In this paper we propose an OFDM (Orthogonal Frequency Division Multiplexing) wireless communication system that
introduces mutual authentication and encryption at the physical layer, without impairing spectral efficiency, exploiting
some freedom degrees of the base-band signal, and using encrypted-hash algorithms. FEC (Forward Error Correction) is
instead performed through variable-rate Turbo Codes. To avoid false rejections, i.e. rejections of enrolled (authorized)
users, we designed and tested a robust hash algorithm. This robustness is obtained both by a segmentation of the hash
domain (based on BCH codes) and by the FEC capabilities of Turbo Codes.
In this paper we propose an Orthogonal Frequency Division Multiplexing Ultra Wide Band (OFDM-UWB) system that
introduces encryption, mutual authentication, and data integrity functions, at the physical layer, without impairing
spectral efficiency. Encryption is performed by rotating the constellation employed in each band by means of a pseudorandom
phase-hopping sequence. Authentication and data integrity, based on encrypted-hash, are directly coupled with
Forward Error Correction (FEC). Dependence of the phase hopping sequence on the transmitted message deny the use of
the phase hopping obtained by means of known and chosen plaintext attacks for decryption of further messages.
Moreover, since phase hopping generation keys change very rapidly they are also difficultly detectable from a hypothetic
man in the middle. Computer simulations confirm the superior performance, even in terms of BER, to a standard PSKOFDM
system, due to the FEC capabilities of encrypted hash.