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...During the Civil War, the Confederacy established its own Patent Office which issued 266 patents, a third of which concerned implements of war.
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US Patent 5214703 - Device for the conversion of a digital block and use of same
US Patent Issued on May 25, 1993
Estimated Patent Expiration Date:
January 7, 2012Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
Estimated Patent Expiration Date:
January 7, 2012Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.AbstractThe device (12) comprises nine encryption stages (61.1, 61.2, 69), the first eight of which are constructed identically. It further comprises a key subblock generation unit (63), an input unit (21), and an output unit (79). It serves for the block-by-block encryption of a plaintext (X) proceeding from a message source (11) into a ciphertext (Y) to be delivered on a transmission line (13), wherein a secret key block (Z) is inputted beforehand via a secure channel 17. The encryption is effected in a step-by-step and parallel manner for four subblocks (X1 -X4 ; W11 -W14 ; W21 -W24 ; W81 -W84 ; Y1 -Y4). Every encryption stage (61.1, 61.2, 69) comprises four first inputs (25-28; 35-38), six and four second inputs (29, 30, 32, 33, 49, 52; 129, 130, 132, 133), respectively, and four outputs (75-78). A total of fifty-two key subblocks (Z1 -Z52) which are formed from the key block (Z) are connected to the second inputs. The device (12) can also serve, without being altered, for the decryption of an incoming ciphertext (Y). Different key subblocks need only be connected to the second inputs for this purpose. | InventorsAssigneeApplicationNo. 781235 filed on 01/07/1992US Classes:380/37, Block/data stream enciphering380/28, PARTICULAR ALGORITHMIC FUNCTION ENCODING380/42Data stream/substitution encipheringField of Search380/36, Time segment interchange380/37, Block/data stream enciphering380/42, Data stream/substitution enciphering380/43, Key sequence signal combined with data signal380/45, Multiple key level380/28, PARTICULAR ALGORITHMIC FUNCTION ENCODING380/29NBS/DES algorithmExaminersPrimary: Swann, Tod R.Attorney, Agent or FirmUS Patent References4275265, Complete substitution permutation enciphering and deciphering circuitIssued on: 06/23/1981 Inventor: Davida , et al.4668103, Polygraphic encryption-decryption communications system Issued on: 05/26/1987 Inventor: Wilson4850019, Data randomization equipment Issued on: 07/18/1989 Inventor: Shimizu , et al.5020106Process for the cryptographic processing of data and cryptographic systems Issued on: 05/28/1991 Inventor: Rabold, et al. International ClassH04K 001/04Foreign Application Priority Data1990-05-18 CH |
