2 ms·
Yes, in the strict sense of the meaning. In general, the comparison of VDFs (a cryptographic building block) and Bitcoin-style PoW (a consensus mechanism) is no
by c0742e9366 5y ago
Yes, in the strict sense of the meaning. In general, the comparison of VDFs (a cryptographic building block) and Bitcoin-style PoW (a consensus mechanism) is not that useful. However, using a VDF as part of a consensus mechanism (see e.g., Chia) does not introduce an energy overhead.
To demystify what a VDF is, consider the delay function (i.e., the majority of the work done to compute a VDF) used by the most prominent proposals:
Let N = p*q be a product of two large primes (so an RSA modulus) and assume that the primes p and q have been immediately thrown away/forgotten after initialization. Then, computing
f(x) = x^(2^T) mod N
is believed (dating back to a paper by Rivest, Shamir and Wagner in 1996) to take T sequential steps provided that T is large enough. For a large T, the only feasible approach seems to be repeated squaring modulo N. That is, compute y = x^2 mod N, y' = y^2 mod N, ... for T times.