Merge branch 'master' into poljar/python-sas

11 files changed, 574 insertions, 5 deletions

diff --git a/android/olm-sdk/src/main/java/org/matrix/olm/OlmPkSigning.java b/android/olm-sdk/src/main/java/org/matrix/olm/OlmPkSigning.java
new file mode 100644
index 0000000..89cb556
--- /dev/null
+++ b/android/olm-sdk/src/main/java/org/matrix/olm/OlmPkSigning.java
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2019 New Vector Ltd
+ *
+ * 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.matrix.olm;
+
+import android.util.Log;
+
+import java.util.Arrays;
+
+public class OlmPkSigning {
+    private static final String LOG_TAG = "OlmPkSigning";
+
+    /** PK Signing Id returned by JNI.
+     * This value uniquely identifies the native PK signing instance.
+     **/
+    private transient long mNativeId;
+
+    public OlmPkSigning() throws OlmException {
+        try {
+            mNativeId = createNewPkSigningJni();
+        } catch (Exception e) {
+            throw new OlmException(OlmException.EXCEPTION_CODE_PK_SIGNING_CREATION, e.getMessage());
+        }
+    }
+
+    private native long createNewPkSigningJni();
+
+    private native void releasePkSigningJni();
+
+    public void releaseSigning() {
+        if (0 != mNativeId) {
+            releasePkSigningJni();
+        }
+        mNativeId = 0;
+    }
+
+    public boolean isReleased() {
+        return (0 == mNativeId);
+    }
+
+    public static native int seedLength();
+
+    public static byte[] generateSeed() throws OlmException {
+        try {
+            return generateSeedJni();
+        } catch (Exception e) {
+            Log.e(LOG_TAG, "## generateSeed(): failed " + e.getMessage());
+            throw new OlmException(OlmException.EXCEPTION_CODE_PK_SIGNING_GENERATE_SEED, e.getMessage());
+        }
+    }
+
+    public static native byte[] generateSeedJni();
+
+    public String initWithSeed(byte[] seed) throws OlmException {
+        try {
+            byte[] pubKey = setKeyFromSeedJni(seed);
+            return new String(pubKey, "UTF-8");
+        } catch (Exception e) {
+            Log.e(LOG_TAG, "## initWithSeed(): failed " + e.getMessage());
+            throw new OlmException(OlmException.EXCEPTION_CODE_PK_SIGNING_INIT_WITH_SEED, e.getMessage());
+        }
+    }
+
+    public native byte[] setKeyFromSeedJni(byte[] seed);
+
+    public String sign(String aMessage) throws OlmException {
+        if (null == aMessage) {
+            return null;
+        }
+
+        byte[] messageBuffer = null;
+        try {
+            messageBuffer = aMessage.getBytes("UTF-8");
+            byte[] signature = pkSignJni(messageBuffer);
+            return new String(signature, "UTF-8");
+        } catch (Exception e) {
+            Log.e(LOG_TAG, "## pkSign(): failed " + e.getMessage());
+            throw new OlmException(OlmException.EXCEPTION_CODE_PK_SIGNING_SIGN, e.getMessage());
+        } finally {
+            if (null != messageBuffer) {
+                Arrays.fill(messageBuffer, (byte) 0);
+            }
+        }
+    }
+
+    private native byte[] pkSignJni(byte[] message);
+}
diff --git a/include/olm/sas.h b/include/olm/sas.h
index 46d4176..ec90ae7 100644
--- a/include/olm/sas.h
+++ b/include/olm/sas.h
@@ -147,6 +147,14 @@ size_t olm_sas_calculate_mac(
     void * mac, size_t mac_length
 );
 
+// for compatibility with an old version of Riot
+size_t olm_sas_calculate_mac_long_kdf(
+    OlmSAS * sas,
+    void * input, size_t input_length,
+    const void * info, size_t info_length,
+    void * mac, size_t mac_length
+);
+
 /** @} */ // end of SAS group
 
 #ifdef __cplusplus
diff --git a/javascript/olm_sas.js b/javascript/olm_sas.js
index d5044ce..a2f82ee 100644
--- a/javascript/olm_sas.js
+++ b/javascript/olm_sas.js
@@ -75,3 +75,19 @@ SAS.prototype['calculate_mac'] = restore_stack(function(input, info) {
     );
     return Pointer_stringify(mac_buffer);
 });
+
+SAS.prototype['calculate_mac_long_kdf'] = restore_stack(function(input, info) {
+    var input_array = array_from_string(input);
+    var input_buffer = stack(input_array);
+    var info_array = array_from_string(info);
+    var info_buffer = stack(info_array);
+    var mac_length = sas_method(Module['_olm_sas_mac_length'])(this.ptr);
+    var mac_buffer = stack(mac_length + NULL_BYTE_PADDING_LENGTH);
+    sas_method(Module['_olm_sas_calculate_mac_long_kdf'])(
+        this.ptr,
+        input_buffer, input_array.length,
+        info_buffer, info_array.length,
+        mac_buffer, mac_length
+    );
+    return Pointer_stringify(mac_buffer);
+});
diff --git a/python/MANIFEST.in b/python/MANIFEST.in
index bfddd4f..db6309d 100644
--- a/python/MANIFEST.in
+++ b/python/MANIFEST.in
@@ -1,3 +1,4 @@
-include olm.h
+include include/olm/olm.h
+include include/olm/pk.h
 include Makefile
 include olm_build.py
diff --git a/python/Makefile b/python/Makefile
index 6283fb5..e4d0611 100644
--- a/python/Makefile
+++ b/python/Makefile
@@ -1,18 +1,26 @@
 all: olm-python2 olm-python3
 
-include/olm/olm.h: ../include/olm/olm.h ../include/olm/inbound_group_session.h ../include/olm/outbound_group_session.h
+OLM_HEADERS = ../include/olm/olm.h ../include/olm/inbound_group_session.h \
+	      ../include/olm/outbound_group_session.h \
+
+include/olm/olm.h: $(OLM_HEADERS)
 	mkdir -p include/olm
 	$(CPP) -I dummy -I ../include ../include/olm/olm.h -o include/olm/olm.h
 # add memset to the header so that we can use it to clear buffers
 	echo 'void *memset(void *s, int c, size_t n);' >> include/olm/olm.h
 
+include/olm/pk.h: include/olm/olm.h ../include/olm/pk.h
+	$(CPP) -I dummy -I ../include ../include/olm/pk.h -o include/olm/pk.h
+
 include/olm/sas.h: include/olm/olm.h ../include/olm/sas.h
 	$(CPP) -I dummy -I ../include ../include/olm/sas.h -o include/olm/sas.h
 
-olm-python2: include/olm/olm.h include/olm/sas.h
+headers: include/olm/olm.h include/olm/pk.h include/olm/sas.h
+
+olm-python2: headers
 	DEVELOP=$(DEVELOP) python2 setup.py build
 
-olm-python3: include/olm/olm.h include/olm/sas.h
+olm-python3: headers
 	DEVELOP=$(DEVELOP) python3 setup.py build
 
 install: install-python2 install-python3
diff --git a/python/olm/__init__.py b/python/olm/__init__.py
index 9ac45b0..d92b0ab 100644
--- a/python/olm/__init__.py
+++ b/python/olm/__init__.py
@@ -36,4 +36,11 @@ from .group_session import (
     OutboundGroupSession,
     OlmGroupSessionError
 )
+from .pk import (
+    PkMessage,
+    PkEncryption,
+    PkDecryption,
+    PkEncryptionError,
+    PkDecryptionError
+)
 from .sas import Sas, OlmSasError
diff --git a/python/olm/pk.py b/python/olm/pk.py
new file mode 100644
index 0000000..b67d5a4
--- /dev/null
+++ b/python/olm/pk.py
@@ -0,0 +1,346 @@
+# -*- coding: utf-8 -*-
+# libolm python bindings
+# Copyright © 2018 Damir Jelić <poljar@termina.org.uk>
+#
+# 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.
+"""libolm PK module.
+
+This module contains bindings to the PK part of the Olm library.
+It contains two classes PkDecryption and PkEncryption that are used to
+establish an encrypted communication channel using public key encryption.
+
+Examples:
+    >>> decryption = PkDecryption()
+    >>> encryption = PkEncryption(decryption.public_key)
+    >>> plaintext = "It's a secret to everybody."
+    >>> message = encryption.encrypt(plaintext)
+    >>> decrypted_plaintext = decryption.decrypt(message)
+
+"""
+
+from builtins import super
+from typing import AnyStr, Type
+from future.utils import bytes_to_native_str
+
+from _libolm import ffi, lib  # type: ignore
+from ._finalize import track_for_finalization
+from ._compat import URANDOM, to_bytearray
+
+
+class PkEncryptionError(Exception):
+    """libolm Pk encryption exception."""
+
+
+class PkDecryptionError(Exception):
+    """libolm Pk decryption exception."""
+
+
+def _clear_pk_encryption(pk_struct):
+    lib.olm_clear_pk_encryption(pk_struct)
+
+
+class PkMessage(object):
+    """A PK encrypted message."""
+
+    def __init__(self, ephemeral_key, mac, ciphertext):
+        # type: (str, str, str) -> None
+        """Create a new PK encrypted message.
+
+        Args:
+            ephemeral_key(str): the public part of the ephemeral key
+            used (together with the recipient's key) to generate a symmetric
+            encryption key.
+            mac(str): Message Authentication Code of the encrypted message
+            ciphertext(str): The cipher text of the encrypted message
+        """
+        self.ephemeral_key = ephemeral_key
+        self.mac = mac
+        self.ciphertext = ciphertext
+
+
+class PkEncryption(object):
+    """PkEncryption class.
+
+    Represents the decryption part of a PK encrypted channel.
+    """
+
+    def __init__(self, recipient_key):
+        # type: (AnyStr) -> None
+        """Create a new PK encryption object.
+
+        Args:
+            recipient_key(str): a public key that will be used for encryption
+        """
+        if not recipient_key:
+            raise ValueError("Recipient key can't be empty")
+
+        self._buf = ffi.new("char[]", lib.olm_pk_encryption_size())
+        self._pk_encryption = lib.olm_pk_encryption(self._buf)
+        track_for_finalization(self, self._pk_encryption, _clear_pk_encryption)
+
+        byte_key = to_bytearray(recipient_key)
+        lib.olm_pk_encryption_set_recipient_key(
+            self._pk_encryption,
+            ffi.from_buffer(byte_key),
+            len(byte_key)
+        )
+
+        # clear out copies of the key
+        if byte_key is not recipient_key:  # pragma: no cover
+            for i in range(0, len(byte_key)):
+                byte_key[i] = 0
+
+    def _check_error(self, ret):  # pragma: no cover
+        # type: (int) -> None
+        if ret != lib.olm_error():
+            return
+
+        last_error = bytes_to_native_str(
+            ffi.string(lib.olm_pk_encryption_last_error(self._pk_encryption)))
+
+        raise PkEncryptionError(last_error)
+
+    def encrypt(self, plaintext):
+        # type: (AnyStr) -> PkMessage
+        """Encrypt a message.
+
+        Returns the encrypted PkMessage.
+
+        Args:
+            plaintext(str): A string that will be encrypted using the
+            PkEncryption object.
+        """
+        byte_plaintext = to_bytearray(plaintext)
+
+        r_length = lib.olm_pk_encrypt_random_length(self._pk_encryption)
+        random = URANDOM(r_length)
+        random_buffer = ffi.new("char[]", random)
+
+        ciphertext_length = lib.olm_pk_ciphertext_length(
+            self._pk_encryption, len(byte_plaintext)
+        )
+        ciphertext = ffi.new("char[]", ciphertext_length)
+
+        mac_length = lib.olm_pk_mac_length(self._pk_encryption)
+        mac = ffi.new("char[]", mac_length)
+
+        ephemeral_key_size = lib.olm_pk_key_length()
+        ephemeral_key = ffi.new("char[]", ephemeral_key_size)
+
+        ret = lib.olm_pk_encrypt(
+            self._pk_encryption,
+            ffi.from_buffer(byte_plaintext), len(byte_plaintext),
+            ciphertext, ciphertext_length,
+            mac, mac_length,
+            ephemeral_key, ephemeral_key_size,
+            random_buffer, r_length
+        )
+
+        try:
+            self._check_error(ret)
+        finally:  # pragma: no cover
+            # clear out copies of plaintext
+            if byte_plaintext is not plaintext:
+                for i in range(0, len(byte_plaintext)):
+                    byte_plaintext[i] = 0
+
+        message = PkMessage(
+            bytes_to_native_str(
+                ffi.unpack(ephemeral_key, ephemeral_key_size)),
+            bytes_to_native_str(
+                ffi.unpack(mac, mac_length)),
+            bytes_to_native_str(
+                ffi.unpack(ciphertext, ciphertext_length))
+        )
+        return message
+
+
+def _clear_pk_decryption(pk_struct):
+    lib.olm_clear_pk_decryption(pk_struct)
+
+
+class PkDecryption(object):
+    """PkDecryption class.
+
+    Represents the decryption part of a PK encrypted channel.
+
+    Attributes:
+        public_key (str): The public key of the PkDecryption object, can be
+            shared and used to create a PkEncryption object.
+
+    """
+
+    def __new__(cls):
+        # type: (Type[PkDecryption]) -> PkDecryption
+        obj = super().__new__(cls)
+        obj._buf = ffi.new("char[]", lib.olm_pk_decryption_size())
+        obj._pk_decryption = lib.olm_pk_decryption(obj._buf)
+        obj.public_key = None
+        track_for_finalization(obj, obj._pk_decryption, _clear_pk_decryption)
+        return obj
+
+    def __init__(self):
+        if False:  # pragma: no cover
+            self._pk_decryption = self._pk_decryption  # type: ffi.cdata
+
+        random_length = lib.olm_pk_private_key_length()
+        random = URANDOM(random_length)
+        random_buffer = ffi.new("char[]", random)
+
+        key_length = lib.olm_pk_key_length()
+        key_buffer = ffi.new("char[]", key_length)
+
+        ret = lib.olm_pk_key_from_private(
+            self._pk_decryption,
+            key_buffer, key_length,
+            random_buffer, random_length
+        )
+        self._check_error(ret)
+        self.public_key = bytes_to_native_str(ffi.unpack(
+            key_buffer,
+            key_length
+        ))
+
+    def _check_error(self, ret):
+        # type: (int) -> None
+        if ret != lib.olm_error():
+            return
+
+        last_error = bytes_to_native_str(
+            ffi.string(lib.olm_pk_decryption_last_error(self._pk_decryption)))
+
+        raise PkDecryptionError(last_error)
+
+    def pickle(self, passphrase=""):
+        # type: (str) -> bytes
+        """Store a PkDecryption object.
+
+        Stores a PkDecryption object as a base64 string. Encrypts the object
+        using the supplied passphrase. Returns a byte object containing the
+        base64 encoded string of the pickled session.
+
+        Args:
+            passphrase(str, optional): The passphrase to be used to encrypt
+                the object.
+        """
+        byte_key = to_bytearray(passphrase)
+
+        pickle_length = lib.olm_pickle_pk_decryption_length(
+            self._pk_decryption
+        )
+        pickle_buffer = ffi.new("char[]", pickle_length)
+
+        ret = lib.olm_pickle_pk_decryption(
+            self._pk_decryption,
+            ffi.from_buffer(byte_key), len(byte_key),
+            pickle_buffer, pickle_length
+        )
+        try:
+            self._check_error(ret)
+        finally:
+            # zero out copies of the passphrase
+            for i in range(0, len(byte_key)):
+                byte_key[i] = 0
+
+        return ffi.unpack(pickle_buffer, pickle_length)
+
+    @classmethod
+    def from_pickle(cls, pickle, passphrase=""):
+        # types: (bytes, str) -> PkDecryption
+        """Restore a previously stored PkDecryption object.
+
+        Creates a PkDecryption object from a pickled base64 string. Decrypts
+        the pickled object using the supplied passphrase.
+        Raises PkDecryptionError on failure. If the passphrase
+        doesn't match the one used to encrypt the session then the error
+        message for the exception will be "BAD_ACCOUNT_KEY". If the base64
+        couldn't be decoded then the error message will be "INVALID_BASE64".
+
+        Args:
+            pickle(bytes): Base64 encoded byte string containing the pickled
+                PkDecryption object
+            passphrase(str, optional): The passphrase used to encrypt the
+                object
+        """
+        if not pickle:
+            raise ValueError("Pickle can't be empty")
+
+        byte_key = to_bytearray(passphrase)
+        pickle_buffer = ffi.new("char[]", pickle)
+
+        pubkey_length = lib.olm_pk_key_length()
+        pubkey_buffer = ffi.new("char[]", pubkey_length)
+
+        obj = cls.__new__(cls)
+
+        ret = lib.olm_unpickle_pk_decryption(
+            obj._pk_decryption,
+            ffi.from_buffer(byte_key), len(byte_key),
+            pickle_buffer, len(pickle),
+            pubkey_buffer, pubkey_length)
+
+        try:
+            obj._check_error(ret)
+        finally:
+            for i in range(0, len(byte_key)):
+                byte_key[i] = 0
+
+        obj.public_key = bytes_to_native_str(ffi.unpack(
+            pubkey_buffer,
+            pubkey_length
+        ))
+
+        return obj
+
+    def decrypt(self, message):
+        # type (PkMessage) -> str
+        """Decrypt a previously encrypted Pk message.
+
+        Returns the decrypted plaintext.
+        Raises PkDecryptionError on failure.
+
+        Args:
+            message(PkMessage): the pk message to decrypt.
+        """
+        ephemeral_key = to_bytearray(message.ephemeral_key)
+        ephemeral_key_size = len(ephemeral_key)
+
+        mac = to_bytearray(message.mac)
+        mac_length = len(mac)
+
+        ciphertext = to_bytearray(message.ciphertext)
+        ciphertext_length = len(ciphertext)
+
+        max_plaintext_length = lib.olm_pk_max_plaintext_length(
+            self._pk_decryption,
+            ciphertext_length
+        )
+        plaintext_buffer = ffi.new("char[]", max_plaintext_length)
+
+        ret = lib.olm_pk_decrypt(
+            self._pk_decryption,
+            ffi.from_buffer(ephemeral_key), ephemeral_key_size,
+            ffi.from_buffer(mac), mac_length,
+            ffi.from_buffer(ciphertext), ciphertext_length,
+            plaintext_buffer, max_plaintext_length)
+        self._check_error(ret)
+
+        plaintext = (ffi.unpack(
+            plaintext_buffer,
+            ret
+        ))
+
+        # clear out copies of the plaintext
+        lib.memset(plaintext_buffer, 0, max_plaintext_length)
+
+        return bytes_to_native_str(plaintext)
diff --git a/python/olm_build.py b/python/olm_build.py
index 1c610a1..0606337 100644
--- a/python/olm_build.py
+++ b/python/olm_build.py
@@ -18,6 +18,7 @@
 from __future__ import unicode_literals
 
 import os
+import subprocess
 
 from cffi import FFI
 
@@ -32,6 +33,8 @@ link_args = ["-L../build"]
 if DEVELOP and DEVELOP.lower() in ["yes", "true", "1"]:
     link_args.append('-Wl,-rpath=../build')
 
+headers_build = subprocess.Popen("make headers", shell=True)
+headers_build.wait()
 
 ffibuilder.set_source(
     "_libolm",
@@ -39,6 +42,7 @@ ffibuilder.set_source(
         #include <olm/olm.h>
         #include <olm/inbound_group_session.h>
         #include <olm/outbound_group_session.h>
+        #include <olm/pk.h>
         #include <olm/sas.h>
     """,
     libraries=["olm"],
@@ -48,6 +52,9 @@ ffibuilder.set_source(
 with open(os.path.join(PATH, "include/olm/olm.h")) as f:
     ffibuilder.cdef(f.read(), override=True)
 
+with open(os.path.join(PATH, "include/olm/pk.h")) as f:
+    ffibuilder.cdef(f.read(), override=True)
+
 with open(os.path.join(PATH, "include/olm/sas.h")) as f:
     ffibuilder.cdef(f.read(), override=True)
 
diff --git a/python/setup.py b/python/setup.py
index 4b0deb1..5742fd9 100644
--- a/python/setup.py
+++ b/python/setup.py
@@ -22,6 +22,10 @@ setup(
     packages=["olm"],
     setup_requires=["cffi>=1.0.0"],
     cffi_modules=["olm_build.py:ffibuilder"],
-    install_requires=["cffi>=1.0.0", "future", "typing"],
+    install_requires=[
+        "cffi>=1.0.0",
+        "future",
+        "typing;python_version<'3.5'"
+    ],
     zip_safe=False
 )
diff --git a/python/tests/pk_test.py b/python/tests/pk_test.py
new file mode 100644
index 0000000..f2aa147
--- /dev/null
+++ b/python/tests/pk_test.py
@@ -0,0 +1,49 @@
+import pytest
+
+from olm import PkDecryption, PkDecryptionError, PkEncryption
+
+
+class TestClass(object):
+    def test_invalid_encryption(self):
+        with pytest.raises(ValueError):
+            PkEncryption("")
+
+    def test_decrytion(self):
+        decryption = PkDecryption()
+        encryption = PkEncryption(decryption.public_key)
+        plaintext = "It's a secret to everybody."
+        message = encryption.encrypt(plaintext)
+        decrypted_plaintext = decryption.decrypt(message)
+        isinstance(decrypted_plaintext, str)
+        assert plaintext == decrypted_plaintext
+
+    def test_invalid_decrytion(self):
+        decryption = PkDecryption()
+        encryption = PkEncryption(decryption.public_key)
+        plaintext = "It's a secret to everybody."
+        message = encryption.encrypt(plaintext)
+        message.ephemeral_key = "?"
+        with pytest.raises(PkDecryptionError):
+            decryption.decrypt(message)
+
+    def test_pickling(self):
+        decryption = PkDecryption()
+        encryption = PkEncryption(decryption.public_key)
+        plaintext = "It's a secret to everybody."
+        message = encryption.encrypt(plaintext)
+
+        pickle = decryption.pickle()
+        unpickled = PkDecryption.from_pickle(pickle)
+        decrypted_plaintext = unpickled.decrypt(message)
+        assert plaintext == decrypted_plaintext
+
+    def test_invalid_unpickling(self):
+        with pytest.raises(ValueError):
+            PkDecryption.from_pickle("")
+
+    def test_invalid_pass_pickling(self):
+        decryption = PkDecryption()
+        pickle = decryption.pickle("Secret")
+
+        with pytest.raises(PkDecryptionError):
+            PkDecryption.from_pickle(pickle, "Not secret")
diff --git a/src/sas.c b/src/sas.c
index c5be73f..b5a3131 100644
--- a/src/sas.c
+++ b/src/sas.c
@@ -139,3 +139,26 @@ size_t olm_sas_calculate_mac(
     _olm_encode_base64((const uint8_t *)mac, SHA256_OUTPUT_LENGTH, (uint8_t *)mac);
     return 0;
 }
+
+// for compatibility with an old version of Riot
+size_t olm_sas_calculate_mac_long_kdf(
+    OlmSAS * sas,
+    void * input, size_t input_length,
+    const void * info, size_t info_length,
+    void * mac, size_t mac_length
+) {
+    if (mac_length < olm_sas_mac_length(sas)) {
+        sas->last_error = OLM_OUTPUT_BUFFER_TOO_SMALL;
+        return (size_t)-1;
+    }
+    uint8_t key[256];
+    _olm_crypto_hkdf_sha256(
+        sas->secret, sizeof(sas->secret),
+        NULL, 0,
+        (const uint8_t *) info, info_length,
+        key, 256
+    );
+    _olm_crypto_hmac_sha256(key, 256, input, input_length, mac);
+    _olm_encode_base64((const uint8_t *)mac, SHA256_OUTPUT_LENGTH, (uint8_t *)mac);
+    return 0;
+}