Inspired by unidirectional error detecting codes that are used in situations where only one kind of bit errors are possible (e.g., it is possible to change a bit "0" into a bit "1", but not the contrary), we propose integrity codes (I-codes) for a radio communication channel, which enable integrity protection of messages exchanged between entities that do not hold any mutual authentication material (i.e. public keys or shared secret keys). The construction of I-codes enables a sender to encode any message such that if its integrity is violated in transmission over a radio channel, the receiver is able to detect it. In order to achieve this, we rely on the physical properties of the radio channel. We analyze in detail the use of I-codes on a radio communication channel and we present their implementation on a Mica2 wireless sensor platform as a "proof of concept". We finally introduce a novel concept called "authentication through presence" that can be used for several applications, including for key establishment and for broadcast authentication over an insecure radio channel. We perform a detailed analysis of the security of our coding scheme and we show that it is secure with respect to a realistic attacker model.

/pdf/integrity-i-codes-message-integrity-protection-and-178i453tsc.pdf

Integrity (I) codes: message integrity protection and authentication over insecure channels

An internally fault-tolerant data error detection and correction integrated circuit device (10) and a method of operating same. The device functions as a bidirectional data buffer between a 32-bit data processor and the remainder of a data processing system and provides a 32-bit datum is provided with a relatively short eight bits of data-protecting parity. The 32-bits of data by eight bits of parity is partitioned into eight 4-bit nibbles and two 4-bit nibbles, respectively. For data flowing towards the processor the data and parity nibbles are checked in parallel and in a single operation employing a dual orthogonal basis technique. The dual orthogonal basis increase the efficiency of the implementation. Any one of ten (eight data, two parity) nibbles are correctable if erroneous, or two different erroneous nibbles are detectable. For data flowing away from the processor the appropriate parity nibble values are calculated and transmitted to the system along with the data. The device regenerates parity values for data flowing in either direction and compares regenerated to generated parity with a totally self-checking equality checker. As such, the device is self-validating and enabled to both detect and indicate an occurrence of an internal failure. A generalization of the device to protect 64-bit data with 16-bit parity to protect against byte-wide errors is also presented.

Fault-tolerant corrector/detector chip for high-speed data processing

In this article, intended for readers with basic knowledge in coding, the codes used in actual systems are surveyed. Error control in high-speed memories is examined, including bit-error-correcting/detecting codes, byte-error-correcting/detecting codes, and codes to detect single-byte errors as well as correct single-bit errors and detect double-bit errors. Tape and disk memory codes for error control in mass memories are discussed. Processor error control and unidirectional error-control codes are covered, including the application of the latter to masking asymmetric line faults. >

Error-control coding in computers

Inspired by unidirectional error detecting codes that are used in situations where only one kind of bit errors are possible (e.g., it is possible to change a bit "0" into a bit "1", but not the contrary), we propose integrity codes (I-codes) for a radio communication channel, which enable integrity protection of messages exchanged between entities that do not hold any mutual authentication material (i.e. public keys or shared secret keys). The construction of I-codes enables a sender to encode any message such that if its integrity is violated in transmission over a radio channel, the receiver is able to detect it. In order to achieve this, we rely on the physical properties of the radio channel and on unidirectional error detecting codes. We analyze in detail the use of I-codes on a radio communication channel and we present their implementation on a wireless platform as a "proof of concept". We further introduce a novel concept called "authentication through presence", whose broad applications include broadcast authentication, key establishment and navigation signal protection. We perform a detailed analysis of the security of our coding scheme and we show that it is secure within a realistic attacker model.

/pdf/integrity-codes-message-integrity-protection-and-1r202ccx9q.pdf

Integrity Codes: Message Integrity Protection and Authentication over Insecure Channels

Several methods of constructing systematic t-error correcting/all unidirectional error-detecting codes are described. These codes can be constructed by adding a tail to a linear t-error correcting code, but other constructions presented are more of an ad hoc nature. These codes will often be found as suitably chosen subsets of nonsystematic tEC/AUED codes. Further bounds on the word length of systematic tEC/AUED codes are derived, and extensive tables are given. >

Constructions and bounds for systematic tEC/AUED codes

The authors present families of binary systematics codes that can correct t random errors and detect more than t unidirectional errors. The first step of the construction is encoding the k information symbols into a codeword of an (n', k, 2t+1) error-correcting code. The second step involves adding more bits to this linear error-correcting code in order to obtain the detection capability of all unidirectional errors. Asymmetric error-correcting codes turn out to be a powerful tool in the proposed construction. The resulting codes significantly improve previous results. Asymptotic estimates and decoding algorithms are presented. >

H. Van Tilborg

Papers

On t-error correcting/all unidirectional error detecting codes