Thanks for the replies. I'm certainly no expert on this stuff. A few years ago, I implemented DES as a learning exercise [1]. I recall reading something at the time about security concerns with DES. That was several years ago, so I'm probably mis-remembering. Wikipedia vaguely refers to concerns about security being a motivation for AES, but doesn't explain what those concerns were [2].

[1] https://github.com/dcuddeback/des_crack

[2] https://en.wikipedia.org/wiki/Data_Encryption_Standard#Repla...