06065008 is referenced by 52 patents and cites 7 patents.

This invention concerns a system and method for securely distributing subsetted fonts from a distributor to a client. The system includes a signing module to construct an authentication tree having leaves formed of glyphs, one or more intermediate levels of nodes computed as one-way functions of the glyphs, and a root computed as a one-way function of the nodes. The signing module digitally signs the root of the authentication tree using a private signing key unique to the font creator or distributor. The system has a subsetting module to construct a font subset file that contains selected glyphs and other data to be included in a font subset. The font subset file also holds the digitally signed root of the font authentication tree and one or more authentication values of the authentication tree that represents non-selected glyphs and data of the font that are not contained in the font subset. The font subset file is distributed to requesting clients. An authentication module at the client authenticates the font subset file received from the distributor. The authentication module reconstructs the root of the authentication tree using the selected glyphs and data in the font subset and the authentication values that represent the non-selected glyphs and data not contained in the font subset. The authentication module also produces an unsigned version of the digitally signed root using a public key of the font creator to produce an unsigned root digest. The authentication module compares the unsigned root to the reconstructed root and if and only if they match, authenticates the font subset file as originating from the distributor (or font creator) and not being subsequently altered.

Title
System and method for secure font subset distribution
Application Number
8/942036
Publication Number
6065008
Application Date
October 1, 1997
Publication Date
May 16, 2000
Inventor
David Meltzer
Seattle
WA, US
Gregory Hitchcock
Woodinville
WA, US
Donald D Chinn
Redmond
WA, US
Josh Benaloh
Redmond
WA, US
Daniel R Simon
Redmond
WA, US
Agent
Lee & Hayes PLLC
Assignee
Microsoft Corporation
WA, US
IPC
G06F 17/30
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