CryptoAPIDecryptor.java
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this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
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package org.apache.poi.poifs.crypt.cryptoapi;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import org.apache.commons.io.input.BoundedInputStream;
import org.apache.poi.EncryptedDocumentException;
import org.apache.poi.poifs.crypt.ChunkedCipherInputStream;
import org.apache.poi.poifs.crypt.CryptoFunctions;
import org.apache.poi.poifs.crypt.Decryptor;
import org.apache.poi.poifs.crypt.EncryptionHeader;
import org.apache.poi.poifs.crypt.EncryptionInfo;
import org.apache.poi.poifs.crypt.EncryptionVerifier;
import org.apache.poi.poifs.crypt.HashAlgorithm;
import org.apache.poi.poifs.filesystem.DirectoryNode;
import org.apache.poi.poifs.filesystem.DocumentInputStream;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.util.BitField;
import org.apache.poi.util.BitFieldFactory;
import org.apache.poi.util.IOUtils;
import org.apache.poi.util.LittleEndian;
import org.apache.poi.util.LittleEndianInputStream;
import org.apache.poi.util.StringUtil;
public class CryptoAPIDecryptor extends Decryptor {
/**
* The fixed part of a stream descriptor entry: streamOffset (4), streamSize (4), block (2),
* nameSize (1), flags (1), reserved2 (4) and the trailing terminator (2). The stream name
* adds 2 bytes per character on top of this, so this is the smallest an entry can be.
*/
private static final int STREAM_DESCRIPTOR_MIN_SIZE = 18;
private long length = -1L;
private int chunkSize = -1;
static class StreamDescriptorEntry {
static final BitField flagStream = BitFieldFactory.getInstance(1);
int streamOffset;
int streamSize;
int block;
int flags;
int reserved2;
String streamName;
}
protected CryptoAPIDecryptor() {}
protected CryptoAPIDecryptor(CryptoAPIDecryptor other) {
super(other);
length = other.length;
chunkSize = other.chunkSize;
}
@Override
public boolean verifyPassword(String password) {
EncryptionVerifier ver = getEncryptionInfo().getVerifier();
SecretKey skey = generateSecretKey(password, ver);
try {
Cipher cipher = initCipherForBlock(null, 0, getEncryptionInfo(), skey, Cipher.DECRYPT_MODE);
byte[] encryptedVerifier = ver.getEncryptedVerifier();
byte[] verifier = new byte[encryptedVerifier.length];
cipher.update(encryptedVerifier, 0, encryptedVerifier.length, verifier);
setVerifier(verifier);
byte[] encryptedVerifierHash = ver.getEncryptedVerifierHash();
byte[] verifierHash = cipher.doFinal(encryptedVerifierHash);
HashAlgorithm hashAlgo = ver.getHashAlgorithm();
MessageDigest hashAlg = CryptoFunctions.getMessageDigest(hashAlgo);
byte[] calcVerifierHash = hashAlg.digest(verifier);
if (Arrays.equals(calcVerifierHash, verifierHash)) {
setSecretKey(skey);
return true;
}
} catch (GeneralSecurityException e) {
throw new EncryptedDocumentException(e);
}
return false;
}
@Override
public Cipher initCipherForBlock(Cipher cipher, int block)
throws GeneralSecurityException {
EncryptionInfo ei = getEncryptionInfo();
SecretKey sk = getSecretKey();
return initCipherForBlock(cipher, block, ei, sk, Cipher.DECRYPT_MODE);
}
protected static Cipher initCipherForBlock(Cipher cipher, int block,
EncryptionInfo encryptionInfo, SecretKey skey, int encryptMode)
throws GeneralSecurityException {
EncryptionVerifier ver = encryptionInfo.getVerifier();
HashAlgorithm hashAlgo = ver.getHashAlgorithm();
byte[] blockKey = new byte[4];
LittleEndian.putUInt(blockKey, 0, block);
MessageDigest hashAlg = CryptoFunctions.getMessageDigest(hashAlgo);
hashAlg.update(skey.getEncoded());
byte[] encKey = hashAlg.digest(blockKey);
EncryptionHeader header = encryptionInfo.getHeader();
int keyBits = header.getKeySize();
encKey = CryptoFunctions.getBlock0(encKey, keyBits / 8);
if (keyBits == 40) {
encKey = CryptoFunctions.getBlock0(encKey, 16);
}
SecretKey key = new SecretKeySpec(encKey, skey.getAlgorithm());
if (cipher == null) {
cipher = CryptoFunctions.getCipher(key, header.getCipherAlgorithm(), null, null, encryptMode);
} else {
cipher.init(encryptMode, key);
}
return cipher;
}
protected static SecretKey generateSecretKey(String password, EncryptionVerifier ver) {
if (password == null) {
throw new IllegalArgumentException("Did not receive a password");
}
if (password.length() > 255) {
password = password.substring(0, 255);
}
HashAlgorithm hashAlgo = ver.getHashAlgorithm();
MessageDigest hashAlg = CryptoFunctions.getMessageDigest(hashAlgo);
hashAlg.update(ver.getSalt());
byte[] hash = hashAlg.digest(StringUtil.getToUnicodeLE(password));
return new SecretKeySpec(hash, ver.getCipherAlgorithm().jceId);
}
@Override
public ChunkedCipherInputStream getDataStream(DirectoryNode dir)
throws IOException, GeneralSecurityException {
throw new IOException("not supported");
}
@Override
public ChunkedCipherInputStream getDataStream(InputStream stream, int size, int initialPos)
throws IOException, GeneralSecurityException {
return new CryptoAPICipherInputStream(stream, size, initialPos);
}
/**
* Decrypt the Document-/SummaryInformation and other optionally streams.
* Opposed to other crypto modes, cryptoapi is record based and can't be used
* to stream-decrypt a whole file.<p>
*
* Summary entries are only encrypted within cryptoapi encrypted files.
* Binary RC4 encrypted files use non-encrypted/default property sets
*
* @param root root directory node of the OLE file containing the encrypted properties
* @param encryptedStream name of the encrypted stream -
* "encryption" for HSSF/HWPF, "encryptedStream" (or encryptedSummary?) for HSLF
*
* @see <a href="http://msdn.microsoft.com/en-us/library/dd943321(v=office.12).aspx">2.3.5.4 RC4 CryptoAPI Encrypted Summary Stream</a>
*/
public POIFSFileSystem getSummaryEntries(DirectoryNode root, String encryptedStream)
throws IOException, GeneralSecurityException {
POIFSFileSystem fsOut = null;
final byte[] summary = readEncryptedStream(root, encryptedStream);
try (
CryptoAPIDocumentInputStream sbis = new CryptoAPIDocumentInputStream(this, summary);
LittleEndianInputStream leis = new LittleEndianInputStream(sbis)
) {
int streamDescriptorArrayOffset = Math.toIntExact(leis.readUInt());
/* int streamDescriptorArraySize = (int) */ leis.readUInt();
long skipN = streamDescriptorArrayOffset - 8L;
if (sbis.skip(skipN) < skipN) {
throw new EOFException("buffer underrun");
}
sbis.setBlock(0);
// The descriptor count is an unsigned 32-bit field. The stream is already fully read
// and every entry takes at least STREAM_DESCRIPTOR_MIN_SIZE bytes, so a count larger
// than the bytes left after it cannot be honest. Checking it up front fails fast with
// a useful message; the entries are then collected as they are parsed rather than
// pre-allocated, so memory stays proportional to the data present.
final long encryptedStreamDescriptorCount = leis.readUInt();
// the array starts at streamDescriptorArrayOffset and the count is its first 4 bytes
final long remaining = summary.length - (streamDescriptorArrayOffset + 4L);
final long maxDescriptorCount = remaining / STREAM_DESCRIPTOR_MIN_SIZE;
if (encryptedStreamDescriptorCount > maxDescriptorCount) {
throw new IOException("Declared stream descriptor count "
+ encryptedStreamDescriptorCount + " exceeds the " + maxDescriptorCount
+ " entries that the remaining " + remaining + " bytes can hold");
}
List<StreamDescriptorEntry> entries = new ArrayList<>();
for (long i = 0; i < encryptedStreamDescriptorCount; i++) {
StreamDescriptorEntry entry = new StreamDescriptorEntry();
entries.add(entry);
entry.streamOffset = Math.toIntExact(leis.readUInt());
entry.streamSize = Math.toIntExact(leis.readUInt());
entry.block = leis.readUShort();
int nameSize = leis.readUByte();
entry.flags = leis.readUByte();
// boolean isStream = StreamDescriptorEntry.flagStream.isSet(entry.flags);
entry.reserved2 = leis.readInt();
entry.streamName = StringUtil.readUnicodeLE(leis, nameSize);
leis.readShort();
assert(entry.streamName.length() == nameSize);
}
fsOut = new POIFSFileSystem(); // NOSONAR
for (StreamDescriptorEntry entry : entries) {
sbis.seek(entry.streamOffset);
sbis.setBlock(entry.block);
try (InputStream is = BoundedInputStream.builder().setInputStream(sbis).setMaxCount(entry.streamSize).get()) {
fsOut.createDocument(is, entry.streamName);
}
}
} catch (Exception e) {
IOUtils.closeQuietly(fsOut);
if (e instanceof GeneralSecurityException gse) {
throw gse;
} else if (e instanceof IOException ioe) {
throw ioe;
} else {
throw new IOException("summary entries can't be read", e);
}
}
return fsOut;
}
private static byte[] readEncryptedStream(DirectoryNode root, String encryptedStream) throws IOException {
try (DocumentInputStream dis =
root.createDocumentInputStream(root.getEntryCaseInsensitive(encryptedStream))) {
return IOUtils.toByteArray(dis);
}
}
/**
* @return the length of the stream returned by {@link #getDataStream(DirectoryNode)}
*/
@Override
public long getLength() {
if (length == -1L) {
throw new IllegalStateException("Decryptor.getDataStream() was not called");
}
return length;
}
@Override
public void setChunkSize(int chunkSize) {
this.chunkSize = chunkSize;
}
@Override
public CryptoAPIDecryptor copy() {
return new CryptoAPIDecryptor(this);
}
private class CryptoAPICipherInputStream extends ChunkedCipherInputStream {
@Override
protected Cipher initCipherForBlock(Cipher existing, int block)
throws GeneralSecurityException {
return CryptoAPIDecryptor.this.initCipherForBlock(existing, block);
}
public CryptoAPICipherInputStream(InputStream stream, long size, int initialPos)
throws GeneralSecurityException {
super(stream, size, chunkSize, initialPos);
}
}
}