asn(n) ASN.1 processing asn(n)
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NAME
asn - ASN.1 BER encoder/decoder
SYNOPSIS
package require Tcl 8.4
package require asn ?0.4?
::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::asnGetPrintableString data_var string_var
::asn::asnGetIA5String data_var string_var
::asn::asnGetUTCTime data_var utc_var
::asn::asnGetBitString data_var bits_var
::asn::asnGetObjectIdentifier data_var oid_var
::asn::asnGetBoolean data_var bool_var
::asn::asnGetNull data_var
::asn::asnGetSequence data_var sequence_var
::asn::asnGetSet data_var set_var
::asn::asnGetApplication data_var appNumber_var
::asn::asnGetContext data_var contextNumber_var
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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 informa-
tion 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 ver-
sion 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.
::asn::asnSet evalue...
Takes zero or more encoded values, packs them into an ASN set
and returns its encoded binary form.
::asn::asnApplicationConstr appNumber evalue...
Takes zero or more encoded values, packs them into an ASN appli-
cation construct and returns its encoded binary form.
::asn::asnApplication appNumber data
Takes a single encoded value data, packs it into an ASN applica-
tion 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.
::asn::asnChoiceConstr appNumber evalue...
Takes zero or more encoded values, packs them into an ASN choice
construct and returns its encoded binary form.
::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 begin-
ning, 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 pro-
cessing 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 asso-
ciated 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::asnGetPrintableString data_var string_var
Assumes that a printable string value 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::asnGetIA5String data_var string_var
Assumes that a IA5 (ASCII) string value 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::asnGetUTCTime data_var utc_var
Assumes that a UTC time value is at the front of the data stored
in the variable named data_var, and stores it into the variable
named by utc_var. The UTC time value is stored as a string,
which has to be decoded with the usual clock scan commands.
Additionally removes all bytes associated with the value from
the data for further processing by the following decoder com-
mands.
::asn::asnGetBitString data_var bits_var
Assumes that a bit string value is at the front of the data
stored in the variable named data_var, and stores it into the
variable named by bits_var as a string containing only 0 and 1.
Additionally removes all bytes associated with the value from
the data for further processing by the following decoder com-
mands.
::asn::asnGetObjectIdentifier data_var oid_var
Assumes that a object identifier (OID) value is at the front of
the data stored in the variable named data_var, and stores it
into the variable named by oid_var as a list of integers. Addi-
tionally removes all bytes associated with the value from the
data for further processing by the following decoder commands.
::asn::asnGetBoolean data_var bool_var
Assumes that a boolean value is at the front of the data stored
in the variable named data_var, and stores it into the variable
named by bool_var. Additionally removes all bytes associated
with the value from the data for further processing by the fol-
lowing decoder commands.
::asn::asnGetNull data_var
Assumes that a NULL value is at the front of the data stored in
the variable named data_var and removes the bytes used to encode
it from the data.
::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 fol-
lowing 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.
::asn::asnGetContext data_var contextNumber_var
Assumes that an ASN context tag construct is at the front of the
data stored in the variable named data_var, and stores its id
into the variable named by contextNumber_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 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 implementa-
tion 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>
Copyright (c) 2004,2005 Michael Schlenker <mic42@users.sourceforge.net>
asn 0.4 asn(n)
