Secret Key Generation from Physics

Amin Gohari, Onur Günlü, Gerhard G. Kramer

Ahmed Badawy, Tarek Elfouly, Tamer M. Khattab +2 more

Within the paradigm of physical layer security, a physical layer characteristic is used as a common source of randomness to generate the secret key. This key is then used to encrypt the data to hide information from eavesdroppers. In this paper, we survey the most recent common sources of randomness used to generate the secret key. We present the steps used to extract the secret key from the estimated common source of randomness. We describe the metrics used to evaluate the strength of the generated key. We follow that with a qualitative comparison between different common sources of randomness along with a proposed new direction which capitalizes on hybridization of sources of randomness. We conclude by a discussion about current open research problems in secret key generation.

Norbert Lütkenhaus

Dongrun Qin, Zhi Jun Ding

Traditional physical-layer (PHY)-based secret key generation schemes typically assume reciprocity of forward and reverse channels in order for facilitated shared secrecy. However, frequency-selective channels for frequency division duplex links as well as calibration difference of transceiver hardwares can invalidate reciprocity assumption and can cause severe key error floors between users. In this paper, we propose two practical PHY-based secret key generation schemes for multiple-input and multiple-output wireless links over non-reciprocal physical channels. One is pilot assistant secret key (PASKey) generation and the other is eigenvalue-based secret key (EVSKey) generation. In PASKey, both legitimate users estimate the same composite channel, while EVSKey exploits the properties of eigenvalues to generate secret bits. Both are effective against secrecy key theft by eavesdroppers. Furthermore, without adopting public training signals, EVSKey manages to generate secret bits even when nearby eavesdroppers collude. Our two schemes are shown to be more efficient and can achieve lower key error ratio than the existing methods.

PT Tuyls, Boris Škorić

Pedro Cruz, Alexandre Miccheleti Lucena, Ricardo Suyama +1 more

Physical layer security (PLS) is an alternative to traditional information security mechanisms.Physical layer secret key generation (PSKG) is a PLS technique that uses channel randomness to generate keys for encryption algorithms.Although several works investigated PSKG in slow fading channels, fast fading scenarios remain a challenge.We propose two predictors to deal with such scenarios, one based on the Recursive Least Squares (RLS) and another based on the Dual Extended Kalman Filter (DEKF).The aim is to mitigate the channel variation effects during PSKG, reducing the errors between keys generated by legitimate users.