1 files changed, 8 insertions, 1 deletions

diff --git a/auth-rsa.c b/auth-rsa.c
index c51400c2a..5b98f2cf2 100644
--- a/auth-rsa.c
+++ b/auth-rsa.c
@@ -14,7 +14,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth-rsa.c,v 1.53 2002/03/25 09:21:13 markus Exp $");
+RCSID("$OpenBSD: auth-rsa.c,v 1.54 2002/03/26 23:13:03 markus Exp $");
 
 #include <openssl/rsa.h>
 #include <openssl/md5.h>
@@ -78,6 +78,13 @@ auth_rsa_verify_response(Key *key, BIGNUM *challenge, u_char response[16])
         MD5_CTX md;
         int len;
 
+        /* don't allow short keys */
+        if (BN_num_bits(key->rsa->n) < 768) {
+                error("auth_rsa_verify_response: n too small: %d bits",
+                    BN_num_bits(key->rsa->n));
+                return (0);
+        }
+
         /* The response is MD5 of decrypted challenge plus session id. */
         len = BN_num_bytes(challenge);
         if (len <= 0 || len > 32)