Using SHA1 in C

I am developing a tool in C which takes in a file as a input. I need to compute the SHA1 sum for the file. This tool needs to be platform compatible with Linux, Mac and开发者_如何学编程 windows. The files are huge in size ranging from 150MB to 2G. I need the tool to be able to compute the SHA at least as fast as the sha1sum Linux utility.

Any suggestions how I could go about incorporating SHA1? I am wary about using the openssl interface, since the clients for the tool would not necessary have openssl installed.

OpenSSL is the de facto standard in C. It needn't be installed since you can supply the library along with your program (or even statically compile it).

OpenSSL is BSD-style licensed, so you can even use just their SHA1 code directly in your program (giving credit), though it may be tricky to decouple it from the library.

My digest package for R includes short standalone C sources for md5, sha1, sha256, ... which were written by Christophe Devine. It is nice code, and it includes a few tests replicating the reference results from the specifications.

I believe his site no longer exists, but when I eg checked Google Code Search for it, the same functions seem to have been included in a number of other open source projects. You can easily extract these sources from my tarballs or even directly from the SVN directory at R-Forge's digest repo.