(no subject)

npellegr at numericable.fr npellegr at numericable.fr
Thu Jan 13 15:03:48 CET 2005


I'm using gnupg with a RSA key pair and SHA-1 as the hash algorithm.
My pair needs my public key but doesn't want to install Gnupg because he's got
his own cryptotool.

I'd like to give him :

1) my public RSA key.
2) the key signature.
I want to do it myself =>  RSA(Kpriv,SHA-1(Kpub))

My pair should be able to :

1) to use the public key I sent to decode the signature.
2) to compute the SHA-1 sum of the public key I sent.
3) to compare the 2 sums.

I do know this is not enough to be sure this is my REAL public key (a known CA
signed certificate would be useful) but that's better than nothing.

So i need to cypher the hash sum of my public key by using my secret key.
(c=m^d [n])

I took a look to the gnupg sources and especially /cypher/rsa.c
and I can see a static function "secret" that does exactly what I need.

=> static void secret(MPI output, MPI input, RSA_secret_key *skey )

My question is : is it planned to enable users to use this function with
GnuPG/RSA users via the command line or should I modify GnuPG myself (but I
wouldn't have a standard GnuPG solution) ?

Nicolas Pellegrin

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