[PATCH] scd: correct length for RSA public key response
wk at gnupg.org
Sun Aug 27 16:37:03 CEST 2017
On Fri, 25 Aug 2017 13:23, arnaud.fontaine at ssi.gouv.fr said:
> For example, with an exponent of 17 bits (e.g. 0x010001 which is
> commonly used on smartcards), 3 bytes are needed to encode it, not 2.
Sure, I just wondered why it seemed to work in the past.
> Actually, when the incorrect expected response length (i.e. Le field) is
> transmitted to the card, the card's answer is missing a byte (i.e. ...
> 6101) so an additional command has to be sent to the card to retrieve
> the last byte. Using the correct length avoids to send the additional
Okay, that explains it.
>>> - + 2 /* tag+len */ + app->app_local->keyattr[keyno].rsa.e_bits/8;
>>> + + 2 /* tag+len */ + (app->app_local->keyattr[keyno].rsa.e_bits + 7)/8;
Also odd lengths are not that common for N, I will do the same for
Thanks for figuring this out.
Die Gedanken sind frei. Ausnahmen regelt ein Bundesgesetz.
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