GB2371401A

GB2371401A - Personal data protector

Info

Publication number: GB2371401A
Application number: GB0101271A
Authority: GB
Inventors: Bryan Kelly
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-01-18
Filing date: 2001-01-18
Publication date: 2002-07-24
Also published as: GB0101271D0

Abstract

A personal data protector which electronically encrypts and decrypts sensitive personal data such as passwords and pin numbers. The cipher is a polyalphabetical substitution cipher based on Vigenere, but which encrypts numbers as well as letters. The cipher encrypts data with the same number of digits as the original data, simplifying and facilitating written storage of the ciphertext. The cipher ensures encryption and decryption occur in a particular fashion dependant only on a user supplied keyword. Encrypted data can be stored in the machine's internal memory. The machine's size can vary, but one of its forms is pocket sized for convenient storage and transport. The encryption method involves assigning one character of the user-input keyword to each character of the message to be encoded. If the message is longer than the keyword, the keyword is repated as many times as necessary. The message character and keyword character are then combined by binary addition of the respective cipher code strings representing each character. The reverse process is performed for decryption.

Description

PERSONAL DATA PROTECTOR This invention relates to a personal data protector, which uses encryption technology.

Many people have passwords, pin numbers or account numbers that need to be remembered for a variety of purposes, such as using a cash machine. Such sensitive personal data should not normally be written down as it may be discovered, and must therefore either be memorised (with the risk of being forgotten) or stored in a password protected electronic device (with the risk of the device being lost or stolen).

One solution is to encrypt the data before it is written down. However the present methods of secure encryption suffer from one or more of the following problems that prevent general use for sensitive personal data: * encryption products are generally software only * the encryption process can be fairly complex and/or long-winded

'access to a relatively expensive and bulky machine is required, such as a personal computer or laptop, making transport to a point-of-use (such as a bank) very inconvenient * encryption can be machine dependant, such that if the machine is unavailable for any reason (e. g. faulty or stolen) decryption may be difficult or impossible.

According to the present invention there is provided a personal data protector, comprising of an electronic unit which contains a cipher that encrypts and decrypts both letters and numbers in a particular fashion dependant only on a keyword set by the user and has a display screen, keypad, numberpad, encrypt button and decrypt button.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which : Figure 1 shows a block diagram illustrating the encryption process Figure 2 shows a block diagram illustrating the decryption process Figure 3 shows the machine in perspective Referring to the drawing, plaintext 1 (i. e. data to be encrypted) is passed through a cipher 2 using a keyword 3 as shown in Fig 1. The ciphertext 4 (i. e. encrypted data) is written down and/or stored in the machine's internal memory 5. Data is decrypted by passing it back through the cipher 2 using the same keyword 3 that encrypted the data, as shown in Fig 2.

The cipher 2 is a polyalphabetical substitution cipher based on the Vigenere cipher, modified to include numbers. The substitution component of the cipher simplifies and facilitates written storage of the ciphertext.

Data is encrypted by mapping characters to binary numeric values, and adding keyword character values to the corresponding plaintext character values, modulo the number of letters in the alphabet for plaintext letters, or modulo the number of digits from 0 to 9 for plaintext numbers. The character mapping is performed to the following binary protocol whereby 7-bit binary numbers are assigned to each letter of the alphabet and the digits 0 to 9:

A 0 0 0 0 0 0 1 B0000010 C 0 0 0 0 0 1 1 D 0 0 0 0 1 0 0 E 0 0 0 0 1 0 1 F0000110 G 0 00011 1 H 0 0 1 0 0 0 0 10001001 J 0 0 0 1 0 1 0 K 0 0 0 1 0 1 1 L 0001100 M 0 0 0 1 1 0 1 N 0 0 0 1 1 1 1 O 0 0 0 1 1 1 1 P 0 0 1 0 0 0 0 Q 0 0 1 0 0 0 1 R 0 0 1 0 0 1 0 S 0 0 1 0 0 1 1 T 0 0 1 0 1 0 0 U 0 0 1 0 1 0 1 V 0 0 1 0 1 1 0 W 0 0 1 0 1 1 1 X 0 0 1 1 0 0 0 Y 0 0 1 1 0 0 1 Z 0 0 1 1 0 1 0 A 0 0 1 1 0 1 1 B0011100 C 0 0 1 1 1 0 1 D0011110 E0011111 F 0 1 0 0 0 0 0 G 0 1 0 0 0 0 1

H 0 1 0 0 0 1 0 I 0 1 0 0 0 1 1 J 0 1 0 0 1 0 0 K 0 1 0 0 1 0 1 L0100110 M 0 1 0 0 1 1 1 N 0 1 0 1 0 0 0 O 0 1 0 1 0 0 1 P0101010 Q 0 1 0 1 0 1 1 R 0 1 0 1 1 0 0 S 0 1 0 1 1 0 1 T0101110 U 0 1 0 1 1 1 1 V 0 1 1 0 0 0 0 W 0 1 1 0 0 0 1 X 0 1 1 0 0 1 0 Y 0 1 1 0 0 1 1 Z 0 1 1 0 1 0 0 0 0 1 1 0 1 0 1 10110110 2 0 1 1 0 1 1 1 3 0 1 1 1 0 0 0 4 0 1 1 1 0 0 1 5 0 1 1 1 0 1 0 6 0 1 1 1 0 1 1 7 0 1 1 1 1 0 0 8 0 1 1 1 1 0 1 9 0 1 1 1 1 1 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 2 1 0 0 0 0 0 1 3 1 0 0 0 0 1 0

4 1000011 5 1 0 0 0 1 0 0 6 1 0 0 0 1 0 1 7 1 0 0 0 1 1 0 81000111 91001000 0 1 0 0 1 0 0 1 1 1 0 0 1 0 1 0 2 1 0 0 1 0 1 1 3 1 0 0 1 1 0 0 4 1 0 0 1 1 0 1 5 1001110 6 1 0 0 1 1 1 1 7 1 0 1 0 0 0 0 8 1 0 1 0 0 0 1 9 1 0 1 0 0 1 0 0 1 0 1 0 0 1 1 1 1 0 1 0 1 0 0 2 1 0 1 0 1 0 1 3 1010110 41010111 4 1 0 1 0 1 1 1 5 1 0 1 1 0 0 0 To encrypt data the characters within the plaintext and keyword are first converted to binary form using a limited portion of the binary protocol of page 2, whereby characters A to Z are assigned binary numbers in the range 0000001 to 0011010, and characters 0 to 9 are assigned binary numbers in the range 0110101 to 0111110. Each binary element of the plaintext is added to the corresponding binary element of the keyword, cycling the keyword if it is smaller than the plaintext. The resultant binary data is then converted back to letters or numbers to form the ciphertext using the binary protocol of page 2.

Decryption is essentially a reverse of the above process. The ciphertext and the keyword are converted into binary, using the same limited portion of the binary protocol on page 2 as used for encryption. Each binary element of the keyword is subtracted from each binary element of the ciphertext. The resultant binary data is converted to letters or numbers using the binary protocol of page 2 to form the plaintext.

The process is now demonstrated using the plaintext 137RET and the keyword KING as an illustration. The plaintext and keyword are first converted to their binary form using the binary protocol of page 2: Plaintext 1 3 7 R E T Plaintext in binary 0110110 OH 1000 0111100 0010010 00001010010100 Keyword KING Keyword in binary 0001011 00010010001110 0000111 Each binary element of the plaintext is added to the corresponding element of the keyword. The keyword is cycled since it is smaller than the plaintext.

Plaintext in binary 011011001110000111100001001000001010010100 Keyword in binary 0001011 00010010001110 0000111 0001011 0001001 Ciphertext in binary 1000001 10000011001010 0011001 0010000 0011101 The resultant ciphertext in binary is then converted to letters or numbers using the binary protocol of page 2: Ciphertext in binary 1000001 10000011001010 0011001 0010000 0011101 Ciphertext 2 2 1 Y P C

Thus the original plaintext 137RET has become the ciphertext 221YPC.

During decryption, the keyword KING in binary is subtracted from the ciphertext 221YPC in binary to reveal the plaintext in binary, from which the plaintext 137RET is obtained using the binary protocol of page 2. Referring to Fig 3, data is encrypted as follows. The machine is switched on using the power button 6. Data is typed in using the keypad 7 and/or numberpad 8. The ENTER button 9 is then pressed. The keyword 3 is then typed in using the keypad 7.

The ENCRYPT button 10 is then pressed. The encrypted data then appears on the display screen 11, and can be stored into the machine's memory 5 by pressing the Min button 12 and/or written down on paper. Errors during typing are corrected by either pressing the DEL button 13 which clears the last entered character, or the AC button 14 which re-sets the machine to its power-up mode.

Data is decrypted by first typing it into the machine, using the keypad 7 and/or numberpad 8, or retrieving it from memory 5 by pressing the RM button 15. The ENTER button 9 is then pressed. The keyword 3 is then typed in using the keypad 7.

The DECRYPT button 16 is then pressed. The decrypted data then appears on the display screen 11.

The machine is portable, with dimensions such that it can be conveniently carried in a pocket or handbag.

The above example describes a simple form of the invention. There are other forms of the invention, such as including the electronic labelling of each data item, including storage of both the label and the encrypted data within internal memory, including storage of multiple label/data entries within internal memory, combining the keypad with the number pad (as seen on mobile phones), and dimensions that make the machine non-portable. In addition, the machine can be integrated with other electronic devices, such as mobile phones, calculators, organisers and electronic diaries.

Claims

CLAIMS 1. A personal data protector, comprising of an electronic unit which contains a cipher that encrypts and decrypts both letters and numbers in a particular fashion dependant only on a keyword set by the user and has a display screen, keypad, numberpad, encrypt button and decrypt button.
2 A personal data protector as claimed in Claim 1 which uses a polyalphabetical substitution cipher that maps characters to numeric values and adds keyword character values to corresponding plaintext character values, modulo the number of letters in the alphabet for plaintext letters, or modulo the number of digits from 0 to 9 for plaintext numbers.
3 A personal data protector as claimed in Claim 2 which uses a binary conversion protocol of the form as presented on page 2 of the Description.
4 A personal data protector as claimed in any preceding Claim, which has the facility to store encrypted data in internal memory.
5 A personal data protector as claimed in Claim 4, which has the facility to electronically label encrypted data and store the labelled encrypted data in internal memory.
6 A personal data protector as claimed in any preceding Claim, which has a keypad combined with the numberpad.
7 A personal data protector as claimed in any of the Claims 1,2, 3,4, 5, or 6 that is part of an electronic calculator.
8 A personal data protector as claimed in any of the Claims 1,2, 3,4, 5, or 6 that is part of an electronic organiser or electronic diary.
9 A personal data protector as claimed in any of the Claims 1,2, 3,4, 5, or 6 that is part of a mobile phone.
10 A personal data protector as claimed in any of the Claims 1,2, 3,4, 5, or 6 that is part of any other electronic device.
11 A personal data protector as claimed in any of the Claims 1,2, 3,4, 5, or 6 which is portable, with dimensions such that it can be conveniently carried in a pocket or handbag.
12 A personal data protector substantially as described herein with reference to Figures 1-3 of the accompanying drawing.