Electromagnetic analysis on ring oscillator-based true random number generators

Security of implementation of ciphers in hardware has already been well studied, nevertheless ciphers are not the only hardware block used for cryptography. True random number generators (TRNGs) are also significant cryptography blocks since they are used to provide secret keys, random protection masks, initial values to other security blocks such as ciphers. The security of TRNG implementations is thus of paramount importance. Recently, electromagnetic channel has been used to efficiently attack ring oscillator based TRNG by fault injection. The work presented in this paper shows that by analyzing electromagnetic emanation of the TRNG under attack in varying conditions, it is possible to obtain significant information on the TRNG such as its position and oscillator frequency, in order to improve the previously published electromagnetic attack.