diff --git a/api/current.xml b/api/current.xml
index c179789236bd4..2777210d7a6a0 100644
--- a/api/current.xml
+++ b/api/current.xml
@@ -37880,6 +37880,21 @@
 <parameter name="pkg2" type="java.lang.String">
 </parameter>
 </method>
+<method name="checkSignatures"
+ return="int"
+ abstract="true"
+ native="false"
+ synchronized="false"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="uid1" type="int">
+</parameter>
+<parameter name="uid2" type="int">
+</parameter>
+</method>
 <method name="clearPackagePreferredActivities"
  return="void"
  abstract="true"
@@ -121998,6 +122013,21 @@
 <parameter name="pkg2" type="java.lang.String">
 </parameter>
 </method>
+<method name="checkSignatures"
+ return="int"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+<parameter name="uid1" type="int">
+</parameter>
+<parameter name="uid2" type="int">
+</parameter>
+</method>
 <method name="clearPackagePreferredActivities"
  return="void"
  abstract="false"
diff --git a/core/java/android/app/ApplicationContext.java b/core/java/android/app/ApplicationContext.java
index 7e71088dcb6a7..a74fbe4017734 100644
--- a/core/java/android/app/ApplicationContext.java
+++ b/core/java/android/app/ApplicationContext.java
@@ -1663,6 +1663,15 @@ class ApplicationContext extends Context {
             }
         }
 
+        @Override
+        public int checkSignatures(int uid1, int uid2) {
+            try {
+                return mPM.checkUidSignatures(uid1, uid2);
+            } catch (RemoteException e) {
+                throw new RuntimeException("Package manager has died", e);
+            }
+        }
+
         @Override
         public String[] getPackagesForUid(int uid) {
             try {
diff --git a/core/java/android/content/pm/IPackageManager.aidl b/core/java/android/content/pm/IPackageManager.aidl
index d9f298de3982f..776061209c2cb 100644
--- a/core/java/android/content/pm/IPackageManager.aidl
+++ b/core/java/android/content/pm/IPackageManager.aidl
@@ -75,6 +75,8 @@ interface IPackageManager {
     
     int checkSignatures(String pkg1, String pkg2);
     
+    int checkUidSignatures(int uid1, int uid2);
+    
     String[] getPackagesForUid(int uid);
     
     String getNameForUid(int uid);
diff --git a/core/java/android/content/pm/PackageManager.java b/core/java/android/content/pm/PackageManager.java
index bca171591dd3a..3a178a1d3c21e 100644
--- a/core/java/android/content/pm/PackageManager.java
+++ b/core/java/android/content/pm/PackageManager.java
@@ -865,6 +865,7 @@ public abstract class PackageManager {
      * {@link #SIGNATURE_SECOND_NOT_SIGNED}, {@link #SIGNATURE_NO_MATCH},
      * or {@link #SIGNATURE_UNKNOWN_PACKAGE}.
      *
+     * @see #checkSignatures(int, int)
      * @see #SIGNATURE_MATCH
      * @see #SIGNATURE_NEITHER_SIGNED
      * @see #SIGNATURE_FIRST_NOT_SIGNED
@@ -874,6 +875,34 @@ public abstract class PackageManager {
      */
     public abstract int checkSignatures(String pkg1, String pkg2);
 
+    /**
+     * Like {@link #checkSignatures(String, String)}, but takes UIDs of
+     * the two packages to be checked.  This can be useful, for example,
+     * when doing the check in an IPC, where the UID is the only identity
+     * available.  It is functionally identical to determining the package
+     * associated with the UIDs and checking their signatures.
+     *
+     * @param pkg1 First UID whose signature will be compared.
+     * @param pkg2 Second UID whose signature will be compared.
+     * @return Returns an integer indicating whether there is a matching
+     * signature: the value is >= 0 if there is a match (or neither package
+     * is signed), or < 0 if there is not a match.  The match result can be
+     * further distinguished with the success (>= 0) constants
+     * {@link #SIGNATURE_MATCH}, {@link #SIGNATURE_NEITHER_SIGNED}; or
+     * failure (< 0) constants {@link #SIGNATURE_FIRST_NOT_SIGNED},
+     * {@link #SIGNATURE_SECOND_NOT_SIGNED}, {@link #SIGNATURE_NO_MATCH},
+     * or {@link #SIGNATURE_UNKNOWN_PACKAGE}.
+     *
+     * @see #checkSignatures(int, int)
+     * @see #SIGNATURE_MATCH
+     * @see #SIGNATURE_NEITHER_SIGNED
+     * @see #SIGNATURE_FIRST_NOT_SIGNED
+     * @see #SIGNATURE_SECOND_NOT_SIGNED
+     * @see #SIGNATURE_NO_MATCH
+     * @see #SIGNATURE_UNKNOWN_PACKAGE
+     */
+    public abstract int checkSignatures(int uid1, int uid2);
+
     /**
      * Retrieve the names of all packages that are associated with a particular
      * user id.  In most cases, this will be a single package name, the package
diff --git a/services/java/com/android/server/PackageManagerService.java b/services/java/com/android/server/PackageManagerService.java
index e14f80594aa8d..aac13b6abe08d 100644
--- a/services/java/com/android/server/PackageManagerService.java
+++ b/services/java/com/android/server/PackageManagerService.java
@@ -1138,25 +1138,57 @@ class PackageManagerService extends IPackageManager.Stub {
                     || p2 == null || p2.mExtras == null) {
                 return PackageManager.SIGNATURE_UNKNOWN_PACKAGE;
             }
-            return checkSignaturesLP(p1, p2);
+            return checkSignaturesLP(p1.mSignatures, p2.mSignatures);
         }
     }
 
-    int checkSignaturesLP(PackageParser.Package p1, PackageParser.Package p2) {
-        if (p1.mSignatures == null) {
-            return p2.mSignatures == null
+    public int checkUidSignatures(int uid1, int uid2) {
+        synchronized (mPackages) {
+            Signature[] s1;
+            Signature[] s2;
+            Object obj = mSettings.getUserIdLP(uid1);
+            if (obj != null) {
+                if (obj instanceof SharedUserSetting) {
+                    s1 = ((SharedUserSetting)obj).signatures.mSignatures;
+                } else if (obj instanceof PackageSetting) {
+                    s1 = ((PackageSetting)obj).signatures.mSignatures;
+                } else {
+                    return PackageManager.SIGNATURE_UNKNOWN_PACKAGE;
+                }
+            } else {
+                return PackageManager.SIGNATURE_UNKNOWN_PACKAGE;
+            }
+            obj = mSettings.getUserIdLP(uid2);
+            if (obj != null) {
+                if (obj instanceof SharedUserSetting) {
+                    s2 = ((SharedUserSetting)obj).signatures.mSignatures;
+                } else if (obj instanceof PackageSetting) {
+                    s2 = ((PackageSetting)obj).signatures.mSignatures;
+                } else {
+                    return PackageManager.SIGNATURE_UNKNOWN_PACKAGE;
+                }
+            } else {
+                return PackageManager.SIGNATURE_UNKNOWN_PACKAGE;
+            }
+            return checkSignaturesLP(s1, s2);
+        }
+    }
+
+    int checkSignaturesLP(Signature[] s1, Signature[] s2) {
+        if (s1 == null) {
+            return s2 == null
                     ? PackageManager.SIGNATURE_NEITHER_SIGNED
                     : PackageManager.SIGNATURE_FIRST_NOT_SIGNED;
         }
-        if (p2.mSignatures == null) {
+        if (s2 == null) {
             return PackageManager.SIGNATURE_SECOND_NOT_SIGNED;
         }
-        final int N1 = p1.mSignatures.length;
-        final int N2 = p2.mSignatures.length;
+        final int N1 = s1.length;
+        final int N2 = s2.length;
         for (int i=0; i<N1; i++) {
             boolean match = false;
             for (int j=0; j<N2; j++) {
-                if (p1.mSignatures[i].equals(p2.mSignatures[j])) {
+                if (s1[i].equals(s2[j])) {
                     match = true;
                     break;
                 }
@@ -2907,9 +2939,9 @@ class PackageManagerService extends IPackageManager.Stub {
                     allowed = true;
                 } else if (p.info.protectionLevel == PermissionInfo.PROTECTION_SIGNATURE
                         || p.info.protectionLevel == PermissionInfo.PROTECTION_SIGNATURE_OR_SYSTEM) {
-                    allowed = (checkSignaturesLP(p.owner, pkg)
+                    allowed = (checkSignaturesLP(p.owner.mSignatures, pkg.mSignatures)
                                     == PackageManager.SIGNATURE_MATCH)
-                            || (checkSignaturesLP(mPlatformPackage, pkg)
+                            || (checkSignaturesLP(mPlatformPackage.mSignatures, pkg.mSignatures)
                                     == PackageManager.SIGNATURE_MATCH);
                     if (p.info.protectionLevel == PermissionInfo.PROTECTION_SIGNATURE_OR_SYSTEM) {
                         if ((pkg.applicationInfo.flags&ApplicationInfo.FLAG_SYSTEM) != 0) {
@@ -3556,7 +3588,8 @@ class PackageManagerService extends IPackageManager.Stub {
         // First find the old package info and check signatures
         synchronized(mPackages) {
             oldPackage = mPackages.get(pkgName);
-            if(checkSignaturesLP(pkg, oldPackage) != PackageManager.SIGNATURE_MATCH) {
+            if(checkSignaturesLP(pkg.mSignatures, oldPackage.mSignatures)
+                    != PackageManager.SIGNATURE_MATCH) {
                 res.returnCode = PackageManager.INSTALL_PARSE_FAILED_INCONSISTENT_CERTIFICATES;
                 return;
             }
diff --git a/test-runner/android/test/mock/MockPackageManager.java b/test-runner/android/test/mock/MockPackageManager.java
index 63a177ec39705..4a50c5dac7197 100644
--- a/test-runner/android/test/mock/MockPackageManager.java
+++ b/test-runner/android/test/mock/MockPackageManager.java
@@ -138,6 +138,11 @@ public class MockPackageManager extends PackageManager {
         throw new UnsupportedOperationException();
     }
 
+    @Override
+    public int checkSignatures(int uid1, int uid2) {
+        throw new UnsupportedOperationException();
+    }
+
     @Override
     public String[] getPackagesForUid(int uid) {
         throw new UnsupportedOperationException();