A team of cryptographers in France have cracked the longest encryption to date. Taking 35 million computing hours to crack a 240 digits long encryption key, they broke the previous record by just eight characters. The key, although only a third of the length of most encryption keys, was cracked by the usage of several computers running simultaneously to convert the 35 million computing hours into a reasonable time frame.
The cryptography victory was double-edged as not only did they solve a more complex encryption key than the previous record holders but they did it in less time than what it took the former record holders to do. New cryptographical records are regularly set as the calibre of the available computer hardware increases. Although the press release did note that the marked increase in their capability to crack the encryption key was much more than what could be explained by an increase in the hardware power alone, the software improvements were also of considerable help.
The encryption, known as the RSA key, relies on huge numbers that are the product of two prime numbers. Other encryption algorithms base their security on the difficulty of solving specific discrete logarithm problems. With sufficiently big enough key sizes, there is no known way of cracking the encryption that they provide.
The new record includes the factoring of RSA-240 with 240 decimal places and a size of 795 bits. The same team of researchers also computed a discrete logarithm of the same size. The sum of the computation time for both new records is 4000 core-years, using Intel Xeon Gold 6130s (running at 2.1 GHz). Like previous records, this record was accomplished using an algorithm called Number Field Sieve, which can be used to perform both integer factoring and finite field discrete logarithms.