File management apparatus
First Claim
1. A file management apparatus that encrypts a plaintext to generate a ciphertext, stores the ciphertext, and decrypts the ciphertext, the file management apparatus comprising:
- a key storage medium storing key information beforehand;
registration means for encrypting the key information using a password to generate an encrypted key;
encryption means for encrypting a plaintext based on the key information to generate a ciphertext;
switch means for switching between (a) generating key information by decrypting the encrypted key using the password and (b) reading the key information from the key storage medium; and
decryption means for decrypting the ciphertext based on one of the generated key information and the read key information.
2 Assignments
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Accused Products
Abstract
A password registration unit encrypts key information using an input password, and stores the generated encrypted key as a file into a computer. A file encryption unit generates a file key arbitrarily, encrypts the file key using the key information, encrypts a plaintext using the file key to generate a ciphertext, and stores an encrypted file including the encrypted file key in its header part and the ciphertext in its data part. A file decryption unit decrypts the encrypted file key using the key information to obtain a file key, or receives an input of a password, decrypts the encrypted key using the password to obtain key information, and decrypts the encrypted file key using the key information to obtain a file key. The file decryption unit then decrypts the ciphertext using the obtained file key.
183 Citations
37 Claims
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1. A file management apparatus that encrypts a plaintext to generate a ciphertext, stores the ciphertext, and decrypts the ciphertext, the file management apparatus comprising:
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a key storage medium storing key information beforehand;
registration means for encrypting the key information using a password to generate an encrypted key;
encryption means for encrypting a plaintext based on the key information to generate a ciphertext;
switch means for switching between (a) generating key information by decrypting the encrypted key using the password and (b) reading the key information from the key storage medium; and
decryption means for decrypting the ciphertext based on one of the generated key information and the read key information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A file encryption apparatus that encrypts a plaintext to generate a ciphertext and stores the ciphertext into a memory unit thereof, the file management apparatus comprising:
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a key storage medium storing key information beforehand;
registration means for receiving an input of a password, encrypts the key information using the received password to generate an encrypted key, and writes the generated encrypted key to the memory unit; and
encryption means for encrypting a plaintext using a file key to generate a ciphertext, encrypting the file key using the key information to generate an encrypted file key, and writing the ciphertext in association with the encrypted file key, to the memory unit. - View Dependent Claims (17)
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18. A file management apparatus that encrypts a plain text to generate a ciphertext, stores the ciphertext, and decrypts the ciphertext, the file management apparatus comprising:
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a key storage medium storing key information beforehand;
registration means for encrypting a password using the key information to generate an encrypted password;
encryption means for encrypting a plaintext using a file key to generate a ciphertext, encrypting the file key based on a password obtained by decrypting the encrypted password to generate a first encrypted file key, and encrypting the file key based on the key information to generate a second encrypted file key;
switch means for switching between (a) decrypting the first encrypted file key based on the password and (b) decrypting the second encrypted file key based on the key information, to generate a file key; and
decryption means for decrypting the ciphertext using the generated file key. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37)
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36. A file encryption apparatus that encrypts a plaintext to generate a ciphertext and stores the ciphertext in a memory unit thereof, the file encryption apparatus comprising:
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a key storage medium storing key information beforehand;
registration means for receiving an input of a password, encrypts the received password using the key information to generate an encrypted password, and writes the generated encrypted password to the memory unit; and
encryption means for decrypting the encrypted password using the key information to generate a password, encrypts a plaintext using a file key to generate a ciphertext, encrypts the file key using the password to generate a first encrypted file key, encrypts the file key using the key information to generate a second encrypted file key, and writes the ciphertext in association with the first encrypted file key and the second encrypted file key, to the memory unit.
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Specification