LOMBOK (Indonesia) • An Indonesian woman who exposed her cheating boss has been slapped with a six-month jail term for her trouble.

The supreme court's shock ruling overturned an earlier court decision that had cleared the woman, Baiq Nuril Maknun, of breaking a controversial law against spreading indecent material.

''I'm saddened and shocked by this sentence,'' Maknun's husband Lalu Muhamad Isnaini said yesterday in reaction to the ruling.

The case stretches back to 2012 when Maknun recorded a conversation in which the principal of the school where she worked on the island of Lombok revealed graphic sexual details about an affair he was having with another colleague.

Co-workers of the school administrator - who herself had rebuffed the principal's repeated advances - later convinced Maknun to release the recording in a bid to expose the man's history of lecherous behaviour, said her lawyer Joko Jumadi.

''The principal shared very graphic details about his affair with the school's treasurer in the recording,'' he said. In response, the principal fired Maknun and filed a complaint with the authorities.

Maknun was initially cleared of the charges by a court in Lombok, next to holiday hot spot Bali.

But, last week, Indonesia's top court reversed that ruling, finding her guilty of violating the electronic information law and sentencing her to six months' jail along with a 500 million rupiah (S$47,000) fine.

The 36-year-old Maknun told local reporters the ruling was unfair. ''I'm just a victim - what did I do wrong?'' she said at the time.

Indonesia's corruption-riddled justice system has long been criticised for the quality of its rulings, while the electronic information law itself has come under fire for being too vague and open to misuse.

AGENCE FRANCE-PRESSE