diff options
Diffstat (limited to 'crypto/bn/bn_exp.c')
| -rw-r--r-- | crypto/bn/bn_exp.c | 60 |
1 files changed, 30 insertions, 30 deletions
diff --git a/crypto/bn/bn_exp.c b/crypto/bn/bn_exp.c index b29df546d5..ef67843fc2 100644 --- a/crypto/bn/bn_exp.c +++ b/crypto/bn/bn_exp.c @@ -174,36 +174,36 @@ int BN_mod_exp(BIGNUM *r, const BIGNUM *a, const BIGNUM *p, const BIGNUM *m, bn_check_top(p); bn_check_top(m); - /*- - * For even modulus m = 2^k*m_odd, it might make sense to compute - * a^p mod m_odd and a^p mod 2^k separately (with Montgomery - * exponentiation for the odd part), using appropriate exponent - * reductions, and combine the results using the CRT. - * - * For now, we use Montgomery only if the modulus is odd; otherwise, - * exponentiation using the reciprocal-based quick remaindering - * algorithm is used. - * - * (Timing obtained with expspeed.c [computations a^p mod m - * where a, p, m are of the same length: 256, 512, 1024, 2048, - * 4096, 8192 bits], compared to the running time of the - * standard algorithm: - * - * BN_mod_exp_mont 33 .. 40 % [AMD K6-2, Linux, debug configuration] - * 55 .. 77 % [UltraSparc processor, but - * debug-solaris-sparcv8-gcc conf.] - * - * BN_mod_exp_recp 50 .. 70 % [AMD K6-2, Linux, debug configuration] - * 62 .. 118 % [UltraSparc, debug-solaris-sparcv8-gcc] - * - * On the Sparc, BN_mod_exp_recp was faster than BN_mod_exp_mont - * at 2048 and more bits, but at 512 and 1024 bits, it was - * slower even than the standard algorithm! - * - * "Real" timings [linux-elf, solaris-sparcv9-gcc configurations] - * should be obtained when the new Montgomery reduction code - * has been integrated into OpenSSL.) - */ + /*- + * For even modulus m = 2^k*m_odd, it might make sense to compute + * a^p mod m_odd and a^p mod 2^k separately (with Montgomery + * exponentiation for the odd part), using appropriate exponent + * reductions, and combine the results using the CRT. + * + * For now, we use Montgomery only if the modulus is odd; otherwise, + * exponentiation using the reciprocal-based quick remaindering + * algorithm is used. + * + * (Timing obtained with expspeed.c [computations a^p mod m + * where a, p, m are of the same length: 256, 512, 1024, 2048, + * 4096, 8192 bits], compared to the running time of the + * standard algorithm: + * + * BN_mod_exp_mont 33 .. 40 % [AMD K6-2, Linux, debug configuration] + * 55 .. 77 % [UltraSparc processor, but + * debug-solaris-sparcv8-gcc conf.] + * + * BN_mod_exp_recp 50 .. 70 % [AMD K6-2, Linux, debug configuration] + * 62 .. 118 % [UltraSparc, debug-solaris-sparcv8-gcc] + * + * On the Sparc, BN_mod_exp_recp was faster than BN_mod_exp_mont + * at 2048 and more bits, but at 512 and 1024 bits, it was + * slower even than the standard algorithm! + * + * "Real" timings [linux-elf, solaris-sparcv9-gcc configurations] + * should be obtained when the new Montgomery reduction code + * has been integrated into OpenSSL.) + */ #define MONT_MUL_MOD #define MONT_EXP_WORD |