trivialdrivesample/util/Security.java

/* Copyright (c) 2012 Google Inc.
 *
 * 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 com.example.android.trivialdrivesample.util;

import android.text.TextUtils;
import android.util.Log;

import org.json.JSONException;
import org.json.JSONObject;


import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import java.security.Signature;
import java.security.SignatureException;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;

/**
 * Security-related methods. For a secure implementation, all of this code
 * should be implemented on a server that communicates with the
 * application on the device. For the sake of simplicity and clarity of this
 * example, this code is included here and is executed on the device. If you
 * must verify the purchases on the phone, you should obfuscate this code to
 * make it harder for an attacker to replace the code with stubs that treat all
 * purchases as verified.
 */
public class Security {
    private static final String TAG = "IABUtil/Security";

    private static final String KEY_FACTORY_ALGORITHM = "RSA";
    private static final String SIGNATURE_ALGORITHM = "SHA1withRSA";

    /**
     * Verifies that the data was signed with the given signature, and returns
     * the verified purchase. The data is in JSON format and signed
     * with a private key. The data also contains the {@link PurchaseState}
     * and product ID of the purchase.
     * @param base64PublicKey the base64-encoded public key to use for verifying.
     * @param signedData the signed JSON string (signed, not encrypted)
     * @param signature the signature for the data, signed with the private key
     */
    public static boolean verifyPurchase(String base64PublicKey, String signedData, String signature) {
        if (TextUtils.isEmpty(signedData) || TextUtils.isEmpty(base64PublicKey) ||
                TextUtils.isEmpty(signature)) {
            Log.e(TAG, "Purchase verification failed: missing data.");
            return false;
        }

        PublicKey key = Security.generatePublicKey(base64PublicKey);
        return Security.verify(key, signedData, signature);
    }

    /**
     * Generates a PublicKey instance from a string containing the
     * Base64-encoded public key.
     *
     * @param encodedPublicKey Base64-encoded public key
     * @throws IllegalArgumentException if encodedPublicKey is invalid
     */
    public static PublicKey generatePublicKey(String encodedPublicKey) {
        try {
            byte[] decodedKey = Base64.decode(encodedPublicKey);
            KeyFactory keyFactory = KeyFactory.getInstance(KEY_FACTORY_ALGORITHM);
            return keyFactory.generatePublic(new X509EncodedKeySpec(decodedKey));
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        } catch (InvalidKeySpecException e) {
            Log.e(TAG, "Invalid key specification.");
            throw new IllegalArgumentException(e);
        } catch (Base64DecoderException e) {
            Log.e(TAG, "Base64 decoding failed.");
            throw new IllegalArgumentException(e);
        }
    }

    /**
     * Verifies that the signature from the server matches the computed
     * signature on the data.  Returns true if the data is correctly signed.
     *
     * @param publicKey public key associated with the developer account
     * @param signedData signed data from server
     * @param signature server signature
     * @return true if the data and signature match
     */
    public static boolean verify(PublicKey publicKey, String signedData, String signature) {
        Signature sig;
        try {
            sig = Signature.getInstance(SIGNATURE_ALGORITHM);
            sig.initVerify(publicKey);
            sig.update(signedData.getBytes());
            if (!sig.verify(Base64.decode(signature))) {
                Log.e(TAG, "Signature verification failed.");
                return false;
            }
            return true;
        } catch (NoSuchAlgorithmException e) {
            Log.e(TAG, "NoSuchAlgorithmException.");
        } catch (InvalidKeyException e) {
            Log.e(TAG, "Invalid key specification.");
        } catch (SignatureException e) {
            Log.e(TAG, "Signature exception.");
        } catch (Base64DecoderException e) {
            Log.e(TAG, "Base64 decoding failed.");
        }
        return false;
    }
}
1	/* Copyright (c) 2012 Google Inc.
2	*
3	* Licensed under the Apache License, Version 2.0 (the "License");
4	* you may not use this file except in compliance with the License.
5	* You may obtain a copy of the License at
6	*
7	* http://www.apache.org/licenses/LICENSE-2.0
8	*
9	* Unless required by applicable law or agreed to in writing, software
10	* distributed under the License is distributed on an "AS IS" BASIS,
11	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12	* See the License for the specific language governing permissions and
13	* limitations under the License.
14	*/
15
16	package com.example.android.trivialdrivesample.util;
17
18	import android.text.TextUtils;
19	import android.util.Log;
20
21	import org.json.JSONException;
22	import org.json.JSONObject;
23
24
25	import java.security.InvalidKeyException;
26	import java.security.KeyFactory;
27	import java.security.NoSuchAlgorithmException;
28	import java.security.PublicKey;
29	import java.security.Signature;
30	import java.security.SignatureException;
31	import java.security.spec.InvalidKeySpecException;
32	import java.security.spec.X509EncodedKeySpec;
33
34	/**
35	* Security-related methods. For a secure implementation, all of this code
36	* should be implemented on a server that communicates with the
37	* application on the device. For the sake of simplicity and clarity of this
38	* example, this code is included here and is executed on the device. If you
39	* must verify the purchases on the phone, you should obfuscate this code to
40	* make it harder for an attacker to replace the code with stubs that treat all
41	* purchases as verified.
42	*/
43	public class Security {
44	private static final String TAG = "IABUtil/Security";
45
46	private static final String KEY_FACTORY_ALGORITHM = "RSA";
47	private static final String SIGNATURE_ALGORITHM = "SHA1withRSA";
48
49	/**
50	* Verifies that the data was signed with the given signature, and returns
51	* the verified purchase. The data is in JSON format and signed
52	* with a private key. The data also contains the {@link PurchaseState}
53	* and product ID of the purchase.
54	* @param base64PublicKey the base64-encoded public key to use for verifying.
55	* @param signedData the signed JSON string (signed, not encrypted)
56	* @param signature the signature for the data, signed with the private key
57	*/
58	public static boolean verifyPurchase(String base64PublicKey, String signedData, String signature) {
59	if (TextUtils.isEmpty(signedData) \|\| TextUtils.isEmpty(base64PublicKey) \|\|
60	TextUtils.isEmpty(signature)) {
61	Log.e(TAG, "Purchase verification failed: missing data.");
62	return false;
63	}
64
65	PublicKey key = Security.generatePublicKey(base64PublicKey);
66	return Security.verify(key, signedData, signature);
67	}
68
69	/**
70	* Generates a PublicKey instance from a string containing the
71	* Base64-encoded public key.
72	*
73	* @param encodedPublicKey Base64-encoded public key
74	* @throws IllegalArgumentException if encodedPublicKey is invalid
75	*/
76	public static PublicKey generatePublicKey(String encodedPublicKey) {
77	try {
78	byte[] decodedKey = Base64.decode(encodedPublicKey);
79	KeyFactory keyFactory = KeyFactory.getInstance(KEY_FACTORY_ALGORITHM);
80	return keyFactory.generatePublic(new X509EncodedKeySpec(decodedKey));
81	} catch (NoSuchAlgorithmException e) {
82	throw new RuntimeException(e);
83	} catch (InvalidKeySpecException e) {
84	Log.e(TAG, "Invalid key specification.");
85	throw new IllegalArgumentException(e);
86	} catch (Base64DecoderException e) {
87	Log.e(TAG, "Base64 decoding failed.");
88	throw new IllegalArgumentException(e);
89	}
90	}
91
92	/**
93	* Verifies that the signature from the server matches the computed
94	* signature on the data. Returns true if the data is correctly signed.
95	*
96	* @param publicKey public key associated with the developer account
97	* @param signedData signed data from server
98	* @param signature server signature
99	* @return true if the data and signature match
100	*/
101	public static boolean verify(PublicKey publicKey, String signedData, String signature) {
102	Signature sig;
103	try {
104	sig = Signature.getInstance(SIGNATURE_ALGORITHM);
105	sig.initVerify(publicKey);
106	sig.update(signedData.getBytes());
107	if (!sig.verify(Base64.decode(signature))) {
108	Log.e(TAG, "Signature verification failed.");
109	return false;
110	}
111	return true;
112	} catch (NoSuchAlgorithmException e) {
113	Log.e(TAG, "NoSuchAlgorithmException.");
114	} catch (InvalidKeyException e) {
115	Log.e(TAG, "Invalid key specification.");
116	} catch (SignatureException e) {
117	Log.e(TAG, "Signature exception.");
118	} catch (Base64DecoderException e) {
119	Log.e(TAG, "Base64 decoding failed.");
120	}
121	return false;
122	}
123	}