Venezuelan here. It’s difficult to understand if you are not familiar with Venezuelan law, but bear with me.
We vote electronically. There’s a registry of citizens, paired with biometric data, so everyone votes only once. Every ID is linked to a single voting center, and a single voting poll within that center. Each voting machine will only let people registered to vote there. Each person who votes is given a tiny paper receipt that they must personally deposit in a voting urn. At the end of the election there’s a tally, electronic, the machine then prints that tally along with several cryptographic hashes. These hashes are a mix of poll station authorities keys and the numbers reported. Every poll station has authorities and witnesses from each party. This tallies and copies of them are distributed to these people and to as many people as there is print paper and ink available. Lay people are allowed to witness said process and keep a copy of the tally, with only limits to the building’s capacity and material available. Finally, the machine transmits the same data as in the tally papers via an internet encrypted connection to a single totalization center. Then each center is free to audit the tallies by opening the urns in one or all the poll stations and count them by hand to make sure it matches the electronic tally.
There should be witnesses from each party inside the totalization center to see the process of totalization live. Then the election authorities must print the bulletins from the totalization center and publish the results in their entirety, proclaim the results etc. All of this is constitutional law.
Now, for what really happened. At several voting centers witnessed were forbidden from keeping printed tallies. Some places even used violence from the armed forces. Witnesses from all parties except two where forbidden to enter the totalization center by intelligence forces right at the door. The results transmission was halted by the electoral authorities at 20% of data transmitted, no explanation given (they alleged later that North Macedonia hacked the system, I’m not kidding). Then, one of the only witnesses allowed inside claims that the results with Maduro winning read by the electoral president were not printed inside the totalization center, but elsewhere. This is illegal. The results announced were allegedly with 60% of the data. The announcement claims that the results were irreversible. This a technical term, defined by law and statistical sciences, that means that even if the losing candidate had 75% or more of the remaining votes it would not alter the announced winner. But this was not true, for the data as announced.
Now, for how the fraud is being proven. The opposition leader worked for months on creating a network of witnesses with the sole job of gathering printed tallies from each and every polling station at the end of the voting. This tallies were digitized and given to the opposition party for them to totalize on their own. This data was published today on a web page with roughly 80% of the tallies from all polling stations obtained. They show an entirely different result than what the electoral authority claims. Each cryptographic hash is visible and verifiable. People with tallies have been checking and proving that they are consistent with what they have and the hashes match correctly.
Finally, the election authority certified Maduro without publishing the detailed results by polling station. This is also illegal, as certification of results must only happen with 100% of the results tallied and published. Today the web page of the CNE remains offline and no detailed results can be officially seen. This is why most Democratic governments and international institutions are calling for the government to publish the tallies fully, as is our law.