NAME

       unber - ASN.1 BER Decoder

SYNOPSIS

       unber [-1] [-iindent] [-m] [-p] [-sskip] [-thex-string] [-] [infile...]

DESCRIPTION

       unber presents the internal structure of BER-encoded files as human readable text.  A single dash denotes
       the standard input.

       (The DER and CER formats are subsets of the BER and are also supported.)

OPTIONS

       -1     Do not attempt to read the next BER structure after the first one.  This  may  be  useful  if  the
              input  contains  garbage past the single BER sequence.  By default, unber continues decoding until
              the end of file (input stream).

       -i indent
              Use the specified number of spaces for output indentation. Default is 4 spaces.

       -m     Generate shorter output while still preserving BER encoding information.

       -p     Do not attempt pretty-printing of known ASN.1 types (BOOLEAN, INTEGER, OBJECT IDENTIFIER, etc). By
              default,  some ASN.1 types are converted into the text representation. This option is required for
              enber(1).

       -s skip
              Ignore the first skip bytes in the input stream; useful for stripping  off  lower  level  protocol
              framing data.

       -t hex-string
              Interpret  the  hex-string  as  a sequence of hexadecimal values representing the start of BER TLV
              encoding. Print the human readable explanation.

XML FORMAT

       unber dumps the output in the regular XML format  which  preserves  most  of  the  information  from  the
       underlying binary encoding.

       The XML opening tag format is as follows:

       <tform O="off" T="tag" TL="tl_len" V="{Indefinite|v_len}" [A="type"] [F]>

       Where:

       tform  Encoding form the value is in: primitive ("P") or constructed ("C") or constructed with indefinite
              length ("I")

       off    Offset of the encoded element in the unber input stream.

       tag    The tag class and value in human readable form.

       tl_len The length of the TL (BER Tag and Length) encoding.

       v_len  The length of the value (V, encoded by the L), may be "Indefinite".

       type   Likely name of the underlying ASN.1 type (for UNIVERSAL tags).

       [F]    Indicates that the value was reformatted (pretty-printed). This will never appear  in  the  output
              produced using -p command line option.

       Sample XML output:

       <I O="0" T="[UNIVERSAL 16]" TL="2" V="Indefinite" A="SEQUENCE">
         <P O="2" T="[UNIVERSAL 19]" TL="2" V="2" A="PrintableString">US</P>
         <C O="6" T="[UNIVERSAL 16]" TL="2" V="6" A="SEQUENCE">
           <P O="8" T="[UNIVERSAL 2]" TL="2" V="4" A="INTEGER" F>832970823</P>
         </C O="14" T="[UNIVERSAL 16]" A="SEQUENCE" L="8">
       </I O="14" T="[UNIVERSAL 0]" TL="2" L="16">

EXAMPLES

       Decode the given Tag/Length sequence specified in hexadecimal form:

           unber  -t "bf 20"

       Decode the DER file using two-spaces indentation:

           unber  -i 2   filename.der

       Decode the binary stream taken from the standard input:

           cat ... | unber -

       Decode the binary stream and encode it back into an identical stream (see enber(1)):

           cat ... | unber -p - | enber - > filename.ber

FOOTNOTES

       The constructed XML output is not necessarily well-formed.

       When indefinite length encoding is being used, the BER sequence, which is not terminated with the end-of-
       content octets, will cause the terminating </I> XML tag to disappear.  Thus, invalid BER framing directly
       causes invalid XML output.

       The enber(1) utility understands such XML correctly.

SEE ALSO

       enber(1), asn1c(1)

AUTHORS

       Lev Walkin <vlm@lionet.info>