Short message service cipher
First Claim
Patent Images
1. A cellular telephone encryption system for protecting messages for a handset, the cellular telephone encryption system comprising:
- a key that is larger than the messages;
an index indicating a reference point for a cryptographic pad, wherein the cryptographic pad is a subset of the key and is pulled from a set of pseudorandom locations in the key, and wherein the pseudorandom locations are selected for each message to insure that the entire length of the key is utilized for each message;
a cryptographic algorithm that cryptographically processes a message as a function of the cryptographic pad; and
a wireless transceiver that sends or receives the message;
wherein the cryptographic algorithm takes a character from a payload of the message and replaces it with a different character selected from a predefined character set that is different from the character set from which the key is constructed.
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Abstract
A wireless phone system and methods performed thereon for cryptographically processing SMS messages is disclosed. A cryptographic pad is used to replace characters in a payload of a SMS message with coded characters. The cryptographic pad is used by the receiver of the SMS message to decode it. The cryptographic pad is one of two or more possible cryptographic pads stored in the receiver. In one embodiment, the two or more possible cryptographic pads are sent as a key where a particular cryptographic pad is referenced in the key using an index.
72 Citations
40 Claims
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1. A cellular telephone encryption system for protecting messages for a handset, the cellular telephone encryption system comprising:
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a key that is larger than the messages; an index indicating a reference point for a cryptographic pad, wherein the cryptographic pad is a subset of the key and is pulled from a set of pseudorandom locations in the key, and wherein the pseudorandom locations are selected for each message to insure that the entire length of the key is utilized for each message; a cryptographic algorithm that cryptographically processes a message as a function of the cryptographic pad; and a wireless transceiver that sends or receives the message; wherein the cryptographic algorithm takes a character from a payload of the message and replaces it with a different character selected from a predefined character set that is different from the character set from which the key is constructed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for cryptographically processing short message service (SMS) messages of a handset, the method comprising:
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loading a key into a memory, wherein the key is larger than the messages; determining an index within the key; determining a replacement character that is a function of a cryptographic pad located by the index, wherein during processing of a particular SMS message, the cryptographic pad is pulled from a set of pseudorandom locations in the key, the pseudorandom locations selected for each message such that the entire length of the key is utilized for each message, and wherein the replacement character is selected from a predefined character set that is different from the character set from which the key is constructed; and replacing a character in the payload of the SMS message with the replacement character. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for cryptographically processing short message service (SMS) messages of a handset, the method comprising:
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providing a value that identifies a cryptographic pad, from a plurality of cryptographic pads within a key that is larger than the SMS messages and that is stored in a memory, to use to cryptographically process a SMS message; loading the identified cryptographic pad from a set of pseudorandom locations in the key, the pseudorandom locations selected for each SMS message such that the entire length of the key is utilized for each SMS message; determining a replacement character that is a function of the cryptographic pad identified by the value, wherein the replacement character is selected from a predefined character set that is different from the character set from which the key is constructed; and replacing a character in the payload of the SMS message with the replacement character. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31)
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32. A method for cryptographically processing messages, the method comprising:
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storing a key into a memory, wherein the key is larger than the messages; encrypting a first message using a first cryptographic pad that is a first subset of the key, the first cryptographic pad being pulled from a first set of pseudorandom locations in the key, the pseudorandom locations selected for each message to insure that the entire length of the key is utilized for each message; and encrypting a second message using a second cryptographic pad that is a second subset of the key, the second cryptographic pad being pulled from a second set of pseudorandom locations in the key; wherein encrypting a message comprises replacing each character of the message with a respective replacement character selected from a predefined character set that is different from the character set from which the key is constructed. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40)
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Specification