From 1e855ebfcf74bb9a05d9f3cbefa4d6488dc41e1b Mon Sep 17 00:00:00 2001 From: Marius Schilder Date: Fri, 17 Nov 2017 18:41:02 -0800 Subject: [PATCH] g: speed up prime generation by ~40% (1024 bit). We were using bn_modexp() to perform a simple modular square. A bn_modexp_word() does this faster. BRANCH=none BUG=b:68167013 TEST=generate 128 primes from prng seed and verify they're same as before; tcg_test passes Change-Id: I411a7d3fe2d68f93dc40bf74b941a637f9aa20ed Reviewed-on: https://chromium-review.googlesource.com/778057 Commit-Ready: Marius Schilder Tested-by: Marius Schilder Reviewed-by: Marius Schilder Reviewed-by: Nagendra Modadugu Reviewed-by: Vadim Bendebury --- chip/g/dcrypto/bn.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/chip/g/dcrypto/bn.c b/chip/g/dcrypto/bn.c index 5c92f82fda..3131139f89 100644 --- a/chip/g/dcrypto/bn.c +++ b/chip/g/dcrypto/bn.c @@ -1070,13 +1070,11 @@ static int bn_probable_prime(const struct LITE_BIGNUM *p) int s = 0; uint32_t ONE_buf = 1; - uint32_t TWO_buf = 2; uint8_t r_buf[RSA_MAX_BYTES / 2]; uint8_t A_buf[RSA_MAX_BYTES / 2]; uint8_t y_buf[RSA_MAX_BYTES / 2]; struct LITE_BIGNUM ONE; - struct LITE_BIGNUM TWO; struct LITE_BIGNUM r; struct LITE_BIGNUM A; struct LITE_BIGNUM y; @@ -1105,7 +1103,6 @@ static int bn_probable_prime(const struct LITE_BIGNUM *p) DCRYPTO_bn_wrap(&A, A_buf, bn_size(p)); DCRYPTO_bn_wrap(&y, y_buf, bn_size(p)); - DCRYPTO_bn_wrap(&TWO, &TWO_buf, sizeof(TWO_buf)); for (j = 0; j < rounds; j++) { int i; @@ -1130,7 +1127,7 @@ static int bn_probable_prime(const struct LITE_BIGNUM *p) /* y = y ^ 2 mod p */ for (i = 0; i < s - 1; i++) { bn_copy(&A, &y); - bn_modexp(&y, &A, &TWO, p); + bn_modexp_word(&y, &A, 2, p); if (bn_eq(&y, &ONE)) return 0;