Iran's leadership has repeatedly said over the past couple of years that the destructive Stuxnet computer worm was easily vanquished and caused little damage to the centrifuges carrying out uranium enrichment.
Whatever the truth of this statement, it is clear that the damage of Stuxnet is enduring in the deep, lingering suspicion of Iranian officials, scientists and researchers towards vital computer networks.
Every few months since Stuxnet struck, news has emerged from Iran of yet another cyber-attack on one of the country's vital infrastructures, valiantly deflected by Persian software experts. From what we do know about Stuxnet, it was the product of a large team of programmers who spent many months constructing it, an effort that could have been undertaken only by a country at the forefront of computer technology. In other words, if the same team was to embark on another assault, they would surpass themselves.
It is hard to believe that any of the recent reported attacks, including "Wiper", the mysterious virus that last week disrupted the computers of Iran's oil export facilities, came from the same source. But for a long time to come, the authors of the Stuxnet code have no need to create a repeat performance. The shockwaves are still reverberating and every bog-standard virus written by teenage hackers over a wet weekend will generate enough hysteria in Tehran to prompt the precautionary shutdown of thousands of computers.
But the Iranian regime's fear of computers and the internet goes much wider than viruses and worms infesting the labs of their weapons programmes.
The memory of the failed Green Revolution, in which the internet was extensively used to rally protesters and distribute information, is still fresh in their memory. After all, it was the inspiration for the subsequent uprisings throughout the Arab world and the Supreme Leadership is convinced, with some justification, that the Americans are using social networks and other internet tools to undermine their authority among the younger Iranian generation.
In recent weeks, the Revolutionary Guards have staged processions alongside giant, demonic logos of Facebook and Twitter converted to look like web-agents of the Great Satan, the United States. But since they realise that propaganda and fatwas will not work on their own (it is illegal to own a private TV satellite dish, but everyone does anyway), they are now exploring ways to create a "Halal-net".
There are two possible ways to do so. One is to cut off Iran entirely from the World Wide Web, setting up in its stead an intranet for Iranians only. The other is to place powerful web-filters on the gateway servers, which will block access to all subversive websites.
Either option poses significant technological challenges. Even if they overcome these, there are still the Iranian dissidents to reckon with. So far they have proved very capable of locating and exploiting every crack in the walls of the Islamic Republic and will be no less successful in breaking the web barriers.