GRC | PPP - Implementation

The "Display previous" and "Display next" passcard links appearing at the bottom of the PPP card display page provide direct "url access" to previous and succeeding PPP cards. This is made possible by a direct URL access facility of GRC's PPP display and printing system. For example, this link will display a standard set of three PPP passcards with the following passcard first:

himomcard

This is made possible by GRC's Direct URL Access facility which allows a standard web browser URL link to specify everything about the contents and display of PPP passcards. Using this facility, third party PPP implementers who do not wish to implement their own PPP printing systems can provide their users with a link to GRC's page to fulfill that function.

Note that using a URL in this manner carries with it the responsibility to keep the URL's link contents private. The communication with GRC's server will be protected by a secure SSL connection, so neither the link's text nor GRC's passcode reply page can be intercepted. However, the link's text which contains your private PPP sequence key will be available on YOUR computer. Therefore the link itself must be treated with appropriate security.

GRC's direct URL access has the form of a standard parameterized URL with a base portion of https://www.grc.com/ppp? followed by one or more numbered parameters taking the form {number}={value} with number/value pairs separated by an "&" ampersand character.

The available parameters are described in this chart:

PPP direct URL access parameters

Usage: https://www.grc.com/ppp?{number}={value}[[&{number}={value}]]

1	=	Sequence Key (Required - no default value) The PPP sequence key is specified with 64 lowercase hexadecimal characters (0-9 a-f). This parameter has no default value since the URL facility was designed to produce specific URL-specified passcards.
2	=	First requested passcard (Optional - default 1) A decimal number containing the digits (0-9) and optional but ignored commas. The set of three displayed passcards will begin at this number. If the first requested passcard is not specified, the first three passcards for the specified sequence key will be generated and displayed.
3	=	Passcode length (Optional - default 4) A decimal number ranging between two (2) and sixteen (16) specifying the length of the passcodes to be generated and displayed. If the passcode length is not specified, the default length of 4 characters will be used for the passcodes.
4	=	Character set (Optional - standard 64-character set) A "URL encoded" ASCII string specifying the character to be used for composing passcodes. In addition to the usual "reserved" or "dangerous" characters such as '&' and '=' that would need to be encoded, the capital letters 'A' through 'Z' must also be encoded to preserve their case. If the character set is not specified, the standard 64-character character set will be used.
5	=	Passcard label (Optional - default is blank label) A "URL encoded" ASCII string specifying the heading label to be used on the passcards. In addition to the usual "reserved" or "dangerous" characters such as '&' and '=' that would need to be encoded, the capital letters 'A' through 'Z' must also be encoded to preserve their case. If a passcard label is not specified, the passcards will have no label.
6	=	Passcard size (Optional - default 14) A decimal number containing the digits (0-9) and optional but ignored commas. The passcards will be displayed for printing at this size. If this parameter is not specified, the three passcards will be displayed at the default size of '14'.
*The only required parameter* is number 1 which specifies and provides the sequence key. All other parameters have logical default values as described above. Therefore every direct PPP access URL must at least have a '1=' parameter followed by 64 lowercase hexadecimal characters. Any specified parameter may only be provided once. A repetition of any parameter will return an error page. Wikipedia's URL encoding reference will further explain URL encoding. This chart: URL Encoded Characters specifies the characters to which GRC's URL encoder applies URL encoding.

You will notice that every display of PPP passcards includes one or two links at the bottom of the page. By filling-in various values on the main PPP.HTM form page, then displaying the resulting passcards, the URLs contained in the bottom-of-page links can be used as samples of proper URL formation.