diff options
Diffstat (limited to 'app/src/main/kotlin/com/pitchedapps/frost/utils/iab/Security.java')
-rw-r--r-- | app/src/main/kotlin/com/pitchedapps/frost/utils/iab/Security.java | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/app/src/main/kotlin/com/pitchedapps/frost/utils/iab/Security.java b/app/src/main/kotlin/com/pitchedapps/frost/utils/iab/Security.java new file mode 100644 index 00000000..ba10e695 --- /dev/null +++ b/app/src/main/kotlin/com/pitchedapps/frost/utils/iab/Security.java @@ -0,0 +1,121 @@ +/* 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.pitchedapps.frost.utils.iab; + +import android.text.TextUtils; +import android.util.Base64; +import android.util.Log; + +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, Base64.DEFAULT); + 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); + } + } + + /** + * 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) { + byte[] signatureBytes; + try { + signatureBytes = Base64.decode(signature, Base64.DEFAULT); + } catch (IllegalArgumentException e) { + Log.e(TAG, "Base64 decoding failed."); + return false; + } + try { + Signature sig = Signature.getInstance(SIGNATURE_ALGORITHM); + sig.initVerify(publicKey); + sig.update(signedData.getBytes()); + if (!sig.verify(signatureBytes)) { + 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."); + } + return false; + } +} |