The GUIdumpASN application allows you to view and print a human readable version of an Abstract Syntax Notation One (ASN.1) file. ASN.1 is a standard and flexible notation that describes data structures for representing, encoding, transmitting, and decoding data.

Application output can be saved as a text file, and options may be configured to adjust output. The application supports drag-and-drop, so you can run the application and drop a file on it to display the ASN.1. You can also associate file extensions with the application to allow immediate launch when a certain file type is double-clicked.

Update July 27, 2012: This next generation version of the application (now called GUIdumpASN-ng) requires Microsoft .NET framework, version 3.5. It includes printing support native to the application. The installer installs a shortcut to the application in your SendTo menu by default, to simplify decoding any file you come across. In addition to binary DER encoded files, the application also supports PEM-style base 64-encoded files (with the —–BEGIN CERTIFICATE—– style tags). Settings such as the last directory you browsed, display options, window size, and font are all saved between runs of the application.

Update August 29, 2012: Fixed a bug related to decoding output which contained NULL characters.

Download Instructions

Download GDA-ng-setup.exe (408KB). To avoid confusion, please uninstall any versions prior to 2.0 before installing this one.

The underlying software (dumpasn1.c) was written by Peter Gutmann and can be found on Peter Gutmann’s homepage. Gemini Security Solutions just made a wrapper to use the code in a Windows graphical application.

License Restrictions

This software is free for any use; just don’t claim that you wrote it. If you like it, we would appreciate your feedback, please contact us.