Researchers Alex Halderman and Nadia Heninger presented compelling research suggesting that the NSA has developed the capability to decrypt a large number of HTTPS, SSH, and VPN connections. In the time since this research was originally published, the major browser vendors (IE, Chrome, and Firefox) have removed support for 512-bit Diffie-Hellman, addressing the biggest vulnerability. However, 1024-bit encryption remains supported for the forseeable future despite its vulnerability to NSA surveillance. This is not a complete guide, and not all software is covered.”]
Source: https://gizmodo.com/how-to-protect-yourself-from-the-nsa-if-you-use-1024-bi-1736886756