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Android example source code file (CertificateValidatorCache.java)

This example Android source code file (CertificateValidatorCache.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

android, cache_entry_lifetime, cacheentry, certificatefactory, certificatevalidatorcache, certpath, generalsecurityexception, hashmap, integer, os, random, security, sha1messagedigest, string, util

The CertificateValidatorCache.java Android example source code

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.net.http;

import android.os.SystemClock;

import android.security.Sha1MessageDigest;

import java.security.cert.Certificate;
import java.security.cert.CertificateFactory;
import java.security.cert.CertPath;
import java.security.GeneralSecurityException;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Random;


/**
 * Validator cache used to speed-up certificate chain validation. The idea is
 * to keep each secure domain name associated with a cryptographically secure
 * hash of the certificate chain successfully used to validate the domain. If
 * we establish connection with the domain more than once and each time receive
 * the same list of certificates, we do not have to re-validate.
 * 
 * {@hide}
 */
class CertificateValidatorCache {

    // TODO: debug only!
    public static long mSave = 0;
    public static long mCost = 0;
    // TODO: debug only!

    /**
     * The cache-entry lifetime in milliseconds (here, 10 minutes)
     */
    private static final long CACHE_ENTRY_LIFETIME = 10 * 60 * 1000;

    /**
     * The certificate factory
     */
    private static CertificateFactory sCertificateFactory;

    /**
     * The certificate validator cache map (domain to a cache entry)
     */
    private HashMap<Integer, CacheEntry> mCacheMap;

    /**
     * Random salt
     */
    private int mBigScrew;

    /**
     * @param certificate The array of server certificates to compute a
     * secure hash from
     * @return The secure hash computed from server certificates
     */
    public static byte[] secureHash(Certificate[] certificates) {
        byte[] secureHash = null;

        // TODO: debug only!
        long beg = SystemClock.uptimeMillis();
        // TODO: debug only!

        if (certificates != null && certificates.length != 0) {
            byte[] encodedCertPath = null;
            try {
                synchronized (CertificateValidatorCache.class) {
                    if (sCertificateFactory == null) {
                        try {
                            sCertificateFactory =
                                CertificateFactory.getInstance("X.509");
                        } catch(GeneralSecurityException e) {
                            if (HttpLog.LOGV) {
                                HttpLog.v("CertificateValidatorCache:" +
                                          " failed to create the certificate factory");
                            }
                        }
                    }
                }

                CertPath certPath =
                    sCertificateFactory.generateCertPath(Arrays.asList(certificates));
                if (certPath != null) {
                    encodedCertPath = certPath.getEncoded();
                    if (encodedCertPath != null) {
                      Sha1MessageDigest messageDigest =
                          new Sha1MessageDigest();
                      secureHash = messageDigest.digest(encodedCertPath);
                    }
                }
            } catch (GeneralSecurityException e) {}
        }

        // TODO: debug only!
        long end = SystemClock.uptimeMillis();
        mCost += (end - beg);
        // TODO: debug only!

        return secureHash;
    }

    /**
     * Creates a new certificate-validator cache
     */
    public CertificateValidatorCache() {
        Random random = new Random();
        mBigScrew = random.nextInt();

        mCacheMap = new HashMap<Integer, CacheEntry>();
    }

     /**
     * @param domain The domain to check against
     * @param secureHash The secure hash to check against
     * @return True iff there is a valid (not expired) cache entry
     * associated with the domain and the secure hash
     */
    public boolean has(String domain, byte[] secureHash) {
        boolean rval = false;

        if (domain != null && domain.length() != 0) {
            if (secureHash != null && secureHash.length != 0) {
                CacheEntry cacheEntry = (CacheEntry)mCacheMap.get(
                    new Integer(mBigScrew ^ domain.hashCode()));
                if (cacheEntry != null) {
                    if (!cacheEntry.expired()) {
                        rval = cacheEntry.has(domain, secureHash);
                        // TODO: debug only!
                        if (rval) {
                            mSave += cacheEntry.mSave;
                        }
                        // TODO: debug only!
                    } else {
                        mCacheMap.remove(cacheEntry);
                    }
                }
            }
        }

        return rval;
    }

    /**
     * Adds the (domain, secureHash) tuple to the cache
     * @param domain The domain to be added to the cache
     * @param secureHash The secure hash to be added to the cache
     * @return True iff succeeds
     */
    public boolean put(String domain, byte[] secureHash, long save) {
        if (domain != null && domain.length() != 0) {
            if (secureHash != null && secureHash.length != 0) {
                mCacheMap.put(
                    new Integer(mBigScrew ^ domain.hashCode()),
                    new CacheEntry(domain, secureHash, save));

                return true;
            }
        }

        return false;
    }

    /**
     * Certificate-validator cache entry. We have one per domain
     */
    private class CacheEntry {

        /**
         * The hash associated with this cache entry
         */
        private byte[] mHash;

        /**
         * The time associated with this cache entry
         */
        private long mTime;

        // TODO: debug only!
        public long mSave;
        // TODO: debug only!

        /**
         * The host associated with this cache entry
         */
        private String mDomain;

        /**
         * Creates a new certificate-validator cache entry
         * @param domain The domain to be associated with this cache entry
         * @param secureHash The secure hash to be associated with this cache
         * entry
         */
        public CacheEntry(String domain, byte[] secureHash, long save) {
            mDomain = domain;
            mHash = secureHash;
            // TODO: debug only!
            mSave = save;
            // TODO: debug only!
            mTime = SystemClock.uptimeMillis();
        }

        /**
         * @return True iff the cache item has expired
         */
        public boolean expired() {
            return CACHE_ENTRY_LIFETIME < SystemClock.uptimeMillis() - mTime;
        }

        /**
         * @param domain The domain to check
         * @param secureHash The secure hash to check
         * @return True iff the given domain and hash match those associated
         * with this entry
         */
        public boolean has(String domain, byte[] secureHash) {
            if (domain != null && 0 < domain.length()) {
                if (!mDomain.equals(domain)) {
                    return false;
                }
            }

            if (secureHash != null) {
                int hashLength = secureHash.length;
                if (0 < hashLength) {
                    if (hashLength == mHash.length) {
                        for (int i = 0; i < hashLength; ++i) {
                            if (secureHash[i] != mHash[i]) {
                                return false;
                            }
                        }
                        return true;
                    }
                }
            }

            return false;
        }
    }
};

Other Android examples (source code examples)

Here is a short list of links related to this Android CertificateValidatorCache.java source code file:

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