[pixelbeat__]

Padding is only required if concatenating / streaming encoded data. I.e. when there are padding chars _within_ the encoded stream.

Padding chars at the end (of stream / file / string) can be inferred from the length already processed, and thus are not strictly necessary.

Note how padding is treated is quite subtle, and has resulted in interesting variations in handling as discussed at: https://eprint.iacr.org/2022/361.pdf