PHP AES/Rijndael Encryption Confusion

AES is not exactly synonymous with “Rijndael”. AES is a (restricted) variant of Rijndael. AES has a fixed block size of 128 bits and a key size of 128, 192, or 256 bits, whereas Rijndael is specified with block and key sizes in any multiple of 32 bits, both with a minimum of 128 and a maximum of 256 bits. […]