From 7253995013820dfc5eb3511da80f1777cc69c168 Mon Sep 17 00:00:00 2001 From: Gilles Khouzam Date: Mon, 22 Sep 2014 17:08:51 -0700 Subject: [PATCH] Fix issue where BN_nist_mod_521 fails on optimized Windows ARM devices. This looks like a compiler issue are the wrong code is being generated. Rewriting the code to avoid the temporary variables fixes the issue. The assembly code looks good and the behavior is correct. --- crypto/bn/bn_nist.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/crypto/bn/bn_nist.c b/crypto/bn/bn_nist.c index abd53df..20203e0 100644 --- a/crypto/bn/bn_nist.c +++ b/crypto/bn/bn_nist.c @@ -1071,7 +1071,7 @@ int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field, int top = a->top, i; BN_ULONG *r_d, *a_d = a->d, t_d[BN_NIST_521_TOP], - val,tmp,*res; + *res; PTR_SIZE_INT mask; static const BIGNUM _bignum_nist_p_521_sqr = { (BN_ULONG *)_nist_p_521_sqr, @@ -1106,13 +1106,12 @@ int BN_nist_mod_521(BIGNUM *r, const BIGNUM *a, const BIGNUM *field, /* upper 521 bits, copy ... */ nist_cp_bn_0(t_d,a_d + (BN_NIST_521_TOP-1), top - (BN_NIST_521_TOP-1),BN_NIST_521_TOP); /* ... and right shift */ - for (val=t_d[0],i=0; i>BN_NIST_521_RSHIFT; - val = t_d[i+1]; - t_d[i] = (tmp | val<> BN_NIST_521_RSHIFT) | + (t_d[i+1] << BN_NIST_521_LSHIFT)) & BN_MASK2; } - t_d[i] = val>>BN_NIST_521_RSHIFT; + t_d[i] = t_d[i]>>BN_NIST_521_RSHIFT; /* lower 521 bits */ r_d[i] &= BN_NIST_521_TOP_MASK; -- 1.9.4.msysgit.1