By setting the modulus to a prime number whose modular multiplicative order is "smooth" (that is, p-1 is divisible by only small prime numbers), discrete logarithms can be calculated quickly using the [[wikipedia:Pohlig-Hellman algorithm|Pohlig-Hellman algorithm]]. If the prime chosen is greater than the modulus, but the same bit size, the discrete logarithm is the private exponent. | By setting the modulus to a prime number whose modular multiplicative order is "smooth" (that is, p-1 is divisible by only small prime numbers), discrete logarithms can be calculated quickly using the [[wikipedia:Pohlig-Hellman algorithm|Pohlig-Hellman algorithm]]. If the prime chosen is greater than the modulus, but the same bit size, the discrete logarithm is the private exponent. |