Signal was co-developed by Brian Acton, who also helped develop WhatsApp (File)
Amid growing outrage over the Pegasus phone-hacking row, Signal - pitched by itself as a more secure version of WhatsApp - took a swipe at the government over new IT laws requiring messaging apps to break encryption, 'trace' chats and identify users in a conversation chain.
"Looks like the Indian government has been secretly attempting to surveil political opposition leaders, journalists, activists... Interesting coincidence that they've also been advocating legislation to weaken encryption..." a tweet from the app's handle said.
The tweet contained a link to a report by The Guardian, which headlined claims that Congress MP Rahul Gandhi was among potential targets of surveillance by the Narendra Modi government.
Signal's tweet comes as social media and messaging platforms in India push back against new IT laws that will require them to break (or weaken) encryption levels of all messages in order to 'trace' chats the Modi government deems a threat to law and order or national security.
WhatsApp - which, like Signal, offers end-to-end encryption (meaning it cannot access or view user content) - has filed a legal challenge, saying the law "fundamentally undermines right to privacy".
In a petition filed before the Delhi High Court in May, it referred to a 2017 Supreme Court ruling that said privacy must be preserved unless outweighed by legality, necessity and proportionality.
The government said it "fully recognises and respects users' right to privacy", but it insists the new laws are designed to prevent abuse and misuse of, and on, social media and IM platforms.
IT Minister Ashwini Vaishnaw last week said the rules - which have been strongly advocated by the government - will "...protect users and ensure a safer social media ecosystem in India".
Concerns were raised over sharing of encrypted data with authorities, particularly since Delhi Police last year flagged two instances of goons organising themselves on WhatsApp - the attack on students and teachers in Delhi's JNU and clashes over the citizenship law.
Signal's tweet also comes amid a massive row over Israeli spyware Pegasus, and allegations the government used it to spy on journalists and opposition leaders critical of the government.
The government has denied any "unauthorised interception", and declared the reports to be "sensational", "over-the-top" and aimed at maligning the image of Indian democracy.
According to developers NSO Group, the controversial software is sold only to "vetted governments" who are contractually obliged to use it for law enforcement and fighting terrorism.
Pegasus works by infiltrating phones via 'zero-click' attacks - which do not require interaction from the phone's owner - on or Apple's iMessage or WhatsApp, which is, by some margin, the world's most widely-used instant messaging service, with 400 million users in India alone.
Signal rose to prominence in India earlier this year, after a revision to WhatsApp's privacy policy - which would allow it to share information with parent company Facebook - triggered a row over safety and confidentiality of user data, and its potential misuse.
Co-founder Brian Acton spoke to NDTV in January to say "Signal absolutely scores above WhatsApp in privacy", and that it is "important to protect people from... abuse of power".