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Bug #4374

[ext/openssl] ASN1.decode wrong for infinite length values

Added by MartinBosslet (Martin Bosslet) over 9 years ago. Updated over 9 years ago.

Status:
Closed
Priority:
Normal
Target version:
ruby -v:
ruby 1.9.2p136 (2010-12-25 revision 30365) [i686-linux]
Backport:
[ruby-core:35123]

Description

=begin
Hi all,

ASN.1 decoding behaves incorrectly for DER encodings with infinite length values. Two examples:

require 'openssl'
require 'pp'

eoc = OpenSSL::ASN1::EndOfContent.new
int = OpenSSL::ASN1::Integer.new (1)

inner = OpenSSL::ASN1::Sequence.new([int, eoc])
inner.infinite_length = true

outer = OpenSSL::ASN1::Sequence.new([inner, eoc])
outer.infinite_length = true

asn1 = OpenSSL::ASN1.decode(outer.to_der)

pp asn1

=> #,
#,
#]>]>

The end of content DER for the outer Sequence is incorrectly stored with the values
of the inner sequence. Although after encoding the resulting DER will be correct, the
structure should rather look like this:

#,
#]>,
#]>

Another example:

require 'openssl'
require 'pp'

eoc = OpenSSL::ASN1::EndOfContent.new
oct = OpenSSL::ASN1::OctetString.new ("\x01")

inner = OpenSSL::ASN1::Constructive.new([oct, eoc], OpenSSL::ASN1::OCTET_STRING)
inner.infinite_length = true

outer = OpenSSL::ASN1::Constructive.new([inner, eoc], OpenSSL::ASN1::OCTET_STRING)
outer.infinite_length = true

asn1 = OpenSSL::ASN1.decode(outer.to_der)

pp asn1

=> ,
#,
#]>]>]>]>

Here it's worse, because when calling asn1.to_der it will even result in an error:

test.rb:17:in to_der': invalid constructed encoding (OpenSSL::ASN1::ASN1Error)
from test.rb:17:in
each'
from test.rb:17:in to_der'
from test.rb:17:in
'

The problem are the defaults for tagging and tag_class in ossl_asn1_initialize that are not
intuitive and are defaults for tagged DER values instead of "normal" values.

The correct structure for the above would look like this:

#,
#]>,
#]>

The attached patch fixes the problems and has also "more natural" defaults for
ossl_asn1_initialize.

Regards,
Martin
=end


Files

fix_asn1.diff (3.62 KB) fix_asn1.diff MartinBosslet (Martin Bosslet), 02/07/2011 02:52 AM

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