_NSAKEY was a variable name discovered in Windows NT 4 SP5 in 1999 by Andrew D. Fernandes of Cryptonym Corporation. The variable contained a 1024-bit public key; such keys are used in public-key cryptography for encryption and authentication. Because of the name, however, it was speculated that the key would allow the United States National Security Agency (NSA) to subvert any Windows user's security. Microsoft denied the speculation and said that the key's name came from the fact that NSA was the technical review authority for U.S. cryptography export controls.