He specializes in applied cryptography, privacy-enhanced information storage systems, anonymous cryptocurrencies, elliptic curve crypto-systems, and satellite television piracy.

His dissertation was titled "Cryptography for Secure and Private Databases: Enabling Practical Data Access without Compromising Privacy".

[5] As Ars Technica notes, this was "a strange request on its face", as this use of the NSA logo by Green was not "reasonably calculated to convey the impression that such use is approved, endorsed, or authorized by the National Security Agency", and linking classified information published by news organizations is legally entirely uncontroversial.

[7][8][9][10][11] Green currently holds the position of Associate Professor at the Johns Hopkins Information Security Institute.

At AT&T Labs he worked on a variety of projects including audio coding/secure content distribution, streaming video and wireless localization services.

Green is a member of the technical advisory board for the Linux Foundation Core Infrastructure Initiative, formed to address critical Internet security concerns in the wake of the Heartbleed security bug disclosed in April 2014 in the OpenSSL cryptography library.