Reken launches on-device AI tool to fight phishing and fraud

Reken, a cybersecurity startup led by former Google fraud specialist Shuman Ghosemajumder, is launching an on-device AI platform aimed at phishing, deepfakes and other online scams. The company says the approach matters because AI has made fraudulent messages harder for people to judge, while cloud-based scanning can add privacy and speed concerns.

Ghosemajumder, who was known at Google for leading work against click fraud, later joined Shape Security early in its life. F5 bought Shape Security for $1 billion in 2020, according to Fortune.

Reken is coming out of two years of private development with a platform it calls Reken Private Core and an initial product named Northstar. Fortune reported that Ghosemajumder co-founded the company in 2024 with Rich Griffiths, a former Shape Security colleague, and that Reken has raised $10 million in seed funding from investors including Greycroft and FPV Ventures.

AI models that run on the user’s machine

Reken says Private Core uses small proprietary AI models that operate directly on a user’s device. Ghosemajumder told Fortune the company’s technical challenge was getting those models to work quickly on ordinary corporate laptops without graphics processing units.

Some security firms, including Abnormal and Doppel, also use AI to inspect communications, Fortune reported. Ghosemajumder said many rival systems send data to cloud services, which he argues can create breach risks, latency and added costs when outside AI models from companies such as OpenAI, Anthropic or Google DeepMind are involved.

Google and Apple have been reported to be working on on-device AI phishing detection, according to Fortune, but neither has released such a product. Reken is pitching Northstar as a corporate defense that can assess threats at the moment an employee receives a message.

Ghosemajumder told Fortune that traditional security-awareness training is a poor answer to increasingly convincing phishing and authorized push payment fraud. He said workers should not have to act like digital forensics specialists and argued that AI should catch signs people miss.

Verifying trusted senders

Northstar does not rely only on identifying whether text was generated by AI. Ghosemajumder told Fortune that such a signal has become less useful as businesses adopt AI writing tools for normal work, since a chatbot-drafted email is often harmless.

Instead, Reken says Northstar also looks for positive evidence that a message came from a legitimate sender, such as a bank or retailer. The company’s broader plan is to build what it calls the Reken Network, where communications inside participating organizations can be verified and then extended to suppliers and partners.

Ghosemajumder compared that idea to Apple’s iMessage trust cues, Fortune reported, while saying Reken wants to provide stronger verification across business networks. He also acknowledged privacy questions around shared threat data and said Reken plans to aggregate and anonymize information so the network can improve without exposing individual users’ data.

The FBI’s Internet Crime Complaint Center recorded $20.9 billion in reported cybercrime losses in 2025, up 26% from the prior year, according to Fortune. The bureau also added AI-related crime as a category for the first time and logged more than 22,000 such complaints. A 2026 RBC poll found that 83% of respondents assume online messages are scams unless proven otherwise.

Reken has faced AI-enabled impersonation itself, Ghosemajumder told Fortune. He said an intern received messages pretending to be from him during the intern’s first week after criminals used LinkedIn to identify the new hire’s reporting chain.

Northstar is available through an early access program for corporations, government agencies and universities starting Monday, Fortune reported. Ghosemajumder said it has been tested in Fortune 500 settings, though he did not name customers, and Reken plans more products and third-party development on Private Core.

This story draws on original reporting from Fortune.