What is claimed is:

1. A method of encrypting a data message comprising a series of unencrypted data values, the method comprising the steps of:
generating a matrix of possible unencrypted data values; and for a given unencrypted data value:
locating the unencrypted data value in the matrix and substituting for the given unencrypted data value a pointer to the unencrypted data value within the matrix; and prior to having completed encryption of the data message, changing a location of a given unencrypted data value within the matrix in a pseudo random fashion; wherein the change in location of the given unencrypted data value within the matrix does not reveal a new location of other different unencrypted data values.

2. The method of claim 1 comprising the further steps of:
successively subtracting from one of an unencrypted data value and a previously encrypted data value each of a plurality of predetermined parameters;
wherein the predetermined parameters are selected so as to ensure that a machine limit on number representation is encountered.

3. A method of encrypting a data message comprising a series of unencrypted data values, the method comprising the steps of:
encrypting an unencrypted data value multiple times using a plurality of encryption algorithms arranged in pipeline fashion, at least one of said encryption algorithms using a random number obtained from a random number generator seeded with a predetermined parameter of the encryption process; wherein one of a plurality of encryption algorithms comprises generating a matrix of possible unencrypted data values and, for a given unencrypted data value:
locating the unencrypted data value in the matrix and substituting for the given unencrypted data value a pointer to the unencrypted data value within the matrix; and changing a location of a given unencrypted data value within the matrix.

4. A method of securely exchanging a data message between a first user and a second user using a common cryptographic key without exchanging the key, the method comprising the steps of:
specifying a computer file of arbitrary size commonly available to both the first user and the second user; the first user using the computer file of arbitrary size to generate the common key and encrypt the data message, the common key being of a predetermined large size; transmitting the encrypted message to the second user through an in-band channel; and the second user using the computer file to generate the common key and decrypt the data message, wherein the common key generating steps do not require the computer file to be of a predetermined size.

5. The method of claim 4, comprising the further steps of:
generating a session specific key; transmitting the session specific key through the in-band channel; and using the session specific key to scramble the common key prior to using the common key.

6. Using a copy of a program having an assigned serial number, a method of encrypting a data message so as to allow decryption of the data message only by a specified target audience, the method comprising the steps:
specifying a target audience and selecting a variable length portion of the serial number; performing a sequence of operations on the variable length portion to form a key; and using the key during encryption of the data message.

7. The method of claim 6 wherein the variable length portion is of 0 length, and the specified target audience includes all users of said program, regardless of serial number.

8. The method of claim 6 wherein the variable length portion is of maximum length, and the specified target audience includes only the user of a copy of said program bearing a specific serial number.

9. The method of claim 6 wherein the variable length portion is of an intermediate length, and the specified target audience includes users of copies of said program bearing serial numbers having a common portion and a distinct portion.

10. A method of encrypting a data message comprising a series of unencrypted data values, comprising the steps of:
generating a random number; deriving a random value using said random number; and logically combining said random value with a data value to be encrypted, wherein different bits of the data value to be encrypted are randomly toggled from one logical state to another logical state.

11. A method of encrypting a data message comprising a series of unencrypted data values, the method comprising the steps of:
providing a multiplicity N of encryption algorithms; generating a random number; deriving a random value using said random number; and performing an N-way branch and encrypting the data value to be encrypted using a random one of said N encryption algorithms.

12. A method of encrypting a data message comprising a series of unencrypted data values, the method comprising the steps of:
building a matrix of paired values, values of a pair being multiplicative inverses of one another in accordance with modulo arithmetic; scrambling the matrix; generating a random number; deriving a random value using said random number; selecting a pair of values based on said random number; and encrypting a data value to be encrypted by multiplying it by one value of said pair of values.

13. A method of encrypting a data message comprising a series of data values to produce an encrypted data message, the method comprising the steps of:
a user specifying a date limit restricting the dates on which the data message may be decrypted; deriving from the data limit a derived key; and encrypting the data message using at least the derived key.

14. A method of decrypting an encrypted data message having combined therewith an encrypted date limit restricting the dates on which the encrypted data message may be decrypted, the method comprising the steps of:
deriving from the current date a derived key; and attempting to decrypt the encrypted data message using at least the derived key; wherein, if the current date does not correspond to a date limit imposed during encryption, decryption fails.

15. The method of claim 4, wherein a copy of the computer file is local to the first and second user.

16. The method of claim 15, wherein the computer file has a primary purpose other than in the cryptographic algorithm.

Next: Background of the invention

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