The name of the whistle-blower can be obtained by court order. If the imputation made by the allegation has caused unjust harm or damage to a person, they can argue that the Law of Torts needs to be applied. The court will then decide on the merit of the case and possibly order CASA to release the name and all paperwork associated with the complaint and any internal correspondence. CASA could/would, of course appeal. This can get expensive and time consuming and that's probably what CaSA would like to see happen- they have no interest in justice, they are too busy covering their ass.
If you are ever caught in this situation and found "not guilty" of what you have been accused of, this is my advice:
Initially return to the line and resist ANY attempt for instant justice or gratification. Don't ask any one about who said what. Don't engage on any 'fishing expeditions'....yet. Be a good guy, don't engage in discussion of the case other than to say stuff like "well, I'm glad that's over and my name's been cleared".
Get legal advice. Speak to a union rep and gradually uncover the facts. Take notes, keep a daily diary and record any conversations that you have with management or colleagues. Don't go to HR as they are only there to protect the company's interest, not yours. A company Harrassment Contact Officer, could possibly be approached, but they have a strict code which limits their involvement. However, they can be called as a witness at a later date. This may or may not work in your interest so be careful what you say and DON'T name ANYBODY as a 'suspect'. A contact officer is legally bound to confidentiality, but can be called to give evidence.
Insist that the company issue a memo that recognises that your reputation haste been besmirched by a false allegation and they you have been totally absolved in an investigation. The memo should also have words to the effect that any gossip or discussion regarding this will be treated as workplace harassment and dealt with accordingly (the company would face massive legal repercussions should they fail to take strenuous action in this regard). If they fail to do this, get legal advice. You could sue them for allowing a hostile work environment.
In the event that you are in any way harassed/ostracised/passed over by either management or other staff, take notes, recordings, diarise, get witnesses etc. only when you have iron-clad evidence should you take action and lodge a claim for damages. If there are any repercussions, go for unfair dismissal or workplace Harrassment. By this stage, with patience, you should have them by the balls.