diff --git a/.gitignore b/.gitignore
index 199e52f78088aae2c804bffc67a2a104928655a8..fed024541dd11163b940ba3d5aa4880c09c33c93 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,6 +2,7 @@
/CHANGELOG.html
/docs/megolm.html
/docs/olm.html
+/docs/signing.html
/olm-*.tgz
/README.html
/tracing/README.html
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 0ab2eeb868afce2c8d119b0dd231922529e0e656..a35eedf0ff8d3fad36c8a246ec1a00221e249625 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,8 +1,26 @@
+Changes in `2.0.0 <http://matrix.org/git/olm/commit/?h=2.0.0>`_
+===============================================================
+
+This release includes the following changes since 1.3.0:
+
+* Fix a buffer bounds check when decoding group messages.
+* Update ``olm_group_decrypt`` to return the ratchet index for decrypted
+ messages.
+* Fix ``olm_pickle_account``, ``olm_pickle_session``,
+ ``olm_pickle_inbound_group_session`` and
+ ``olm_pickle_outbound_group_session`` to correctly return the length of the
+ pickled object.
+* Add a `specification <./docs/megolm.rst>`_ of the Megolm ratchet, and add
+ some information on mitigating unknown key-share attacks to the `Olm
+ specification <./docs/olm.rst>`_.
+* Add an ``install-headers`` target to the Makefile (and run it when installing
+ the library). (Credit to Emmanuel Gil Peyrot).
+
Changes in `1.3.0 <http://matrix.org/git/olm/commit/?h=1.3.0>`_
===============================================================
-The release updates the group session identifier to avoid collisions.
-The group sessions are now identified by their ed25519 public key.
+This release updates the group session identifier to avoid collisions.
+Group sessions are now identified by their ed25519 public key.
These changes alter the pickle format of outbound group sessions, attempting
to unpickle an outbound group session created with a previous version of olm
diff --git a/Makefile b/Makefile
index 4877dfb31490aaac964ff76bb66dd8f07acd4e07..77aa485f85789ac7f3addcafa2b53ccc651c0422 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
#!/usr/bin/make -f
-MAJOR := 1
-MINOR := 3
+MAJOR := 2
+MINOR := 0
PATCH := 0
VERSION := $(MAJOR).$(MINOR).$(PATCH)
PREFIX ?= /usr/local
@@ -46,6 +46,7 @@ JS_POST := javascript/olm_outbound_group_session.js \
DOCS := tracing/README.html \
docs/megolm.html \
docs/olm.html \
+ docs/signing.html \
README.html \
CHANGELOG.html
diff --git a/README.rst b/README.rst
index 21ae529593b7893dbe357849980339d2b4e4ce7b..be1fb1a1270a86a830f30fc67dc79e00a28de9ba 100644
--- a/README.rst
+++ b/README.rst
@@ -5,8 +5,12 @@ An implementation of the Double Ratchet cryptographic ratchet described by
https://github.com/trevp/double_ratchet/wiki, written in C and C++11 and
exposed as a C API.
-The specification of the Olm ratchet can be found in docs/olm.rst or
-https://matrix.org/docs/spec/olm.html
+The specification of the Olm ratchet can be found in ``docs/olm.rst`` or
+https://matrix.org/docs/spec/olm.html.
+
+This library also includes an implementation of the Megolm cryptographic
+ratchet, as specified in ``docs/megolm.rst`` or
+https://matrix.org/docs/spec/megolm.html.
Building
--------
diff --git a/docs/Axolotl.svg b/docs/double_ratchet.svg
similarity index 100%
rename from docs/Axolotl.svg
rename to docs/double_ratchet.svg
diff --git a/docs/megolm.rst b/docs/megolm.rst
index 78539636fc8955b152fa612a63cf50e2de12913a..03ee426476686055448dabc46a5b94b147c0b00e 100644
--- a/docs/megolm.rst
+++ b/docs/megolm.rst
@@ -27,7 +27,7 @@ The Megolm ratchet is intended for encrypted messaging applications where there
may be a large number of recipients of each message, thus precluding the use of
peer-to-peer encryption systems such as `Olm`_.
-It also allows a receipient to decrypt received messages multiple times. For
+It also allows a recipient to decrypt received messages multiple times. For
instance, in client/server applications, a copy of the ciphertext can be stored
on the (untrusted) server, while the client need only store the session keys.
@@ -143,7 +143,7 @@ copy of the counter, ratchet, and public key.
Message encryption
~~~~~~~~~~~~~~~~~~
-This version of Megolm uses AES-256_ in CBC_ mode with `PCKS#7`_ padding and
+This version of Megolm uses AES-256_ in CBC_ mode with `PKCS#7`_ padding and
HMAC-SHA-256_ (truncated to 64 bits). The 256 bit AES key, 256 bit HMAC key,
and 128 bit AES IV are derived from the megolm ratchet :math:`R_i`:
@@ -199,9 +199,9 @@ session.
In order to maintain the ability to decrypt conversation history, inbound
sessions should store a copy of their earliest known ratchet value (unless they
-explicitly want to drop the ability to decrypt that history). They may also
-choose to cache calculated ratchet values, but the decision of which ratchet
-states to cache is left to the application.
+explicitly want to drop the ability to decrypt that history - see `Partial
+Forward Secrecy`_\ ). They may also choose to cache calculated ratchet values,
+but the decision of which ratchet states to cache is left to the application.
Data exchange formats
---------------------
@@ -269,7 +269,79 @@ protocol). The MAC protects all of the bytes preceding the MAC.
The length of the signature is determined by the signing algorithm being used
(64 bytes in this version of the protocol). The signature covers all of the
-bytes preceding the signaure.
+bytes preceding the signature.
+
+Limitations
+-----------
+
+Message Replays
+---------------
+
+A message can be decrypted successfully multiple times. This means that an
+attacker can re-send a copy of an old message, and the recipient will treat it
+as a new message.
+
+To mitigate this it is recommended that applications track the ratchet indices
+they have received and that they reject messages with a ratchet index that
+they have already decrypted.
+
+Lack of Transcript Consistency
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In a group conversation, there is no guarantee that all recipients have
+received the same messages. For example, if Alice is in a conversation with Bob
+and Charlie, she could send different messages to Bob and Charlie, or could
+send some messages to Bob but not Charlie, or vice versa.
+
+Solving this is, in general, a hard problem, particularly in a protocol which
+does not guarantee in-order message delivery. For now it remains the subject of
+future research.
+
+Lack of Backward Secrecy
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Once the key to a Megolm session is compromised, the attacker can decrypt any
+future messages sent via that session.
+
+In order to mitigate this, the application should ensure that Megolm sessions
+are not used indefinitely. Instead it should periodically start a new session,
+with new keys shared over a secure channel.
+
+.. TODO: Can we recommend sensible lifetimes for Megolm sessions? Probably
+ depends how paranoid we're feeling, but some guidelines might be useful.
+
+Partial Forward Secrecy
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Each recipient maintains a record of the ratchet value which allows them to
+decrypt any messages sent in the session after the corresponding point in the
+conversation. If this value is compromised, an attacker can similarly decrypt
+those past messages.
+
+To mitigate this issue, the application should offer the user the option to
+discard historical conversations, by winding forward any stored ratchet values,
+or discarding sessions altogether.
+
+Dependency on secure channel for key exchange
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The design of the Megolm ratchet relies on the availability of a secure
+peer-to-peer channel for the exchange of session keys. Any vulnerabilities in
+the underlying channel are likely to be amplified when applied to Megolm
+session setup.
+
+For example, if the peer-to-peer channel is vulnerable to an unknown key-share
+attack, the entire Megolm session become similarly vulnerable. For example:
+Alice starts a group chat with Eve, and shares the session keys with Eve. Eve
+uses the unknown key-share attack to forward the session keys to Bob, who
+believes Alice is starting the session with him. Eve then forwards messages
+from the Megolm session to Bob, who again believes they are coming from
+Alice. Provided the peer-to-peer channel is not vulnerable to this attack, Bob
+will realise that the key-sharing message was forwarded by Eve, and can treat
+the Megolm session as a forgery.
+
+A second example: if the peer-to-peer channel is vulnerable to a replay
+attack, this can be extended to entire Megolm sessions.
License
-------
@@ -285,6 +357,6 @@ Version 2.0 <http://www.apache.org/licenses/LICENSE-2.0>`_.
.. _`SHA-256`: https://tools.ietf.org/html/rfc6234
.. _`AES-256`: http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
.. _`CBC`: http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
-.. _`PCKS#7`: https://tools.ietf.org/html/rfc2315
+.. _`PKCS#7`: https://tools.ietf.org/html/rfc2315
.. _`Olm`: ./olm.html
.. _`Protocol Buffers encoding`: https://developers.google.com/protocol-buffers/docs/encoding
diff --git a/docs/olm.rst b/docs/olm.rst
index 99417e079849e9a2e1de2bc58d344ca24070e41c..093cb473875a951805b139b070f8912544de1aa2 100644
--- a/docs/olm.rst
+++ b/docs/olm.rst
@@ -30,7 +30,7 @@ Initial setup
~~~~~~~~~~~~~
The setup takes four Curve25519_ inputs: Identity keys for Alice and Bob,
-:math:`I_A` and :math:`I_B`, and ephemeral keys for Alice and Bob,
+:math:`I_A` and :math:`I_B`, and one-time keys for Alice and Bob,
:math:`E_A` and :math:`E_B`. A shared secret, :math:`S`, is generated using
`Triple Diffie-Hellman`_. The initial 256 bit root key, :math:`R_0`, and 256
bit chain key, :math:`C_{0,0}`, are derived from the shared secret using an
@@ -279,7 +279,7 @@ Olm Authenticated Encryption
Version 1
~~~~~~~~~
-Version 1 of Olm uses AES-256_ in CBC_ mode with `PCKS#7`_ padding for
+Version 1 of Olm uses AES-256_ in CBC_ mode with `PKCS#7`_ padding for
encryption and HMAC-SHA-256_ (truncated to 64 bits) for authentication. The
256 bit AES key, 256 bit HMAC key, and 128 bit AES IV are derived from the
message key using HKDF-SHA-256_ using the default salt and an info of
@@ -298,6 +298,37 @@ and the IV :math:`AES\_IV_{i,j}` to give the cipher-text, :math:`X_{i,j}`.
Then the entire message (including the Version Byte and all Payload Bytes) are
passed through HMAC-SHA-256. The first 8 bytes of the MAC are appended to the message.
+Message authentication concerns
+-------------------------------
+
+To avoid unknown key-share attacks, the application must include identifying
+data for the sending and receiving user in the plain-text of (at least) the
+pre-key messages. Such data could be a user ID, a telephone number;
+alternatively it could be the public part of a keypair which the relevant user
+has proven ownership of.
+
+.. admonition:: Example attacks
+
+ 1. Alice publishes her public Curve25519 identity key, :math:`I_A`. Eve
+ publishes the same identity key, claiming it as her own. Bob downloads
+ Eve's keys, and associates :math:`I_A` with Eve. Alice sends a message to
+ Bob; Eve intercepts it before forwarding it to Bob. Bob believes the
+ message came from Eve rather than Alice.
+
+ This is prevented if Alice includes her user ID in the plain-text of the
+ pre-key message, so that Bob can see that the message was sent by Alice
+ originally.
+
+ 2. Bob publishes his public Curve25519 identity key, :math:`I_B`. Eve
+ publishes the same identity key, claiming it as her own. Alice downloads
+ Eve's keys, and associates :math:`I_B` with Eve. Alice sends a message to
+ Eve; Eve cannot decrypt it, but forwards it to Bob. Bob believes the
+ Alice sent the message to him, wheras Alice intended it to go to Eve.
+
+ This is prevented by Alice including the user ID of the intended recpient
+ (Eve) in the plain-text of the pre-key message. Bob can now tell that the
+ message was meant for Eve rather than him.
+
IPR
---
@@ -323,4 +354,4 @@ an entirely new implementation written by the Matrix.org team.
.. _`SHA-256`: https://tools.ietf.org/html/rfc6234
.. _`AES-256`: http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf
.. _`CBC`: http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
-.. _`PCKS#7`: https://tools.ietf.org/html/rfc2315
+.. _`PKCS#7`: https://tools.ietf.org/html/rfc2315
diff --git a/docs/signing.rst b/docs/signing.rst
new file mode 100644
index 0000000000000000000000000000000000000000..73877947d0be9509090adefe21f330ba29f8ab76
--- /dev/null
+++ b/docs/signing.rst
@@ -0,0 +1,118 @@
+.. Copyright 2016 OpenMarket 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.
+
+
+Signature keys and user identity in libolm
+==========================================
+
+The use of any public-key based cryptography system such as Olm presents the
+need for our users Alice and Bob to verify that they are in fact communicating
+with each other, rather than a man-in-the-middle. Typically this requires an
+out-of-band process in which Alice and Bob verify that they have the correct
+public keys for each other. For example, this might be done via physical
+presence or via a voice call.
+
+In the basic `Olm <olm.html>`_ protocol, it is sufficient to compare the public
+Curve25519 identity keys. As a naive example, Alice would meet Bob and ensure
+that the identity key she downloaded from the key server matched that shown by
+his device. This prevents the eavesdropper Eve from decrypting any messages
+sent from Alice to Bob, or from masquerading as Bob to send messages to Alice:
+she has neither Alice's nor Bob's private identity key, so cannot successfully
+complete the triple-DH calculation to compute the shared secret, :math:`S`,
+which in turn prevents her decrypting intercepted messages, or from creating
+new messages with valid MACs. Obviously, for protection to be complete, Bob
+must similarly verify Alice's key.
+
+However, the use of the Curve25519 key as the "fingerprint" in this way makes
+it difficult to carry out signing operations. For instance, it may be useful to
+cross-sign identity keys for different devices, or, as discussed below, to sign
+one-time keys. Curve25519 keys are intended for use in DH calculations, and
+their use to calculate signatures is non-trivial.
+
+The solution adopted in this library is to generate a signing key for each
+user. This is an `Ed25519`_ keypair, which is used to calculate a signature on
+an object including both the public Ed25519 signing key and the public
+Curve25519 identity key. It is then the **public Ed25519 signing key** which is
+used as the device fingerprint which Alice and Bob verify with each other.
+
+By verifying the signatures on the key object, Alice and Bob then get the same
+level of assurance about the ownership of the Curve25519 identity keys as if
+they had compared those directly.
+
+Signing one-time keys
+---------------------
+
+The Olm protocol requires users to publish a set of one-time keys to a key
+server. To establish an Olm session, the originator downloads a key for the
+recipient from this server. The decision of whether to sign these one-time keys
+is left to the application. There are both advantages and disadvantages to
+doing so.
+
+Consider the scenario where one-time keys are unsigned. Alice wants to initiate
+an Olm session with Bob. Bob uploads his one-time keys, :math:`E_B`, but Eve
+replaces them with ones she controls, :math:`E_E`. Alice downloads one of the
+compromised keys, and sends a pre-key message using a shared secret :math:`S`,
+where:
+
+.. math::
+ S = ECDH\left(I_A,\,E_E\right)\;\parallel\;ECDH\left(E_A,\,I_B\right)\;
+ \parallel\;ECDH\left(E_A,\,E_E\right)
+
+Eve cannot decrypt the message because she does not have the private parts of
+either :math:`E_A` nor :math:`I_B`, so cannot calculate
+:math:`ECDH\left(E_A,\,I_B\right)`. However, suppose she later compromises
+Bob's identity key :math:`I_B`. This would give her the ability to decrypt any
+pre-key messages sent to Bob using the compromised one-time keys, and is thus a
+problematic loss of forward secrecy. If Bob signs his keys with his Ed25519
+signing key (and Alice verifies the signature before using them), this problem
+is avoided.
+
+On the other hand, signing the one-time keys leads to a reduction in
+deniability. Recall that the shared secret is calculated as follows:
+
+.. math::
+ S = ECDH\left(I_A,\,E_B\right)\;\parallel\;ECDH\left(E_A,\,I_B\right)\;
+ \parallel\;ECDH\left(E_A,\,E_B\right)
+
+If keys are unsigned, a forger can make up values of :math:`E_A` and
+:math:`E_B`, and construct a transcript of a conversation which looks like it
+was between Alice and Bob. Alice and Bob can therefore plausibly deny their
+partition in any conversation even if they are both forced to divulge their
+private identity keys, since it is impossible to prove that the transcript was
+a conversation between the two of them, rather than constructed by a forger.
+
+If :math:`E_B` is signed, it is no longer possible to construct arbitrary
+transcripts. Given a transcript and Alice and Bob's identity keys, we can now
+show that at least one of Alice or Bob was involved in the conversation,
+because the ability to calculate :math:`ECDH\left(I_A,\,E_B\right)` requires
+knowledge of the private parts of either :math:`I_A` (proving Alice's
+involvement) or :math:`E_B` (proving Bob's involvement, via the
+signature). Note that it remains impossible to show that *both* Alice and Bob
+were involved.
+
+In conclusion, applications should consider whether to sign one-time keys based
+on the trade-off between forward secrecy and deniability.
+
+License
+-------
+
+This document is licensed under the `Apache License, Version 2.0
+<http://www.apache.org/licenses/LICENSE-2.0>`_.
+
+Feedback
+--------
+
+Questions and feedback can be sent to richard at matrix.org.
+
+.. _`Ed25519`: http://ed25519.cr.yp.to/
diff --git a/fuzzers/README.rst b/fuzzers/README.rst
new file mode 100644
index 0000000000000000000000000000000000000000..d052303c284ffae3741373f534ce06e447833832
--- /dev/null
+++ b/fuzzers/README.rst
@@ -0,0 +1,51 @@
+Fuzzers
+=======
+
+This directory contains a collection of fuzzing tools. Each tests a different
+entry point to the code.
+
+Usage notes:
+
+1. Install AFL:
+
+ .. code::
+
+ apt-get install afl
+
+2. Build the fuzzers:
+
+ .. code::
+
+ make fuzzers
+
+3. Some of the tests (eg ``fuzz_decrypt`` and ``fuzz_group_decrypt``) require a
+ session file. You can use the ones generated by the python test script
+ (``python/test.sh``).
+
+4. Make some work directories:
+
+ .. code::
+
+ mkdir -p fuzzing/in fuzzing/out
+
+5. Generate starting input:
+
+ .. code::
+
+ echo "Test" > fuzzing/in/test
+
+6. Run the test under ``afl-fuzz``:
+
+ .. code::
+
+ afl-fuzz -i fuzzing/in -o fuzzing/out -- \
+ ./build/fuzzers/fuzz_<fuzzing_tool> [<test args>]
+
+7. To resume with the data produced by an earlier run:
+
+ .. code::
+
+ afl-fuzz -i- -o existing_output_dir [...etc...]
+
+8. If it shows failures, pipe the failure case into
+ ``./build/fuzzers/debug_<fuzzing_tool>``, fix, and repeat.
diff --git a/fuzzers/fuzz_group_decrypt.cpp b/fuzzers/fuzz_group_decrypt.cpp
index 1fc99d7eb85577e7e76fd60f585e410b6a97edc1..bb12d0e14f64224d5601b89a76ebedbf9c7c4cae 100644
--- a/fuzzers/fuzz_group_decrypt.cpp
+++ b/fuzzers/fuzz_group_decrypt.cpp
@@ -54,6 +54,8 @@ int main(int argc, const char *argv[]) {
uint8_t plaintext[max_length];
+ uint32_t ratchet_index;
+
size_t length = check_error(
olm_inbound_group_session_last_error,
session,
@@ -61,7 +63,7 @@ int main(int argc, const char *argv[]) {
olm_group_decrypt(
session,
message_buffer, message_length,
- plaintext, max_length
+ plaintext, max_length, &ratchet_index
)
);
diff --git a/include/olm/inbound_group_session.h b/include/olm/inbound_group_session.h
index 59146c2a388bb67f4f442bc118fa0e20086cfe81..f8a0bc327abcac7ed2ac4aa50f8f5cfe1eb62b6d 100644
--- a/include/olm/inbound_group_session.h
+++ b/include/olm/inbound_group_session.h
@@ -140,7 +140,8 @@ size_t olm_group_decrypt(
uint8_t * message, size_t message_length,
/* output */
- uint8_t * plaintext, size_t max_plaintext_length
+ uint8_t * plaintext, size_t max_plaintext_length,
+ uint32_t * message_index
);
diff --git a/include/olm/olm.h b/include/olm/olm.h
index 3257e53428fcba95d41a757934052135392e4cd3..5764eb2b0ac480bee3d611adb84c687c672bbeb3 100644
--- a/include/olm/olm.h
+++ b/include/olm/olm.h
@@ -320,7 +320,8 @@ int olm_session_has_received_message(
/** Checks if the PRE_KEY message is for this in-bound session. This can happen
* if multiple messages are sent to this account before this account sends a
- * message in reply. Returns olm_error() on failure. If the base64
+ * message in reply. Returns 1 if the session matches. Returns 0 if the session
+ * does not match. Returns olm_error() on failure. If the base64
* couldn't be decoded then olm_session_last_error will be "INVALID_BASE64".
* If the message was for an unsupported protocol version then
* olm_session_last_error() will be "BAD_MESSAGE_VERSION". If the message
@@ -333,7 +334,8 @@ size_t olm_matches_inbound_session(
/** Checks if the PRE_KEY message is for this in-bound session. This can happen
* if multiple messages are sent to this account before this account sends a
- * message in reply. Returns olm_error() on failure. If the base64
+ * message in reply. Returns 1 if the session matches. Returns 0 if the session
+ * does not match. Returns olm_error() on failure. If the base64
* couldn't be decoded then olm_session_last_error will be "INVALID_BASE64".
* If the message was for an unsupported protocol version then
* olm_session_last_error() will be "BAD_MESSAGE_VERSION". If the message
diff --git a/include/olm/outbound_group_session.h b/include/olm/outbound_group_session.h
index 90ccca3b34a1125794657a7f20874aaa996e4d74..663f1d2c4e1b0d78991e52221009b217c7f9d027 100644
--- a/include/olm/outbound_group_session.h
+++ b/include/olm/outbound_group_session.h
@@ -96,7 +96,7 @@ size_t olm_init_outbound_group_session_random_length(
*/
size_t olm_init_outbound_group_session(
OlmOutboundGroupSession *session,
- uint8_t const * random, size_t random_length
+ uint8_t *random, size_t random_length
);
/**
diff --git a/javascript/demo/group_demo.js b/javascript/demo/group_demo.js
index 1b8f7ab96731ca1930e37ee11586e969cea7aaab..42a3d843f6127a74ecf7e6aef103015963499205 100644
--- a/javascript/demo/group_demo.js
+++ b/javascript/demo/group_demo.js
@@ -403,8 +403,8 @@ DemoUser.prototype.decryptGroup = function(jsonpacket, callback) {
throw new Error("Unknown session id " + session_id);
}
- var plaintext = session.decrypt(packet.body);
- done(plaintext);
+ var result = session.decrypt(packet.body);
+ done(result.plaintext);
}, callback);
};
diff --git a/javascript/olm_inbound_group_session.js b/javascript/olm_inbound_group_session.js
index 605823382cd34438ef40aadfc7d6599b2e87362a..1b7fcfe52c1a90f1a4e861b815cae67900b093c7 100644
--- a/javascript/olm_inbound_group_session.js
+++ b/javascript/olm_inbound_group_session.js
@@ -73,10 +73,12 @@ InboundGroupSession.prototype['decrypt'] = restore_stack(function(
// So we copy the array to a new buffer
var message_buffer = stack(message_array);
var plaintext_buffer = stack(max_plaintext_length + NULL_BYTE_PADDING_LENGTH);
+ var message_index = stack(4);
var plaintext_length = inbound_group_session_method(Module["_olm_group_decrypt"])(
this.ptr,
message_buffer, message_array.length,
- plaintext_buffer, max_plaintext_length
+ plaintext_buffer, max_plaintext_length,
+ message_index
);
// Pointer_stringify requires a null-terminated argument (the optional
@@ -86,7 +88,10 @@ InboundGroupSession.prototype['decrypt'] = restore_stack(function(
0, "i8"
);
- return Pointer_stringify(plaintext_buffer);
+ return {
+ "plaintext": Pointer_stringify(plaintext_buffer),
+ "message_index": Module['getValue'](message_index, "i32")
+ }
});
InboundGroupSession.prototype['session_id'] = restore_stack(function() {
diff --git a/javascript/package.json b/javascript/package.json
index df43ce123fc1176fbcab97e1348ca08b2deba612..b65fb2edb8c6ae86871b1dd25544bc117e8f5dc8 100644
--- a/javascript/package.json
+++ b/javascript/package.json
@@ -1,6 +1,6 @@
{
"name": "olm",
- "version": "1.3.0",
+ "version": "2.0.0",
"description": "An implementation of the Double Ratchet cryptographic ratchet",
"main": "olm.js",
"files": [
diff --git a/python/olm/__main__.py b/python/olm/__main__.py
index cf9158db9a2161636d01a1351e5fd9097f086597..eb76301a611a9604e2ef177037741de9516855fd 100755
--- a/python/olm/__main__.py
+++ b/python/olm/__main__.py
@@ -328,7 +328,7 @@ def do_group_decrypt(args):
session = InboundGroupSession()
session.unpickle(args.key, read_base64_file(args.session_file))
message = args.message_file.read()
- plaintext = session.decrypt(message)
+ plaintext, message_index = session.decrypt(message)
with open(args.session_file, "wb") as f:
f.write(session.pickle(args.key))
args.plaintext_file.write(plaintext)
diff --git a/python/olm/_base.py b/python/olm/_base.py
index bc5c2063733abfe664ad84e0dead7d475f13251d..80720d970e43120b6d80294d8bf398f4d6044a02 100644
--- a/python/olm/_base.py
+++ b/python/olm/_base.py
@@ -7,7 +7,7 @@ def read_random(n):
return f.read(n)
lib = cdll.LoadLibrary(os.path.join(
- os.path.dirname(__file__), "..", "..", "build", "libolm.so.1")
+ os.path.dirname(__file__), "..", "..", "build", "libolm.so.2")
)
lib.olm_error.argtypes = []
diff --git a/python/olm/account.py b/python/olm/account.py
index 7673329795aa9e64e403bcd3b576dedd7e3d6bb9..3fa10491902035cf5e7ba23e7a76adc0074fcdff 100644
--- a/python/olm/account.py
+++ b/python/olm/account.py
@@ -41,6 +41,7 @@ account_function(lib.olm_account_one_time_keys_length)
account_function(lib.olm_account_one_time_keys, c_void_p, c_size_t)
account_function(lib.olm_account_mark_keys_as_published)
account_function(lib.olm_account_max_number_of_one_time_keys)
+account_function(lib.olm_pickle_account_length)
account_function(
lib.olm_account_generate_one_time_keys_random_length,
c_size_t
diff --git a/python/olm/inbound_group_session.py b/python/olm/inbound_group_session.py
index d5547fdfd1ea9ea04b9aa055874c3d82e2812d97..27a569c766167558a9e0cf7d58efbd79ec5a9896 100644
--- a/python/olm/inbound_group_session.py
+++ b/python/olm/inbound_group_session.py
@@ -43,6 +43,7 @@ inbound_group_session_function(
lib.olm_group_decrypt,
c_void_p, c_size_t, # message
c_void_p, c_size_t, # plaintext
+ POINTER(c_uint32), # message_index
)
inbound_group_session_function(lib.olm_inbound_group_session_id_length)
@@ -82,11 +83,14 @@ class InboundGroupSession(object):
)
plaintext_buffer = create_string_buffer(max_plaintext_length)
message_buffer = create_string_buffer(message)
+
+ message_index = c_uint32()
plaintext_length = lib.olm_group_decrypt(
self.ptr, message_buffer, len(message),
- plaintext_buffer, max_plaintext_length
+ plaintext_buffer, max_plaintext_length,
+ byref(message_index)
)
- return plaintext_buffer.raw[:plaintext_length]
+ return plaintext_buffer.raw[:plaintext_length], message_index
def session_id(self):
id_length = lib.olm_inbound_group_session_id_length(self.ptr)
diff --git a/python/olm/session.py b/python/olm/session.py
index 308f220a6596b24558d3573aa5d9a2d0b850045b..19d43d3ecf726b18cc2593fae78bfb26bab9f743 100644
--- a/python/olm/session.py
+++ b/python/olm/session.py
@@ -58,6 +58,7 @@ session_function(
c_void_p, c_size_t, # Identity Key
c_void_p, c_size_t, # Pre Key Message
)
+session_function(lib.olm_pickle_session_length)
session_function(lib.olm_encrypt_message_type)
session_function(lib.olm_encrypt_random_length)
session_function(lib.olm_encrypt_message_length, c_size_t)
diff --git a/src/inbound_group_session.c b/src/inbound_group_session.c
index bf000080b0f6685cdfbc99a0d49c31d7e4fe9c4e..a54e55f0e91dd6eb2427a858833770a3432bea12 100644
--- a/src/inbound_group_session.c
+++ b/src/inbound_group_session.c
@@ -263,7 +263,8 @@ size_t olm_group_decrypt_max_plaintext_length(
static size_t _decrypt(
OlmInboundGroupSession *session,
uint8_t * message, size_t message_length,
- uint8_t * plaintext, size_t max_plaintext_length
+ uint8_t * plaintext, size_t max_plaintext_length,
+ uint32_t * message_index
) {
struct _OlmDecodeGroupMessageResults decoded_results;
size_t max_length, r;
@@ -286,6 +287,10 @@ static size_t _decrypt(
return (size_t)-1;
}
+ if (message_index != NULL) {
+ *message_index = decoded_results.message_index;
+ }
+
/* verify the signature. We could do this before decoding the message, but
* we allow for the possibility of future protocol versions which use a
* different signing mechanism; we would rather throw "BAD_MESSAGE_VERSION"
@@ -349,7 +354,8 @@ static size_t _decrypt(
size_t olm_group_decrypt(
OlmInboundGroupSession *session,
uint8_t * message, size_t message_length,
- uint8_t * plaintext, size_t max_plaintext_length
+ uint8_t * plaintext, size_t max_plaintext_length,
+ uint32_t * message_index
) {
size_t raw_message_length;
@@ -361,7 +367,8 @@ size_t olm_group_decrypt(
return _decrypt(
session, message, raw_message_length,
- plaintext, max_plaintext_length
+ plaintext, max_plaintext_length,
+ message_index
);
}
diff --git a/src/message.cpp b/src/message.cpp
index 05fe2c79a0c31958e7ef1267e5aeb2f733246047..1c11a4a194f9b0462af7e68b95068fcd11df3c14 100644
--- a/src/message.cpp
+++ b/src/message.cpp
@@ -214,11 +214,13 @@ void olm::decode_message(
reader.ciphertext = nullptr;
reader.ciphertext_length = 0;
- if (pos == end) return;
if (input_length < mac_length) return;
+
+ if (pos == end) return;
reader.version = *(pos++);
while (pos != end) {
+ unknown = pos;
pos = decode(
pos, end, RATCHET_KEY_TAG,
reader.ratchet_key, reader.ratchet_key_length
@@ -234,7 +236,6 @@ void olm::decode_message(
if (unknown == pos) {
pos = skip_unknown(pos, end);
}
- unknown = pos;
}
}
@@ -303,6 +304,7 @@ void olm::decode_one_time_key_message(
reader.version = *(pos++);
while (pos != end) {
+ unknown = pos;
pos = decode(
pos, end, ONE_TIME_KEY_ID_TAG,
reader.one_time_key, reader.one_time_key_length
@@ -322,7 +324,6 @@ void olm::decode_one_time_key_message(
if (unknown == pos) {
pos = skip_unknown(pos, end);
}
- unknown = pos;
}
}
@@ -377,9 +378,12 @@ void _olm_decode_group_message(
results->ciphertext_length = 0;
if (input_length < trailer_length) return;
+
+ if (pos == end) return;
results->version = *(pos++);
while (pos != end) {
+ unknown = pos;
pos = decode(
pos, end, GROUP_MESSAGE_INDEX_TAG,
results->message_index, has_message_index
@@ -391,7 +395,6 @@ void _olm_decode_group_message(
if (unknown == pos) {
pos = skip_unknown(pos, end);
}
- unknown = pos;
}
results->has_message_index = (int)has_message_index;
diff --git a/src/outbound_group_session.c b/src/outbound_group_session.c
index 4e4561a11cfd03c937a614b68ecabd30a924017a..ae4569490b0e04204fc8c82eeab8671bb0b484f2 100644
--- a/src/outbound_group_session.c
+++ b/src/outbound_group_session.c
@@ -154,20 +154,23 @@ size_t olm_init_outbound_group_session_random_length(
size_t olm_init_outbound_group_session(
OlmOutboundGroupSession *session,
- uint8_t const * random, size_t random_length
+ uint8_t *random, size_t random_length
) {
+ const uint8_t *random_ptr = random;
+
if (random_length < olm_init_outbound_group_session_random_length(session)) {
/* Insufficient random data for new session */
session->last_error = OLM_NOT_ENOUGH_RANDOM;
return (size_t)-1;
}
- megolm_init(&(session->ratchet), random, 0);
- random += MEGOLM_RATCHET_LENGTH;
+ megolm_init(&(session->ratchet), random_ptr, 0);
+ random_ptr += MEGOLM_RATCHET_LENGTH;
- _olm_crypto_ed25519_generate_key(random, &(session->signing_key));
- random += ED25519_RANDOM_LENGTH;
+ _olm_crypto_ed25519_generate_key(random_ptr, &(session->signing_key));
+ random_ptr += ED25519_RANDOM_LENGTH;
+ _olm_unset(random, random_length);
return 0;
}
diff --git a/src/pickle_encoding.c b/src/pickle_encoding.c
index 5d5f8d73c2a431472f528528c22af03d0149cdda..a56e9e3066953bbba01da26b6341d4ad69ffa537 100644
--- a/src/pickle_encoding.c
+++ b/src/pickle_encoding.c
@@ -60,7 +60,7 @@ size_t _olm_enc_output(
raw_output, length
);
_olm_encode_base64(raw_output, length, output);
- return raw_length;
+ return base64_length;
}
diff --git a/tests/test_group_session.cpp b/tests/test_group_session.cpp
index 99309277998cea6b2dc1324a288fc8166fb62118..ad67adb277ec96b0aa05bd68c5b65f32cf5f6f9e 100644
--- a/tests/test_group_session.cpp
+++ b/tests/test_group_session.cpp
@@ -28,23 +28,26 @@ int main() {
size_t pickle_length = olm_pickle_outbound_group_session_length(session);
uint8_t pickle1[pickle_length];
- olm_pickle_outbound_group_session(session,
- "secret_key", 10,
- pickle1, pickle_length);
+ size_t res = olm_pickle_outbound_group_session(
+ session, "secret_key", 10, pickle1, pickle_length
+ );
+ assert_equals(pickle_length, res);
+
uint8_t pickle2[pickle_length];
memcpy(pickle2, pickle1, pickle_length);
uint8_t buffer2[size];
OlmOutboundGroupSession *session2 = olm_outbound_group_session(buffer2);
- size_t res = olm_unpickle_outbound_group_session(session2,
- "secret_key", 10,
- pickle2, pickle_length);
+ res = olm_unpickle_outbound_group_session(
+ session2, "secret_key", 10, pickle2, pickle_length
+ );
assert_not_equals((size_t)-1, res);
assert_equals(pickle_length,
olm_pickle_outbound_group_session_length(session2));
- olm_pickle_outbound_group_session(session2,
- "secret_key", 10,
- pickle2, pickle_length);
+ res = olm_pickle_outbound_group_session(
+ session2, "secret_key", 10, pickle2, pickle_length
+ );
+ assert_equals(pickle_length, res);
assert_equals(pickle1, pickle2, pickle_length);
}
@@ -59,23 +62,25 @@ int main() {
size_t pickle_length = olm_pickle_inbound_group_session_length(session);
uint8_t pickle1[pickle_length];
- olm_pickle_inbound_group_session(session,
- "secret_key", 10,
- pickle1, pickle_length);
+ size_t res = olm_pickle_inbound_group_session(
+ session, "secret_key", 10, pickle1, pickle_length
+ );
+ assert_equals(pickle_length, res);
+
uint8_t pickle2[pickle_length];
memcpy(pickle2, pickle1, pickle_length);
uint8_t buffer2[size];
OlmInboundGroupSession *session2 = olm_inbound_group_session(buffer2);
- size_t res = olm_unpickle_inbound_group_session(session2,
- "secret_key", 10,
- pickle2, pickle_length);
+ res = olm_unpickle_inbound_group_session(
+ session2, "secret_key", 10, pickle2, pickle_length
+ );
assert_not_equals((size_t)-1, res);
assert_equals(pickle_length,
olm_pickle_inbound_group_session_length(session2));
- olm_pickle_inbound_group_session(session2,
- "secret_key", 10,
- pickle2, pickle_length);
+ res = olm_pickle_inbound_group_session(
+ session2, "secret_key", 10, pickle2, pickle_length
+ );
assert_equals(pickle1, pickle2, pickle_length);
}
@@ -161,10 +166,12 @@ int main() {
memcpy(msgcopy, msg, msglen);
size = olm_group_decrypt_max_plaintext_length(inbound_session, msgcopy, msglen);
uint8_t plaintext_buf[size];
+ uint32_t message_index;
res = olm_group_decrypt(inbound_session, msg, msglen,
- plaintext_buf, size);
+ plaintext_buf, size, &message_index);
assert_equals(plaintext_length, res);
assert_equals(plaintext, plaintext_buf, res);
+ assert_equals(message_index, uint32_t(0));
}
{
@@ -208,9 +215,11 @@ int main() {
memcpy(msgcopy, message, msglen);
uint8_t plaintext_buf[size];
+ uint32_t message_index;
res = olm_group_decrypt(
- inbound_session, msgcopy, msglen, plaintext_buf, size
+ inbound_session, msgcopy, msglen, plaintext_buf, size, &message_index
);
+ assert_equals(message_index, uint32_t(0));
assert_equals(plaintext_length, res);
assert_equals(plaintext, plaintext_buf, res);
@@ -227,7 +236,7 @@ int main() {
memcpy(msgcopy, message, msglen);
res = olm_group_decrypt(
inbound_session, msgcopy, msglen,
- plaintext_buf, size
+ plaintext_buf, size, &message_index
);
assert_equals((size_t)-1, res);
assert_equals(
diff --git a/tests/test_olm.cpp b/tests/test_olm.cpp
index af2c9f7ee66804be2bbbfd2b06049c9acac8bf9a..b24cd90b65ab39e53a9a7b4a52349192284a6438 100644
--- a/tests/test_olm.cpp
+++ b/tests/test_olm.cpp
@@ -49,7 +49,9 @@ mock_random(ot_random, sizeof(ot_random));
std::size_t pickle_length = ::olm_pickle_account_length(account);
std::uint8_t pickle1[pickle_length];
-::olm_pickle_account(account, "secret_key", 10, pickle1, pickle_length);
+std::size_t res = ::olm_pickle_account(account, "secret_key", 10, pickle1, pickle_length);
+assert_equals(pickle_length, res);
+
std::uint8_t pickle2[pickle_length];
std::memcpy(pickle2, pickle1, pickle_length);
@@ -59,10 +61,10 @@ assert_not_equals(std::size_t(-1), ::olm_unpickle_account(
account2, "secret_key", 10, pickle2, pickle_length
));
assert_equals(pickle_length, ::olm_pickle_account_length(account2));
-::olm_pickle_account(account2, "secret_key", 10, pickle2, pickle_length);
+res = ::olm_pickle_account(account2, "secret_key", 10, pickle2, pickle_length);
+assert_equals(pickle_length, res);
assert_equals(pickle1, pickle2, pickle_length);
-
}
@@ -122,7 +124,9 @@ mock_random(random2, sizeof(random2));
std::size_t pickle_length = ::olm_pickle_session_length(session);
std::uint8_t pickle1[pickle_length];
-::olm_pickle_session(session, "secret_key", 10, pickle1, pickle_length);
+std::size_t res = ::olm_pickle_session(session, "secret_key", 10, pickle1, pickle_length);
+assert_equals(pickle_length, res);
+
std::uint8_t pickle2[pickle_length];
std::memcpy(pickle2, pickle1, pickle_length);
@@ -132,10 +136,10 @@ assert_not_equals(std::size_t(-1), ::olm_unpickle_session(
session2, "secret_key", 10, pickle2, pickle_length
));
assert_equals(pickle_length, ::olm_pickle_session_length(session2));
-::olm_pickle_session(session2, "secret_key", 10, pickle2, pickle_length);
+res = ::olm_pickle_session(session2, "secret_key", 10, pickle2, pickle_length);
+assert_equals(pickle_length, res);
assert_equals(pickle1, pickle2, pickle_length);
-
}
{ /** Loopback test */
@@ -161,6 +165,9 @@ std::uint8_t o_random[::olm_account_generate_one_time_keys_random_length(
mock_random_b(o_random, sizeof(o_random));
::olm_account_generate_one_time_keys(b_account, 42, o_random, sizeof(o_random));
+std::uint8_t a_id_keys[::olm_account_identity_keys_length(a_account)];
+::olm_account_identity_keys(a_account, a_id_keys, sizeof(a_id_keys));
+
std::uint8_t b_id_keys[::olm_account_identity_keys_length(b_account)];
std::uint8_t b_ot_keys[::olm_account_one_time_keys_length(b_account)];
::olm_account_identity_keys(b_account, b_id_keys, sizeof(b_id_keys));
@@ -172,8 +179,8 @@ std::uint8_t a_rand[::olm_create_outbound_session_random_length(a_session)];
mock_random_a(a_rand, sizeof(a_rand));
assert_not_equals(std::size_t(-1), ::olm_create_outbound_session(
a_session, a_account,
- b_id_keys + 15, 43,
- b_ot_keys + 25, 43,
+ b_id_keys + 15, 43, // B's curve25519 identity key
+ b_ot_keys + 25, 43, // B's curve25519 one time key
a_rand, sizeof(a_rand)
));
@@ -198,6 +205,31 @@ std::uint8_t b_session_buffer[::olm_account_size()];
b_session, b_account, tmp_message_1, sizeof(message_1)
);
+// Check that the inbound session matches the message it was created from.
+std::memcpy(tmp_message_1, message_1, sizeof(message_1));
+assert_equals(std::size_t(1), ::olm_matches_inbound_session(
+ b_session,
+ tmp_message_1, sizeof(message_1)
+));
+
+// Check that the inbound session matches the key this message is supposed
+// to be from.
+std::memcpy(tmp_message_1, message_1, sizeof(message_1));
+assert_equals(std::size_t(1), ::olm_matches_inbound_session_from(
+ b_session,
+ a_id_keys + 15, 43, // A's curve125519 identity key.
+ tmp_message_1, sizeof(message_1)
+));
+
+// Check that the inbound session isn't from a different user.
+std::memcpy(tmp_message_1, message_1, sizeof(message_1));
+assert_equals(std::size_t(0), ::olm_matches_inbound_session_from(
+ b_session,
+ b_id_keys + 15, 43, // B's curve25519 identity key.
+ tmp_message_1, sizeof(message_1)
+));
+
+// Check that we can decrypt the message.
std::memcpy(tmp_message_1, message_1, sizeof(message_1));
std::uint8_t plaintext_1[::olm_decrypt_max_plaintext_length(
b_session, 0, tmp_message_1, sizeof(message_1)