US5008935A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Efficient method for encrypting superblocks of data
Assignee: Nokia Bell Labs
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Filing: 1989-06-30
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Granted: 1991-04-16
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Expires: 2009-06-30
Abstract
Abstract This invention relates to an arrangement for encrypting data for storage in a computer and/or for transmission to another data processing system. The plain text data is divided into buffers and the buffers are divided into blocks. The blocks are encrypted under the control of a first key using any block encryption method such as the Data Encryption Standard (DES). Individual bytes of the encrypted blocks of a buffer are then permuted under the control of a second key to form an encrypted buffer. Advantageously, the number of permutations for even a modest size buffer, say 256 bytes, is enormous, making unauthorized decryption using key searching methods computationally infeasible.
Inventors
- 👤 Thomas J. Roberts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:40
CPC Classifications
H; H04; H04L; H04L9/00; H04L9/06; H04L9/0618; H04L9/0625; H04L2209/00; H04L2209/12; H04L2209/24
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
74 words
A method of encrypting superblocks of data comprising the steps of: encrypting each of a plurality of blocks of each of said superblocks, using a first key, each encrypted block and each unencrypted block comprising a plurality of segments, each segment comprising a plurality of bits; and permuting successive segments of said plurality of encrypted blocks over the range of each of said superblocks, using a second key, to form encrypted superblocks of data.
Claim 2
Independent Claim
74 words
A method of encrypting superblocks of data comprising the steps of: encrypting each of a plurality of blocks of each of said superblocks, using a first key, each encrypted block and each unencrypted block comprising a plurality of segments, each segment comprising a plurality of bits; and permuting successive segments of said plurality of encrypted blocks over the range of each of said superblocks, using a second key, to form encrypted superblocks of data.
Claim 3
Dependent Claim
30 words
The method of claim 1 wherein said permuting comprises: storing said successive segments of said plurality of blocks in locations of memory determined by successive elements of said second key.
Claim 4
Dependent Claim
10 words
The method of claim 2 wherein said segments are bytes.
Claim 5
Dependent Claim
26 words
The method of claim 2 wherein a processor having a word length n permutes said successive segments and wherein said segments are words of length n.
Claim 6
Dependent Claim
77 words
Apparatus for encrypting superblocks of data comprising: means for encrypting each of a plurality of blocks of said superblocks of data, using a first key to form intermediate data, wherein each encrypted block and each unencrypted block comprises a plurality of segments, and each segment comprises a plurality of bits; and means for permuting segments of said intermediate data over the range of each of said superblocks using a second key to form encrypted superblocks of data.
Claim 7
Dependent Claim
77 words
Apparatus for encrypting superblocks of data comprising: means for encrypting each of a plurality of blocks of said superblocks of data, using a first key to form intermediate data, wherein each encrypted block and each unencrypted block comprises a plurality of segments, and each segment comprises a plurality of bits; and means for permuting segments of said intermediate data over the range of each of said superblocks using a second key to form encrypted superblocks of data.
Claim 8
Dependent Claim
38 words
The apparatus of claim 5 wherein said means for permuting comprises a processor, operative under the control of a program for storing successive segments of said intermediate data in locations determined by successive elements of said second key.
Claim 9
Dependent Claim
14 words
The apparatus of claim 6 wherein said segments of said intermediate data are bytes.
Claim 10
Dependent Claim
25 words
The apparatus of claim 6 wherein said processor has a word length n and said segments of said intermediate data are words of length n.
Claim 11
Independent Claim
70 words
A method of encrypting superblocks of data comprising the steps of: encrypting a plurality of blocks of each of said superblocks, using a key, each encrypted block and each unencrypted block comprising a plurality of segments, each segment comprising a plurality of bits; and permuting successive segments of said plurality of encrypted blocks over the range of each of said superblocks, using said key, to form encrypted superblocks of data.
Claim 12
Independent Claim
70 words
A method of encrypting superblocks of data comprising the steps of: encrypting a plurality of blocks of each of said superblocks, using a key, each encrypted block and each unencrypted block comprising a plurality of segments, each segment comprising a plurality of bits; and permuting successive segments of said plurality of encrypted blocks over the range of each of said superblocks, using said key, to form encrypted superblocks of data.
Claim 13
Dependent Claim
29 words
The method of claim 9 wherein said permuting comprises: storing said successive segments of said plurality of blocks in locations of memory determined by successive elements of said key.
Claim 14
Dependent Claim
10 words
The method of claim 10 wherein said segments are bytes.
Claim 15
Dependent Claim
26 words
The method of claim 10 wherein a processor having a word length n permutes said successive segments and wherein said segments are words of length n.
Claim 16
Independent Claim
144 words
A method of encrypting a superblock of 4M bytes of plain text data comprising the steps of: encrypting M 4-byte blocks of said superblock of plain text, using a first key, to form 4M bytes of intermediate data; and permuting successive bytes of each byte of said intermediate data over the range of said superblock, using a second key, to form an encrypted superblock of data corresponding to said superblock of plain text data; wherein said first and second key are formed from a password supplied by a user of said encryption method; wherein said first key comprises a table of 256 3-byte words selected according to values of plain text and partially encoded bytes of a block; and wherein said second key comprises 4M different address offsets for storage of successive bytes of said intermediate data to form said encrypted superblock of data.
Claim 17
Independent Claim
144 words
A method of encrypting a superblock of 4M bytes of plain text data comprising the steps of: encrypting M 4-byte blocks of said superblock of plain text, using a first key, to form 4M bytes of intermediate data; and permuting successive bytes of each byte of said intermediate data over the range of said superblock, using a second key, to form an encrypted superblock of data corresponding to said superblock of plain text data; wherein said first and second key are formed from a password supplied by a user of said encryption method; wherein said first key comprises a table of 256 3-byte words selected according to values of plain text and partially encoded bytes of a block; and wherein said second key comprises 4M different address offsets for storage of successive bytes of said intermediate data to form said encrypted superblock of data.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-04-15 | 1994-10-15 | 1995-04-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-15 | 1998-10-15 | 1999-04-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-15 | 2002-10-15 | 2003-04-16 | $7700.00 | Window Closed / Lapsed |