CityDefend technology

Old approaches to searching encrypted data are slow, insecure, and unscalable.

Conventional encryption processes prevent businesses from searching and sifting through vast amounts of data, inhibiting the ability to operate on and use cloud hosted data effectively.

There are currently two solutions to this:


Slide 1) Download, decrypt, search.

The limitations of this system are…

X Slow:

all documents must be processed before searching

X Network latency:

downloading every encrypted file to decrypt and search results in network congestion and delays due to network speed



The limitations of this system are…

X Client-side computations:

index tables are computationally heavy to produce – as the number of files and keywords increases, the table size increases exponentially.

X Index table modification:

each new file requires the index table to be reproduced.

X Network latency:

uploading both the encrypted files and the large index tables results in slow network response times.

X Storage requirements:

server-side storage requirements are high due to the large index tables.

X Security leakage:

index tables can provide information about file contents due to search pattern leakage.

CityDefend technology uses
Homomorphic searchable encryption

CityDefend allows keywords to be searched directly over encrypted documents.



Our Testimonials

Our recent collaboration was focused towards the design and development of single-keyword and multi-keyword Searchable Encryption schemes. We were successfully able to implement and deploy the schemes on BT Alpha Cloud testbed. We are especially thankful to the team at City, University of London for helping us showcase this work at the BT Innovation Week.

Dr Ali Sajjad

Senior Cloud Security Researcher | British Telecommunications Plc

We worked with Rajarajan and his team at City, University of London for an Innovate UK project concerning Privacy Preserving Speech Processing in the Cloud. The project had the ambitious aim to develop encrypted processing of speech and Rajarajan and his team’s expertise were instrumental in helping us to plot a course through this new and challenging field. The project was a great success, culminating in a patent for Searchable Encryption applied to Speech Transcripts on the Cloud.

Dr Cornelius Glackin

Research Scientist | Intelligent Voice Limited

Assuring cloud confidence through Searchable Encryption as a Service