diff --git a/core/src/main/java/org/springframework/security/core/userdetails/User.java b/core/src/main/java/org/springframework/security/core/userdetails/User.java
index a1216af40e..9b3f813c44 100644
--- a/core/src/main/java/org/springframework/security/core/userdetails/User.java
+++ b/core/src/main/java/org/springframework/security/core/userdetails/User.java
@@ -33,8 +33,14 @@ import org.springframework.util.Assert;
  * Implemented with value object semantics (immutable after construction, like a <code>String</code>).
  * Developers may use this class directly, subclass it, or write their own {@link UserDetails} implementation from
  * scratch.
+ * <p>
+ * {@code equals} and {@code hashcode} implementations are based on the {@code username} property only, as the
+ * intention is that lookups of the same user principal object (in a user registry, for example) will match
+ * where the objects represent the same user, not just when all the properties (authorities, password for
+ * example) are the same.
  *
  * @author Ben Alex
+ * @author Luke Taylor
  */
 public class User implements UserDetails {
     //~ Instance fields ================================================================================================
@@ -156,61 +162,27 @@ public class User implements UserDetails {
         }
     }
 
+    /**
+     * Returns {@code true} if the supplied object is a {@code User} instance with the
+     * same {@code username} value.
+     * <p>
+     * In other words, the objects are equal if they have the same username, representing the
+     * same principal.
+     */
     @Override
     public boolean equals(Object rhs) {
-        if (!(rhs instanceof User) || (rhs == null)) {
-            return false;
+        if (rhs instanceof User) {
+            return username.equals(((User) rhs).username);
         }
-
-        User user = (User) rhs;
-
-        // We rely on constructor to guarantee any User has non-null
-        // authorities
-        if (!authorities.equals(user.authorities)) {
-            return false;
-        }
-
-        // We rely on constructor to guarantee non-null username and password
-        return (this.getPassword().equals(user.getPassword()) && this.getUsername().equals(user.getUsername())
-                && (this.isAccountNonExpired() == user.isAccountNonExpired())
-                && (this.isAccountNonLocked() == user.isAccountNonLocked())
-                && (this.isCredentialsNonExpired() == user.isCredentialsNonExpired())
-                && (this.isEnabled() == user.isEnabled()));
+        return false;
     }
 
+    /**
+     * Returns the hashcode of the {@code username}.
+     */
     @Override
     public int hashCode() {
-        int code = 9792;
-
-        for (GrantedAuthority authority : getAuthorities()) {
-            code = code * (authority.hashCode() % 7);
-        }
-
-        if (this.getPassword() != null) {
-            code = code * (this.getPassword().hashCode() % 7);
-        }
-
-        if (this.getUsername() != null) {
-            code = code * (this.getUsername().hashCode() % 7);
-        }
-
-        if (this.isAccountNonExpired()) {
-            code = code * -2;
-        }
-
-        if (this.isAccountNonLocked()) {
-            code = code * -3;
-        }
-
-        if (this.isCredentialsNonExpired()) {
-            code = code * -5;
-        }
-
-        if (this.isEnabled()) {
-            code = code * -7;
-        }
-
-        return code;
+        return username.hashCode();
     }
 
     @Override
diff --git a/core/src/test/java/org/springframework/security/core/userdetails/UserTests.java b/core/src/test/java/org/springframework/security/core/userdetails/UserTests.java
index e1621f6645..5c3165e342 100644
--- a/core/src/test/java/org/springframework/security/core/userdetails/UserTests.java
+++ b/core/src/test/java/org/springframework/security/core/userdetails/UserTests.java
@@ -19,7 +19,9 @@ import static org.junit.Assert.*;
 
 import java.io.ByteArrayOutputStream;
 import java.io.ObjectOutputStream;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import org.junit.Test;
 import org.springframework.security.core.GrantedAuthority;
@@ -37,24 +39,24 @@ public class UserTests {
     //~ Methods ========================================================================================================
 
     @Test
-    public void testEquals() {
-        User user1 = new User("rod", "koala", true, true, true, true,ROLE_12);
+    public void equalsReturnsTrueIfUsernamesAreTheSame() {
+        User user1 = new User("rod", "koala", true, true, true, true, ROLE_12);
 
         assertFalse(user1.equals(null));
         assertFalse(user1.equals("A STRING"));
         assertTrue(user1.equals(user1));
-        assertTrue(user1.equals(new User("rod", "koala", true, true, true, true,ROLE_12)));
-        // Equal as the new User will internally sort the GrantedAuthorities in the correct order, before running equals()
-        assertTrue(user1.equals(new User("rod", "koala", true, true, true, true,
-                        AuthorityUtils.createAuthorityList("ROLE_TWO","ROLE_ONE"))));
-        assertFalse(user1.equals(new User("DIFFERENT_USERNAME", "koala", true, true, true, true, ROLE_12)));
-        assertFalse(user1.equals(new User("rod", "DIFFERENT_PASSWORD", true, true, true, true, ROLE_12)));
-        assertFalse(user1.equals(new User("rod", "koala", false, true, true, true, ROLE_12)));
-        assertFalse(user1.equals(new User("rod", "koala", true, false, true, true, ROLE_12)));
-        assertFalse(user1.equals(new User("rod", "koala", true, true, false, true, ROLE_12)));
-        assertFalse(user1.equals(new User("rod", "koala", true, true, true, false, ROLE_12)));
-        assertFalse(user1.equals(new User("rod", "koala", true, true, true, true,
-                AuthorityUtils.createAuthorityList("ROLE_ONE"))));
+        assertTrue(user1.equals(new User("rod", "notthesame", true, true, true, true, ROLE_12)));
+    }
+
+    @Test
+    public void hashLookupOnlyDependsOnUsername() throws Exception {
+        User user1 = new User("rod", "koala", true, true, true, true, ROLE_12);
+        Set<UserDetails> users = new HashSet<UserDetails>();
+        users.add(user1);
+
+        assertTrue(users.contains(new User("rod", "koala", true, true, true, true, ROLE_12)));
+        assertTrue(users.contains(new User("rod", "anotherpass", false, false, false, false, AuthorityUtils.createAuthorityList("ROLE_X"))));
+        assertFalse(users.contains(new User("bod", "koala", true, true, true, true, ROLE_12)));
     }
 
     @Test
@@ -116,9 +118,9 @@ public class UserTests {
     }
 
     @Test
-    public void testUserIsEnabled() throws Exception {
+    public void enabledFlagIsFalseForDisabledAccount() throws Exception {
         UserDetails user = new User("rod", "koala", false, true, true, true, ROLE_12);
-        assertTrue(!user.isEnabled());
+        assertFalse(user.isEnabled());
     }
 
     @Test