Calculating digests and generating identifiers

Let's start by looking at how to use hashing functions with Node.js for the first two use cases presented previously – calculating the digests of messages or files to guarantee their integrity and generating unique identifiers.

For both these situations, the modern, recommended hashing function is SHA-256, which is part of the SHA-2 family. As its name suggests, SHA-256 returns a hash that is 256-bit in length or 32 bytes.

Other variants in the SHA-2 family exist, such as SHA-384 or SHA-512, which create hashes of 384 or 512 bits (48 or 64 bytes), respectively. These, although far less common, can be useful in cases where additional resistance to collision is needed, as we'll explore at the end of this chapter.

Hashing a short message or string

With Node.js, routines to calculate SHA-256 hashes are built into the crypto module. Using them requires just a few lines of code, as shown in the following sha256Digest...