Two well-known encryption experts declare the Dual_EC_DRBG random number generator in question to be useless. Bruce Schneier of BT Counterpane and Phil Zimmermann of PGP and Zfone say the scheme should not be used by anyone for the time being. Schneier: “We dont know where the constants came from in the first place. We only know that whoever came up with them could have the key to this backdoor” Zimmermann: “It is actually very risky to put in a backdoor because somebody is going to find out””]
Source: https://www.csoonline.com/article/2121968/backdoor-concern-over-us-crypto-standard.html