Nettle is a cryptographic library designed to fit easily in a wide range of toolkits and applications. It began as a collection of low-level cryptography functions from lsh in 2001. Since June 2009 (version 2.0) Nettle is a GNU package.
Contents
Features
Since version 3, nettle provides
the AES block cipher - a subset of Rijndael, with assembly optimizations for x86 and sparc
the ARCFOUR, also known as RC4 stream cipher, with x86 and sparc assembly
the ARCTWO, also known as RC2, stream cipher
BLOWFISH,
CAMELLIA, with x86 and x86_64 assembly optimizations
CAST-128
DES and
3DES block ciphers
the ChaCha stream cipher, with assembly for x86_64
GOSTHASH94
the MD2, MD4 and MD5 with x86 assembly digests
the PBKDF2 key derivation function
the POLY1305 with assembly for x86_64 and UMAC message authentication codes
RIPEMD160
the Salsa20 stream cipher with assembly for x86_64 and ARM
the SERPENT block cipher with assembly for x86_64
SHA-1 with x86, x86_64 and ARM assembly
the SHA-2 (SHA-224, SHA-256, SHA-384, and SHA-512) digests
SHA-3 a subset of the Keccak digest family
the TWOFISH block cipher
RSA
DSA and ECDSA public-key algorithms
the Yarrow pRNG
Version 3.1 introduced support for Curve25519 and EdDSA operations. The public-key algorithms use GMP.
Nettle is used by
GnuTLS
AIDE since v0.19
License and motivation
An API which fits one application well may not work well in a different context resulting in a proliferation of cryptographic libraries designed for particular applications. Nettle is an attempt to avoid this problem by doing one thing (the low-level cryptography) and providing a simple and general interface to it. In particular, Nettle doesn't do algorithm selection, memory allocation or any I/O. Thus Nettle is intended to provide a core cryptography library upon which numerous application and context specific interfaces can be built. The code, test cases, benchmarks, documentation, etc. of these interfaces can then be shared without having to replicate Nettle's cryptographic code.
Nettle is primarily licensed under a dual licence scheme comprising The GNU General Public License version 2 or later and The GNU Lesser General Public License version 3 or later. A few individual files are licensed under more permissive licences or in the public domain. The copyright notices at the top of the library's source files precisely define the licence status of particular files.
The Nettle manual "is in the public domain" and may be used and reproduced freely.