Nettle-2.0 was released June 8. Since then, Nettle has been dubbed a GNU package, and I'm therefore reannouncing this release here. The original announcement is included below. Future releases will be distributed at ftp.gnu.org, but unfortunately, I haven't been able to set that up before summer vacations (and I leave my signing keys at home).
What is Nettle? A quote from the introduction in the Nettle Manual:
Nettle is a cryptographic library that is designed to fit easily in more or less any context: In crypto toolkits for object-oriented languages (C++, Python, Pike, ...), in applications like LSH or GNUPG, or even in kernel space. In most contexts, you need more than the basic cryptographic algorithms, you also need some way to keep track of available algorithms, their properties and variants. You often have some algorithm selection process, often dictated by a protocol you want to implement.
And as the requirements of applications differ in subtle and not so subtle ways, an API that fits one application well can be a pain to use in a different context. And that is why there are so many different cryptographic libraries around.
Nettle tries to avoid this problem by doing one thing, the low-level crypto stuff, and providing a simple but general interface to it. In particular, Nettle doesn't do algorithm selection. It doesn't do memory allocation. It doesn't do any I/O.
The idea is that one can build several application and context specific interfaces on top of Nettle, and share the code, test cases, benchmarks, documentation, etc. Examples are the Nettle module for the Pike language, and LSH, which both use an object-oriented abstraction on top of the library.
Nettle is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation. See the file COPYING for details. Most, but not all, of Nettle can also be used under the terms of the GNU Lesser General Public License; please read the Copyright section of the manual if you want to exercise this option.
The Nettle home page is http://www.lysator.liu.se/~nisse/nettle/.
Happy hacking, /Niels Möller
Original announcement:
NEWS for the 2.0 release
This release breaks binary compatibility by splitting the library into two. Some other smaller changes that are not backwards compatible are also done at the same time.
* The nettle library is split into two libraries, libnettle and libhogweed. libnettle contains the symmetric crypto algorithms that don't depend on GMP, while libhogweed contains the public key algorithms that depend on GMP. Using a single library worked fine with static linking, but not with dynamic linking. Consider an application that uses nettle and which doesn't use any public key cryptography. If this application is linked dynamically to nettle, it would have to be linked also with GMP if and only if public key support was enabled when the nettle library was installed.
The library names are libnettle.so.3.0 and libhogweed.so.1.0, with sonames libnettle.so.3 and libhogweed.so.1.
* Function typedefs have been changed to non-pointer types. E.g, the
typedef void (nettle_hash_init_func *)(void *ctx);
of previous versions is replaced by
typedef void (nettle_hash_init_func)(void *ctx);
This makes it possible to use the type when declaring functions, like
nettle_hash_init_func foo_hash_init;
void foo_hash_init(void *ctx) { ... }
* Changes to the yarrow256 interface. The automatic seed file generation, and the seed_file member in struct yarrow256_ctx, has been removed. To generate a new seed file, use yarrow256_random. The function yarrow256_force_reseed has been replaced by the two functions yarrow256_fast_reseed and yarrow256_slow_reseed, which were previously static. This interface change makes it easier to mix in the current content of the seed file before overwriting it with newly generated data.
Other changes:
* Nettle manual now contributed to the public domain, to enable remixing into documentation of programs that use Nettle.
* The sexp-conv program preserves comments when using the advanced syntax for output. Optionally locks the output file.
* The base64 decoder recognizes ASCII FF (form feed) and VT (vertical tab) as white space.
* New x86_64 implementations of AES and SHA1. On a 2.2 GHz opteron, SHA1 was benchmarked at 250 MByte/s, and AES-128 at 110 MByte/s.
* Performance of AES increased by 20-30% on x86.
* New programs in the examples directory: erathostenes and next-prime.
Available at
http://www.lysator.liu.se/~nisse/archive/nettle-2.0.tar.gz ftp://ftp.lysator.liu.se/pub/security/lsh/nettle-2.0.tar.gz
as usual.
Regards, /Niels