Reduce chances of issuer and serial number duplication by use of random

initial serial numbers.

PR: 842

CHANGES

@@ -4,6 +4,15 @@
 
  Changes between 0.9.7c and 0.9.8  [xx XXX xxxx]
 
+  *) Reduce the chances of duplicate issuer name and serial numbers (in
+     violation of RFC3280) using the OpenSSL certificate creation utilities. 
+     This is done by creating a random 64 bit value for the initial serial
+     number when a serial number file is created or when a self signed
+     certificate is created using 'openssl req -x509'. The initial serial
+     number file is now moved from CA.pl to the 'ca' utility with a new
+     option -create_serial.
+     [Steve Henson]
+
   *) Reduced header interdepencies by declaring more opaque objects in
      ossl_typ.h. As a consequence, including some headers (eg. engine.h) will
      give fewer recursive includes, which could break lazy source code - so

apps/CA.pl.in

@@ -84,9 +84,6 @@ foreach (@ARGV) {
 		mkdir "${CATOP}/crl", $DIRMODE ;
 		mkdir "${CATOP}/newcerts", $DIRMODE;
 		mkdir "${CATOP}/private", $DIRMODE;
-		open OUT, ">${CATOP}/serial";
-		print OUT "01\n";
-		close OUT;
 		open OUT, ">${CATOP}/index.txt";
 		close OUT;
 	    }
@@ -105,7 +102,8 @@ foreach (@ARGV) {
 		    print "Making CA certificate ...\n";
 		    system ("$REQ -new -keyout " .
 			"${CATOP}/private/$CAKEY -out ${CATOP}/$CAREQ");
-		    system ("$CA -out ${CATOP}/$CACERT $CADAYS -batch " . 
+		    system ("$CA -create_serial " .
+			"-out ${CATOP}/$CACERT $CADAYS -batch " . 
 			"-keyfile ${CATOP}/private/$CAKEY -selfsign " .
 			"-infiles ${CATOP}/$CAREQ ");
 		    $RET=$?;

apps/apps.c

@@ -1434,12 +1434,9 @@ BIGNUM *load_serial(char *serialfile, int create, ASN1_INTEGER **retai)
 			}
 		else
 			{
-			ASN1_INTEGER_set(ai,1);
 			ret=BN_new();
-			if (ret == NULL)
+			if (ret == NULL || !rand_serial(ret, ai))
 				BIO_printf(bio_err, "Out of memory\n");
-			else
-				BN_one(ret);
 			}
 		}
 	else
@@ -1601,6 +1598,33 @@ int rotate_serial(char *serialfile, char *new_suffix, char *old_suffix)
 	return 0;
 	}
 
+int rand_serial(BIGNUM *b, ASN1_INTEGER *ai)
+	{
+	BIGNUM *btmp;
+	int ret = 0;
+	if (b)
+		btmp = b;
+	else
+		btmp = BN_new();
+
+	if (!btmp)
+		return 0;
+
+	if (!BN_pseudo_rand(btmp, SERIAL_RAND_BITS, 0, 0))
+		goto error;
+	if (ai && !BN_to_ASN1_INTEGER(btmp, ai))
+		goto error;
+
+	ret = 1;
+	
+	error:
+
+	if (!b)
+		BN_free(btmp);
+	
+	return ret;
+	}
+
 CA_DB *load_index(char *dbfile, DB_ATTR *db_attr)
 	{
 	CA_DB *retdb = NULL;

apps/apps.h

@@ -309,6 +309,7 @@ typedef struct ca_db_st
 BIGNUM *load_serial(char *serialfile, int create, ASN1_INTEGER **retai);
 int save_serial(char *serialfile, char *suffix, BIGNUM *serial, ASN1_INTEGER **retai);
 int rotate_serial(char *serialfile, char *new_suffix, char *old_suffix);
+int rand_serial(BIGNUM *b, ASN1_INTEGER *ai);
 CA_DB *load_index(char *dbfile, DB_ATTR *dbattr);
 int index_index(CA_DB *db);
 int save_index(char *dbfile, char *suffix, CA_DB *db);
@@ -338,4 +339,6 @@ X509_NAME *parse_name(char *str, long chtype, int multirdn);
 
 #define APP_PASS_LEN	1024
 
+#define SERIAL_RAND_BITS	64
+
 #endif

apps/ca.c

@@ -241,6 +241,7 @@ int MAIN(int argc, char **argv)
 	{
 	ENGINE *e = NULL;
 	char *key=NULL,*passargin=NULL;
+	int create_ser = 0;
 	int free_key = 0;
 	int total=0;
 	int total_done=0;
@@ -354,6 +355,8 @@ EF_ALIGNMENT=0;
 			subj= *(++argv);
 			/* preserve=1; */
 			}
+		else if (strcmp(*argv,"-create_serial") == 0)
+			create_ser = 1;
 		else if (strcmp(*argv,"-multivalue-rdn") == 0)
 			multirdn=1;
 		else if (strcmp(*argv,"-startdate") == 0)
@@ -1097,7 +1100,7 @@ bad:
 			goto err;
 			}
 
-		if ((serial=load_serial(serialfile, 0, NULL)) == NULL)
+		if ((serial=load_serial(serialfile, create_ser, NULL)) == NULL)
 			{
 			BIO_printf(bio_err,"error while loading serial number\n");
 			goto err;

apps/req.c

@@ -919,7 +919,9 @@ loop:
 				}
 			else
 				{
-				if (!ASN1_INTEGER_set(X509_get_serialNumber(x509ss),0L)) goto end;
+				if (!rand_serial(NULL,
+					X509_get_serialNumber(x509ss)))
+						goto end;
 				}
 
 			if (!X509_set_issuer_name(x509ss, X509_REQ_get_subject_name(req))) goto end;