For information on how they're encoded, please see ITU recommendation X.690 (DER). The full documentation on ASN.1 (the notation language) can be found in ITU recommendation X.680; you can also see http://www.oss.com/asn1/dubuisson.html (for a complete overview) and http://www.oss.com/asn1/larmouth.html (for a complete reference).
Please note that trying to read the documents published by the ITU is like trying to wikipath through 40 links to get to the information you're looking for. I wholeheartedly recommend staying away from them unless you absolutely need them. -Kyle H On Tue, Feb 10, 2009 at 2:46 PM, Tomasz Kaźmierczak <tome...@wp.eu> wrote: > I've managed to base64 decode a public key (at least I think so;). > Now I'm trying to understand how to interpret the key data. I've found the > definitions of RSAPublicKey and RSAPrivateKey structures (in the > "PKCS #1: RSA Cryptography Standard"), but there is no information > about what are the lengths of those structures' fields. > > The keys I'm dealing with are 1024 bit keys. The RSAPublicKey structure > consists only of the modulus (n) and the public exponent (e), so I assume > that first 128 bytes of the structure is the modulus and the rest 12 bytes > is the exponent (the structure as a whole has 140 bytes). Is this assumption > right? > And what if I didn't know that the key is 1024 bits long, how would I know > how many bytes represent the modulus and how many represent the > exponent? > > The RSAPrivateKey is a bigger problem - the structure consists of more > fields. How do I know what are their sizes in bytes (again, in my case, the > modulus should be 140 bytes and exponents - 12 bytes each, but there > are some more fields...)? In particular, what's the size of the "version" > field? > > > Dr. Stephen Henson pisze: >> >> On Fri, Feb 06, 2009, Tomasz Ka??mierczak wrote: >> >> >>> >>> Ok. And it is of course base64 encoded, right? >>> And what about the public key (-----BEGIN RSA PUBLIC KEY-----)? It looks >>> the same way as the private key file, but it is shorter. >>> >>> >> >> As I said in the other message thats an RSAPublicKey structure, see >> PKCS#1. >> >> Steve. >> -- >> Dr Stephen N. Henson. Email, S/MIME and PGP keys: see homepage >> OpenSSL project core developer and freelance consultant. >> Homepage: http://www.drh-consultancy.demon.co.uk >> ______________________________________________________________________ >> OpenSSL Project http://www.openssl.org >> User Support Mailing List openssl-users@openssl.org >> Automated List Manager majord...@openssl.org >> >> >> > > ______________________________________________________________________ > OpenSSL Project http://www.openssl.org > User Support Mailing List openssl-users@openssl.org > Automated List Manager majord...@openssl.org > ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager majord...@openssl.org
