Method and apparatus for embedding authentication information within digital data
First Claim
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1. A method for extracting a bit string of information from a digital data block which includes the bit string of information and digital data comprising a digital representation of an object, the bit string of information encoding knowledge of interest to a receiver of the digital data block, comprising the steps of:
- a) providing a digital data block having digital representation data comprising a digital representation of an object and a bit string of information embedded and encrypted therein, said bit string of information encoding knowledge of interest to a receiver of the digital data block and having been encrypted according to a predetermined encryption process and embedded according to a predetermined embedding process so that said bit string is not readily noticeable when said digital data block is converted into a non-digital form;
b) processing said digital data block having said bit string embedded and encrypted therein by both a de-embedding step and a decryption step to segregate said bit string from said digital representation data in said digital data block, said de-embedding step being the inverse of said predetermined embedding process and said decryption step being the inverse of said predetermined encryption process; and
c) retrieving said segregated bit string of information encoding knowledge of interest to a receiver of said digital data block.
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Abstract
Arbitrary digital information is embedded within a stream of digital data, in a way that avoids detection by a casual observer and that allows a user to determine whether the digital data have been modified from their intended form. The embedded information may only be extracted as authorized and may be used to verify that the original digital data stream has not been modified.
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Citations
73 Claims
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1. A method for extracting a bit string of information from a digital data block which includes the bit string of information and digital data comprising a digital representation of an object, the bit string of information encoding knowledge of interest to a receiver of the digital data block, comprising the steps of:
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a) providing a digital data block having digital representation data comprising a digital representation of an object and a bit string of information embedded and encrypted therein, said bit string of information encoding knowledge of interest to a receiver of the digital data block and having been encrypted according to a predetermined encryption process and embedded according to a predetermined embedding process so that said bit string is not readily noticeable when said digital data block is converted into a non-digital form; b) processing said digital data block having said bit string embedded and encrypted therein by both a de-embedding step and a decryption step to segregate said bit string from said digital representation data in said digital data block, said de-embedding step being the inverse of said predetermined embedding process and said decryption step being the inverse of said predetermined encryption process; and c) retrieving said segregated bit string of information encoding knowledge of interest to a receiver of said digital data block. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method for retrieving digital representation data from a digital data block which includes the digital representation data and a bit string of information embedded and encrypted therein, the bit string of information encoding knowledge of interest to a receiver of the digital data block, the method comprising the steps of:
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a) providing a digital data block having digital representation data comprising a digital representation of an object and a bit string of information embedded and encrypted therein, said bit string of information encoding knowledge of interest to a receiver of the digital data block and having been encrypted according to a predetermined encryption process and embedded according to a predetermined embedding process so that said bit string is not readily noticeable when said digital data block is converted into a non-digital form; b) processing said digital data block having said bit string embedded and encrypted therein by both a de-embedding step and a decryption step to segregate said bit string from said digital representation data in said digital data block, said de-embedding step being the inverse of said predetermined embedding process and said decryption step being the inverse of said encryption process; c) retrieving said segregated bit string of information encoding knowledge of interest to a receiver of said digital data block; and d) retrieving said digital representation data from said digital data block having said bit string segregated therefrom. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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49. A method for extracting a bit string of information from a digital data block, the bit string of information having been encrypted according to a predetermined encryption process and then embedded in the digital data block according to a predetermined embedding process, the bit string of information encoding knowledge of interest to a receiver of the digital data block and not being readily noticeable when the digital data block having the bit string embedded and encrypted therein is converted into a non-digital form, the method comprising the steps of:
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a) providing said digital data block having said bit string of information encrypted and embedded therein; b) extracting an encrypted bit string from said digital data block by using an inverse of said predetermined embedding process; c) decrypting said encrypted bit string by using an inverse of said predetermined encryption process; and d) retrieving said bit string of information after said decrypting step. - View Dependent Claims (50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73)
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Specification