Here are the data structures with brief descriptions:

CbzrtpCallbacks_struct	All the callback functions provided by the client needed by the ZRTP engine
CbzrtpChannelContext_struct	The zrtp context of a channel
CbzrtpCommitMessage_struct	Hello ACK Message rfc 5.3 This message contains no data but only a length and message type which are stored in the bzrtpPacket_t structure There the no need to define a structure type for this packet
CbzrtpConfirmMessage_struct	Confirm Message rfc 5.7 Confirm1 and Confirm2 messages have the same structure Confirm1 is generated by the responder and Confirm2 by the initiator Part of the message is encrypted using the negotiated block cipher for media encryption. Keys ares zrtpkeyr for responder and zrtpkeyi for initiator
CbzrtpContext_struct	Structure of the ZRTP engine context Store current state, timers, HMAC and encryption keys
CbzrtpDHPartMessage_struct	DHPart Message rfc 5.5 and rfc 5.6 DHPart1 and DHPart2 message have the same structure DHPart1 is generated by the responder, and DHPart2 by the initiator
CbzrtpEvent_struct	The event type, used as a parameter for the state function
CbzrtpGoClearMessage_struct	Conf2 ACK Message rfc 5.8 This message contains no data but only a length and message type which are stored in the bzrtpPacket_t structure There the no need to define a structure type for this packet
CbzrtpHelloMessage_struct	Hello Message rfc 5.2
CbzrtpPacket_struct	Store all zrtpPacket informations according to type a specific structure type is mapped to the void * data pointer
CbzrtpPingAckMessage_struct	PingAck Message The Ping and PingACK messages are unrelated to the rest of the ZRTP protocol. No ZRTP endpoint is required to generate a Ping message, but every ZRTP endpoint MUST respond to a Ping message with a PingACK message
CbzrtpPingMessage_struct	Relay ACK Message rfc 5.14 This message contains no data but only a length and message type which are stored in the bzrtpPacket_t structure There the no need to define a structure type for this packet
CbzrtpSASRelayMessage_struct	Clear ACK Message rfc 5.12 This message contains no data but only a length and message type which are stored in the bzrtpPacket_t structure There the no need to define a structure type for this packet
CbzrtpSrtpSecrets_struct
CbzrtpTimer_struct	Timer structure : The timer mechanism receives a tick giving a current time in ms a timer object will check on tick reception if it must fire or not
CcachedSecrets_struct	A set of cached secrets retrieved from the cache as defined
CcachedSecretsHash_struct	The hash of cached secret truncated to the 64 leftmost bits aux secret ID is not part of it because channel context dependend while these one are session wise