Three Chinese researchers have further refined an attack on the encryption standard frequently used to digitally sign documents, making the attack 64 times faster and leaving cryptographers to debate whether the standard, known as the Secure Hash Algorithm, should be phased out more quickly than planned. The attack, presented last week at the Crypto conference in Santa Barbara, Calif., would allow a forger to create two documents that return the same digital fingerprint, a short sequence of numbers that represent the contents of a much larger document…
