Cummins confirmed on Thursday (Friday AEDT) Khawaja had called to inform him he would be writing the book, which will be released days after the end of Australia's first Test tour of South Africa since the infamous match.
How much will be written about the ball-tampering scandal that rocked Australian cricket remains to be seen.
Khawaja is a childhood friend of former opening partner David Warner, who copped a 12-month ban out of the ball-tampering scandal.
At the time, Warner was painted as the architect of the ploy, with captain Steve Smith also suspended for a year and Cameron Bancroft nine months.
There had been a report at the time that Khawaja had suggested the team should take joint responsibility over the incident, rather than just the three players.
However, a Cricket Australia investigation found no other player had knowledge of the plan to apply sandpaper to the ball, a point that has long been maintained.
Australia's bowlers have also previously issued a statement denying their knowledge that "a foreign substance" would be taken onto the field .
In his autobiography next month which has been penned without a ghost writer, there is no suggestion Khawaja will suggest anything other than what investigations found.
Cummins was asked ahead of Friday's first Test in Durban if Khawaja had specified how much detail he would go into and if he would agree with his former teammates' version of events.
"You would have to ask him," Cummins responded.
"It's obviously a long time ago. All the investigations, everything was done back then. Answered every question a million times.
"It was dealt with then, all I can say is as a group we've moved on. Very happy with the last eight or nine years, how we've been as a group and evolved.
"He didn't go into too much detail ... As always it was 'no worries, you can tell your story, that's fine'."
It has been hard to escape talk of the 2018 series in the lead up to the first Test.
Cummins noted on Thursday there was a larger than normal media turn-out in Durban, with this also the battle between the world's top-two sides.
Beyond the ball-tampering scandal, the 2018 series was littered with clashes between the two teams from the middle of the pitch to dressing-room stairwells.
But tensions have thawed significantly since, with neither side expecting similar dramas.
"It was quite a big series that 2018, it was pretty full on," Cummins said.
"After that, I think pretty much every Test team in the world felt like they'd made some adjustments.
"This group is quite a different group in how we approach playing, and I'm really proud of how the guys have been since that 2018 series."
