Among the organisations that have signed the letter are Wickr, Twilio, the World Privacy Forum, New America’s Open Technology Institute, Electronic Frontiers Australia, the Electronic Frontier Foundation, International Civil Liberties Monitoring and Advocacy for Principled Action in Government.
The government is expected to introduce legislation during the next sitting of parliament on encryption but it is not clear as to what the law will entail.
Last month, the Australian Greens asked Cyber Security Minister Angus Taylor to outline how the government plans to draft laws to bypass end-to-end encryption without compromising the security of the encrypted data.
The signatories to the letter, including academics, business people and lawyers, said one idea that had been discussed to get around encryption was a legal compulsion for communications hardware or software providers to alter their products to ensure government access.
"This approach may include a specific alteration delineated by government officials, or a general requirement for providers to guarantee access without detailing the precise means through which this would be accomplished," it said.
"Another potential approach that has been discussed is a mandatory decryption requirement for companies, which would effectively prohibit companies from offering some of the strongest security tools available today, or in the future."
The letter said adopting either of these would be a mistake. "Adopting either of these requirements would be a mistake. While we respect the challenges facing law enforcement, changes elicited through either regime would have a deleterious impact on Internet security, including for government and business officials as well as journalists and human rights defenders," it said.
"Impacts would also be felt across important sectors, from banking to infrastructure, including Australia’s continued investments in development and smart cities, with potential consequences seen in increases in online criminal activity and unauthorised access to personal and proprietary data."
The letter also asked the government to commit to supporting strong encryption and also invest in the development and use of encryption that would protect users.
"We recognise this may impact the ability of law enforcement to readily obtain access to some types of evidence and cause them to face friction in seeking such access," it said.
"To mitigate these impacts in a manner that respects human rights and the rule of law, we would welcome the opportunity to engage in a dialogue on education and resources for law and policy makers, as well as law enforcement officials, to help determine what courses of action are available to gain access to evidence in a timely manner."