From f2d45696fc0060f54eac1b1937fa6bcdf7799af0 Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Mon, 22 Dec 2014 20:32:58 +0000
Subject: [PATCH] rsa-recover.c: First stage cleanup: hoist variable
 declarations.

Remove all of the variable declarations from inner blocks and hoist them
to toplevel.  Initialize `mp' variables once, and use their initial
values, rather than writing `MP_NEW' explicitly in the first assignment.

There's no functional change here.

Two small (temporary) warts. Firstly, the handling of `z' and `zz' in
the factoring loop is rather nasty, repeatedly freeing and recreating
`zz'; and secondly `p1' and `q1' are used in two separate places.  To
prevent conflicts here, reset the relevant variables to `MP_NEW' after
freeing them.
---
 pub/rsa-recover.c | 40 +++++++++++++++++++---------------------
 1 file changed, 19 insertions(+), 21 deletions(-)

diff --git a/pub/rsa-recover.c b/pub/rsa-recover.c
index 9f22f230..c09ca4a4 100644
--- a/pub/rsa-recover.c
+++ b/pub/rsa-recover.c
@@ -49,6 +49,14 @@
 
 int rsa_recover(rsa_priv *rp)
 {
+  int i;
+  size_t s;
+  mpmont mm;
+  mp a; mpw aw;
+  mp *g = MP_NEW, *r = MP_NEW, *t = MP_NEW;
+  mp *m1 = MP_NEW, *z = MP_NEW, *zz = MP_NEW;
+  mp *phi = MP_NEW, *p1 = MP_NEW, *q1 = MP_NEW;
+
   /* --- If there is no modulus, calculate it --- */
 
   if (!rp->n) {
@@ -64,7 +72,6 @@ int rsa_recover(rsa_priv *rp)
     /* --- If one is missing, use simple division to recover the other --- */
 
     if (rp->p || rp->q) {
-      mp *r = MP_NEW;
       if (rp->p)
 	mp_div(&rp->q, &r, rp->n, rp->p);
       else
@@ -81,13 +88,6 @@ int rsa_recover(rsa_priv *rp)
     else if (!rp->e || !rp->d)
       return (-1);
     else {
-      mp *t;
-      size_t s;
-      mp a; mpw aw;
-      mp *m1;
-      mpmont mm;
-      int i;
-      mp *z = MP_NEW;
 
       /* --- Work out the appropriate exponent --- *
        *
@@ -95,14 +95,14 @@ int rsa_recover(rsa_priv *rp)
        * %$t$% is odd.
        */
 
-      t = mp_mul(MP_NEW, rp->e, rp->d);
+      t = mp_mul(t, rp->e, rp->d);
       t = mp_sub(t, t, MP_ONE);
       t = mp_odd(t, t, &s);
 
       /* --- Set up for the exponentiation --- */
 
       mpmont_create(&mm, rp->n);
-      m1 = mp_sub(MP_NEW, rp->n, mm.r);
+      m1 = mp_sub(m1, rp->n, mm.r);
 
       /* --- Now for the main loop --- *
        *
@@ -135,7 +135,7 @@ int rsa_recover(rsa_priv *rp)
 	 */
 
 	for (;;) {
-	  mp *zz = mp_sqr(MP_NEW, z);
+	  zz = mp_sqr(zz, z);
 	  zz = mpmont_reduce(&mm, zz, zz);
 	  if (MP_EQ(zz, mm.r)) {
 	    mp_drop(zz);
@@ -146,6 +146,7 @@ int rsa_recover(rsa_priv *rp)
 	  }
 	  mp_drop(z);
 	  z = zz;
+	  zz = MP_NEW;
 	}
       }
 
@@ -182,21 +183,18 @@ int rsa_recover(rsa_priv *rp)
   /* --- If %$e$% or %$d$% is missing, recalculate it --- */
 
   if (!rp->e || !rp->d) {
-    mp *phi;
-    mp *g = MP_NEW;
-    mp *p1, *q1;
 
     /* --- Compute %$\varphi(n)$% --- */
 
-    phi = mp_sub(MP_NEW, rp->n, rp->p);
+    phi = mp_sub(phi, rp->n, rp->p);
     phi = mp_sub(phi, phi, rp->q);
     phi = mp_add(phi, phi, MP_ONE);
-    p1 = mp_sub(MP_NEW, rp->p, MP_ONE);
-    q1 = mp_sub(MP_NEW, rp->q, MP_ONE);
+    p1 = mp_sub(p1, rp->p, MP_ONE);
+    q1 = mp_sub(q1, rp->q, MP_ONE);
     mp_gcd(&g, 0, 0, p1, q1);
     mp_div(&phi, 0, phi, g);
-    mp_drop(p1);
-    mp_drop(q1);
+    mp_drop(p1); p1 = MP_NEW;
+    mp_drop(q1); q1 = MP_NEW;
 
     /* --- Recover the other exponent --- */
 
@@ -226,12 +224,12 @@ int rsa_recover(rsa_priv *rp)
   /* --- Compute %$d \bmod (p - 1)$% and %$d \bmod (q - 1)$% --- */
 
   if (!rp->dp) {
-    mp *p1 = mp_sub(MP_NEW, rp->p, MP_ONE);
+    p1 = mp_sub(p1, rp->p, MP_ONE);
     mp_div(0, &rp->dp, rp->d, p1);
     mp_drop(p1);
   }
   if (!rp->dq) {
-    mp *q1 = mp_sub(MP_NEW, rp->q, MP_ONE);
+    q1 = mp_sub(q1, rp->q, MP_ONE);
     mp_div(0, &rp->dq, rp->d, q1);
     mp_drop(q1);
   }
-- 
2.11.0