If you gpg sign AND encrypt, do you sign-then-encrypt or encrypt-then-sign?

There has long been a (very strong) argument for mac-then-encrypt being worse than encrypt-then-mac (see e.g. padding oracle attacks), with eventually authenticated encryption (an effective "mac AND encrypt") eventually seen as even better than both; at least in the context of TLS and similar protocols.

For message signing however, you really want to keep the transferrability property of the signature.

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it occurs to me you could sign-then-encrypt-then-sign if ciphertext malleability concerns you. unless i missed something.

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@waxwing sign then encrypt, but why sign again the --armor output?

But u leave uc valuable key noise if u sign again, that could help to get faster break the encrypt that protect ur sign or am i here missing something?

@dflate

> sign then encrypt

it probably wasn't clear, but i was actually asking which of the two gpg does if you --sign and --encrypt, so are you answering here?

> But u leave uc valuable key noise if u sign again

I don't understand 'uc' there, but .. that's an interesting point to raise. On one hand, it's at least true in abstract, every +1 signature can leak something, if the scheme is sound that should be negligible.

Another consideration: signing ciphertext makes it non-repudiable.

@waxwing uc under circumstances

i assumed --armor sign and then encrypt the output is a good practice, but not sure how those parameters are interpreted if in one sweep on one cmdlline hmm lets check the source ...

@waxwing in gnupg it looks like it does
sign encrypt if u use both options.
on one cmdline. afaics

case aSignEncr:
cmdname="--sign --encrypt";
break;

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