Patent ID: 7050584
Filing Date: 2006-05-23
Classification: H04L

Abstract:
1. A method for producing a regenerated private key by a computer for a predetermined asymmetric cryptographic key pair which includes an original private key and a corresponding public key, the regenerated private key being identical to the original private key, the original private key and the public key having been generated by receiving a predetermined initial value entered by a user; processing the predetermined initial value to obtain a base value for obtaining first and second prime numbers; checking whether the base value is a prime number and, when the base value is not a prime number, increasing the base value by a predetermined increment to obtain a new value; repeating the step of checking until the first and second prime numbers are obtained; storing an index to obtain a stored index, the stored index being a number indicating how many times, in the step of checking, the base value has been increased until the first prime number or the second prime number are obtained; calculating the original private key using the first and second prime numbers; and calculating the public key using the original private key and the first and second prime numbers, the method comprising: receiving a user input of the predetermined initial value by the computer; processing the predetermined initial value to obtain a base value for obtaining the first and second prime numbers; increasing the base value by a value determined by the index previously stored and the predetermined increment to obtain the first and second prime numbers; and producing the regenerated private key using the first and second prime numbers.