I appreciate that the author clearly states that security, i.e., output can't be reversed back to the input, is a non-requirement. We can't criticize the author too much for that either, because, as a rule, "random-looking id generator" algorithms will always be either not secure, or not short, or not collision-free. Or they'll be a key-value database.
A secure "random-looking id generator" is called a block cipher. Block ciphers with less than 128 bits of output are widely considered insecure: this corresponds to about 22 base64 characters.
Going further, you probably do want to use a secure algorithm. History is full of people thinking "we don't need this to be secure, it's not used for security-sensitive things" and later regretting it. Some case studies at [1].
A secure "random-looking id generator" is called a block cipher. Block ciphers with less than 128 bits of output are widely considered insecure: this corresponds to about 22 base64 characters.
Going further, you probably do want to use a secure algorithm. History is full of people thinking "we don't need this to be secure, it's not used for security-sensitive things" and later regretting it. Some case studies at [1].
[1] https://www.schneier.com/blog/archives/2016/04/security_risk... .