diff options
Diffstat (limited to 'libs/libaxolotl/src/group_cipher.c')
| -rw-r--r-- | libs/libaxolotl/src/group_cipher.c | 326 |
1 files changed, 326 insertions, 0 deletions
diff --git a/libs/libaxolotl/src/group_cipher.c b/libs/libaxolotl/src/group_cipher.c new file mode 100644 index 0000000000..752c2e16d4 --- /dev/null +++ b/libs/libaxolotl/src/group_cipher.c @@ -0,0 +1,326 @@ +#include "group_cipher.h" + +#include <assert.h> +#include <string.h> +#include "axolotl_internal.h" +#include "protocol.h" +#include "sender_key.h" +#include "sender_key_record.h" +#include "sender_key_state.h" + +struct group_cipher +{ + axolotl_store_context *store; + const axolotl_sender_key_name *sender_key_id; + axolotl_context *global_context; + int (*decrypt_callback)(group_cipher *cipher, axolotl_buffer *plaintext, void *decrypt_context); + int inside_callback; + void *user_data; +}; + +static int group_cipher_get_sender_key(group_cipher *cipher, sender_message_key **sender_key, sender_key_state *state, uint32_t iteration); +static int group_cipher_decrypt_callback(group_cipher *cipher, axolotl_buffer *plaintext, void *decrypt_context); + +int group_cipher_create(group_cipher **cipher, + axolotl_store_context *store, const axolotl_sender_key_name *sender_key_id, + axolotl_context *global_context) +{ + group_cipher *result_cipher; + + assert(store); + assert(global_context); + + result_cipher = malloc(sizeof(group_cipher)); + if(!result_cipher) { + return AX_ERR_NOMEM; + } + memset(result_cipher, 0, sizeof(group_cipher)); + + result_cipher->store = store; + result_cipher->sender_key_id = sender_key_id; + result_cipher->global_context = global_context; + + *cipher = result_cipher; + return 0; +} + +void group_cipher_set_user_data(group_cipher *cipher, void *user_data) +{ + assert(cipher); + cipher->user_data = user_data; +} + +void *group_cipher_get_user_data(group_cipher *cipher) +{ + assert(cipher); + return cipher->user_data; +} + +void group_cipher_set_decryption_callback(group_cipher *cipher, + int (*callback)(group_cipher *cipher, axolotl_buffer *plaintext, void *decrypt_context)) +{ + assert(cipher); + cipher->decrypt_callback = callback; +} + +int group_cipher_encrypt(group_cipher *cipher, + const uint8_t *padded_plaintext, size_t padded_plaintext_len, + ciphertext_message **encrypted_message) +{ + int result = 0; + sender_key_message *result_message = 0; + sender_key_record *record = 0; + sender_key_state *state = 0; + sender_message_key *sender_key = 0; + sender_chain_key *next_chain_key = 0; + axolotl_buffer *sender_cipher_key = 0; + axolotl_buffer *sender_cipher_iv = 0; + axolotl_buffer *ciphertext = 0; + + assert(cipher); + axolotl_lock(cipher->global_context); + + if(cipher->inside_callback == 1) { + result = AX_ERR_INVAL; + goto complete; + } + + result = axolotl_sender_key_load_key(cipher->store, &record, cipher->sender_key_id); + if(result < 0) { + goto complete; + } + + result = sender_key_record_get_sender_key_state(record, &state); + if(result < 0) { + goto complete; + } + + result = sender_chain_key_create_message_key(sender_key_state_get_chain_key(state), &sender_key); + if(result < 0) { + goto complete; + } + + sender_cipher_key = sender_message_key_get_cipher_key(sender_key); + sender_cipher_iv = sender_message_key_get_iv(sender_key); + + result = axolotl_encrypt(cipher->global_context, &ciphertext, AX_CIPHER_AES_CBC_PKCS5, + axolotl_buffer_data(sender_cipher_key), axolotl_buffer_len(sender_cipher_key), + axolotl_buffer_data(sender_cipher_iv), axolotl_buffer_len(sender_cipher_iv), + padded_plaintext, padded_plaintext_len); + if(result < 0) { + goto complete; + } + + result = sender_key_message_create(&result_message, + sender_key_state_get_key_id(state), + sender_message_key_get_iteration(sender_key), + axolotl_buffer_data(ciphertext), axolotl_buffer_len(ciphertext), + sender_key_state_get_signing_key_private(state), + cipher->global_context); + if(result < 0) { + goto complete; + } + + result = sender_chain_key_create_next(sender_key_state_get_chain_key(state), &next_chain_key); + if(result < 0) { + goto complete; + } + + sender_key_state_set_chain_key(state, next_chain_key); + + result = axolotl_sender_key_store_key(cipher->store, cipher->sender_key_id, record); + +complete: + if(result >= 0) { + *encrypted_message = (ciphertext_message *)result_message; + } + else { + if(result == AX_ERR_INVALID_KEY_ID) { + result = AX_ERR_NO_SESSION; + } + AXOLOTL_UNREF(result_message); + } + axolotl_buffer_free(ciphertext); + AXOLOTL_UNREF(next_chain_key); + AXOLOTL_UNREF(sender_key); + AXOLOTL_UNREF(record); + axolotl_unlock(cipher->global_context); + return result; +} + +int group_cipher_decrypt(group_cipher *cipher, + sender_key_message *ciphertext, void *decrypt_context, + axolotl_buffer **plaintext) +{ + int result = 0; + axolotl_buffer *result_buf = 0; + sender_key_record *record = 0; + sender_key_state *state = 0; + sender_message_key *sender_key = 0; + axolotl_buffer *sender_cipher_key = 0; + axolotl_buffer *sender_cipher_iv = 0; + axolotl_buffer *ciphertext_body = 0; + + assert(cipher); + axolotl_lock(cipher->global_context); + + if(cipher->inside_callback == 1) { + result = AX_ERR_INVAL; + goto complete; + } + + result = axolotl_sender_key_load_key(cipher->store, &record, cipher->sender_key_id); + if(result < 0) { + goto complete; + } + + if(sender_key_record_is_empty(record)) { + result = AX_ERR_NO_SESSION; + axolotl_log(cipher->global_context, AX_LOG_WARNING, "No sender key for: %s::%s::%d", + cipher->sender_key_id->group_id, + cipher->sender_key_id->sender.name, + cipher->sender_key_id->sender.device_id); + goto complete; + } + + result = sender_key_record_get_sender_key_state_by_id(record, &state, sender_key_message_get_key_id(ciphertext)); + if(result < 0) { + goto complete; + } + + result = sender_key_message_verify_signature(ciphertext, sender_key_state_get_signing_key_public(state)); + if(result < 0) { + goto complete; + } + + result = group_cipher_get_sender_key(cipher, &sender_key, state, sender_key_message_get_iteration(ciphertext)); + if(result < 0) { + goto complete; + } + + sender_cipher_key = sender_message_key_get_cipher_key(sender_key); + sender_cipher_iv = sender_message_key_get_iv(sender_key); + ciphertext_body = sender_key_message_get_ciphertext(ciphertext); + + result = axolotl_decrypt(cipher->global_context, &result_buf, AX_CIPHER_AES_CBC_PKCS5, + axolotl_buffer_data(sender_cipher_key), axolotl_buffer_len(sender_cipher_key), + axolotl_buffer_data(sender_cipher_iv), axolotl_buffer_len(sender_cipher_iv), + axolotl_buffer_data(ciphertext_body), axolotl_buffer_len(ciphertext_body)); + if(result < 0) { + goto complete; + } + + result = group_cipher_decrypt_callback(cipher, result_buf, decrypt_context); + if(result < 0) { + goto complete; + } + + result = axolotl_sender_key_store_key(cipher->store, cipher->sender_key_id, record); + +complete: + AXOLOTL_UNREF(sender_key); + AXOLOTL_UNREF(record); + if(result >= 0) { + *plaintext = result_buf; + } + else { + if(result == AX_ERR_INVALID_KEY || result == AX_ERR_INVALID_KEY_ID) { + result = AX_ERR_INVALID_MESSAGE; + } + axolotl_buffer_free(result_buf); + } + axolotl_unlock(cipher->global_context); + return result; +} + +int group_cipher_get_sender_key(group_cipher *cipher, sender_message_key **sender_key, sender_key_state *state, uint32_t iteration) +{ + int result = 0; + sender_message_key *result_key = 0; + sender_chain_key *chain_key = 0; + sender_chain_key *next_chain_key = 0; + sender_message_key *message_key = 0; + + chain_key = sender_key_state_get_chain_key(state); + AXOLOTL_REF(chain_key); + + if(sender_chain_key_get_iteration(chain_key) > iteration) { + if(sender_key_state_has_sender_message_key(state, iteration)) { + result_key = sender_key_state_remove_sender_message_key(state, iteration); + if(!result_key) { + result = AX_ERR_UNKNOWN; + } + goto complete; + } + else { + result = AX_ERR_DUPLICATE_MESSAGE; + axolotl_log(cipher->global_context, AX_LOG_WARNING, + "Received message with old counter: %d, %d", + sender_chain_key_get_iteration(chain_key), iteration); + goto complete; + } + } + + if(iteration - sender_chain_key_get_iteration(chain_key) > 2000) { + result = AX_ERR_INVALID_MESSAGE; + axolotl_log(cipher->global_context, AX_LOG_WARNING, "Over 2000 messages into the future!"); + goto complete; + } + + while(sender_chain_key_get_iteration(chain_key) < iteration) { + result = sender_chain_key_create_message_key(chain_key, &message_key); + if(result < 0) { + goto complete; + } + + result = sender_key_state_add_sender_message_key(state, message_key); + if(result < 0) { + goto complete; + } + AXOLOTL_UNREF(message_key); + + result = sender_chain_key_create_next(chain_key, &next_chain_key); + if(result < 0) { + goto complete; + } + + AXOLOTL_UNREF(chain_key); + chain_key = next_chain_key; + next_chain_key = 0; + } + + result = sender_chain_key_create_next(chain_key, &next_chain_key); + if(result < 0) { + goto complete; + } + + sender_key_state_set_chain_key(state, next_chain_key); + result = sender_chain_key_create_message_key(chain_key, &result_key); + +complete: + AXOLOTL_UNREF(message_key); + AXOLOTL_UNREF(chain_key); + AXOLOTL_UNREF(next_chain_key); + if(result >= 0) { + *sender_key = result_key; + } + return result; +} + +static int group_cipher_decrypt_callback(group_cipher *cipher, axolotl_buffer *plaintext, void *decrypt_context) +{ + int result = 0; + if(cipher->decrypt_callback) { + cipher->inside_callback = 1; + result = cipher->decrypt_callback(cipher, plaintext, decrypt_context); + cipher->inside_callback = 0; + } + return result; +} + +void group_cipher_free(group_cipher *cipher) +{ + if(cipher) { + free(cipher); + } +} |