Mathematicians are close to solving a 150 year-old theory - and the solution could add up to problems for internet commerce.
The Riemann hypothesis, formulated by Georg Friedrich Bernhard Riemann in 1859, would explain the apparently random pattern of prime numbers.
Such numbers are the key to internet cryptography and help banks keep customer's credit card data safe and secure.
Louis de Branges, a French-born mathematician at Purdue University in the US, has claimed to have proof of the Riemann hypothesis, according to The Guardian.
The hypothesis is one of seven 'millennium problems'.
The US-based Clay Mathematics Institute offered $1m (£563,000) to anyone that could solve one of these problems four years ago.
De Branges's colleagues, however, are not convinced that ecommerce is finished - yet.
'The proof he has announced is rather incomprehensible. Now mathematicians are less sure that the million has been won," Professor Marcus du Sautoy of Oxford University told The Guardian.
But du Sautoy accepts that the proof could have large implications for internet commerce.
'The proof should give us more understanding of how the primes work. If it does, it will bring the whole of ecommerce to its knees, overnight. So there are very big implications.'