Why are hash algorithms like SHA-1 so important?
SHA-1 is widely used in security protocols and applications including: encryption used to securely connect to websites, Virtual Private Networks (VPNs), secure email delivery, Public Key Infrastructure (PKI) and most secure network connectivity. Some of the more popular SHA-1 based protocols include TLS, SSL, PGP, SSH, S/MIME, and IPSec.
As a unique mathematical fingerprint of its message input, a hash must meet two conditions to be useful. It must be:
For example, if the electronic message to be hashed were a 3,000 word essay, the change of a single comma would create a new, unique hash. SHA-1 hashes are 40 digits long, and if secure, the hash could not be mathematically reversed back to the electronic version of the 3000 word essay.
Like all systems, with enough effort, a hash can be broken. If an attacker can successfully manipulate a hash algorithm to yield the same output from two different inputs, a collision occurs, opening the door to forgery and impersonation. Similarly, if the hash algorithm can be mathematically reversed to reveal the original message, the hash algorithm’s useful life is over.