OID Converter

The OID converter is a handy little tool to convert ASN.1 OIDs from readable dotted decimal notation to binary hexadecimal Distinguished Encoding Rules (DER) representation and vice versa. If you're into x.509 certificates, this may be useful to you, too.

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Synopsis

OID encoder/decoder - Matthias Gaertner 1999/2001 - Freeware
Usage:
 OID [-C] [-o<outfile>] {-i<infile>|1.2.3.4}
   converts dotted form to ASCII HEX DER output.
 OID -x [-o<outfile>] {-i<infile>|hex-digits}
   decodes ASCII HEX DER and gives dotted form.

Examples

The OID for rsaSignatureWithripemd160 is 1.3.36.3.3.1.2 (just as an example).

• Convert this to binary, hexadecimal output to stdout:
  >oid 1.3.36.3.3.1.2
06 06 2B 24 03 03 01 02
• Convert this to binary, "C" source output to stdout:
  >oid -C 1.3.36.3.3.1.2
"\x06\x06\x2B\x24\x03\x03\x01\x02"
• Convert this to binary, write hex output to a file:
  >oid -o r160oid.hex 1.3.36.3.3.1.2
  This is similar to
  >oid 1.3.36.3.3.1.2 > r160oid.hex
• Use the decoder to get the dotted form back from the binary data:
  >oid -x -i r160oid.hex
UNIVERSAL OID.1.3.36.3.3.1.2

Bug in v1.0

A bug was pointed out to me recently. The original version would not correctly encode OIDs that contain the component 128. Version 1.1 fixes this. As an example, v1.0 would incorrectly encode

while the corrected version will encode this as

(Thanks to Eric Grenier of Cisco for the hint, 24Mar2006)

Related Stuff

• A comprehensive (and probably definitive, for this repository is intended to move to the ITU website by the end of the year 2005) OID repository is available at: http://oid.elibel.tm.fr (Thanks to Olivier Dubuisson of France Telecom for the hint, 24Aug2005)
• The (definitive?) reference for OIDs on the Internet is http://www.alvestrand.no.
• A very convenient ASN.1 BER/DER decoder is available from Peter Gutman: dumpasn1 [local copy] (you also need the config file [local copy]).

Copyright

This code was written by me, Matthias Gärtner. It is freeware. Do with it whatever you want. Use at your own risk. No warranty of any kind.

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