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/*
* Copyright 2004-2019 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.store.fs;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import org.h2.security.AES;
import org.h2.security.BlockCipher;
import org.h2.security.SHA256;
import org.h2.util.MathUtils;
/**
* An encrypted file.
*/
public class FilePathEncrypt extends FilePathWrapper {
private static final String SCHEME = "encrypt";
/**
* Register this file system.
*/
public static void register() {
FilePath.register(new FilePathEncrypt());
}
@Override
public FileChannel open(String mode) throws IOException {
String[] parsed = parse(name);
FileChannel file = FileUtils.open(parsed[1], mode);
byte[] passwordBytes = parsed[0].getBytes(StandardCharsets.UTF_8);
return new FileEncrypt(name, passwordBytes, file);
}
@Override
public String getScheme() {
return SCHEME;
}
@Override
protected String getPrefix() {
String[] parsed = parse(name);
return getScheme() + ":" + parsed[0] + ":";
}
@Override
public FilePath unwrap(String fileName) {
return FilePath.get(parse(fileName)[1]);
}
@Override
public long size() {
long size = getBase().size() - FileEncrypt.HEADER_LENGTH;
size = Math.max(0, size);
if ((size & FileEncrypt.BLOCK_SIZE_MASK) != 0) {
size -= FileEncrypt.BLOCK_SIZE;
}
return size;
}
@Override
public OutputStream newOutputStream(boolean append) throws IOException {
return new FileChannelOutputStream(open("rw"), append);
}
@Override
public InputStream newInputStream() throws IOException {
return new FileChannelInputStream(open("r"), true);
}
/**
* Split the file name into algorithm, password, and base file name.
*
* @param fileName the file name
* @return an array with algorithm, password, and base file name
*/
private String[] parse(String fileName) {
if (!fileName.startsWith(getScheme())) {
throw new IllegalArgumentException(fileName +
" doesn't start with " + getScheme());
}
fileName = fileName.substring(getScheme().length() + 1);
int idx = fileName.indexOf(':');
String password;
if (idx < 0) {
throw new IllegalArgumentException(fileName +
" doesn't contain encryption algorithm and password");
}
password = fileName.substring(0, idx);
fileName = fileName.substring(idx + 1);
return new String[] { password, fileName };
}
/**
* Convert a char array to a byte array, in UTF-16 format. The char array is
* not cleared after use (this must be done by the caller).
*
* @param passwordChars the password characters
* @return the byte array
*/
public static byte[] getPasswordBytes(char[] passwordChars) {
// using UTF-16
int len = passwordChars.length;
byte[] password = new byte[len * 2];
for (int i = 0; i < len; i++) {
char c = passwordChars[i];
password[i + i] = (byte) (c >>> 8);
password[i + i + 1] = (byte) c;
}
return password;
}
/**
* An encrypted file with a read cache.
*/
public static class FileEncrypt extends FileBase {
/**
* The block size.
*/
static final int BLOCK_SIZE = 4096;
/**
* The block size bit mask.
*/
static final int BLOCK_SIZE_MASK = BLOCK_SIZE - 1;
/**
* The length of the file header. Using a smaller header is possible,
* but would mean reads and writes are not aligned to the block size.
*/
static final int HEADER_LENGTH = BLOCK_SIZE;
private static final byte[] HEADER = "H2encrypt\n".getBytes();
private static final int SALT_POS = HEADER.length;
/**
* The length of the salt, in bytes.
*/
private static final int SALT_LENGTH = 8;
/**
* The number of iterations. It is relatively low; a higher value would
* slow down opening files on Android too much.
*/
private static final int HASH_ITERATIONS = 10;
private final FileChannel base;
/**
* The current position within the file, from a user perspective.
*/
private long pos;
/**
* The current file size, from a user perspective.
*/
private long size;
private final String name;
private XTS xts;
private byte[] encryptionKey;
public FileEncrypt(String name, byte[] encryptionKey, FileChannel base) {
// don't do any read or write operations here, because they could
// fail if the file is locked, and we want to give the caller a
// chance to lock the file first
this.name = name;
this.base = base;
this.encryptionKey = encryptionKey;
}
private void init() throws IOException {
if (xts != null) {
return;
}
this.size = base.size() - HEADER_LENGTH;
boolean newFile = size < 0;
byte[] salt;
if (newFile) {
byte[] header = Arrays.copyOf(HEADER, BLOCK_SIZE);
salt = MathUtils.secureRandomBytes(SALT_LENGTH);
System.arraycopy(salt, 0, header, SALT_POS, salt.length);
writeFully(base, 0, ByteBuffer.wrap(header));
size = 0;
} else {
salt = new byte[SALT_LENGTH];
readFully(base, SALT_POS, ByteBuffer.wrap(salt));
if ((size & BLOCK_SIZE_MASK) != 0) {
size -= BLOCK_SIZE;
}
}
AES cipher = new AES();
cipher.setKey(SHA256.getPBKDF2(
encryptionKey, salt, HASH_ITERATIONS, 16));
encryptionKey = null;
xts = new XTS(cipher);
}
@Override
protected void implCloseChannel() throws IOException {
base.close();
}
@Override
public FileChannel position(long newPosition) throws IOException {
this.pos = newPosition;
return this;
}
@Override
public long position() throws IOException {
return pos;
}
@Override
public int read(ByteBuffer dst) throws IOException {
int len = read(dst, pos);
if (len > 0) {
pos += len;
}
return len;
}
@Override
public int read(ByteBuffer dst, long position) throws IOException {
int len = dst.remaining();
if (len == 0) {
return 0;
}
init();
len = (int) Math.min(len, size - position);
if (position >= size) {
return -1;
} else if (position < 0) {
throw new IllegalArgumentException("pos: " + position);
}
if ((position & BLOCK_SIZE_MASK) != 0 ||
(len & BLOCK_SIZE_MASK) != 0) {
// either the position or the len is unaligned:
// read aligned, and then truncate
long p = position / BLOCK_SIZE * BLOCK_SIZE;
int offset = (int) (position - p);
int l = (len + offset + BLOCK_SIZE - 1) / BLOCK_SIZE * BLOCK_SIZE;
ByteBuffer temp = ByteBuffer.allocate(l);
readInternal(temp, p, l);
temp.flip();
temp.limit(offset + len);
temp.position(offset);
dst.put(temp);
return len;
}
readInternal(dst, position, len);
return len;
}
private void readInternal(ByteBuffer dst, long position, int len)
throws IOException {
int x = dst.position();
readFully(base, position + HEADER_LENGTH, dst);
long block = position / BLOCK_SIZE;
while (len > 0) {
xts.decrypt(block++, BLOCK_SIZE, dst.array(), dst.arrayOffset() + x);
x += BLOCK_SIZE;
len -= BLOCK_SIZE;
}
}
private static void readFully(FileChannel file, long pos, ByteBuffer dst)
throws IOException {
do {
int len = file.read(dst, pos);
if (len < 0) {
throw new EOFException();
}
pos += len;
} while (dst.remaining() > 0);
}
@Override
public int write(ByteBuffer src, long position) throws IOException {
init();
int len = src.remaining();
if ((position & BLOCK_SIZE_MASK) != 0 ||
(len & BLOCK_SIZE_MASK) != 0) {
// either the position or the len is unaligned:
// read aligned, and then truncate
long p = position / BLOCK_SIZE * BLOCK_SIZE;
int offset = (int) (position - p);
int l = (len + offset + BLOCK_SIZE - 1) / BLOCK_SIZE * BLOCK_SIZE;
ByteBuffer temp = ByteBuffer.allocate(l);
int available = (int) (size - p + BLOCK_SIZE - 1) / BLOCK_SIZE * BLOCK_SIZE;
int readLen = Math.min(l, available);
if (readLen > 0) {
readInternal(temp, p, readLen);
temp.rewind();
}
temp.limit(offset + len);
temp.position(offset);
temp.put(src);
temp.limit(l);
temp.rewind();
writeInternal(temp, p, l);
long p2 = position + len;
size = Math.max(size, p2);
int plus = (int) (size & BLOCK_SIZE_MASK);
if (plus > 0) {
temp = ByteBuffer.allocate(plus);
writeFully(base, p + HEADER_LENGTH + l, temp);
}
return len;
}
writeInternal(src, position, len);
long p2 = position + len;
size = Math.max(size, p2);
return len;
}
private void writeInternal(ByteBuffer src, long position, int len)
throws IOException {
ByteBuffer crypt = ByteBuffer.allocate(len);
crypt.put(src);
crypt.flip();
long block = position / BLOCK_SIZE;
int x = 0, l = len;
while (l > 0) {
xts.encrypt(block++, BLOCK_SIZE, crypt.array(), crypt.arrayOffset() + x);
x += BLOCK_SIZE;
l -= BLOCK_SIZE;
}
writeFully(base, position + HEADER_LENGTH, crypt);
}
private static void writeFully(FileChannel file, long pos,
ByteBuffer src) throws IOException {
int off = 0;
do {
int len = file.write(src, pos + off);
off += len;
} while (src.remaining() > 0);
}
@Override
public int write(ByteBuffer src) throws IOException {
int len = write(src, pos);
if (len > 0) {
pos += len;
}
return len;
}
@Override
public long size() throws IOException {
init();
return size;
}
@Override
public FileChannel truncate(long newSize) throws IOException {
init();
if (newSize > size) {
return this;
}
if (newSize < 0) {
throw new IllegalArgumentException("newSize: " + newSize);
}
int offset = (int) (newSize & BLOCK_SIZE_MASK);
if (offset > 0) {
base.truncate(newSize + HEADER_LENGTH + BLOCK_SIZE);
} else {
base.truncate(newSize + HEADER_LENGTH);
}
this.size = newSize;
pos = Math.min(pos, size);
return this;
}
@Override
public void force(boolean metaData) throws IOException {
base.force(metaData);
}
@Override
public FileLock tryLock(long position, long size, boolean shared)
throws IOException {
return base.tryLock(position, size, shared);
}
@Override
public String toString() {
return name;
}
}
/**
* An XTS implementation as described in
* IEEE P1619 (Standard Architecture for Encrypted Shared Storage Media).
* See also
* http://axelkenzo.ru/downloads/1619-2007-NIST-Submission.pdf
*/
static class XTS {
/**
* Galois field feedback.
*/
private static final int GF_128_FEEDBACK = 0x87;
/**
* The AES encryption block size.
*/
private static final int CIPHER_BLOCK_SIZE = 16;
private final BlockCipher cipher;
XTS(BlockCipher cipher) {
this.cipher = cipher;
}
/**
* Encrypt the data.
*
* @param id the (sector) id
* @param len the number of bytes
* @param data the data
* @param offset the offset within the data
*/
void encrypt(long id, int len, byte[] data, int offset) {
byte[] tweak = initTweak(id);
int i = 0;
for (; i + CIPHER_BLOCK_SIZE <= len; i += CIPHER_BLOCK_SIZE) {
if (i > 0) {
updateTweak(tweak);
}
xorTweak(data, i + offset, tweak);
cipher.encrypt(data, i + offset, CIPHER_BLOCK_SIZE);
xorTweak(data, i + offset, tweak);
}
if (i < len) {
updateTweak(tweak);
swap(data, i + offset, i - CIPHER_BLOCK_SIZE + offset, len - i);
xorTweak(data, i - CIPHER_BLOCK_SIZE + offset, tweak);
cipher.encrypt(data, i - CIPHER_BLOCK_SIZE + offset, CIPHER_BLOCK_SIZE);
xorTweak(data, i - CIPHER_BLOCK_SIZE + offset, tweak);
}
}
/**
* Decrypt the data.
*
* @param id the (sector) id
* @param len the number of bytes
* @param data the data
* @param offset the offset within the data
*/
void decrypt(long id, int len, byte[] data, int offset) {
byte[] tweak = initTweak(id), tweakEnd = tweak;
int i = 0;
for (; i + CIPHER_BLOCK_SIZE <= len; i += CIPHER_BLOCK_SIZE) {
if (i > 0) {
updateTweak(tweak);
if (i + CIPHER_BLOCK_SIZE + CIPHER_BLOCK_SIZE > len &&
i + CIPHER_BLOCK_SIZE < len) {
tweakEnd = tweak.clone();
updateTweak(tweak);
}
}
xorTweak(data, i + offset, tweak);
cipher.decrypt(data, i + offset, CIPHER_BLOCK_SIZE);
xorTweak(data, i + offset, tweak);
}
if (i < len) {
swap(data, i, i - CIPHER_BLOCK_SIZE + offset, len - i + offset);
xorTweak(data, i - CIPHER_BLOCK_SIZE + offset, tweakEnd);
cipher.decrypt(data, i - CIPHER_BLOCK_SIZE + offset, CIPHER_BLOCK_SIZE);
xorTweak(data, i - CIPHER_BLOCK_SIZE + offset, tweakEnd);
}
}
private byte[] initTweak(long id) {
byte[] tweak = new byte[CIPHER_BLOCK_SIZE];
for (int j = 0; j < CIPHER_BLOCK_SIZE; j++, id >>>= 8) {
tweak[j] = (byte) (id & 0xff);
}
cipher.encrypt(tweak, 0, CIPHER_BLOCK_SIZE);
return tweak;
}
private static void xorTweak(byte[] data, int pos, byte[] tweak) {
for (int i = 0; i < CIPHER_BLOCK_SIZE; i++) {
data[pos + i] ^= tweak[i];
}
}
private static void updateTweak(byte[] tweak) {
byte ci = 0, co = 0;
for (int i = 0; i < CIPHER_BLOCK_SIZE; i++) {
co = (byte) ((tweak[i] >> 7) & 1);
tweak[i] = (byte) (((tweak[i] << 1) + ci) & 255);
ci = co;
}
if (co != 0) {
tweak[0] ^= GF_128_FEEDBACK;
}
}
private static void swap(byte[] data, int source, int target, int len) {
for (int i = 0; i < len; i++) {
byte temp = data[source + i];
data[source + i] = data[target + i];
data[target + i] = temp;
}
}
}
}
