Lack of Randomness

[ghost]

During our work with ABY I noticed that the generated keys for the Yao sharing are deterministic. If the sharing algorithm is run two times the same keys are used.

This undermines the security of the entire protocol since Yao's garbled circuit must not be reused. An attacker can generate all server-keys and learn the secret server input.

[dd23]

You are right, ABY currently uses a fixed seed to generate randomness and thus keys are deterministic. This is intentional and used for debugging.

If you want to change this and have actual random (and different) values in every run you should change
src/abycore/aby/abyparty.cpp:44
from
m_cCrypt = new crypto(seclvl.symbits, (uint8_t*) const_seed[pid]);
to
m_cCrypt = new crypto(seclvl.symbits);