SHA

SHA-0 (Secure Hash Algorithm) was a proposal by the U.S. government that was replaced by SHA-1 in FIPS 180-1. SHA-1 addresses the weakness found in SHA-0 by adding an additional circular shift operation, thus deprecated SHA-0. SHA-1 has a reported weakness as far as hash collisions are concerned and awareness should be raised if you are implementing it.

If you have the sha1 application installed, you can make use of the command like so:

$ sha1 /etc/passwd
SHA1 (/etc/passwd) = c7ae5b7306797d9f1f5fba85683cdd36ba8d1a08

Using SHA256+ in OpenBSD and NetBSD

As of OpenBSD 4.5 and NetBSD 4.0 the cksum command does SHA256, SHA384 and SHA512 the command is done like so:

$ cksum -a sha256 /dev/null           
SHA256 (/dev/null) = e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
$ cksum -a sha384 /dev/null
SHA384 (/dev/null) = 38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da274edebfe76f65fbd51ad2f14898b95b
$ cksum -a sha512 /dev/null 
SHA512 (/dev/null) = cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e

A neat feature in OpenBSD is the -b flag in cksum which outputs the SHA checksum in base64:

$ cksum -a sha512 -b /dev/null
SHA512 (/dev/null) = z4PhNX7vuL3xVChQ1m2AB9Yg5AULVxXcg/SpIdNs6c5H0NE8XYXysP+DGNKHfuwvY7kxvUdBeoGlODJ6+SfaPg==

The checksum is against the binary, NOT the hexdump of normal sha512.

SHA256 in FreeBSD

FreeBSD 7.0-stable has a sha256 program:

$ sha256 /dev/null
SHA256 (/dev/null) =  e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

SHA256+ in Solaris 10

Use the digest command:

$ digest -v -a sha256 /dev/null
sha256 (/dev/null) = e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
$ digest -v -a sha384 /dev/null
sha384 (/dev/null) = 38b060a751ac96384cd9327eb1b1e36a21fdb71114be07434c0cc7bf63f6e1da274edebfe76f65fbd51ad2f14898b95b       
$ digest -v -a sha512 /dev/null
sha512 (/dev/null) = cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e

Using SHA256+ in Linux

On Debian/Ubuntu:

$ shasum -a 256 /dev/null
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b936ca495991b7852b855  /dev/null
# -a, --algorithm   1 (default), 224, 256, 384, 512, 512224, 512256

In this example it's OpenSuse 10.3, one has to use the openssl package:

> openssl dgst -sha256 /dev/null
SHA256(/dev/null)= e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 
> openssl dgst -sha512 /dev/null
SHA512(/dev/null)= cf83e1357eefb8bdf1542850d66d8007d620e4050b5715dc83f4a921d36ce9ce47d0d13c5d85f2b0ff8318d2877eec2f63b931bd47417a81a538327af927da3e

There doesn't seem to be a sha384 though.