Raluca Ada Popa found a fix for one of cybersecurity’s most fundamental challenges: securing computer systems without relying on firewalls to keep hackers out.

Popa’s breakthrough work started with practical database management systems that could work on encrypted data. Though encrypting data had worked for simple messaging applications like WhatsApp, it was too sluggish for systems that needed to also run calculations on the data, like databases and web applications. But Popa found a way to make computation on encrypted data practical. Today, her encryption systems work with a range of applications and provide a level of protection that firewalls cannot: even if attackers break in, they have no way to decipher the data.

Popa says her techniques allow systems to operate as if they’ve been blindfolded. They’re able to compute on data without actually seeing it—which is opening the cybersecurity field to a host of new applications. A more recent innovation of hers, Helen, can be used by hospitals to share and aggregate patient records without compromising confidentiality. Another of her systems, Opaque, secures hardware systems against potentially compromised software and is now used by such companies as IBM.