+ - Kartikey Mahendra Bhatt (CAST6)
+ - Jon Oberheide (ARC4)
+ - Jouni Malinen (Michael MIC)
+ - NTT(Nippon Telegraph and Telephone Corporation) (Camellia)
+
+SHA1 algorithm contributors:
+ - Jean-Francois Dive
+
+DES algorithm contributors:
+ - Raimar Falke
+ - Gisle Sælensminde
+ - Niels Möller
+
+Blowfish algorithm contributors:
+ - Herbert Valerio Riedel
+ - Kyle McMartin
+
+Twofish algorithm contributors:
+ - Werner Koch
+ - Marc Mutz
+
+SHA256/384/512 algorithm contributors:
+ - Andrew McDonald
+ - Kyle McMartin
+ - Herbert Valerio Riedel
+
+AES algorithm contributors:
+ - Alexander Kjeldaas
+ - Herbert Valerio Riedel
+ - Kyle McMartin
+ - Adam J. Richter
+ - Fruhwirth Clemens (i586)
+ - Linus Torvalds (i586)
+
+CAST5 algorithm contributors:
+ - Kartikey Mahendra Bhatt (original developers unknown, FSF copyright).
+
+TEA/XTEA algorithm contributors:
+ - Aaron Grothe
+ - Michael Ringe
+
+Khazad algorithm contributors:
+ - Aaron Grothe
+
+Whirlpool algorithm contributors:
+ - Aaron Grothe
+ - Jean-Luc Cooke
+
+Anubis algorithm contributors:
+ - Aaron Grothe
+
+Tiger algorithm contributors:
+ - Aaron Grothe
+
+VIA PadLock contributors:
+ - Michal Ludvig
+
+Camellia algorithm contributors:
+ - NTT(Nippon Telegraph and Telephone Corporation) (Camellia)
+
+Generic scatterwalk code by Adam J. Richter <adam@yggdrasil.com>
+
+Please send any credits updates or corrections to:
+Herbert Xu <herbert@gondor.apana.org.au>
+++ /dev/null
-
- Scatterlist Cryptographic API
-
-INTRODUCTION
-
-The Scatterlist Crypto API takes page vectors (scatterlists) as
-arguments, and works directly on pages. In some cases (e.g. ECB
-mode ciphers), this will allow for pages to be encrypted in-place
-with no copying.
-
-One of the initial goals of this design was to readily support IPsec,
-so that processing can be applied to paged skb's without the need
-for linearization.
-
-
-DETAILS
-
-At the lowest level are algorithms, which register dynamically with the
-API.
-
-'Transforms' are user-instantiated objects, which maintain state, handle all
-of the implementation logic (e.g. manipulating page vectors) and provide an
-abstraction to the underlying algorithms. However, at the user
-level they are very simple.
-
-Conceptually, the API layering looks like this:
-
- [transform api] (user interface)
- [transform ops] (per-type logic glue e.g. cipher.c, compress.c)
- [algorithm api] (for registering algorithms)
-
-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 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).
-
-Here's an example of how to use the API:
-
- #include <crypto/hash.h>
- #include <linux/err.h>
- #include <linux/scatterlist.h>
-
- struct scatterlist sg[2];
- char result[128];
- struct crypto_ahash *tfm;
- struct ahash_request *req;
-
- tfm = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
- if (IS_ERR(tfm))
- fail();
-
- /* ... set up the scatterlists ... */
-
- req = ahash_request_alloc(tfm, GFP_ATOMIC);
- if (!req)
- fail();
-
- ahash_request_set_callback(req, 0, NULL, NULL);
- ahash_request_set_crypt(req, sg, result, 2);
-
- if (crypto_ahash_digest(req))
- fail();
-
- ahash_request_free(req);
- crypto_free_ahash(tfm);
-
-
-Many real examples are available in the regression test module (tcrypt.c).
-
-
-DEVELOPER NOTES
-
-Transforms may only be allocated in user context, and cryptographic
-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
-size (typically 8 bytes). This prevents having to do any copying
-across non-aligned page fragment boundaries.
-
-
-ADDING NEW ALGORITHMS
-
-When submitting a new algorithm for inclusion, a mandatory requirement
-is that at least a few test vectors from known sources (preferably
-standards) be included.
-
-Converting existing well known code is preferred, as it is more likely
-to have been reviewed and widely tested. If submitting code from LGPL
-sources, please consider changing the license to GPL (see section 3 of
-the LGPL).
-
-Algorithms submitted must also be generally patent-free (e.g. IDEA
-will not be included in the mainline until around 2011), and be based
-on a recognized standard and/or have been subjected to appropriate
-peer review.
-
-Also check for any RFCs which may relate to the use of specific algorithms,
-as well as general application notes such as RFC2451 ("The ESP CBC-Mode
-Cipher Algorithms").
-
-It's a good idea to avoid using lots of macros and use inlined functions
-instead, as gcc does a good job with inlining, while excessive use of
-macros can cause compilation problems on some platforms.
-
-Also check the TODO list at the web site listed below to see what people
-might already be working on.
-
-
-BUGS
-
-Send bug reports to:
-linux-crypto@vger.kernel.org
-Cc: Herbert Xu <herbert@gondor.apana.org.au>,
- David S. Miller <davem@redhat.com>
-
-
-FURTHER INFORMATION
-
-For further patches and various updates, including the current TODO
-list, see:
-http://gondor.apana.org.au/~herbert/crypto/
-
-
-AUTHORS
-
-James Morris
-David S. Miller
-Herbert Xu
-
-
-CREDITS
-
-The following people provided invaluable feedback during the development
-of the API:
-
- Alexey Kuznetzov
- Rusty Russell
- Herbert Valerio Riedel
- Jeff Garzik
- Michael Richardson
- Andrew Morton
- Ingo Oeser
- Christoph Hellwig
-
-Portions of this API were derived from the following projects:
-
- Kerneli Cryptoapi (http://www.kerneli.org/)
- Alexander Kjeldaas
- Herbert Valerio Riedel
- Kyle McMartin
- Jean-Luc Cooke
- David Bryson
- Clemens Fruhwirth
- Tobias Ringstrom
- Harald Welte
-
-and;
-
- Nettle (http://www.lysator.liu.se/~nisse/nettle/)
- Niels Möller
-
-Original developers of the crypto algorithms:
-
- Dana L. How (DES)
- Andrew Tridgell and Steve French (MD4)
- Colin Plumb (MD5)
- Steve Reid (SHA1)
- Jean-Luc Cooke (SHA256, SHA384, SHA512)
- Kazunori Miyazawa / USAGI (HMAC)
- Matthew Skala (Twofish)
- Dag Arne Osvik (Serpent)
- Brian Gladman (AES)
- Kartikey Mahendra Bhatt (CAST6)
- Jon Oberheide (ARC4)
- Jouni Malinen (Michael MIC)
- NTT(Nippon Telegraph and Telephone Corporation) (Camellia)
-
-SHA1 algorithm contributors:
- Jean-Francois Dive
-
-DES algorithm contributors:
- Raimar Falke
- Gisle Sælensminde
- Niels Möller
-
-Blowfish algorithm contributors:
- Herbert Valerio Riedel
- Kyle McMartin
-
-Twofish algorithm contributors:
- Werner Koch
- Marc Mutz
-
-SHA256/384/512 algorithm contributors:
- Andrew McDonald
- Kyle McMartin
- Herbert Valerio Riedel
-
-AES algorithm contributors:
- Alexander Kjeldaas
- Herbert Valerio Riedel
- Kyle McMartin
- Adam J. Richter
- Fruhwirth Clemens (i586)
- Linus Torvalds (i586)
-
-CAST5 algorithm contributors:
- Kartikey Mahendra Bhatt (original developers unknown, FSF copyright).
-
-TEA/XTEA algorithm contributors:
- Aaron Grothe
- Michael Ringe
-
-Khazad algorithm contributors:
- Aaron Grothe
-
-Whirlpool algorithm contributors:
- Aaron Grothe
- Jean-Luc Cooke
-
-Anubis algorithm contributors:
- Aaron Grothe
-
-Tiger algorithm contributors:
- Aaron Grothe
-
-VIA PadLock contributors:
- Michal Ludvig
-
-Camellia algorithm contributors:
- NTT(Nippon Telegraph and Telephone Corporation) (Camellia)
-
-Generic scatterwalk code by Adam J. Richter <adam@yggdrasil.com>
-
-Please send any credits updates or corrections to:
-Herbert Xu <herbert@gondor.apana.org.au>
-
projects / linux.git / commitdiff