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DUMPASN1(1) User Commands DUMPASN1(1)


dumpasn1 - ASN.1 object dump/syntax check program


dumpasn1 [-acdefghilmoprstuvwxz] <file>


An ASN.1 object dump program which will dump data encoded using any of the ASN.1 encoding rules in a variety of user-specified formats.

DumpASN1 - ASN.1 object dump/syntax check program. Copyright Peter Gutmann 1997 - 2016. Last updated 22 October 2019.

Input options:
- = Take input from stdin (some options may not work properly) -<number> = Start <number> bytes into the file -- = End of arg list -c<file> = Read Object Identifier info from alternate config file
(values will override equivalents in global config file)
Output options:

-f<file> = Dump object at offset -<number> to file (allows data to be

extracted from encapsulating objects)

-w<number> = Set width of output, default = 80 columns

Display options:

-a = Print all data in long data blocks, not just the first 128 bytes

-d = Print dots to show column alignment

-g = Display ASN.1 structure outline only (no primitive objects)

-h = Hex dump object header (tag+length) before the decoded output

-hh = Same as -h but display more of the object as hex data

-i = Use shallow indenting, for deeply-nested objects

-l = Long format, display extra info about Object Identifiers

= Maximum nesting level for which to display content

-p = Pure ASN.1 output without encoding information

-t = Display text values next to hex dump of data

-v = Verbose mode, equivalent to -ahlt

Format options:

-e = Don't print encapsulated data inside OCTET/BIT STRINGs

-r = Print bits in BIT STRING as encoded in reverse order

-u = Don't format UTCTime/GeneralizedTime string data

-x = Display size and offset in hex not decimal

Checking options:

-o = Don't check validity of character strings hidden in octet strings

-s = Syntax check only, don't dump ASN.1 structures

-z = Allow zero-length items

Warnings generated by deprecated OIDs require the use of '-l' to be displayed. Program return code is the number of errors found or EXIT_SUCCESS.


This manual page was written by Mathieu Malaterre <> for the Debian GNU/Linux system, but may be used by others.


$HOME/.dumpasn1.cfg, /etc/dumpasn1/dumpasn1.cfg:

This is the configuration file, it will be searched in this order. It contains OIDs commonly used.


quote from Peter Gutmann:

ASN.1 object dumping code, copyright Peter Gutmann <>, based on ASN.1 dump program by David Kemp <>, with contributions from various people including Matthew Hamrick <>, Bruno Couillard <>, Hallvard Furuseth <>, Geoff Thorpe <>, David Boyce <>, John Hughes <>, Life is hard, and then you die <>, Hans-Olof Hermansson <>, Tor Rustad <>, Kjetil Barvik <>, James Sweeny <>, and several other people whose names I've misplaced.

dumpasn1 is available at


Copyright Peter Gutmann 1997 - 2016. Last updated 22 October 2019.

November 2019 dumpasn1 20191022