Concrete security

Cryptographic analysis In cryptography, concrete security or exact security is a practice-oriented approach that aims to give more precise estimates of the computational power and time of the attackers tasks than asymptotic security would allow. It quantifies the security of a cryptosystem by bounding the probability of success for an adversary running for a fixed amount of time.[better source needed] Security proofs with precise analyses are referred to as concrete.[better source needed] Traditionally, provable security is asymptotic: it classifies the hardness of computational problems using polynomial-time reducibility. Secure schemes are defined to be those in which the advantage of any computationally bounded adversary is negligible. While such a theoretical guarantee is important, in practice one needs to know exactly how efficient a reduction is because of the need to instantiate the security parameter - it is not enough to know that "sufficiently large" security parameters will do. An inefficient reduction results either in the success probability for the adversary or the resource requirement of the scheme being greater than desired.[citation needed] Concrete security param