99 lines
3.6 KiB
Java
99 lines
3.6 KiB
Java
package org.thoughtcrime.securesms.glide.cache;
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import androidx.annotation.NonNull;
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import org.thoughtcrime.securesms.util.Util;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.OutputStream;
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import java.security.InvalidAlgorithmParameterException;
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import java.security.InvalidKeyException;
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import java.security.MessageDigest;
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import java.security.NoSuchAlgorithmException;
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import javax.crypto.Cipher;
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import javax.crypto.CipherInputStream;
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import javax.crypto.CipherOutputStream;
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import javax.crypto.Mac;
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import javax.crypto.NoSuchPaddingException;
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import javax.crypto.spec.IvParameterSpec;
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import javax.crypto.spec.SecretKeySpec;
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class EncryptedCoder {
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private static byte[] MAGIC_BYTES = {(byte)0x91, (byte)0x5e, (byte)0x6d, (byte)0xb4,
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(byte)0x09, (byte)0xa6, (byte)0x68, (byte)0xbe,
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(byte)0xe5, (byte)0xb1, (byte)0x1b, (byte)0xd7,
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(byte)0x29, (byte)0xe5, (byte)0x04, (byte)0xcc};
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OutputStream createEncryptedOutputStream(@NonNull byte[] masterKey, @NonNull File file)
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throws IOException
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{
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try {
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byte[] random = Util.getSecretBytes(32);
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Mac mac = Mac.getInstance("HmacSHA256");
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mac.init(new SecretKeySpec(masterKey, "HmacSHA256"));
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FileOutputStream fileOutputStream = new FileOutputStream(file);
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byte[] iv = new byte[16];
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byte[] key = mac.doFinal(random);
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Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
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cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, "AES"), new IvParameterSpec(iv));
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fileOutputStream.write(MAGIC_BYTES);
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fileOutputStream.write(random);
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CipherOutputStream outputStream = new CipherOutputStream(fileOutputStream, cipher);
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outputStream.write(MAGIC_BYTES);
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return outputStream;
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} catch (NoSuchAlgorithmException | InvalidKeyException | NoSuchPaddingException | InvalidAlgorithmParameterException e) {
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throw new AssertionError(e);
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}
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}
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CipherInputStream createEncryptedInputStream(@NonNull byte[] masterKey, @NonNull File file) throws IOException {
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try {
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Mac mac = Mac.getInstance("HmacSHA256");
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mac.init(new SecretKeySpec(masterKey, "HmacSHA256"));
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FileInputStream fileInputStream = new FileInputStream(file);
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byte[] theirMagic = new byte[MAGIC_BYTES.length];
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byte[] theirRandom = new byte[32];
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byte[] theirEncryptedMagic = new byte[MAGIC_BYTES.length];
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Util.readFully(fileInputStream, theirMagic);
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Util.readFully(fileInputStream, theirRandom);
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if (!MessageDigest.isEqual(theirMagic, MAGIC_BYTES)) {
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throw new IOException("Not an encrypted cache file!");
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}
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byte[] iv = new byte[16];
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byte[] key = mac.doFinal(theirRandom);
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Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
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cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"), new IvParameterSpec(iv));
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CipherInputStream inputStream = new CipherInputStream(fileInputStream, cipher);
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Util.readFully(inputStream, theirEncryptedMagic);
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if (!MessageDigest.isEqual(theirEncryptedMagic, MAGIC_BYTES)) {
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throw new IOException("Key change on encrypted cache file!");
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}
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return inputStream;
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} catch (NoSuchAlgorithmException | InvalidKeyException | NoSuchPaddingException | InvalidAlgorithmParameterException e) {
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throw new AssertionError(e);
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}
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}
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}
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