SHA1

Cryptographic Hash Function

one of the SHA family of functions

is employed in a large variety of popular security applications and protocols, including TLS, SSL, PGP, SSH, SMime, and IPSec.

considered safe for Crypto Graphy until late 2004

Federal agencies have been put on notice that National Institute of Standards and Technology officials plan to phase out a widely used cryptographic hash function known as SHA-1 in favor of larger and stronger hash functions such as SHA256 and SHA512.

http://www.schneier.com/blog/archives/2005/02/sha1_broken.html

http://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html