Dean Carter hacks into computers for a living. He's so good, he is paid to do it.

The security consultant for a New Zealand bank was the inspiration for a main character in Louisa Larkin's debut thriller novel, The Genesis Flaw.

Larkin, who works for Sydney climate-change consultancy Energetics, also has a passion for conservation that informs her book.

In The Genesis Flaw, heroine Serena Swift fights the dire consequences of genetically modified food and the people promoting its benefits.

She teams up with a hacker, John Flynn, to bring down the evil empire.

Flynn is based on Carter, who says no personal computer is truly safe. Carter constantly tries to hack into his own bank's system to test the security.

"I hack systems to see how safe they are. There's always someone having a go at hacking into the bank," he says.

"Target businesses and organisations are constantly upgrading to defend themselves."

At Larkin's Sydney book launch he demonstrated just how easy it was to hack into a PC using wireless broadband. He did it within five minutes, accessing passwords and bank details.

Using hacker software available free on the internet, he captured packets of data issued from the PC he was trying to control, cracking passwords in 60 seconds or less.

He was then able to change the passwords so only he could access data.

Of course, in this instance was Larkin's PC and everyone had a laugh.

"The free downloads for hacking are available to the bad guys, but also the good guys so we know what they're using," Carter says.

Hackers are ingenious, he says.

"When you get a smart new mobile phone, you may ask what does it do? A hacker will ask, what else can I do with it?"

To keep your computer safe, Carter warns, do checks as regularly as you get your car serviced.

Update patches, firewalls, anti-virus software, be aware of phishing scams and regularly change default passwords, using a separate password for each account.

Have them written down somewhere safely in the house, but not on a Post It stuck to the computer screen.

Do not use easy to guess passwords.

"You'd be surprised how many people in New Zealand use All Blacks as a password," Carter says.

A password of eight characters or less is the easiest to hack.

The longer you make your password, the safer your PC is.

But no PC is entirely safe, he claims. Eventually there will be a way to get into it.

Larkin's fast-paced book also deals with the increasing crime of identity theft, which in Australia costs A$2 billion a year.

Her hacker character reveals tantalising details on how to create a new one.

"Although it looks credible, its actually not," she says. "For the purpose of the book we had to make it look possible."

Larkin is already writing her second thriller, Thirst, about a catastrophe facing the Antarctic as global warming increases.