pad encryption method and software

• US 5,799,090 A
• Filed: 09/25/1995
• Issued: 08/25/1998
• Est. Priority Date: 09/25/1995
• Status: Expired due to Fees

• Current Assignee: SCM Microsystems US Incorporated (Identive Group Incorporated)
• Original Assignee: SCM Microsystems US Incorporated (Identive Group Incorporated)
• Inventors: Angert, Joseph C.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US08/533,314
• Time in Patent Office: 1,065 Days
• Field of Search: 380/9, 380/28, 380/42, 380/43, 380/46, 380/49, 380/50, 380/59, 380/33, 380/44
• US Class Current: 380/43
• CPC Class Codes: H04L 2209/30 Compression, e.g. Merkle-Damgard construction
• CPC Class Codes: H04L 9/0662 with particular pseudorandom sequence generator
• CPC Class Codes: H04L 9/0863 involving passwords or one-time passwords network architectures or network communication protocols for using one-time keys in a packet data network H04L63/067

Abstract

A pad encryption software architecture includes space on a floppy for storing the pad to be used with the encryption software. The pad is XOR generated with random numbers subject to redetermined offsets. If the pad is smaller than the text to be encrypted, then XOR takes several cycles with redetermined offsets used in XORing the pad with the remaining plain text to be encrypted. The offset is determined from a user selected password. New offsets are determined from old offsets by adding the current offset to the value of the byte in the pad located at the offset value.

Claims

1. A method of generating a pad from a selected file stored in computer memory, comprising:

extracting a first value from a selected file stored in a computer memory,

generating a pseudo random number,

logically combining the first value with the pseudo random number to generate a first random character of a pad, and

successively repeating the prior steps to produce next random characters of a pad.

2. The method according to claim 1, wherein logically combining includes performing an XOR operation.

3. The method of claim 1 further comprising choosing the selected file from one of a plurality of files stored in computer memory before extracting a first value.

4. The method of claim 3 wherein logically combining includes performing an XOR operation.

5. An encryption method comprising:

logically combining characters of a selected character file in a computer memory with random numbers to produce elements of a pad of predetermined dimension, and

logically combining characters of plain text with corresponding elements of the pad.

6. The encryption method of claim 5, wherein the predetermined dimension of the pad is greater than the number of characters of plain text being combined logically.

7. The encryption method of claim 5, wherein the predetermined dimension of the pad is less than the number of characters of plain text being combined logically.

8. The encryption method of claim 5, wherein the corresponding characters of the pad are determined subject to an offset.

9. The encryption method of claim 5 further comprising choosing the selected character file in a computer memory from one of a plurality of character files in the computer memory before logically combining characters of a selected character file.

10. The encryption method of claim 9, wherein the dimension of the pad is greater than the number of characters of plain text being combined logically.

11. The encryption method of claim 9, wherein the dimension of the pad is less than the number of characters of plain text being combined logically.

12. The encryption method of claim 9, wherein the corresponding characters of the pad are determined subject to an offset.

13. An encryption method comprising:

logically combining characters of a selected character file in computer memory with corresponding random numbers to produce a pad of predetermined dimension, and

logically combining characters of plain text with corresponding elements of the pad, wherein the corresponding characters of the pad are determined subject to an offset, and wherein the offset is a function of a selected password.

14. A method for operation on a computer, comprising:

installing an encryption program from an external storage source,

selecting a seed file, and

exclusive ORing pseudo random numbers with characters from the seed file to generate a pad.

15. The method according to claim 14 wherein the pad is stored on a floppy disk.

16. The method according to claim 14 wherein the pad is stored on a flash memory.