commit bf762186c6acddd4937855da495e08ea4204979b
author Brian Smith <brian@briansmith.org> Mon Nov 16 16:05:00 2015 -1000
committer Adam Langley <agl@google.com> Thu Nov 19 01:40:13 2015 +0000
tree 67238c02cbd645e7a45a5644180d32ce7bfab57c
parent 596ab10b0f0325671f496a7f66221effac18bf44

Remove the |ri| field of |BN_MONT_CTX|.

The |ri| field was only used in |BN_MONT_CTX_set|, so make it a local
variable of that function.

Change-Id: Id8c3d44ac2e30e3961311a7b1a6731fe2c33a0eb
Reviewed-on: https://boringssl-review.googlesource.com/6526
Reviewed-by: Adam Langley <agl@google.com>

crypto/bn/montgomery.c

diff --git a/crypto/bn/montgomery.c b/crypto/bn/montgomery.c
index 07e1a41..18da0da 100644
--- a/crypto/bn/montgomery.c
+++ b/crypto/bn/montgomery.c
@@ -157,7 +157,6 @@
       !BN_copy(&to->N, &from->N)) {
     return NULL;
   }
-  to->ri = from->ri;
   to->n0[0] = from->n0[0];
   to->n0[1] = from->n0[1];
   return to;
@@ -190,8 +189,6 @@
   tmod.dmax = 2;
   tmod.neg = 0;
 
-  mont->ri = (BN_num_bits(mod) + (BN_BITS2 - 1)) / BN_BITS2 * BN_BITS2;
-
 #if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2 <= 32)
   /* Only certain BN_BITS2<=32 platforms actually make use of
    * n0[1], and we could use the #else case (with a shorter R
@@ -275,9 +272,10 @@
   mont->n0[1] = 0;
 #endif
 
-  /* setup RR for conversions */
+  /* RR = (2^ri)^2 == 2^(ri*2) == 1 << (ri*2), which has its (ri*2)th bit set. */
+  int ri = (BN_num_bits(mod) + (BN_BITS2 - 1)) / BN_BITS2 * BN_BITS2;
   BN_zero(&(mont->RR));
-  if (!BN_set_bit(&(mont->RR), mont->ri * 2)) {
+  if (!BN_set_bit(&(mont->RR), ri * 2)) {
     goto err;
   }
   if (!BN_mod(&(mont->RR), &(mont->RR), &(mont->N), ctx)) {

include/openssl/bn.h

diff --git a/include/openssl/bn.h b/include/openssl/bn.h
index cbc1ee7..bc30d0a 100644
--- a/include/openssl/bn.h
+++ b/include/openssl/bn.h
@@ -837,7 +837,6 @@
   BIGNUM RR; /* used to convert to montgomery form */
   BIGNUM N;  /* The modulus */
   BN_ULONG n0[2]; /* least significant words of (R*Ri-1)/N */
-  int ri;    /* number of bits in R */
 };
 
 OPENSSL_EXPORT unsigned BN_num_bits_word(BN_ULONG l);