Symmetric-keys algorithms with different keys for encryption and decryption The Symmetric-key algorithm article from Wikipedia states:

The keys may be identical or there may be a simple transformation to go between the two keys.

I am not aware of any symmetric-key cryptosystem that uses different keys for encryption and decryption. What are some examples of such algorithms? Is this correct to call them symmetric-key algorithms?
A relevant example where you usually don't use the same key for encryption and decryption is actually AES (and any SPN-based cipher for that matter).
The simplest point here would be that for AES you'd normally store your expanded key in order of usage in memory (to help with things like prefetching). However this would mean that the e.g. 11 round keys are stored in reverse order for encryption and decryption!
Furthermore for actual AES-NI based implementations you'd go one step further and pre-process your decryption round keys due to the way the hardware decryption instructions work (see e.g. this Intel guide (PDF) on how to do that). Due to this your actual key schedule usually looks completely different for the encryption and decryption direction (though you can somewhat easily transform one into the other). But no one would argue that AES is not a symmetric cipher...
As for the more general angle on this question: If the transformation is a simple operation as suggested on Wikipedia, it would usually be &quot;hidden&quot; from the user. That is one would usually specify the faster expansion for encryption and then add a pre-processing step for the key-usage during decryption.