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ASN1PARSE(1)			    OpenSSL			  ASN1PARSE(1)

       openssl-asn1parse, asn1parse - ASN.1 parsing tool

       openssl asn1parse [-help] [-inform PEM|DER] [-in	filename] [-out
       filename] [-noout] [-offset number] [-length number] [-i] [-oid
       filename] [-dump] [-dlimit num] [-strparse offset] [-genstr string]
       [-genconf file] [-strictpem] [-item name]

       The asn1parse command is	a diagnostic utility that can parse ASN.1
       structures. It can also be used to extract data from ASN.1 formatted

	   Print out a usage message.

       -inform DER|PEM
	   The input format. DER is binary format and PEM (the default)	is
	   base64 encoded.

       -in filename
	   The input file, default is standard input.

       -out filename
	   Output file to place	the DER	encoded	data into. If this option is
	   not present then no data will be output. This is most useful	when
	   combined with the -strparse option.

	   Don't output	the parsed version of the input	file.

       -offset number
	   Starting offset to begin parsing, default is	start of file.

       -length number
	   Number of bytes to parse, default is	until end of file.

       -i  Indents the output according	to the "depth" of the structures.

       -oid filename
	   A file containing additional	OBJECT IDENTIFIERs (OIDs). The format
	   of this file	is described in	the NOTES section below.

	   Dump	unknown	data in	hex format.

       -dlimit num
	   Like	-dump, but only	the first num bytes are	output.

       -strparse offset
	   Parse the contents octets of	the ASN.1 object starting at offset.
	   This	option can be used multiple times to "drill down" into a
	   nested structure.

       -genstr string, -genconf	file
	   Generate encoded data based on string, file or both using
	   ASN1_generate_nconf(3) format. If file only is present then the
	   string is obtained from the default section using the name asn1.
	   The encoded data is passed through the ASN1 parser and printed out
	   as though it	came from a file, the contents can thus	be examined
	   and written to a file using the out option.

	   If this option is used then -inform will be ignored.	Without	this
	   option any data in a	PEM format input file will be treated as being
	   base64 encoded and processed	whether	it has the normal PEM BEGIN
	   and END markers or not. This	option will ignore any data prior to
	   the start of	the BEGIN marker, or after an END marker in a PEM

       -item name
	   Attempt to decode and print the data	as ASN1_ITEM name. This	can be
	   used	to print out the fields	of any supported ASN.1 structure if
	   the type is known.

       The output will typically contain lines like this:

	 0:d=0	hl=4 l=	681 cons: SEQUENCE


	 229:d=3  hl=3 l= 141 prim: BIT	STRING
	 373:d=2  hl=3 l= 162 cons: cont [ 3 ]
	 376:d=3  hl=3 l= 159 cons: SEQUENCE
	 379:d=4  hl=2 l=  29 cons: SEQUENCE
	 381:d=5  hl=2 l=   3 prim: OBJECT	      :X509v3 Subject Key Identifier
	 386:d=5  hl=2 l=  22 prim: OCTET STRING
	 410:d=4  hl=2 l= 112 cons: SEQUENCE
	 412:d=5  hl=2 l=   3 prim: OBJECT	      :X509v3 Authority	Key Identifier
	 417:d=5  hl=2 l= 105 prim: OCTET STRING
	 524:d=4  hl=2 l=  12 cons: SEQUENCE


       This example is part of a self-signed certificate. Each line starts
       with the	offset in decimal. d=XX	specifies the current depth. The depth
       is increased within the scope of	any SET	or SEQUENCE. hl=XX gives the
       header length (tag and length octets) of	the current type. l=XX gives
       the length of the contents octets.

       The -i option can be used to make the output more readable.

       Some knowledge of the ASN.1 structure is	needed to interpret the

       In this example the BIT STRING at offset	229 is the certificate public
       key.  The contents octets of this will contain the public key
       information. This can be	examined using the option -strparse 229	to

	   0:d=0  hl=3 l= 137 cons: SEQUENCE
	   3:d=1  hl=3 l= 129 prim: INTEGER	      :E5D21E1F5C8D208EA7A2166C7FAF9F6BDF2059669C60876DDB70840F1A5AAFA59699FE471F379F1DD6A487E7D5409AB6A88D4A9746E24B91D8CF55DB3521015460C8EDE44EE8A4189F7A7BE77D6CD3A9AF2696F486855CF58BF0EDF2B4068058C7A947F52548DDF7E15E96B385F86422BEA9064A3EE9E1158A56E4A6F47E5897
	 135:d=1  hl=2 l=   3 prim: INTEGER	      :010001

       If an OID is not	part of	OpenSSL's internal table it will be
       represented in numerical	form (for example The	file passed to
       the -oid	option allows additional OIDs to be included. Each line
       consists	of three columns, the first column is the OID in numerical
       format and should be followed by	white space. The second	column is the
       "short name" which is a single word followed by white space. The	final
       column is the rest of the line and is the "long name". asn1parse
       displays	the long name. Example:

       "	      shortName	      A	long name"

       Parse a file:

	openssl	asn1parse -in file.pem

       Parse a DER file:

	openssl	asn1parse -inform DER -in file.der

       Generate	a simple UTF8String:

	openssl	asn1parse -genstr 'UTF8:Hello World'

       Generate	and write out a	UTF8String, don't print	parsed output:

	openssl	asn1parse -genstr 'UTF8:Hello World' -noout -out utf8.der

       Generate	using a	config file:

	openssl	asn1parse -genconf asn1.cnf -noout -out	asn1.der

       Example config file:



	field2=EXP:0, UTF8:some	random string

       There should be options to change the format of output lines. The
       output of some ASN.1 types is not well handled (if at all).


       Copyright 2000-2017 The OpenSSL Project Authors.	All Rights Reserved.

       Licensed	under the OpenSSL license (the "License").  You	may not	use
       this file except	in compliance with the License.	 You can obtain	a copy
       in the file LICENSE in the source distribution or at

1.1.1o				  2022-05-03			  ASN1PARSE(1)


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