On Thursday, January 17, 2013 5:39:57 PM UTC+1, Piet van Oostrum wrote: > > Converting to X.501 isn't difficult (assuming this is a 2048 bit key): > > > Get rid of the 'RSA' in header and trailer > > > Prepend X.501 header 'MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8A' to the data > > > Reformat the lines to 64 characters. > > > > This solution is a bit restricted as it only works if the key is 2048 > > bits and uses an exponent of 65537 (which is the default). Otherwise it > > fails. > > > > Here is a robust solution that works for all PKCS#1 keys. Instead of > > using a fixed X.501 header it calculates the header. We could do a > > complete ASN.1 encoding, but most of the parts are fixed. The only > > variable parts are two length fields. So I just plug these into the > > fixed stuff. This saves using one of the ASN.1 libraries. We do have to > > work in binary (DER format) instead of base64, however. >
Thank you very much Piet, I'm just starting to grasp these cryptography related concepts and your code is helping me a lot to understand how to handle these keys in a low level. I'm updating my code incorporating your new contribution! Just to let you know, during my previous research I had found a python-Crypto related solution that also uses DER and ASN.1 [1], but it uses a different approach (I guess). I suspect that this approach is also possible with M2Crypto because it has a method for constructing RSA keys [2]. [1] http://stackoverflow.com/a/10574723 [2] http://www.heikkitoivonen.net/m2crypto/api/M2Crypto.RSA-module.html#new_pub_key Thanks again! Marc PS: Sorry for my email format, I'm using google groups and it seems to ignore any mailing best practice. -- http://mail.python.org/mailman/listinfo/python-list
