Putting a password on an image

ImageSafe allows a password to be specified for an image. The applet created can then only be viewed by someone who has a corresponding small file (about 1300 bytes) installed on their computer and which their browser can locate. This small password file is generated automatically by ImageSafe

Specifying the password

Select the option to use a password and then enter a password into the password box. Passwords can be any length and contain any characters but should not be blank. Once the password is entered any ImageSafe applet subsequently created will require the presence of a password file to be seen.

Anonymity of password files

It should be emphasized that a password file is anonymous. It does not identify in any way the origin of the password file or any information about the person or computer that created it. It only provides validation that an image or set of images were protected with a particular password.

Generating password files

To generate the password file, set a password and press the "Create password" button. Select a name for the password file and save it. The file must have a ".jar" suffix. When the authorized viewer of your images receives the file, perhaps by e-mail, they can put it anywhere on their disk but the browser finds it by referring to the "classpath" environment variable.

Telling the browser about a password file

Let's suppose the password file is called "access.jar" and is to be found on a PC's disk as "c:\files\access.jar" On a windows95/98 system the "autoexec.bat" file should then contain the line
set classpath=c:\files\access.jar

After rebooting this classpath setting will kick in and all images created with THE SAME password as that used to create the password file can be viewed.

Password file interference

There is a one in one hundred chance that two password files on a single computer could interfere with one another. If this happens the authorizing password file is masked by another different password file. The result is that images can't be viewed even though access is authorized. The solution is to re-create the password file again. Just re-creating without changing the password should fix the problem. Let the author know if the odds of one in a hundred are two high. There is a fix which involves downloading a larger version of the ImageSafe product.

The password valid-until date

It's sometimes desirable to permit access but only for a limited time. A password file can be given a "valid-until" date. After this date the password file generated with this option set, will not work any more. Many different password files can be created with different view-by dates but the same password.