Methods of encoding and decoding data
First Claim
1. A process that receives as input variable length user data comprising at least 56 octets, the process comprising:
- an initialization process comprising the initialization of intermediate text which is of the same length as the length of the variable length user data;
at least one pass of at least one pass function, each pass function comprising;
the invocation of at least one round function, each round function;
receiving inputs comprising;
at least one reversible input selected from the intermediate text;
at least two irreversible inputs selected from the intermediate text, so that each pair of the at least two irreversible inputs selected from the intermediate text is separated by at least one bit of intermediate text; and
generating at least one reversible output that updates the intermediate text;
and in which;
the sum of the length of the reversible and irreversible inputs received by the round function from the intermediate text is less than the length of the intermediate text in bits minus eight times the length of the sum of the output bits of the round function;
and comprising a sequence of steps that ensures each block of intermediate text is updated at least once from the output of a unique round function invocation; and
an output function which releases a set of bits from the intermediate text only after the pass function has updated the intermediate text at least once.
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Abstract
A cryptographic process (100) receives variable length user data (150) as input and performs an initialization process, at least one pass of at least one pass function and an output function. The pass function the invokes at least one round function (171). Each round function (171) receives inputs which are at least one reversible input (151) selected from the intermediate text (150), at least two irreversible inputs (152, 157) selected from the intermediate text (150), so that each pair of the at least two irreversible inputs (152, 157) are selected from the intermediate text (150) so that they separated by at least one bit of intermediate text (150). The round function (171) generates at least one reversible output (151) that updates the intermediate text (150). The sum of the length of the reversible (151) and irreversible (152, 157) inputs received by the round function (171) from the intermediate text (150) is less than the length of the intermediate text (150) in bits minus eight times the length of the sum of the output bits (151) of the round function (171). The output function (171) ensures each block of intermediate text (150) is updated at least once from the output of a unique round function (171) invocation. The output function releases a set of bits from the intermediate text (150) only after the pass function has updated the intermediate text (150) at least once.
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Citations
12 Claims
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1. A process that receives as input variable length user data comprising at least 56 octets, the process comprising:
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an initialization process comprising the initialization of intermediate text which is of the same length as the length of the variable length user data;
at least one pass of at least one pass function, each pass function comprising;
the invocation of at least one round function, each round function;
receiving inputs comprising;
at least one reversible input selected from the intermediate text;
at least two irreversible inputs selected from the intermediate text, so that each pair of the at least two irreversible inputs selected from the intermediate text is separated by at least one bit of intermediate text; and
generating at least one reversible output that updates the intermediate text;
and in which;
the sum of the length of the reversible and irreversible inputs received by the round function from the intermediate text is less than the length of the intermediate text in bits minus eight times the length of the sum of the output bits of the round function;
and comprising a sequence of steps that ensures each block of intermediate text is updated at least once from the output of a unique round function invocation; and
an output function which releases a set of bits from the intermediate text only after the pass function has updated the intermediate text at least once. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus that receives as input variable length user data comprising at least 56 octets, the apparatus comprising:
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an initialization module which implements an initialization process, the initialization process comprising the initialization of intermediate text which is of the same length as the length of the variable length user data;
a pass function module which implements at least one pass of at least one pass function, each pass function comprising;
the invocation of at least one round function, each round function;
receiving inputs comprising;
at least one reversible input selected from the intermediate text;
at least two irreversible inputs selected from the intermediate text, so that each pair of the at least two irreversible inputs selected from the intermediate text is separated by at least one bit of intermediate text; and
generating at least one reversible output that updates the intermediate text;
and in which;
the sum of the length of the reversible and irreversible inputs received by the round function from the intermediate text is less than the length of the intermediate text in bits minus eight times the length of the sum of the output bits of the round function;
and comprising a sequence of steps that ensures each block of intermediate text is updated at least once from the output of a unique round function invocation; and
an output module which implements an output function, which output function releases a set of bits from the intermediate text only after the pass function has updated the intermediate text at least once. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification