Generate a SHA1

You can generate a SHA1 directly on the website with JDigest, a program in Java which will run safely in your navigator. NOTE: To install Java on your machine, follow the instructions on www.java.com.

IMPORTANT: Running a Java program in a browser has become delicate. In many cases, this option is brutally blocked for security reasons. If installing Java or starting our applet is just impossible, read the section Use a command to generate a SHA1.


Click on SHA1 on your personal home page. A security alert is displayed:

JDigest will read a file on your disk, compute its SHA1 digest and display it. IMPORTANT: JDigest doesn't transfer the file to a server. The entire process is local.

You can click on More Information to verify that the program was actually signed by mcPaLo Signing Authority and control its digest:


Check I accept the risk and want to run this application.

To never see this security alert again, you can click on Show Options and check Do not show this again for apps from the publisher and location above.

Press Run. JDigest starts:

Click on the button Open a file and choose a file on your disk. JDigest displays its SHA1 digest. Select the whole text and press Ctrl-C to copy it. Press Ctrl-V to paste it in the encoder.

If you wish to remove the authorization to run the program, launch the Java control panel:

$ jcontrol

NOTE: Under Windows, the program of the control panel is called javacpl.

Click on the Security tab. Display the certificates. Look in the list for the certificate delivered by the entity mcPaLo Signing Authority and delete it.

Use a command to generate a SHA1

To obtain the SHA1 digest of a file under Linux, use the command sha1sum:

$ sha1sum signmii.png
6efae7a28b0aad242eb70615103beff430ebbe14  signmii.png

Under Windows download and save in the folder C:\Windows the command sha1sum provided by GnuPG: sha1sum.exe.

Start a command processor - Start > All Programs > Accessories > Command Prompt. In the window of the command processor, type sha1sum and press Enter:

usage: sha1sum filenames

Go with the explorer in the folder containing the file whose SHA1 digest you want. In the window of the command processor, type sha1sum followed by a space without pressing Enter. Drop the file from the folder in the window of the command processor. The name of the file completes the command-line. Press Enter.

C:\>sha1sum "C:\Program Files\sha1sum\sha1sum.exe"
4a578ecd09a2d0c8431bdd8cf3d5c5f3ddcddfc9  C:\Program Files\sha1sum\sha1sum.exe

Click with the right button of the mouse in the window of the command processor. Click on Select in the menu. Select with the mouse the entire text of the SHA1 without the file name. Press Enter to copy the selection. Paste the SHA1 in a text file.

Under Mac OS X, start the Terminal application, type shasum followed by a space without pressing Enter, drop the file in the window of the Terminal, the name of the file comes to complete the command-line, press Enter.

$ shasum signmii.png
6efae7a28b0aad242eb70615103beff430ebbe14  signmii.png

Encode a signmii


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