treilly 2004/05/02 01:07:23
Modified: id/src/java/org/apache/commons/id/uuid
VersionFourGenerator.java
Log:
Adds flag for secure PRNG
Removes singleton constructor
Revision Changes Path
1.4 +102 -38
jakarta-commons-sandbox/id/src/java/org/apache/commons/id/uuid/VersionFourGenerator.java
Index: VersionFourGenerator.java
===================================================================
RCS file:
/home/cvs/jakarta-commons-sandbox/id/src/java/org/apache/commons/id/uuid/VersionFourGenerator.java,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- VersionFourGenerator.java 28 Apr 2004 03:13:15 -0000 1.3
+++ VersionFourGenerator.java 2 May 2004 08:07:23 -0000 1.4
@@ -15,6 +15,8 @@
*/
package org.apache.commons.id.uuid;
+import java.security.NoSuchAlgorithmException;
+import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import java.util.Random;
@@ -44,48 +46,110 @@
/** Byte position of the clock sequence and reserved field */
private static final short CLOCK_SEQ_HI_AND_RESERVED_BYTE_8 = 8;
- /** SecureRandom used to generate UUID's */
- private static Random secureRandom;
+ /** Random used to generate UUID's */
+ private static final Random regularRandom = new Random();
- /** The singleton instance of this class */
- private static VersionFourGenerator instance;
+ /** SecureRandom used to generate UUID's */
+ private static Random secureRandom;
- /**
- * <p>Constructs a new VersionFourGenerator.</p>
- */
- private VersionFourGenerator() {
- super();
- try {
- secureRandom = SecureRandom.getInstance("SHA1PRNG", "SUN");
+ /** The pseudo-random number generator to use */
+ private static String usePRNG = "SHA1PRNG";
+
+ /** The pseudo-random number generator package name to use */
+ private static String usePRNGPackage = "SUN";
+
+ /**
+ * <p>Constructs a new VersionFourGenerator.</p>
+ */
+ public VersionFourGenerator() {
+ super();
}
- catch (Exception e) {
- secureRandom = new Random();
+
+ /**
+ * <p>Returns a new version four UUID.</p>
+ *
+ * @return Object a new version 4 UUID.
+ */
+ public Object nextIdentifier() {
+ return nextUUID(false);
}
- }
- /**
- * <p>Returns the singleton instance of VersionFourGenerator.</p>
- *
- * @return the singleton instance of VersionFourGenerator.
- */
- public static VersionFourGenerator getInstance() {
- if (instance == null) {
- instance = new VersionFourGenerator();
+ /**
+ * <p>Returns a new version four UUID.</p>
+ * <p>This overloaded method may produce both UUID's using a
<code>SecureRandom</code> as well as using normal
+ * <code>Random</code>
+ * </p>
+ *
+ * @param secure indicates whether or not to use <code>SecureRandom</code>
in generating the random bits.
+ * @return a new version four UUID that was generated by either a
<code>Random</code> or <code>SecureRandom</code>.
+ * @throws NoSuchAlgorithmException thrown if the secure option is true and
the PRNG algorithm is not available.
+ * @throws NoSuchProviderException thrown if the secure option is true and
the PRNG provider package is not available.
+ */
+ public Object nextIdentifier(boolean secure) throws
NoSuchAlgorithmException, NoSuchProviderException {
+ if (secure) {
+ return nextUUID(true);
+ }
+ return nextUUID(false);
+ }
+
+ /**
+ * <p>Returns a new version four UUID.</p>
+ *
+ * @return Object a new version 4 UUID.
+ */
+ private UUID nextUUID() {
+ //Call nextUUID with secure = false
+ return nextUUID(false);
+ }
+
+ /**
+ * <p>Returns a new version four UUID using either
<code>SecureRandom</code> or <code>Random</code>.</p>
+ *
+ * @param secure boolean flag indicating whether to use
<code>SecureRandom</code> or <code>Random</code>.
+ * @return a new version four UUID using either <code>SecureRandom</code>
or <code>Random</code>.
+ */
+ private UUID nextUUID(boolean secure) {
+ byte[] raw = new byte[UUID.BYTE_LENGTH];
+ if (secure) {
+ //Initialize the secure random if null.
+ if (secureRandom == null) {
+ try {
+ if (usePRNGPackage != null) {
+ secureRandom = SecureRandom.getInstance(usePRNG,
usePRNGPackage);
+ } else {
+ secureRandom = SecureRandom.getInstance(usePRNG);
+ }
+ } catch (NoSuchAlgorithmException nsae) {
+ secure = false; //Fail back to default PRNG/Random
+ } catch (NoSuchProviderException nspe) {
+ secure = false; //Fail back to default PRNG/Random
+ }
+ secureRandom.nextBytes(raw);
+ }
+ }
+
+ if (!secure) {
+ regularRandom.nextBytes(raw);
+ }
+
+ raw[CLOCK_SEQ_HI_AND_RESERVED_BYTE_8] &= UUID.VARIANT_IETF_DRAFT;
+ raw[TIME_HI_AND_VERSION_BYTE_6] &= 0x0F;
+ raw[TIME_HI_AND_VERSION_BYTE_6] |= (UUID.VERSION_FOUR << 4);
+
+ return new UUID(raw);
}
- return instance;
- }
- /**
- * Returns a new version 4 uuid.
- *
- * @return Object a new version 4 UUID.
- */
- public Object nextIdentifier() {
- byte[] raw = new byte[UUID.BYTE_LENGTH];
- secureRandom.nextBytes(raw);
- raw[CLOCK_SEQ_HI_AND_RESERVED_BYTE_8] &= UUID.VARIANT_IETF_DRAFT;
- raw[TIME_HI_AND_VERSION_BYTE_6] &= 0x0F;
- raw[TIME_HI_AND_VERSION_BYTE_6] |= (UUID.VERSION_FOUR << 4);
- return new UUID(raw);
+ /**
+ * <p>Allows clients to set the pseudo-random number generator
implementation used when generating a version four uuid with
+ * the secure option. The secure option uses a <code>SecureRandom</code>.
The packageName string may be null to specify
+ * no preferred package.</p>
+ *
+ * @param prngName the pseudo-random number generator implementation name.
For example "SHA1PRNG".
+ * @param packageName the package name for the PRNG provider. For example
"SUN".
+ */
+ public static void setPRNGProvider(String prngName, String packageName) {
+ VersionFourGenerator.usePRNG = prngName;
+ VersionFourGenerator.usePRNGPackage = packageName;
+ VersionFourGenerator.secureRandom = null;
+ }
}
-}
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