The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Feb. 03, 2015

Filed:

Aug. 24, 2010
Applicants:

Yoichi Shibata, Tokyo, JP;

Hirosato Tsuji, Tokyo, JP;

Mitsuru Matsui, Tokyo, JP;

Inventors:

Yoichi Shibata, Tokyo, JP;

Hirosato Tsuji, Tokyo, JP;

Mitsuru Matsui, Tokyo, JP;

Assignee:
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G06F 21/00 (2013.01); H04L 9/28 (2006.01); H04L 9/06 (2006.01);
U.S. Cl.
CPC ...
H04L 9/28 (2013.01); H04L 9/06 (2013.01); H04L 9/0656 (2013.01);
Abstract

The object is to enable cipher communication even when a cipher key in a one-time pad cipher (Vernam cipher) is running short. A one-time pad encrypting part encrypts communication data by the one-time pad cipher by sequentially using part of a one-time pad cipher key stored in a one-time pad cipher key storage part, to generate encrypted data. A block-encrypting part encrypts communication data by a block cipher by using a block-cipher key stored in a block-cipher key storage part, to generate encrypted data. An encryption control part controls whether the communication data is to be encrypted by the one-time pad encrypting part, or by the block-encrypting part, depending on a remaining bit count of the one-time pad cipher key stored in the one-time pad cipher key storage part.


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