In the first week of October, the NIA acted on a tip-off and arrested six youths from Kerala for their suspected links with the Islamic terror group ISIS.
Those arrested include Manseed alias Omar al-Hindi, who is reported to be the chief of the group.
While five persons were arrested from Kannur district, the sixth was arrested from Kozhikode.
Reports state that during the interrogation, the arrested youths said that they were inspired by the teachings of Zakir Naik.
Several revelations were made during the interrogation, including the groupâ€™s plans to carry out Nice-like attacks on religious events in Kochi. It also came to be known that the module headed by Manseed had been using an e-mail service called Tutanota as a means of communication.
The members used both Tutanota and Telegram mobile applications and changed names frequently to avoid being detected.
The usage of messaging services with end-to-end-encryption has increasingly made security agencies stare at a blank wall, as third party access is blocked in such applications.
What is Tutanota?
Founded in 2011, Tutanota is a Germany-based encrypted e-mail startup that aims at making email communication easier and more secure.
According to an article published in Techcrunch in 2015, attachment encryption and support for different devices is what differentiates Tutanota from similar services such as ProtonMail, StartMail and Hushmail.
Co-founder Arne MĂ¶hle told Techcrunch that the product has users across the world, with a sizable portion in the US, which Mohle attributes to growing concerns about privacy.
How Tutanota works
Tutanota uses end-to-end encryption, with the encryption of the messages done locally, on the client device. This is secured with the userâ€™s own password before being uploaded and sent to the recipient via Tutanotaâ€™s servers. The messages are then decrypted on the recipientâ€™s device, says the report.
This means that the email message is accessible only to the sender and the receiver and a third party, including the email authorities, cannot have access to the material.
The service also lets users optionally encrypt emails that are sent to regular email addresses, by securing it with a password.
The New Indian Express reports that on checking the electronic devices confiscated from the arrested youths, the NIA officials have been able to trace several emails sent through the service.
With over 2 million users, the email service gets its name from a Latin word which means "secret message."
The report says that the accounts are largely temporary accounts, with the receiver getting a notification when the sender sends an email communication. Along with the notification, the receiver also gets a password set by the sender, in order to access the email.
The ISIS module in Hyderabad is reported to have used the same email service to communicate, too.