Pulling the Plug

Cryptographic hash functions have a number of properties. For example, one requirement is that a unique checksum with a fixed length can be generated from arbitrary data. Collisions – where two different datasets have the same checksum – must be practically impossible. Finally, cryptographic hash functions are one-way functions, which ensures that it is virtually impossible to reconstruct the original data from the checksum. These properties are ideal for integrity checking arbitrary data, because it is practically impossible to change a message without also changing the message’s checksum. Typical applications for digital signatures include X.509 certificates, PGP/GPG keys, software packages, and DNS entries. Of course, signatures like this are also used when you transmit data over a network to ensure the integrity of the transmitted data. Insecure Hash Functions If…