US005751813A [ill Patent Number: [45] Date of Patent:
[54] USE OF AN ENCRYPTION SERVER FOR ENCRYPTING MESSAGES
[75] Inventor: David Dorenbos, Elmhurst, El. [73] Assignee: Motorola, Inc.. Schaumburg, HI.
[21] Appl. No.: 639/157
[22] Filed: Apr. 29, 1996
[51] Int. Cl.6 H04L9/00
[52] U.S. Cl 380/49; 380/25
[58] Field of Search 380/49, 25
[56] References Cited
U.S. PATENT DOCUMENTS
5,455,865 10/1995 Periman 380/49
5,479,514 12/1995 Klonowski 380/47
5,574,785 11/1996 Ueno 380/2
An encryption server receives a first encrypted message (105) and decrypts (403) the encrypted message using a first key, yielding a decrypted message comprising a second encrypted message (105A), an identification of a sender of the first encrypted message, and an identification of a first recipient. The second encrypted message, the identification of the sender, and the identification of the first recipient are determined (405) from the decrypted message. The second encrypted message and the identification of the sender are encrypted (409) with a second key. yielding a third encrypted message (109). The third encrypted message (109) is transmitted to the first recipient
34 Claims, 4 Drawing Sheets
