Mailing List Archive: GnuPG: devel

Length of public exponent in OpenPGP card specification

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klaus at flittner

Sep 26, 2009, 3:50 PM

Post #1 of 2 (544 views)
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Length of public exponent in OpenPGP card specification

Hello,

in the specification[1] the algorithm attributes contain a field for
the length of the public exponent. The available implementation of the
card[2] has a fixed value of 32 bits, but key import accepts a value of
65537 (17 bits) and key generation also produces only keys with e of
65537. What is the use of this field then?

Regards
Klaus Flittner

[1] http://www.g10code.com/docs/openpgp-card-2.0.pdf
[2] http://shop.kernelconcepts.de/product_info.php?cPath=1_26&products_id=42

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wk at gnupg

Sep 27, 2009, 4:06 AM

Post #2 of 2 (511 views)
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Re: Length of public exponent in OpenPGP card specification [In reply to]

On Sun, 27 Sep 2009 00:50, klaus [at] flittner said:

> in the specification[1] the algorithm attributes contain a field for
> the length of the public exponent. The available implementation of the
> card[2] has a fixed value of 32 bits, but key import accepts a value of
> 65537 (17 bits) and key generation also produces only keys with e of
> 65537. What is the use of this field then?

It is the size of the variable describing the length of the exponent.
For example you need 17 bits to express 65537, thus it first easily into
32 bits.

Salam-Shalom,

Werner

--
Die Gedanken sind frei. Auschnahme regelt ein Bundeschgesetz.

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