[pycrypto] providing signature in base64

[Legrandin]

Hi Cornelius,

I think M2Crypto signs by default using PKCS#1 v1.5.
You can try the Crypto.Signature.PKCS1_v1_5 module in pycrypto.
Something along these lines:

===
import Crypto.Signature.PKCS1_v1_5 as PKCS

signature = sign.decode("base64")
hash = sha256(licStr)
RSAKey = RSA.importKey(public)
ret =  PKCS.verify(hash, RSAKey, signature)
===

2012/5/9 Cornelius Kölbel <cornelius.koelbel at lsexperts.de>:
> Hi,
>
> i discovered the number.bytes_to_long function, which does the trick,
>
> but the signature validation still fails.
>
> I assume I would have to b64decode my signature prior to converting it.
> But it fails :-/
>
> ret =  RSAKey.verify(hash, (number.bytes_to_long(sign.decode("base64")),) )
> print ret
>
> ret =  RSAKey.verify(hash, (number.bytes_to_long(base64.b64decode(sign)),))
> print ret
>
> Any hint on that?
>
> The signature was created with openssl/M2Crypto.
> And I'd like to mirgate to pycrypto.
>
> Kind regards
> Cornelius
>
> Am 09.05.2012 16:28, schrieb Cornelius Kölbel:
>> Hello,
>>
>> I have a signature provided in base64 like this:
>>
>> XQgVBkxrmJXqN2+xkJx8dGRecadoLi61vjBTsl+kYibji0pf6ZsxYF2ewniV7pIbtjQxxIridBRtLo9d1Rpq6QvjvuVbVzqqimQeFZnQTp9scSfAbKCtDe1F4lEWCLP6s/6op3jgPpmgd0p5kPaA4iWLM5IjleT7kxgniggBXIky1aMq4L8DtLujcfHNLeJyXpw9TDPg/2KEYZGT1WqiXIeIuYPt7UySOVnmgIoQYstu7C5Vsy5hjzBfhpVvKaPjXEDeETL4UoO2S9H+hu0x932HyyiNTYCpY9VFQnptsVtTkkOvEqhY3xxYix4nzeU+vXc4hFFnhAZMJbPYmuPy5w==
>>
>> but I am breaking my head how to pass this to the verify function.
>>
>> I create the RSA Object from a PEM encoded public key. This works fine.
>>
>> But when I try to unpack the base64 encoded signature, I do not get ONE
>> long but a tuple with 32 long int.
>>
>>     long_signature= struct.unpack('Q'*32, sign.decode("base64"))
>>     hash = sha256(licStr).digest()
>>     RSAKey = RSA.importKey(public)
>>     ret =  RSAKey.verify(hash, long_signature)
>>
>> I know that this is more a matter of how to handle the unpack function,
>> but did not find anything about this.
>>
>> Thanks a lot and kind regards
>> Cornelius
>
>
>
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