Australia's electronic spy agency reportedly has access to a top secret program that has successfully cracked the encryption used by hundreds of millions of people to protect the privacy of their emails, phone calls and online business transactions.

Documents disclosed by US intelligence whistleblower Edward Snowden reveal the program run by the US National Security Agency, codenamed Bullrun, has been used to secretly descramble high-level internet security systems globally.

They show the NSA and British Government Communications Headquarters (GCHQ) have successfully cracked the encryption used in personal communications such as email and telephone calls as well as global commerce and banking systems.

An undated ''briefing sheet'' on the program, provided to British analysts when they are cleared for access to Bullrun, was published on Friday in The New York Times and The Guardian newspapers.

It states that the Australian Signals Directorate - until recently called the Defence Signals Directorate (DSD) - was expected to be granted access.