David, you are right, but I meant the difference in speed for public exponents like F4=0x10001 (17 bits), 0x40000081 (31 bits), or at least 0xFFFFFFFFFFFFFFFE (64 bits). Certainly for nowadays RSA keylengths you will see a difference in operation time for a public exponent with few dozen and a secret with some thousand bits. But for small and very small public exponents you will not observe it: In case of 0x10001 you perform 17 BIGNUM-Operations, for 0x40000081 only 33, i.e. less than twice. Remember also that there is some org stuff in both cases.
But you are of course free to use a public exponent like 41=0x29 as GPG does (faster than F4) and with the proposed patch you can generate these keys with our lovely OpenSSL package ;-) /Ann. > Try openssl speed rsa > Private key (large exponent) operations are 1-2 > orders of magnitude slower than public key (small exponent), easily > observed. Depending on key length and traffic volume this can be > very important. > > --David > > Annie Yousar via RT wrote: >> Small exponents give the advantage of faster signature >> verification, but in fact you can't really observe that. A prime >> exponent e theoretically speeds up the prime factor search, >> remember that e must be coprime with (p-1) and (q-1), which is more >> likely if e is prime. But this is in the GHz Century also not very >> important. ______________________________________________________________________ OpenSSL Project http://www.openssl.org Development Mailing List [email protected] Automated List Manager [EMAIL PROTECTED]
