Introduction

sha is a simple program that hashes files. It uses the National Institute of Standards and Technology's Secure Hash Algorithm. It can use SHA-1, SHA-256, SHA-384, or SHA-512, which generate respectively, hashes of 160, 256, 384, or 512 bits. sha can be used in scripts to do, for example, file integrity checking.

Using sha is simple. Just pass the names of one or more files on the command line.

You may want to perform a sanity check on sha before relying on it. A program called "shatest" is built along with sha. If you run shatest, it will display the results of running the various SHA algorithms on a set of known test vectors. If the resultant hash matches what is expected, "PASS" will be displayed. Otherwise it will display "FAIL."