man asn () - ASN.1 BER encoder/decoder

NAME

asn - ASN.1 BER encoder/decoder

SYNOPSIS

package require Tcl 8.2 package require asn ?0.1? ::asn::asnSequence evalue... ::asn::asnSet evalue... ::asn::asnApplicationConstr appNumber evalue... ::asn::asnApplication appNumber data ::asn::asnChoice appNumber evalue... ::asn::asnChoiceConstr appNumber evalue... ::asn::asnInteger number ::asn::asnEnumeration number ::asn::asnBoolean bool ::asn::asnOctetString string ::asn::asnGetResponse chan data_var ::asn::asnGetInteger data_var int_var ::asn::asnGetEnumeration data_var enum_var ::asn::asnGetOctetString data_var string_var ::asn::asnGetSequence data_var sequence_var ::asn::asnGetSet data_var set_var ::asn::asnGetApplication data_var appNumber_var

DESCRIPTION

The asn package provides partial de- and encoder commands for BER encoded ASN.1 data.

ASN.1 is a standard Abstract Syntax Notation, and BER are its Basic Encoding Rules.

See http://asn1.elibel.tm.fr/en/standards/index.htm for more information about the standard.

Also see http://luca.ntop.org/Teaching/Appunti/asn1.html for A Layman's Guide to a Subset of ASN.1, BER, and DER, an RSA Laboratories Technical Note by Burton S. Kaliski Jr. (Revised November 1, 1993). A text version of this note is part of the module sources and should be read by any implementor.

PUBLIC API

ENCODER

::asn::asnSequence evalue...
Takes zero or more encoded values, packs them into an ASN sequence and returns its encoded binary form. NOTE: Shouldn't that be one or more ?! However the command does no checking of this.
::asn::asnSet evalue...
Takes zero or more encoded values, packs them into an ASN set and returns its encoded binary form. NOTE: Shouldn't that be one or more ?! However the command does no checking of this.
::asn::asnApplicationConstr appNumber evalue...
Takes zero or more encoded values, packs them into an ASN application construct and returns its encoded binary form. NOTE: Shouldn't that be one or more ?! However the command does no checking of this.
::asn::asnApplication appNumber data
Takes a single encoded value data, packs it into an ASN application construct and returns its encoded binary form.
::asn::asnChoice appNumber evalue...
Takes zero or more encoded values, packs them into an ASN choice construct and returns its encoded binary form. NOTE: Shouldn't that be one or more ?! However the command does no checking of this.
::asn::asnChoiceConstr appNumber evalue...
Takes zero or more encoded values, packs them into an ASN choice construct and returns its encoded binary form. NOTE: Shouldn't that be one or more ?! However the command does no checking of this. The only difference between this and the ::asn::asnChoice coming before seems to lie in the tag value.
::asn::asnInteger number
Returns the encoded form of the specified integer number.
::asn::asnEnumeration number
Returns the encoded form of the specified enumeration id number.
::asn::asnBoolean bool
Returns the encoded form of the specified boolean value bool.
::asn::asnOctetString string
Returns the encoded form of the specified string.

DECODER

General notes:

[1]
All decoder commands take two arguments. These arguments are variable names, except for ::asn::asnGetResponse. The first variable contains the encoded ASN value to decode at the beginning, and more, and the second variable is where the value is stored to. The remainder of the input after the decoded value is stored back into the datavariable.
[2]
After extraction the data variable is always modified first, before by writing the extracted value to its variable. This means that if both arguments refer to the same variable, it will always contain the extracted value after the call, and not the remainder of the input.

::asn::asnGetResponse chan data_var
Reads an encoded ASN sequence from the channel chan and stores it into the variable named by data_var.
::asn::asnGetInteger data_var int_var
Assumes that an encoded integer value is at the front of the data stored in the variable named data_var, extracts and stores it into the variable named by int_var. Additionally removes all bytes associated with the value from the data for further processing by the following decoder commands.
::asn::asnGetEnumeration data_var enum_var
Assumes that an enumeration id is at the front of the data stored in the variable named data_var, and stores it into the variable named by enum_var. Additionally removes all bytes associated with the value from the data for further processing by the following decoder commands.
::asn::asnGetOctetString data_var string_var
Assumes that a string is at the front of the data stored in the variable named data_var, and stores it into the variable named by string_var. Additionally removes all bytes associated with the value from the data for further processing by the following decoder commands.
::asn::asnGetSequence data_var sequence_var
Assumes that an ASN sequence is at the front of the data stored in the variable named data_var, and stores it into the variable named by sequence_var. Additionally removes all bytes associated with the value from the data for further processing by the following decoder commands. The data in sequence_var is encoded binary and has to be further decoded according to the definition of the sequence, using the decoder commands here.
::asn::asnGetSet data_var set_var
Assumes that an ASN set is at the front of the data stored in the variable named data_var, and stores it into the variable named by set_var. Additionally removes all bytes associated with the value from the data for further processing by the following decoder commands. The data in set_var is encoded binary and has to be further decoded according to the definition of the set, using the decoder commands here.
::asn::asnGetApplication data_var appNumber_var
Assumes that an ASN application construct is at the front of the data stored in the variable named data_var, and stores its id into the variable named by appNumber_var. Additionally removes all bytes associated with the value from the data for further processing by the following decoder commands. It is the responsibility of the caller to decode the remainder of the application construct based on the id retrieved by this command, using the decoder commands here.

EXAMPLES

Examples for the usage of this package can be found in the implementation of package ldap.

KEYWORDS

asn, ber, cer, der, internet, protocol, x.208, x.209

COPYRIGHT

Copyright (c) 2004 Andreas Kupries <andreas_kupries@users.sourceforge.net>
Copyright (c) 2004 Jochen Loewer <loewerj@web.de>