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From: Evren Esat Ozkan on 4 Jul 2008 09:36
Hello,

I'm trying to encrypt a string with RSA. But it needs to be compitable
with Dave's JavaScript RSA implementation*. I'm already read and tried
lots of different things about RSA and RSA in Python. But could not
produce the same result with the javascript library.

My experiments could be seen at: http://dpaste.com/hold/60741/

* JavaScript RSA Library: http://www.ohdave.com/rsa/

Python libraries which I tried;
* PyCrtypo: http://www.amk.ca/python/code/crypto.html
* rsa library from http://www.stuvel.eu/rsa

How could I create the same results with the JS library in Python.


Any help would be appreciated

Evren,
From: marek.rocki on 4 Jul 2008 11:19
Evren Esat Ozkan napisa³(a):
> Hello,
>
> I'm trying to encrypt a string with RSA. But it needs to be compitable
> with Dave's JavaScript RSA implementation*. I'm already read and tried
> lots of different things about RSA and RSA in Python. But could not
> produce the same result with the javascript library.
>
> My experiments could be seen at: http://dpaste.com/hold/60741/
>
> * JavaScript RSA Library: http://www.ohdave.com/rsa/
>
> Python libraries which I tried;
> * PyCrtypo: http://www.amk.ca/python/code/crypto.html
> * rsa library from http://www.stuvel.eu/rsa
>
> How could I create the same results with the JS library in Python.
>
>
> Any help would be appreciated
>
> Evren,

It seems that this Javascript is doing weird things to its input,
namely processing it in reverse. Try encrypting ciphertext[::-1]
instead of just ciphertext.

public_modulus_hex = '9F2E..snip..4BC7'
public_exponent_hex = '10001'
public_modulus = int(public_modulus_hex, 16)
public_exponent = int(public_exponent_hex, 16)

def encrypt(plaintext_text):
# Beware, plaintext must be short enough to fit in a single block!
plaintext = int(plaintext_text.encode('hex'), 16)
ciphertext = pow(plaintext, public_exponent, public_modulus)
return '%X' % ciphertext # return hex representation

print encrypt('12345')
print encrypt('12345'[::-1]) # Will return the value compatible with
JS output

Regards,
Marek
From: Evren Esat Ozkan on 17 Jul 2008 08:48
Hi,

Thank you very much. Your code is worked like a charm and saved my
honeymoon :)

Thanks again,
Evren


On Jul 4, 6:19 pm, marek.ro...(a)wp.pl wrote:
> Evren Esat Ozkan napisa³(a):
>
>
>
>
>
> > Hello,
>
> > I'm trying to encrypt a string with RSA. But it needs to be compitable
> > with Dave's JavaScript RSA implementation*. I'm already read and tried
> > lots of different things about RSA and RSA in Python. But could not
> > produce the same result with the javascript library.
>
> > My experiments could be seen at:http://dpaste.com/hold/60741/
>
> > * JavaScript RSA Library:http://www.ohdave.com/rsa/
>
> > Python libraries which I tried;
> > * PyCrtypo:http://www.amk.ca/python/code/crypto.html
> > * rsa library fromhttp://www.stuvel.eu/rsa
>
> > How could I create the same results with the JS library in Python.
>
> > Any help would be appreciated
>
> > Evren,
>
> It seems that this Javascript is doing weird things to its input,
> namely processing it in reverse. Try encrypting ciphertext[::-1]
> instead of just ciphertext.
>
> public_modulus_hex = '9F2E..snip..4BC7'
> public_exponent_hex = '10001'
> public_modulus = int(public_modulus_hex, 16)
> public_exponent = int(public_exponent_hex, 16)
>
> def encrypt(plaintext_text):
>         # Beware, plaintext must be short enough to fit in a single block!
>         plaintext = int(plaintext_text.encode('hex'), 16)
>         ciphertext = pow(plaintext, public_exponent, public_modulus)
>         return '%X' % ciphertext # return hex representation
>
> print encrypt('12345')
> print encrypt('12345'[::-1]) # Will return the value compatible with
> JS output
>
> Regards,
> Marek

From: Paul Rubin on 17 Jul 2008 11:19
Evren Esat Ozkan <sleytr(a)gmail.com> writes:
> I'm trying to encrypt a string with RSA. But it needs to be compitable
> with Dave's JavaScript RSA implementation*.

What exactly are you trying to do? That Javascript implementation
looks like bad news. If you're trying to secure a web page, use SSL,
don't mess around with trying to encrypt it with Javascript.
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