diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/olm/error.h | 13 | ||||
| -rw-r--r-- | include/olm/inbound_group_session.h | 153 | ||||
| -rw-r--r-- | include/olm/megolm.h | 95 | ||||
| -rw-r--r-- | include/olm/message.h | 98 | ||||
| -rw-r--r-- | include/olm/message.hh | 12 | ||||
| -rw-r--r-- | include/olm/olm.h | 3 | ||||
| -rw-r--r-- | include/olm/outbound_group_session.h | 181 | ||||
| -rw-r--r-- | include/olm/pickle_encoding.h | 76 |
8 files changed, 631 insertions, 0 deletions
diff --git a/include/olm/error.h b/include/olm/error.h index a4f373e..98d2cf5 100644 --- a/include/olm/error.h +++ b/include/olm/error.h @@ -31,8 +31,21 @@ enum OlmErrorCode { OLM_BAD_ACCOUNT_KEY = 8, /*!< The supplied account key is invalid */ OLM_UNKNOWN_PICKLE_VERSION = 9, /*!< The pickled object is too new */ OLM_CORRUPTED_PICKLE = 10, /*!< The pickled object couldn't be decoded */ + + OLM_BAD_SESSION_KEY = 11, /*!< Attempt to initialise an inbound group + session from an invalid session key */ + OLM_UNKNOWN_MESSAGE_INDEX = 12, /*!< Attempt to decode a message whose + * index is earlier than our earliest + * known session key. + */ + + /* remember to update the list of string constants in error.c when updating + * this list. */ }; +/** get a string representation of the given error code. */ +const char * _olm_error_to_string(enum OlmErrorCode error); + #ifdef __cplusplus } // extern "C" #endif diff --git a/include/olm/inbound_group_session.h b/include/olm/inbound_group_session.h new file mode 100644 index 0000000..e24f377 --- /dev/null +++ b/include/olm/inbound_group_session.h @@ -0,0 +1,153 @@ +/* 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. + */ +#ifndef OLM_INBOUND_GROUP_SESSION_H_ +#define OLM_INBOUND_GROUP_SESSION_H_ + +#include <stddef.h> +#include <stdint.h> + +#ifdef __cplusplus +extern "C" { +#endif + +typedef struct OlmInboundGroupSession OlmInboundGroupSession; + +/** get the size of an inbound group session, in bytes. */ +size_t olm_inbound_group_session_size(); + +/** + * Initialise an inbound group session object using the supplied memory + * The supplied memory should be at least olm_inbound_group_session_size() + * bytes. + */ +OlmInboundGroupSession * olm_inbound_group_session( + void *memory +); + +/** + * A null terminated string describing the most recent error to happen to a + * group session */ +const char *olm_inbound_group_session_last_error( + const OlmInboundGroupSession *session +); + +/** Clears the memory used to back this group session */ +size_t olm_clear_inbound_group_session( + OlmInboundGroupSession *session +); + +/** Returns the number of bytes needed to store an inbound group session */ +size_t olm_pickle_inbound_group_session_length( + const OlmInboundGroupSession *session +); + +/** + * Stores a group session as a base64 string. Encrypts the session using the + * supplied key. Returns the length of the session on success. + * + * Returns olm_error() on failure. If the pickle output buffer + * is smaller than olm_pickle_inbound_group_session_length() then + * olm_inbound_group_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL" + */ +size_t olm_pickle_inbound_group_session( + OlmInboundGroupSession *session, + void const * key, size_t key_length, + void * pickled, size_t pickled_length +); + +/** + * Loads a group session from a pickled base64 string. Decrypts the session + * using the supplied key. + * + * Returns olm_error() on failure. If the key doesn't match the one used to + * encrypt the account then olm_inbound_group_session_last_error() will be + * "BAD_ACCOUNT_KEY". If the base64 couldn't be decoded then + * olm_inbound_group_session_last_error() will be "INVALID_BASE64". The input + * pickled buffer is destroyed + */ +size_t olm_unpickle_inbound_group_session( + OlmInboundGroupSession *session, + void const * key, size_t key_length, + void * pickled, size_t pickled_length +); + + +/** + * Start a new inbound group session, based on the parameters supplied. + * + * Returns olm_error() on failure. On failure last_error will be set with an + * error code. The last_error will be: + * + * * OLM_INVALID_BASE64 if the session_key is not valid base64 + * * OLM_BAD_SESSION_KEY if the session_key is invalid + */ +size_t olm_init_inbound_group_session( + OlmInboundGroupSession *session, + uint32_t message_index, + + /* base64-encoded key */ + uint8_t const * session_key, size_t session_key_length +); + +/** + * Get an upper bound on the number of bytes of plain-text the decrypt method + * will write for a given input message length. The actual size could be + * different due to padding. + * + * The input message buffer is destroyed. + * + * Returns olm_error() on failure. + */ +size_t olm_group_decrypt_max_plaintext_length( + OlmInboundGroupSession *session, + uint8_t * message, size_t message_length +); + +/** + * Decrypt a message. + * + * The input message buffer is destroyed. + * + * Returns the length of the decrypted plain-text, or olm_error() on failure. + * + * On failure last_error will be set with an error code. The last_error will + * be: + * * OLM_OUTPUT_BUFFER_TOO_SMALL if the plain-text buffer is too small + * * OLM_INVALID_BASE64 if the message is not valid base-64 + * * OLM_BAD_MESSAGE_VERSION if the message was encrypted with an unsupported + * version of the protocol + * * OLM_BAD_MESSAGE_FORMAT if the message headers could not be decoded + * * OLM_BAD_MESSAGE_MAC if the message could not be verified + * * OLM_UNKNOWN_MESSAGE_INDEX if we do not have a session key corresponding to the + * message's index (ie, it was sent before the session key was shared with + * us) + */ +size_t olm_group_decrypt( + OlmInboundGroupSession *session, + + /* input; note that it will be overwritten with the base64-decoded + message. */ + uint8_t * message, size_t message_length, + + /* output */ + uint8_t * plaintext, size_t max_plaintext_length +); + + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif /* OLM_INBOUND_GROUP_SESSION_H_ */ diff --git a/include/olm/megolm.h b/include/olm/megolm.h new file mode 100644 index 0000000..e4e5d0b --- /dev/null +++ b/include/olm/megolm.h @@ -0,0 +1,95 @@ +/* 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. + */ + +#ifndef OLM_MEGOLM_H_ +#define OLM_MEGOLM_H_ + +/** + * implementation of the Megolm multi-part ratchet used in group chats. + */ + +#include <stdint.h> +#include <stdlib.h> + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * number of bytes in each part of the ratchet; this should be the same as + * the length of the hash function used in the HMAC (32 bytes for us, as we + * use HMAC-SHA-256) + */ +#define MEGOLM_RATCHET_PART_LENGTH 32 /* SHA256_OUTPUT_LENGTH */ + +/** + * number of parts in the ratchet; the advance() implementations rely on + * this being 4. + */ +#define MEGOLM_RATCHET_PARTS 4 + +#define MEGOLM_RATCHET_LENGTH (MEGOLM_RATCHET_PARTS * MEGOLM_RATCHET_PART_LENGTH) + +typedef struct Megolm { + uint8_t data[MEGOLM_RATCHET_PARTS][MEGOLM_RATCHET_PART_LENGTH]; + uint32_t counter; +} Megolm; + + +/** + * The cipher used in megolm-backed conversations + * + * (AES256 + SHA256, with keys based on an HKDF with info of MEGOLM_KEYS) + */ +extern const struct _olm_cipher *megolm_cipher; + +/** + * initialize the megolm ratchet. random_data should be at least + * MEGOLM_RATCHET_LENGTH bytes of randomness. + */ +void megolm_init(Megolm *megolm, uint8_t const *random_data, uint32_t counter); + +/** Returns the number of bytes needed to store a megolm */ +size_t megolm_pickle_length(const Megolm *megolm); + +/** + * Pickle the megolm. Returns a pointer to the next free space in the buffer. + */ +uint8_t * megolm_pickle(const Megolm *megolm, uint8_t *pos); + +/** + * Unpickle the megolm. Returns a pointer to the next item in the buffer. + */ +const uint8_t * megolm_unpickle(Megolm *megolm, const uint8_t *pos, + const uint8_t *end); + + +/** advance the ratchet by one step */ +void megolm_advance(Megolm *megolm); + +/** + * get the key data in the ratchet. The returned data is + * MEGOLM_RATCHET_LENGTH bytes long. + */ +#define megolm_get_data(megolm) ((const uint8_t *)((megolm)->data)) + +/** advance the ratchet to a given count */ +void megolm_advance_to(Megolm *megolm, uint32_t advance_to); + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif /* OLM_MEGOLM_H_ */ diff --git a/include/olm/message.h b/include/olm/message.h new file mode 100644 index 0000000..e80d54c --- /dev/null +++ b/include/olm/message.h @@ -0,0 +1,98 @@ +/* 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. + */ + +/** + * functions for encoding and decoding messages in the Olm protocol. + * + * Some of these functions have only C++ bindings, and are declared in + * message.hh; in time, they should probably be converted to plain C and + * declared here. + */ + +#ifndef OLM_MESSAGE_H_ +#define OLM_MESSAGE_H_ + +#include <stdint.h> +#include <stddef.h> + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * The length of the buffer needed to hold a group message. + */ +size_t _olm_encode_group_message_length( + size_t group_session_id_length, + uint32_t chain_index, + size_t ciphertext_length, + size_t mac_length +); + +/** + * Writes the message headers into the output buffer. + * + * version: version number of the olm protocol + * session_id: group session identifier + * session_id_length: length of session_id + * message_index: message index + * ciphertext_length: length of the ciphertext + * output: where to write the output. Should be at least + * olm_encode_group_message_length() bytes long. + * ciphertext_ptr: returns the address that the ciphertext + * should be written to, followed by the MAC. + * + * Returns the size of the message, up to the MAC. + */ +size_t _olm_encode_group_message( + uint8_t version, + const uint8_t *session_id, + size_t session_id_length, + uint32_t message_index, + size_t ciphertext_length, + uint8_t *output, + uint8_t **ciphertext_ptr +); + + +struct _OlmDecodeGroupMessageResults { + uint8_t version; + const uint8_t *session_id; + size_t session_id_length; + uint32_t message_index; + int has_message_index; + const uint8_t *ciphertext; + size_t ciphertext_length; +}; + + +/** + * Reads the message headers from the input buffer. + */ +void _olm_decode_group_message( + const uint8_t *input, size_t input_length, + size_t mac_length, + + /* output structure: updated with results */ + struct _OlmDecodeGroupMessageResults *results +); + + + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif /* OLM_MESSAGE_H_ */ diff --git a/include/olm/message.hh b/include/olm/message.hh index 5ce0a62..bd912d9 100644 --- a/include/olm/message.hh +++ b/include/olm/message.hh @@ -12,6 +12,18 @@ * See the License for the specific language governing permissions and * limitations under the License. */ + + +/** + * functions for encoding and decoding messages in the Olm protocol. + * + * Some of these functions have plain-C bindings, and are declared in + * message.h; in time, all of the functions declared here should probably be + * converted to plain C and moved to message.h. + */ + +#include "message.h" + #include <cstddef> #include <cstdint> diff --git a/include/olm/olm.h b/include/olm/olm.h index 8abac49..dbaf71e 100644 --- a/include/olm/olm.h +++ b/include/olm/olm.h @@ -19,6 +19,9 @@ #include <stddef.h> #include <stdint.h> +#include "olm/inbound_group_session.h" +#include "olm/outbound_group_session.h" + #ifdef __cplusplus extern "C" { #endif diff --git a/include/olm/outbound_group_session.h b/include/olm/outbound_group_session.h new file mode 100644 index 0000000..90859e9 --- /dev/null +++ b/include/olm/outbound_group_session.h @@ -0,0 +1,181 @@ +/* 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. + */ +#ifndef OLM_OUTBOUND_GROUP_SESSION_H_ +#define OLM_OUTBOUND_GROUP_SESSION_H_ + +#include <stddef.h> +#include <stdint.h> + +#ifdef __cplusplus +extern "C" { +#endif + +typedef struct OlmOutboundGroupSession OlmOutboundGroupSession; + +/** get the size of an outbound group session, in bytes. */ +size_t olm_outbound_group_session_size(); + +/** + * Initialise an outbound group session object using the supplied memory + * The supplied memory should be at least olm_outbound_group_session_size() + * bytes. + */ +OlmOutboundGroupSession * olm_outbound_group_session( + void *memory +); + +/** + * A null terminated string describing the most recent error to happen to a + * group session */ +const char *olm_outbound_group_session_last_error( + const OlmOutboundGroupSession *session +); + +/** Clears the memory used to back this group session */ +size_t olm_clear_outbound_group_session( + OlmOutboundGroupSession *session +); + +/** Returns the number of bytes needed to store an outbound group session */ +size_t olm_pickle_outbound_group_session_length( + const OlmOutboundGroupSession *session +); + +/** + * Stores a group session as a base64 string. Encrypts the session using the + * supplied key. Returns the length of the session on success. + * + * Returns olm_error() on failure. If the pickle output buffer + * is smaller than olm_pickle_outbound_group_session_length() then + * olm_outbound_group_session_last_error() will be "OUTPUT_BUFFER_TOO_SMALL" + */ +size_t olm_pickle_outbound_group_session( + OlmOutboundGroupSession *session, + void const * key, size_t key_length, + void * pickled, size_t pickled_length +); + +/** + * Loads a group session from a pickled base64 string. Decrypts the session + * using the supplied key. + * + * Returns olm_error() on failure. If the key doesn't match the one used to + * encrypt the account then olm_outbound_group_session_last_error() will be + * "BAD_ACCOUNT_KEY". If the base64 couldn't be decoded then + * olm_outbound_group_session_last_error() will be "INVALID_BASE64". The input + * pickled buffer is destroyed + */ +size_t olm_unpickle_outbound_group_session( + OlmOutboundGroupSession *session, + void const * key, size_t key_length, + void * pickled, size_t pickled_length +); + + +/** The number of random bytes needed to create an outbound group session */ +size_t olm_init_outbound_group_session_random_length( + const OlmOutboundGroupSession *session +); + +/** + * Start a new outbound group session. Returns olm_error() on failure. On + * failure last_error will be set with an error code. The last_error will be + * NOT_ENOUGH_RANDOM if the number of random bytes was too small. + */ +size_t olm_init_outbound_group_session( + OlmOutboundGroupSession *session, + uint8_t const * random, size_t random_length +); + +/** + * The number of bytes that will be created by encrypting a message + */ +size_t olm_group_encrypt_message_length( + OlmOutboundGroupSession *session, + size_t plaintext_length +); + +/** + * Encrypt some plain-text. Returns the length of the encrypted message or + * olm_error() on failure. On failure last_error will be set with an + * error code. The last_error will be OUTPUT_BUFFER_TOO_SMALL if the output + * buffer is too small. + */ +size_t olm_group_encrypt( + OlmOutboundGroupSession *session, + uint8_t const * plaintext, size_t plaintext_length, + uint8_t * message, size_t message_length +); + + +/** + * Get the number of bytes returned by olm_outbound_group_session_id() + */ +size_t olm_outbound_group_session_id_length( + const OlmOutboundGroupSession *session +); + +/** + * Get a base64-encoded identifier for this session. + * + * Returns the length of the session id on success or olm_error() on + * failure. On failure last_error will be set with an error code. The + * last_error will be OUTPUT_BUFFER_TOO_SMALL if the id buffer was too + * small. + */ +size_t olm_outbound_group_session_id( + OlmOutboundGroupSession *session, + uint8_t * id, size_t id_length +); + +/** + * Get the current message index for this session. + * + * Each message is sent with an increasing index; this returns the index for + * the next message. + */ +uint32_t olm_outbound_group_session_message_index( + OlmOutboundGroupSession *session +); + +/** + * Get the number of bytes returned by olm_outbound_group_session_key() + */ +size_t olm_outbound_group_session_key_length( + const OlmOutboundGroupSession *session +); + +/** + * Get the base64-encoded current ratchet key for this session. + * + * Each message is sent with a diffent ratchet key. This function returns the + * ratchet key that will be used for the next message. + * + * Returns the length of the ratchet key on success or olm_error() on + * failure. On failure last_error will be set with an error code. The + * last_error will be OUTPUT_BUFFER_TOO_SMALL if the buffer was too small. + */ +size_t olm_outbound_group_session_key( + OlmOutboundGroupSession *session, + uint8_t * key, size_t key_length +); + + + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif /* OLM_OUTBOUND_GROUP_SESSION_H_ */ diff --git a/include/olm/pickle_encoding.h b/include/olm/pickle_encoding.h new file mode 100644 index 0000000..03611df --- /dev/null +++ b/include/olm/pickle_encoding.h @@ -0,0 +1,76 @@ +/* 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. + */ + +/* functions for encrypting and decrypting pickled representations of objects */ + +#ifndef OLM_PICKLE_ENCODING_H_ +#define OLM_PICKLE_ENCODING_H_ + +#include <stddef.h> +#include <stdint.h> + +#include "olm/error.h" + +#ifdef __cplusplus +extern "C" { +#endif + + +/** + * Get the number of bytes needed to encode a pickle of the length given + */ +size_t _olm_enc_output_length(size_t raw_length); + +/** + * Get the point in the output buffer that the raw pickle should be written to. + * + * In order that we can use the same buffer for the raw pickle, and the encoded + * pickle, the raw pickle needs to be written at the end of the buffer. (The + * base-64 encoding would otherwise overwrite the end of the input before it + * was encoded.) + */ + uint8_t *_olm_enc_output_pos(uint8_t * output, size_t raw_length); + +/** + * Encrypt and encode the given pickle in-situ. + * + * The raw pickle should have been written to enc_output_pos(pickle, + * raw_length). + * + * Returns the number of bytes in the encoded pickle. + */ +size_t _olm_enc_output( + uint8_t const * key, size_t key_length, + uint8_t *pickle, size_t raw_length +); + +/** + * Decode and decrypt the given pickle in-situ. + * + * Returns the number of bytes in the decoded pickle, or olm_error() on error, + * in which case *last_error will be updated, if last_error is non-NULL. + */ +size_t _olm_enc_input( + uint8_t const * key, size_t key_length, + uint8_t * input, size_t b64_length, + enum OlmErrorCode * last_error +); + + +#ifdef __cplusplus +} // extern "C" +#endif + +#endif /* OLM_PICKLE_ENCODING_H_ */ |