密码库LibTomCrypt学习记录——（0）LibTomCrypt简介

LibTom系列是加拿大的汤姆St. 丹尼斯用标准C语言写成，该系列库包四个组成部分：LibTomMath、 LibTomCrypt、 LibTomNet,和 LibTomPoly。LibTomMath和LibTomCrypt是最成熟的组成部分。LibTom系列地址是：http://www.libtom.org/

LibTomCrypt是一个简单易用的加密工具，它提供给开发者相当多的大家熟悉的分组密码、单向hash函数、伪随机数生成器、公钥加密和其他的一些程序算法。它用标准的纯C语言写成。它有一个标准的API允许新密码，hashes函数，伪随机数生成器，添加和删除，它的特点是用很容易使用这些函数。LibTomCrypt是免费*的软件。

开源密码库众多，其中非常著名的还有OpenSSL、crypto++等。以下简要说明：

1. OpenSSL ：C语言实现，整个软件包大概可以分成三个主要的功能部分：密码算法库、SSL协议库以及应用程序。OpenSSL的目录结构自然也是围绕这三个功能部分进行规划的。作为一个基于密码学的安全开发包，OpenSSL提供的功能相当强大和全面，囊括了主要的密码算法、常用的**和证书封装管理功能以及SSL协议，并提供了丰富的应用程序供测试或其它目的使用。支持跨平台。代码量比较庞大，经过很多次调整，目前的结构不再清晰明了，要代码剥离的话非常痛苦，使用起来不是很方便。
2. Crypto++：C++语言实现，代码庞大且复杂，使用起来不方便。支持跨平台。
3. LibTomCrypt：短小精干，结构清晰明了，速度中等。适合初学密码学的学生和期望对密码学有进一步了解的人士。名气和使用广泛性不如OpenSSL和Crypto++。

LibTom的作者汤姆St. 丹尼斯还是位80后，在LibTom系列的主页中有他的自我介绍。下文是丹尼斯的自我介绍，来至于http://www.libtom.org/pages/about.html.

I'm a Canadian, from Ottawa, the nations capital.  I was born in 1982, raised, educated, and live here in town.  I hold an associates degree (equiv) from Algonquin College in computer science and engineering.  I grad'ed from college in 2004.  I'm the published author of two texts on cryptography, as well as the lead author of a half-dozen open source projects, three of which are fairly prominent in the community (my users include several large corporations, OSS projects such as OLPC and Tcl, universities such as Harvard and EPFL, etc.).  

I study the piano.  I used to play when I was younger, took a near decade break and now am back into the study.  I only play conservatory pieces :-) and hope to someday regain my talent from my youth and perform in public once again.

I'm a dedicated fan of the Toorcon conference scene.  I've given talks there for the last three years as well as sponsor stipends and other activities (such as parties).  As a policy I refuse to attend IACR conferences due to the excessive costs which exclude many students from attending.  I prefer the small conference scene, but can see myself liking defcon one day.  

I originally wanted to go the formal academia route and become a professor, realizing that was a lofty goal I devoted my energies to the projects (and a healthy respect for having a good time).  Finally if you wanted to see what I look like, the following is a photo from Toorcon in 2006.  Keep in mind this is Sunday afternoon, after a solid weekend (plus Friday) of partying :-)

汤姆St. 丹尼斯