pub/rsa-gen.c: Don't leak `t'.

[catacomb] / pub / rsa-gen.c

diff --git a/pub/rsa-gen.c b/pub/rsa-gen.c
index 730673e33388f0be37377dd73c07d2a1ca554f27..c9a2da604a459e62560bbde0ff824b93a378f293 100644 (file)
--- a/pub/rsa-gen.c
+++ b/pub/rsa-gen.c
@@ -77,15 +77,26 @@ again:
   if ((rp->p = strongprime("p", MP_NEWSEC, nbits/2, r, n, event, ectx)) == 0)
     goto fail_p;
 
-  /* --- Do painful fiddling with GCD steppers --- */
+  /* --- Do painful fiddling with GCD steppers --- *
+   *
+   * Also, arrange that %$q \ge \lceil 2^{N-1}/p \rceil$%, so that %$p q$%
+   * has the right length.
+   */
 
   {
     mp *q;
+    mp *t = MP_NEW, *u = MP_NEW;
     rabin rb;
 
     if ((q = strongprime_setup("q", MP_NEWSEC, &g.jp, nbits / 2,
                               r, n, event, ectx)) == 0)
       goto fail_q;
+    t = mp_lsl(t, MP_ONE, nbits - 1);
+    mp_div(&t, &u, t, rp->p);
+    if (!MP_ZEROP(u)) t = mp_add(t, t, MP_ONE);
+    if (MP_CMP(q, <, t)) q = mp_leastcongruent(q, t, q, g.jp.m);
+    mp_drop(t);
+
     g.r = mp_lsr(MP_NEW, rp->p, 1);
     g.g = MP_NEW;
     g.max = MP_256;