# Re: RSA decryption exponent d (c++)

*From*: mm <mm@xxxxxxxxxx>*Date*: Fri, 31 Mar 2006 15:43:24 +0200

TJakobsen a écrit :

hehe sorry but i dont really understand how to use this in my program

as im only a high school student (last year though). We don't have

advanced mathematics yet and we haven't really worked with any of the

mathematics related to RSA such as modulo etc.

could someone be so kind as to go through this Extended Euclidian

algorithn using the numbers i've used in my program please?

so we can calculate d.

thanks in advance.

All those who answered you are right, you _should_ use the Euclidean

algorithm, but, since the numbers you are using are very small, you

also can find the needed inverse with an exhaustive search, i.e.,

for i := 1 to PhiN-1 do

if ((i * e) mod PhiN) = 1 then

begin

d := i;

Break;

end;

mm

.

**Follow-Ups**:**Re: RSA decryption exponent d (c++)***From:*Carlos Moreno

**References**:**RSA decryption exponent d (c++)***From:*TJakobsen

**Re: RSA decryption exponent d (c++)***From:*Kristian Gjøsteen

**Re: RSA decryption exponent d (c++)***From:*TJakobsen

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