1 files changed, 114 insertions, 0 deletions
diff --git a/libs/libsignal/src/group_cipher.h b/libs/libsignal/src/group_cipher.h
new file mode 100644
index 0000000000..50b194c06f
--- /dev/null
+++ b/libs/libsignal/src/group_cipher.h
@@ -0,0 +1,114 @@
+#ifndef GROUP_CIPHER_H
+#define GROUP_CIPHER_H
+
+#include <stdint.h>
+#include <stddef.h>
+#include "signal_protocol_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * The main entry point for Signal Protocol group encrypt/decrypt operations.
+ *
+ * Once a session has been established with group_session_builder and a
+ * sender_key_distribution_message has been distributed to each member of
+ * the group, this class can be used for all subsequent encrypt/decrypt
+ * operations within that session (i.e. until group membership changes).
+ */
+
+/**
+ * Construct a group cipher for encrypt/decrypt operations.
+ *
+ * The store and global contexts must remain valid for the lifetime of the
+ * group cipher.
+ *
+ * When finished, free the returned instance by calling group_cipher_free().
+ *
+ * @param cipher set to a freshly allocated group cipher instance
+ * @param store the signal_protocol_store_context to store all state information in
+ * @param sender_key_id the sender that messages will be encrypted to or decrypted from
+ * @param global_context the global library context
+ * @return 0 on success, or negative on failure
+ */
+int group_cipher_create(group_cipher **cipher,
+        signal_protocol_store_context *store, const signal_protocol_sender_key_name *sender_key_id,
+        signal_context *global_context);
+
+/**
+ * Set the optional user data pointer for the group cipher.
+ *
+ * This is to give callback functions a way of accessing app specific
+ * context information for this cipher.
+ */
+void group_cipher_set_user_data(group_cipher *cipher, void *user_data);
+
+/**
+ * Get the optional user data pointer for the group cipher.
+ *
+ * This is to give callback functions a way of accessing app specific
+ * context information for this cipher.
+ */
+void *group_cipher_get_user_data(group_cipher *cipher);
+
+/**
+ * Set the callback function that is called during the decrypt process.
+ *
+ * The callback function is called from within group_cipher_decrypt() after
+ * decryption is complete but before the updated session state has been
+ * committed to the session store. If the callback function returns a
+ * negative value, then the decrypt function will immediately fail with
+ * an error.
+ *
+ * This a callback allows some implementations to store the committed plaintext
+ * to their local message store first, in case they are concerned with a crash
+ * or write error happening between the time the session state is updated but
+ * before they're able to successfully store the plaintext to disk.
+ *
+ * @param callback the callback function to set
+ */
+void group_cipher_set_decryption_callback(group_cipher *cipher,
+        int (*callback)(group_cipher *cipher, signal_buffer *plaintext, void *decrypt_context));
+
+/**
+ * Encrypt a message.
+ *
+ * @param padded_plaintext The plaintext message bytes, optionally padded to a constant multiple.
+ * @param padded_plaintext_len The length of the data pointed to by padded_message
+ * @param encrypted_message Set to a ciphertext message encrypted to the group+sender+device tuple.
+ *
+ * @retval SG_SUCCESS Success
+ * @retval SG_ERR_NO_SESSION if there is no established session for this contact.
+ * @retval SG_ERR_INVALID_KEY if there is no valid private key for this session.
+ */
+int group_cipher_encrypt(group_cipher *cipher,
+        const uint8_t *padded_plaintext, size_t padded_plaintext_len,
+        ciphertext_message **encrypted_message);
+
+/**
+ * Decrypt a message.
+ *
+ * @param ciphertext The sender_key_message to decrypt.
+ * @param decrypt_context Optional context pointer associated with the
+ *   ciphertext, which is passed to the decryption callback function
+ * @param plaintext Set to a newly allocated buffer containing the plaintext.
+ *
+ * @retval SG_SUCCESS Success
+ * @retval SG_ERR_INVALID_MESSAGE if the input is not valid ciphertext.
+ * @retval SG_ERR_DUPLICATE_MESSAGE if the input is a message that has already been received.
+ * @retval SG_ERR_LEGACY_MESSAGE if the input is a message formatted by a protocol version that
+ *                               is no longer supported.
+ * @retval SG_ERR_NO_SESSION if there is no established session for this contact.
+ */
+int group_cipher_decrypt(group_cipher *cipher,
+        sender_key_message *ciphertext, void *decrypt_context,
+        signal_buffer **plaintext);
+
+void group_cipher_free(group_cipher *cipher);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* GROUP_CIPHER_H */