X-Git-Url: https://git.distorted.org.uk/~mdw/sgt/putty/blobdiff_plain/14ec1d8392d27cd5f9dc923ff7dc6416827d4060..16bd1b88e5af81eaecab85795407cd768a296af4:/sshrsa.c

diff --git a/sshrsa.c b/sshrsa.c
index 3bd971f8..4ec95f23 100644
--- a/sshrsa.c
+++ b/sshrsa.c
@@ -273,9 +273,18 @@ static Bignum rsa_privkey_op(Bignum input, struct RSAKey *key)
 	    bignum_cmp(random, key->modulus) >= 0) {
 	    freebn(random);
 	    continue;
-	} else {
-	    break;
 	}
+
+        /*
+         * Also, make sure it has an inverse mod modulus.
+         */
+        random_inverse = modinv(random, key->modulus);
+        if (!random_inverse) {
+	    freebn(random);
+	    continue;
+        }
+
+        break;
     }
 
     /*
@@ -294,7 +303,6 @@ static Bignum rsa_privkey_op(Bignum input, struct RSAKey *key)
      */
     random_encrypted = crt_modpow(random, key->exponent,
                                   key->modulus, key->p, key->q, key->iqmp);
-    random_inverse = modinv(random, key->modulus);
     input_blinded = modmul(input, random_encrypted, key->modulus);
     ret_blinded = crt_modpow(input_blinded, key->private_exponent,
                              key->modulus, key->p, key->q, key->iqmp);
@@ -443,6 +451,8 @@ int rsa_verify(struct RSAKey *key)
 
 	freebn(key->iqmp);
 	key->iqmp = modinv(key->q, key->p);
+        if (!key->iqmp)
+            return 0;
     }
 
     /*
@@ -551,6 +561,8 @@ static Bignum getmp(char **data, int *datalen)
     return b;
 }
 
+static void rsa2_freekey(void *key);   /* forward reference */
+
 static void *rsa2_newkey(char *data, int len)
 {
     char *p;
@@ -570,6 +582,11 @@ static void *rsa2_newkey(char *data, int len)
     rsa->p = rsa->q = rsa->iqmp = NULL;
     rsa->comment = NULL;
 
+    if (!rsa->exponent || !rsa->modulus) {
+        rsa2_freekey(rsa);
+        return NULL;
+    }
+
     return rsa;
 }