| 摘要 |
<p>[Problem] To provide a format-preserving encryption device or the like that enables efficient and secure encryption/decryption while preserving a data format. [Solution] The encryption device (10) is equipped with: a unit-block-tweakable encryption means (101) that encrypts a specific single digit of a plain text by using the values of the remaining digits of the plain text other than the specific single digit and an external tweak that is simultaneously input with the plain text; a block permutation means (102) that permutes the respective digits, including the encrypted specific digit of the plain text, by the unit of digit in accordance with a predetermined rule; and a counter updating means (103) that causes the processing by the unit-block-tweakable encryption means and the block permutation means to be repeated for a predetermined number of times. The decryption device (20) performs the reverse processing to that of the encryption device (10).</p> |
