3798360 is referenced by 119 patents and cites 1 patents.

This specification discloses a system that provides multiple level encipherment of a block of data by means of a stepped block cipher process. A data stream consisting of digital information is segmented into blocks of dimension D, each block is enciphered by means of a block cipher cryptographic system operating under the control of a unique subscriber digital key. The cryptographic system develops a first cipher text of equal dimension as the block D. Then the cryptographic system is effectively shifted to accept a plurality of data bits from a second data block and a plurality of bits from the first cipher. The combination of block data bits and ciphertext data bits forms a composite block of dimension equal to the data block D. This combination is introduced to the cryptographic device for developing a second cipher text. The combined output of the second ciphertext and those information symbols from the first ciphertext which were not reintroduced to the cryptographic device are transmitted as a complete unit to a receiving station which will decipher the received multiple level cryptogram by an inverse process.The multiple level encipherment process is also utilized in a variant key embodiment which would encipher a data block D into a cipher C which is a function of a key control block consisting of a random combination binary digits that are continuously changing.In a further embodiment which utilizes multiple level encipherment, there is presented a method for providing secrecy in communications between a central processing unit and its data banks.

Step code ciphering system
Application Number
Publication Number
Application Date
June 30, 1971
Publication Date
March 19, 1974
Feistel Horst
Siber Victor
International Business Machines Corporation
H04l 09/02
H04L 09/06
H04L 09/00
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