Evaluator Description

The Dual Elliptic Curve Random Bit Generator (Dual EC DRBG), as specified in NIST SP800-90A, depends on two parameters, P and Q, both elliptic curve points. The security of Dual EC DRBG relies on the difficulty of computing the discrete logarithm of Q base P. While computing discrete logarithms is a cryptographically hard problem, infeasible from an attack perspective, it would be possible for these parameters to be generated in such a way that this logarithm is known. This has raised concerns that the DRBG could conceal a trapdoor, allowing those who generated P and Q in this way to predict outputs from the DRBG after collecting a small number of sample outputs. It is important to note that Dual EC DRBG is only vulnerable to this attack if the parameters were generated in this way. If the parameters were both generated randomly and independently, this attack would not be feasible. However, because the provenance of the default values for P and Q are not known, security researchers are not able to verify the trustworthiness of this algorithm with the default parameters. For the purposes of scoring this vulnerability, it will be assumed that the relationship between P and Q described above is known to the attacker. SUPPLEMENTAL ITL BULLETIN FOR SEPTEMBER 2013: http://csrc.nist.gov/publications/nistbul/itlbul2013_09_supplemental.pdf