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eralha

Gerar chaves RSA public and private

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eralha

We need a encoding key(e) and a decoding key(d).

We start with E, E should be coprime to (p-1*q-1)

The security of RSA does not depend on E, we can check the primes against (p-1*q-1) until we find one. 3, 5, 7 etc (the security of RSA depends on how hard it is factoring the number we choose as modulus).

3 is coprime to 4265, lets choose 3 as our E.

In order to calculate D we must do an inverse mod operation like so

E^-1 mod (p-1*q-1). Inverse mod can be found on any good calculator and is often shown as M^-1 i am using Hexprobe Multibyte Calculator

so 3^-1 mod 4265 is 2843(d)

now take 3 as our encoding key(e) and 2843 as our decoding key(d).

The RSA rules are now

C = P^E mod m

P = C^D mod m

P = Plain Text

C = Cipher Text

1000^E(3) mod m(4399) = C(1724)

1000 encrypts to 1724, lets decode it now.

1724^D(2843) mod m(4399) = P(1000)

Boas pessoal estou a tentar perceber esta logica, o que nao entendi bem foi como gerar a chave de desencriptação, dame sempre valores esquisitos, as contas que estou a fazer são em action script, mas o meu problema está na matemática.

var modulus:Number = 4399;
var eKey:Number = 3;
var dKey:Number = (eKey^-1)%4265;
var c:Number = Math.pow(1000,eKey)%modulus;
var p:Number = Math.pow(c, dKey)%modulus;
trace("EKEY: "+eKey+" Cypher "+c+" DKEY: "+dKey+" Plain: "+p);

OUTPUT: EKEY: 3 Cypher 1724 DKEY: -4 Plain: 1.1320118003091641e-13

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Rui Carlos

Provavelmente precisas de implementar tu a operação de exponenciação... É que a implementação da linguagem não deve estar a fazer exponenciação modular.

Além disso, os tipos de dados do ActionScript têm precisão suficiente para suportar estas operações?

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