A simple Windows GUI built around Peter Gutmann's ASN.1 data display code dumpasn1.c

guiDumpASN1 checks the syntax of an ASN.1 data file and dumps the content in readable form in a Windows graphical user interface (GUI). Updated v1.1.1 2024-09-19.

Introduction | To Use | Download | Menu Options | About guiDumpASN1 | Contact us

Introduction

This is a simple Windows GUI built around Peter Gutmann's ASN.1 data display code dumpasn1.c (version 20210212) available from https://www.cs.auckland.ac.nz/~pgut001/dumpasn1.c. We just wrote the GUI wrapper. All credit to Peter for the core dumpasn1 code. See About guiDumpASN1.

ASN.1 stands for Abstract Syntax Notation One. It is a formal notation to describe data types used in high-level telecom and security protocols. ASN.1 also specifies data encoding rules, i.e. how to serialize the data. In particular, we support the Basic Encoding Rules (BER) and its stricter subset Distinguished Encoding Rules (DER).

guiDumpASN1 accepts ASN.1 data files in the following formats:

1. binary DER- or BER-encoded form
2. PEM textual encoded form (beginning "-----BEGIN")
3. plain base64-encoded form
4. hexadecimal-encoded form [New in v1.1]

To Use

Download

Download the latest version of guiDumpASN1 for Windows from one of the links below.

Most recent production version 1.1.1 compiled 19 September 2024. Use either

• guiDumpASN1.exe (251 kB) or
• guiDumpASN1.zip (223 kB)

Either unzip the zip file and run the install.exe program inside it, or download the exe program directly and run it. These installation programs should be signed by verified publisher "d.i. management services pty limited".

Trouble installing: If Microsoft Defender Smartscreen gives you a warning, see Unrecognized app error. (TL;DR Click "More info" then "Run anyway"). Check that you see "Publisher: D.I. MANAGEMENT SERVICES PTY LIMITED".

Menu Options

File

Open File (Ctrl+O) - open another file
Save As   - save displayed content to a text file
Reload (Ctrl+R) - reload file from source
Print (Ctrl+P)    - print to default printer (this will use your default NotePad settings)

Edit

Select All (Ctrl+A) - select all text
Copy (Ctrl+C) - copy selected text
Find (Ctrl+F) - Find text
Find Next (F3) - Find next occurence of text

Options

Font - change the display font

Print All Data              - [-a] Print all data in long data blocks, not just the first 128 bytes
Print Dots                  - [-d] Print dots to show column alignment
No Primitives               - [-g] Display ASN.1 structure outline only (no primitive objects)
Hex Headers                 - [-h] Hex dump object header (tag+length) before the decoded output
Shallow Indenting           - [-i] Use shallow indenting, for deeply-nested objects
Long Format                 - [-l] Long format, display extra info about Object Identifiers
Pure Output                 - [-p] Pure ASN.1 output without encoding information
Display Text                - [-t] Display text values next to hex dump of data
No Encapsulated             - [-e] Don't print encapsulated data inside OCTET/BIT STRINGs
Reverse Bitstrings          - [-r] Print bits in BIT STRING as encoded in reverse order
Don't Format Dates          - [-u] Don't format UTCTime/GeneralizedTime string data
Hex Size and Offsets        - [-x] Display size and offset in hex not decimal
Don't Check String Validity - [-o] Don't check validity of character strings hidden in octet strings
Allow Zero-length Items     - [-z] Allow zero-length items

Clear All Options - clear all of the above formatting options
Restore Default Font - set font back to default (Courier New regular 10 pt)

About guiDumpASN1

guiDumpASN1 is a Windows GUI wrapper around Peter Gutmann's dumpasn1 program, written in ANSI C using traditional "win32 api" functions and Windows controls (see references).

It calls the executable dumpasn1.exe, which is a compiled version of dumpasn1.c. For dumpasn1.exe, we just compiled Dr Gutmann's code and we claim no ownership or credit for doing so.

dumpasn1 by Peter Gutmann is the industry standard for displaying the contents of ASN.1 data files. A simple example:

  0   4: SEQUENCE {
  2   2:   SEQUENCE {
  4   0:     NULL
       :     }
       :   }

An executable version dumpasn1.exe of dumpasn1 compiled for Windows is available at DumpASN1 for Windows.

guiDumpASN1 is based on the guiDumpASN-ng program released in 2012 by Gemini Security Solutions, Inc., formerly available at GUIdumpASN (dead link), now sadly no more. We have used guiDumpASN-ng for years and found it most useful. So, as we always do when when a most loved program goes away, we write our own version.

References

Amazingly, these two books from the 1990s and their sample programs are still valid for programming using 21st Century MSVC++ on Windows 10 and 11!

• Petzold, Charles. Programming Windows, Fifth Edition, Microsoft Press, 1998.
• Simon, Richard J. Windows 95 Common Controls & Messages Api Bible , Waite Group Pr, 1996.

Revision History

Contact us

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This page first published 27 July 2024. Last updated 19 September 2024