Cryptographic system using interchangeable key blocks and selectable key fragments
First Claim
1. A cryptographic system for the secure transmission of information between first and second nodes, comprising, at the first node:
- means for generating a key comprising more than one key fragment;
means for arranging the key fragments in a selected order to form a permuted key;
means for generating data indicative of the selected order to the key fragements in the permuted key;
means for encrypting the information with said permuted key;
means for transferring the encrypted information, key and selected order data from the first node to the second node; and
, at the second node;
means for obtaining the selected order of key fragments to reconstruct the permuted key from the transferred key in accordance with the transferred selected order data; and
means for decrypting the information using the permuted key.
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Accused Products
Abstract
A cryptographic system is used for the secure transmission of digitized signals to a plurality of receivers. At the transmission end, a key consisting of two blocks, each including a plurality of key fragments, is generated. For each transmission session, different sets of key fragments may be periodically selected from one of the key blocks and used to encrypt the signals. Data indicative of the set selection is generated. The key is distributed to each receiver. The set selection data is transmitted to all receivers along with the encrypted signals and used to construct the key fragment set for decryption of the transmitted signals. During the transmission session, the other key block may be varied to form a replacement key which is distributed to each receiver. At the end of the session, the functions of the key blocks are interchanged in all receivers at one time by selecting a set in the varied key block for use in encryption and decryption.
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Citations
35 Claims
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1. A cryptographic system for the secure transmission of information between first and second nodes, comprising, at the first node:
- means for generating a key comprising more than one key fragment;
means for arranging the key fragments in a selected order to form a permuted key;
means for generating data indicative of the selected order to the key fragements in the permuted key;
means for encrypting the information with said permuted key;
means for transferring the encrypted information, key and selected order data from the first node to the second node; and
, at the second node;
means for obtaining the selected order of key fragments to reconstruct the permuted key from the transferred key in accordance with the transferred selected order data; and
means for decrypting the information using the permuted key. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
- means for generating a key comprising more than one key fragment;
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15. A cryptographic system of the secure transmission of information between first and second nodes, comprising, at the first node, means for generating a key comprising first and second key blocks, each of said blocks comprising more than one key fragment arranged in a selected order;
- means for designating one of the key blocks as the current key block for encryption and decryption;
means for varying the order of the key fragments in the other key block, means for designating the other key block as the current key block at a time after the order of the key fragments therein has been varied;
means for generating data indicative of the order of the key fragments in the current key block;
means for encrypting the information to be transmitted using the key fragments arranged in the selected order from the then current key block and means for transferring the encrypted information, key, and data from the first node to the second node and, at the second node, means for obtaining the select order of the key fragments from the then current key block in the transferred key in accordance with the transferred data and means for decrypting the encrypted information using the obtained key fragments in the selected order from the then current key block. - View Dependent Claims (16, 17, 18, 19, 20)
- means for designating one of the key blocks as the current key block for encryption and decryption;
- 21. A receiver for use in a system broadcasting information of the type comprising a key having more than one key fragment, the key fragments having been arranged in a selected order to form a permuted key, data indicative of the selected order of the key fragments in the permuted key, and information encrypted using the permuted key, the receiver comprising means for receiving the key, data and encrypted information, means for obtaining the permuted key from the received key in accordance with the received data and means for decrypting the received information using the obtained permuted key.
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25. A receiver for use in a system for broadcasting information of the type comprising:
- a key having first and second key blocks, each of the blocks comprising a plurality of key fragments arranged in a selected order, one of the blocks being designated as the current key block for encrypting and decrypting, while the other block is varied and, thereafter the other key block being designated as the current key block;
data indicative of the order of the key fragments of the then current key block;
information encrypted using the key fragments arranged in the selected order from the then current key block, the receiver comprising means for receiving the key, data and encrypted information, means for obtaining the selected order of the key fragments for the then current key block from the key in accordance with the received data and means for decrypting the received information using the key fragments arranged from the then current key block. - View Dependent Claims (26, 27)
- a key having first and second key blocks, each of the blocks comprising a plurality of key fragments arranged in a selected order, one of the blocks being designated as the current key block for encrypting and decrypting, while the other block is varied and, thereafter the other key block being designated as the current key block;
- 28. A cryptographic method for the secure transmission of information between first and second nodes comprising the steps of, at the first node, generating a key comprising more then one key fragment, arranging the key fragments to form a permuted key, generating data indicative of the order of the key fragments in the permuted key, encrypting the information to be transmitted using the permuted key, transferring the encrypted information, key, and data from the first node to the second node and, at the second node, obtaining the order of the key fragments to reconstruct the permuted key from the transferred key in accordance with the transferred data and decrypting the information using the permuted key.
- 32. A cryptographic method for the secure transmission of information between first and second nodes, comprising the steps of, at the first node, generating a key comprising first and second key blocks, each of the key blocks comprising more than one key fragment arranged in a selected order, selecting one of the key blocks as the current key block for the second key block and, thereafter, selecting the second key block as the current key block, generating data indicative of the selected order of the key fragments in the then current key block, and transferring the encrypted information, key, and data from the first node to the second node and, at the second node, obtaining the selected order of the key fragments in the then current key block from the key in accordance with the data, and decrypting the information using the ordered key fragments of the then current key block from the transferred key information.
Specification