Dual_EC_DRBG (Dual Elliptic Curve Deterministic Random Bit Generator) is an algorithm from the branch of cryptography known as elliptic curve cryptography that was supposed to implement a cryptographically secure pseudorandom number generator (CSPRNG) capable of generating a random bit stream. The algorithm is based on the mathematics of the elliptic curve discrete logarithm problem. Despite public criticism, it was for some time one of the four (now three) CSPRNGs standardized in NIST SP 800-90A as originally published circa March 2007.