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Add support for XEP-XXXX: OMEMO Media Sharing
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smack-core/src/main/java/org/jivesoftware/smack/util/RandomUtils.java
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| /** | ||
| * | ||
| * Copyright © 2019 Paul Schaub | ||
| * | ||
| * 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 org.jivesoftware.smack.util; | ||
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| import java.security.SecureRandom; | ||
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| public class RandomUtils { | ||
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| private static final SecureRandom SECURE_RANDOM = new SecureRandom(); | ||
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| /** | ||
| * Generate a securely random byte array. | ||
| * | ||
| * @param len length of the byte array | ||
| * @return byte array | ||
| */ | ||
| public static byte[] secureRandomBytes(int len) { | ||
| byte[] bytes = new byte[len]; | ||
| SECURE_RANDOM.nextBytes(bytes); | ||
| return bytes; | ||
| } | ||
| } |
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161
smack-experimental/src/main/java/org/jivesoftware/smackx/omemo_media_sharing/AesgcmUrl.java
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| /** | ||
| * | ||
| * Copyright © 2019 Paul Schaub | ||
| * | ||
| * 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 org.jivesoftware.smackx.omemo_media_sharing; | ||
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| import java.net.MalformedURLException; | ||
| import java.net.URL; | ||
| import java.security.InvalidAlgorithmParameterException; | ||
| import java.security.InvalidKeyException; | ||
| import java.security.NoSuchAlgorithmException; | ||
| import javax.crypto.Cipher; | ||
| import javax.crypto.NoSuchPaddingException; | ||
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| import org.jivesoftware.smack.util.Objects; | ||
| import org.jivesoftware.smack.util.StringUtils; | ||
| import org.jivesoftware.smackx.httpfileupload.element.Slot; | ||
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| /** | ||
| * This class represents a aesgcm URL as described in XEP-XXXX: OMEMO Media Sharing. | ||
| * As the builtin {@link URL} class cannot handle the aesgcm protocol identifier, this class | ||
| * is used as a utility class that bundles together a {@link URL}, key and IV. | ||
| * | ||
| * @see <a href="https://xmpp.org/extensions/inbox/omemo-media-sharing.html">XEP-XXXX: OMEMO Media Sharing</a> | ||
| */ | ||
| public class AesgcmUrl { | ||
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| public static final String PROTOCOL = "aesgcm"; | ||
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| private final URL httpsUrl; | ||
| private final byte[] keyBytes; | ||
| private final byte[] ivBytes; | ||
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| /** | ||
| * Private constructor that constructs the {@link AesgcmUrl} from a normal https {@link URL}, a key and iv. | ||
| * | ||
| * @param httpsUrl normal https url as given by the {@link Slot}. | ||
| * @param key byte array of an encoded 256 bit aes key | ||
| * @param iv 16 or 12 byte initialization vector | ||
| */ | ||
| public AesgcmUrl(URL httpsUrl, byte[] key, byte[] iv) { | ||
| this.httpsUrl = Objects.requireNonNull(httpsUrl); | ||
| this.keyBytes = Objects.requireNonNull(key); | ||
| this.ivBytes = Objects.requireNonNull(iv); | ||
| } | ||
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| /** | ||
| * Parse a {@link AesgcmUrl} from a {@link String}. | ||
| * The parsed object will provide a normal {@link URL} under which the offered file can be downloaded, | ||
| * as well as a {@link Cipher} that can be used to decrypt it. | ||
| * | ||
| * @param aesgcmUrlString aesgcm URL as a {@link String} | ||
| */ | ||
| public AesgcmUrl(String aesgcmUrlString) { | ||
| if (!aesgcmUrlString.startsWith(PROTOCOL)) { | ||
| throw new IllegalArgumentException("Provided String does not resemble a aesgcm URL."); | ||
| } | ||
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| // Convert aesgcm Url to https URL | ||
| this.httpsUrl = extractHttpsUrl(aesgcmUrlString); | ||
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| // Extract IV and Key | ||
| byte[][] ivAndKey = extractIVAndKey(aesgcmUrlString); | ||
| this.ivBytes = ivAndKey[0]; | ||
| this.keyBytes = ivAndKey[1]; | ||
| } | ||
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| /** | ||
| * Return a https {@link URL} under which the file can be downloaded. | ||
| * | ||
| * @return https URL | ||
| */ | ||
| public URL getDownloadUrl() { | ||
| return httpsUrl; | ||
| } | ||
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| /** | ||
| * Returns the {@link String} representation of this aesgcm URL. | ||
| * | ||
| * @return aesgcm URL with key and IV. | ||
| */ | ||
| public String getAesgcmUrl() { | ||
| String aesgcmUrl = httpsUrl.toString().replaceFirst(httpsUrl.getProtocol(), PROTOCOL); | ||
| return aesgcmUrl + "#" + StringUtils.encodeHex(ivBytes) + StringUtils.encodeHex(keyBytes); | ||
| } | ||
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| /** | ||
| * Returns a {@link Cipher} in decryption mode, which can be used to decrypt the offered file. | ||
| * | ||
| * @return cipher | ||
| * | ||
| * @throws NoSuchPaddingException if the JVM cannot provide the specified cipher mode | ||
| * @throws NoSuchAlgorithmException if the JVM cannot provide the specified cipher mode | ||
| * @throws InvalidAlgorithmParameterException if the JVM cannot provide the specified cipher | ||
| * (eg. if no BC provider is added) | ||
| * @throws InvalidKeyException if the provided key is invalid | ||
| */ | ||
| public Cipher getDecryptionCipher() throws NoSuchPaddingException, NoSuchAlgorithmException, | ||
| InvalidAlgorithmParameterException, InvalidKeyException { | ||
| return OmemoMediaSharingUtils.decryptionCipherFrom(keyBytes, ivBytes); | ||
| } | ||
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| private static URL extractHttpsUrl(String aesgcmUrlString) { | ||
| // aesgcm -> https | ||
| String httpsUrlString = aesgcmUrlString.replaceFirst(PROTOCOL, "https"); | ||
| // remove #ref | ||
| httpsUrlString = httpsUrlString.substring(0, httpsUrlString.indexOf("#")); | ||
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| try { | ||
| return new URL(httpsUrlString); | ||
| } catch (MalformedURLException e) { | ||
| throw new AssertionError("Failed to convert aesgcm URL to https URL: '" + aesgcmUrlString + "'", e); | ||
| } | ||
| } | ||
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| private static byte[][] extractIVAndKey(String aesgcmUrlString) { | ||
| int startOfRef = aesgcmUrlString.lastIndexOf("#"); | ||
| if (startOfRef == -1) { | ||
| throw new IllegalArgumentException("The provided aesgcm Url does not have a ref part which is " + | ||
| "supposed to contain the encryption key for file encryption."); | ||
| } | ||
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| String ref = aesgcmUrlString.substring(startOfRef + 1); | ||
| byte[] refBytes = StringUtils.hexStringToByteArray(ref); | ||
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| byte[] key = new byte[32]; | ||
| byte[] iv; | ||
| int ivLen; | ||
| // determine the length of the initialization vector part | ||
| switch (refBytes.length) { | ||
| // 32 bytes key + 16 bytes IV | ||
| case 48: | ||
| ivLen = 16; | ||
| break; | ||
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| // 32 bytes key + 12 bytes IV | ||
| case 44: | ||
| ivLen = 12; | ||
| break; | ||
| default: | ||
| throw new IllegalArgumentException("Provided URL has an invalid ref tag (" + ref.length() + "): '" + ref + "'"); | ||
| } | ||
| iv = new byte[ivLen]; | ||
| System.arraycopy(refBytes, 0, iv, 0, ivLen); | ||
| System.arraycopy(refBytes, ivLen, key, 0, 32); | ||
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| return new byte[][] {iv, key}; | ||
| } | ||
| } |
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