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RE: Error in encoding of DSA signature in RFC 2459?
Ilan,
You are correct. The examples in RFC 2459 are incorrect in a number of places with respect to integer encodings - always with the leading 00 octet missing. Several postings have been made to the working group about this, but as far as I am aware the authors have not yet acknowledged the error.
They do get it right in D.3 though where the public key starts as follows:
0319 03 6b 107: . . . BIT STRING
: 00 (0 unused bits)
: 30 68 02 61 00 be aa 8b 77 54 a3 af ca 77 9f 2f
: b0 cf 43 88 ff a6 6d 79 55 5b 61 8c 68 ec 48 1e
Regards,
Darren
------------------------------------------------------------------------
Darren Harter BSc (Hons) CEng MBCS
Entegrity Solutions Corp
http://www.entegrity.co.uk
http://www.entegrity.com
Tel: +44 (0) 1452 371383
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Email: mailto:darren.harter@entegrity.com
-----Original Message-----
From: Ilan Shacham [SMTP:ilans@arx.com]
Sent: Sunday, May 30, 1999 3:58 PM
To: Ietf-Pkix (E-mail)
Subject: Error in encoding of DSA signature in RFC 2459?
The DSA signature is defined in rfc 2459 as
Dss-Sig-Value ::= SEQUENCE {
r INTEGER,
s INTEGER }
where r and s are positive integers (according to the mathematics).
The signature in the first example (D.1) is encoded like this:
0650 03 2f 47: . BIT STRING (0 unused bits)
: 30 2c 02 14 a0 66 c1 76 33 99 13 51 8d 93 64 2f
: ca 13 73 de 79 1a 7d 33 02 14 5d 90 f6 ce 92 4a
: bf 29 11 24 80 28 a6 5a 8e 73 b6 76 02 68
integers are encoded in DER in two's compliment, which means a
positive value with the MSB on, should be encoded with a leading 0
octet, and so the signature sould look like this:
: 30 2d 02 15 00 a0 66 c1 76 33 99 13 51 8d 93 64 2f
: ca 13 73 de 79 1a 7d 33 02 14 5d 90 f6 ce 92 4a
: bf 29 11 24 80 28 a6 5a 8e 73 b6 76 02 68
This is repeated in the next examples too.
Am I missing anything here?
Ilan
------------------------------------------------------------------------
Ilan Shacham mailto:ilans@arx.com
Algorithmic Research Ltd. http://www.arx.com
10 Nevatim St., phone: 972 - 3 - 9279540
Petach-Tikva, Israel Fax: 972 - 3 - 9230864