Provided by: tcllib_1.14-dfsg-1_all bug

NAME

       asn - ASN.1 BER encoder/decoder

SYNOPSIS

       package require Tcl  8.4

       package require asn  ?0.8.4?

       ::asn::asnSequence evalue...

       ::asn::asnSequenceFromList elist

       ::asn::asnSet evalue...

       ::asn::asnSetFromList elist

       ::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::asnContext context data

       ::asn::asnContextConstr context evalue...

       ::asn::asnObjectIdentifier idlist

       ::asn::asnUTCTime utcstring

       ::asn::asnNull

       ::asn::asnBitString string

       ::asn::asnOctetString string

       ::asn::asnNumericString string

       ::asn::asnPrintableString string

       ::asn::asnIA5String string

       ::asn::asnBMPString string

       ::asn::asnUTF8String string

       ::asn::asnString string

       ::asn::defaultStringType ?type?

       ::asn::asnPeekByte data_var byte_var

       ::asn::asnGetLength data_var length_var

       ::asn::asnGetResponse chan data_var

       ::asn::asnGetInteger data_var int_var

       ::asn::asnGetEnumeration data_var enum_var

       ::asn::asnGetOctetString data_var string_var

       ::asn::asnGetString data_var string_var ?type_var?

       ::asn::asnGetNumericString data_var string_var

       ::asn::asnGetPrintableString data_var string_var

       ::asn::asnGetIA5String data_var string_var

       ::asn::asnGetBMPString data_var string_var

       ::asn::asnGetUTF8String 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 ?content_var? ?encodingType_var?

       ::asn::asnGetContext data_var contextNumber_var ?content_var? ?encodingType_var?

       ::asn::asnPeekTag data_var tag_var tagtype_var constr_var

       ::asn::asnTag tagnumber ?class? ?tagstyle?

       ::asn::asnRetag data_var newTag

_________________________________________________________________

DESCRIPTION

       The  asn  package provides partial de- and encoder commands for BER encoded ASN.1 data. It
       can also be used for decoding DER, which is a restricted subset of BER.

       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.

       ::asn::asnSequenceFromList elist
              Takes  a  list  of  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::asnSetFromList elist
              Takes  a list of 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 application construct and
              returns its encoded binary form.

       ::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.

       ::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::asnContext context data
              Takes an encoded value and packs it into a constructed value with application  tag,
              the context number.

       ::asn::asnContextConstr context evalue...
              Takes  zero  or  more  encoded  values and packs them into a constructed value with
              application tag, the context number.

       ::asn::asnObjectIdentifier idlist
              Takes a list of at least 2 integers describing an object  identifier  (OID)  value,
              and returns the encoded value.

       ::asn::asnUTCTime utcstring
              Returns the encoded form of the specified UTC time string.

       ::asn::asnNull
              Returns the NULL encoding.

       ::asn::asnBitString string
              Returns the encoded form of the specified string.

       ::asn::asnOctetString string
              Returns the encoded form of the specified string.

       ::asn::asnNumericString string
              Returns  the  string  encoded as ASN.1 NumericString. Raises an error if the string
              contains characters other than decimal numbers and space.

       ::asn::asnPrintableString string
              Returns the string encoding as ASN.1 PrintableString. Raises an error if the string
              contains  characters  which  are  not allowed by the Printable String datatype. The
              allowed characters are A-Z, a-z, 0-9, space, apostrophe, colon, parentheses,  plus,
              minus, comma, period, forward slash, question mark, and the equals sign.

       ::asn::asnIA5String string
              Returns  the  string  encoded  as  ASN.1  IA5String.  Raises an error if the string
              contains any characters outside of the US-ASCII range.

       ::asn::asnBMPString string
              Returns the string encoded as ASN.1  Basic  Multilingual  Plane  string  (Which  is
              essentialy big-endian UCS2).

       ::asn::asnUTF8String string
              Returns  the string encoded as UTF8 String. Note that some legacy applications such
              as Windows CryptoAPI do not like UTF8 strings. Use BMPStrings if you are not sure.

       ::asn::asnString string
              Returns an encoded form of string, choosing the most restricted ASN.1  string  type
              possible.  If the string contains non-ASCII characters, then there is more than one
              string type which can be used. See ::asn::defaultStringType.

       ::asn::defaultStringType ?type?
              Selects the string type to use for  the  encoding  of  non-ASCII  strings.  Returns
              current  default when called without argument. If the argument type is supplied, it
              should be either UTF8 or BMP to choose UTF8String or BMPString respectively.

   DECODER
       General notes:

       [1]    Nearly 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::asnPeekByte data_var byte_var
              Retrieve  the  first byte of the data, without modifing data_var.  This can be used
              to check for implicit tags.

       ::asn::asnGetLength data_var length_var
              Decode the length information for a block of BER data. The tag has  already  to  be
              removed from the data.

       ::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::asnGetString data_var string_var ?type_var?
              Decodes  a  user-readable  string.  This is a convenience function which is able to
              automatically distinguish all supported ASN.1 string types and  convert  the  input
              value  appropriately.   See  ::asn::asnGetPrintableString,  ::asnGetIA5String, etc.
              below for the type-specific conversion commands.

              If the optional third argument type_var is supplied, then the type of the  incoming
              string is stored in the variable named by it.

              The function throws the error "Invalid command name asnGetSomeUnsupportedString" if
              the unsupported  string  type  Unsupported  is  encountered.  You  can  create  the
              appropriate  function  "asn::asnGetSomeUnsupportedString"  in  your  application if
              neccessary.

       ::asn::asnGetNumericString data_var string_var
              Assumes that a numeric 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::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::asnGetBMPString data_var string_var
              Assumes  that  a  BMP  (two-byte  unicode) 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,  converting it into a proper Tcl string. Additionally removes all bytes
              associated with the value from the data for further  processing  by  the  following
              decoder commands.

       ::asn::asnGetUTF8String data_var string_var
              Assumes that a UTF8 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, converting  it
              into a proper Tcl string.  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 commands.

       ::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 commands.

       ::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.   Additionally 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 following 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 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 ?content_var? ?encodingType_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.  If a content_var is
              specified, then the command places all data  associated  with  it  into  the  named
              variable,  in  the binary form which can be processed using the decoder commands of
              this package.  If a encodingType_var is specified, then that var is set to 1 if the
              encoding is constructed and 0 if it is primitive.

              Otherwise  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 of this package.

       ::asn::asnGetContext data_var contextNumber_var ?content_var? ?encodingType_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.   If  a
              content_var  is specified, then the command places all data associated with it into
              the named variable, in the binary form which can be  processed  using  the  decoder
              commands of this package.  If a encodingType_var is specified, then that var is set
              to 1 if the encoding is constructed and 0 if it is primitive.

              Otherwise 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 of
              this package.

   HANDLING TAGS
       Working with ASN.1 you often need to decode tagged values, which use a tag thats different
       from  the  universal  tag  for a type. In those cases you have to replace the tag with the
       universal tag used for the type, to decode the value.  To decode a tagged  value  use  the
       ::asn::asnRetag  to  change the tag to the appropriate type to use one of the decoders for
       primitive values.  To help with this the module contains three functions:

       ::asn::asnPeekTag data_var tag_var tagtype_var constr_var
              The ::asn::asnPeekTag command can be used to take a peek at the data and decode the
              tag  value,  without  removing  it  from  the data. The tag_var gets set to the tag
              number, while the tagtype_var gets set to the class of the tag. (Either  UNIVERSAL,
              CONTEXT,  APPLICATION  or  PRIVATE). The constr_var is set to 1 if the tag is for a
              constructed value, and to 0 for not constructed. It returns the length of the tag.

       ::asn::asnTag tagnumber ?class? ?tagstyle?
              The ::asn::asnTag can be used to create a tag value. The tagnumber gives the number
              of the tag, while the class gives one of the classes (UNIVERSAL,CONTEXT,APPLICATION
              or PRIVATE). The class may be abbreviated  to  just  the  first  letter  (U,C,A,P),
              default  is UNIVERSAL.  The tagstyle is either C for Constructed encoding, or P for
              primitve encoding. It defaults to P. You can also use 1 instead of C and 0  instead
              of P for direct use of the values returned by ::asn::asnPeekTag.

       ::asn::asnRetag data_var newTag
              Replaces  the  tag in front of the data in data_var with newTag. The new Tag can be
              created using the ::asn::asnTag command.

EXAMPLES

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

BUGS, IDEAS, FEEDBACK

       This document, and the package it describes,  will  undoubtedly  contain  bugs  and  other
       problems.    Please   report   such  in  the  category  asn  of  the  Tcllib  SF  Trackers
       [http://sourceforge.net/tracker/?group_id=12883].   Please  also  report  any  ideas   for
       enhancements you may have for either package and/or documentation.

KEYWORDS

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

CATEGORY

       Networking

COPYRIGHT

       Copyright (c) 2004 Andreas Kupries <andreas_kupries@users.sourceforge.net>
       Copyright (c) 2004 Jochen Loewer <loewerj@web.de>
       Copyright (c) 2004-2011 Michael Schlenker <mic42@users.sourceforge.net>