The encrypted communications firm Silent Circle said Thursday it was tightening access to its mobile apps and secure smartphone to make them harder for terrorists and criminals to use.

The company which makes the encrypted Blackphone handset and Silent Phone applications for private messaging said it took the steps after learning that it had been recommended by the Islamic State group which has claimed credit for the deadly attacks in the French capital.

"We are enacting more aggressive back-end payment technology to reduce the likelihood of evildoers like (the Islamic State group) Isis," said Mike Janke, co-founder and chief executive of the company which is headquartered in Switzerland with offices in Washington.

Janke told AFP that he expects this move to curb use of his company's products because criminals and terrorists often use stolen credit cards or fake addresses.

"Since Isis labeled us as the strongest product, we are going to implement what we feel is responsible and morally acceptable procedures to make it harder for the bad element to get our technology," he said.

Janke said Silent Circle's outside payment processor would implement steps "that can detect stolen credit cards, fake address and other black market means of acquiring our Blackphone or software."

At the same time, Janke said the company would resist efforts and laws that would weaken encryption or allow law enforcement access to private data.

"Nobody wants to see their name at the top of an Isis list," he said.

At the same time, he noted that these encryption and private messaging services are vital for government officials, corporations and democracy activists.

"In some parts of the world secure communications literally means the difference between life and death," he said, adding that intelligence agencies, heads of state and major corporations use the company's products.

Janke said Silent Circle stores no customer data and thus cannot be compelled by subpoena to identify its users.

He added that any type of technology may be used for good or evil purposes.

"Whether it's a cricket bat or a car, one percent of the human population will use it for evil," he said.

"You can't penalize the other 99 percent of the world."