From d6d63fbf0b711c06928bc9d43a2829c218136d4b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Niels=20M=C3=B6ller?= <nisse@lysator.liu.se>
Date: Thu, 8 Jan 2004 13:39:02 +0100
Subject: [PATCH] (bignum_next_prime): Fixed off-by-one error when comparing
input to the largest listed prime. General cleanup, as prime_limit > 0
always. Use TMP_DECL and TMP_ALLOC.
Rev: src/nettle/rsa-keygen.c:1.6
---
rsa-keygen.c | 53 +++++++++++++++++++++++++---------------------------
1 file changed, 25 insertions(+), 28 deletions(-)
diff --git a/rsa-keygen.c b/rsa-keygen.c
index fc465f6f..236bc121 100644
--- a/rsa-keygen.c
+++ b/rsa-keygen.c
@@ -35,6 +35,7 @@
#include "rsa.h"
#include "bignum.h"
+#include "nettle-internal.h"
#ifndef DEBUG
# define DEBUG 0
@@ -69,10 +70,11 @@ bignum_next_prime(mpz_t p, mpz_t n, int count,
void *progress_ctx, nettle_progress_func progress)
{
mpz_t tmp;
- unsigned long *moduli = NULL;
+ TMP_DECL(moduli, unsigned long, NUMBER_OF_PRIMES);
+
unsigned long difference;
- int prime_limit = NUMBER_OF_PRIMES;
-
+ unsigned prime_limit = NUMBER_OF_PRIMES;
+
/* First handle tiny numbers */
if (mpz_cmp_ui(n, 2) <= 0)
{
@@ -87,22 +89,23 @@ bignum_next_prime(mpz_t p, mpz_t n, int count,
mpz_init(tmp);
- if (prime_limit && (mpz_cmp_ui(p, primes[prime_limit]) <= 0) )
- /* Use unly 3, 5 and 7 */
+ if (mpz_cmp_ui(p, primes[prime_limit-1]) <= 0)
+ /* Use only 3, 5 and 7 */
prime_limit = 3;
-
- if (prime_limit)
- {
- /* Compute residues modulo small odd primes */
- int i;
-
- moduli = alloca(prime_limit * sizeof(*moduli));
- for (i = 0; i < prime_limit; i++)
- moduli[i] = mpz_fdiv_ui(p, primes[i]);
- }
-
+
+ /* Compute residues modulo small odd primes */
+ TMP_ALLOC(moduli, prime_limit);
+ {
+ unsigned i;
+ for (i = 0; i < prime_limit; i++)
+ moduli[i] = mpz_fdiv_ui(p, primes[i]);
+ }
+
for (difference = 0; ; difference += 2)
{
+ int composite = 0;
+ unsigned i;
+
if (difference >= ULONG_MAX - 10)
{ /* Should not happen, at least not very often... */
mpz_add_ui(p, p, difference);
@@ -110,20 +113,14 @@ bignum_next_prime(mpz_t p, mpz_t n, int count,
}
/* First check residues */
- if (prime_limit)
+ for (i = 0; i < prime_limit; i++)
{
- int composite = 0;
- int i;
-
- for (i = 0; i < prime_limit; i++)
- {
- if (moduli[i] == 0)
- composite = 1;
- moduli[i] = (moduli[i] + 2) % primes[i];
- }
- if (composite)
- continue;
+ if (moduli[i] == 0)
+ composite = 1;
+ moduli[i] = (moduli[i] + 2) % primes[i];
}
+ if (composite)
+ continue;
mpz_add_ui(p, p, difference);
difference = 0;
--
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