4 extern cvar_t crypto_developer;
5 extern cvar_t crypto_aeslevel;
6 #define ENCRYPTION_REQUIRED (crypto_aeslevel.integer >= 3)
8 extern int crypto_keyfp_recommended_length; // applies to LOCAL IDs, and to ALL keys
10 #define CRYPTO_HEADERSIZE 31
11 // AES case causes 16 to 31 bytes overhead
12 // SHA256 case causes 16 bytes overhead as we truncate to 128bit
21 unsigned char dhkey[DHKEY_SIZE]; // shared key, not NUL terminated
22 char client_idfp[FP64_SIZE+1];
23 char client_keyfp[FP64_SIZE+1]; // NULL if signature fail
24 char server_idfp[FP64_SIZE+1];
25 char server_keyfp[FP64_SIZE+1]; // NULL if signature fail
26 qboolean authenticated;
32 void Crypto_Init(void);
33 void Crypto_Init_Commands(void);
34 void Crypto_Shutdown(void);
35 const void *Crypto_EncryptPacket(crypto_t *crypto, const void *data_src, size_t len_src, void *data_dst, size_t *len_dst, size_t len);
36 const void *Crypto_DecryptPacket(crypto_t *crypto, const void *data_src, size_t len_src, void *data_dst, size_t *len_dst, size_t len);
37 #define CRYPTO_NOMATCH 0 // process as usual (packet was not used)
38 #define CRYPTO_MATCH 1 // process as usual (packet was used)
39 #define CRYPTO_DISCARD 2 // discard this packet
40 #define CRYPTO_REPLACE 3 // make the buffer the current packet
41 int Crypto_ClientParsePacket(const char *data_in, size_t len_in, char *data_out, size_t *len_out, lhnetaddress_t *peeraddress);
42 int Crypto_ServerParsePacket(const char *data_in, size_t len_in, char *data_out, size_t *len_out, lhnetaddress_t *peeraddress);
44 // if len_out is nonzero, the packet is to be sent to the client
46 qboolean Crypto_ServerAppendToChallenge(const char *data_in, size_t len_in, char *data_out, size_t *len_out, size_t maxlen);
47 crypto_t *Crypto_ServerGetInstance(lhnetaddress_t *peeraddress);
48 qboolean Crypto_ServerFinishInstance(crypto_t *out, crypto_t *in); // also clears allocated memory
49 const char *Crypto_GetInfoResponseDataString(void);
51 // retrieves a host key for an address (can be exposed to menuqc, or used by the engine to look up stored keys e.g. for server bookmarking)
52 // pointers may be NULL
53 qboolean Crypto_RetrieveHostKey(lhnetaddress_t *peeraddress, int *keyid, char *keyfp, size_t keyfplen, char *idfp, size_t idfplen, int *aeslevel);
54 int Crypto_RetrieveLocalKey(int keyid, char *keyfp, size_t keyfplen, char *idfp, size_t idfplen); // return value: -1 if more to come, +1 if valid, 0 if end of list
56 size_t Crypto_SignData(const void *data, size_t datasize, int keyid, void *signed_data, size_t signed_size);
63 // < accept (or: reject)
66 // < challenge SP <challenge> NUL vlen <size> d0pk <fingerprints I can auth to> NUL NUL <other fingerprints I accept>
69 // d0pk\cnt\0\challenge\<challenge>\aeslevel\<level> NUL <serverfp> NUL <clientfp>
71 // check if client would get accepted; if not, do "reject" now
72 // require non-control packets to be encrypted require non-control packets to be encrypted
73 // do not send anything yet do not send anything yet
74 // RESET to serverfp RESET to serverfp
75 // d0_blind_id_authenticate_with_private_id_start() = 1
76 // < d0pk\cnt\1\aes\<aesenabled> NUL *startdata*
77 // d0_blind_id_authenticate_with_private_id_challenge() = 1
78 // d0pk\cnt\2 NUL *challengedata* >
79 // d0_blind_id_authenticate_with_private_id_response() = 0
80 // < d0pk\cnt\3 NUL *responsedata*
81 // d0_blind_id_authenticate_with_private_id_verify() = 1
82 // store server's fingerprint NOW
83 // d0_blind_id_sessionkey_public_id() = 1 d0_blind_id_sessionkey_public_id() = 1
85 // IF clientfp AND NOT serverfp:
86 // RESET to clientfp RESET to clientfp
87 // d0_blind_id_authenticate_with_private_id_start() = 1
88 // d0pk\cnt\0\challenge\<challenge>\aeslevel\<level> NUL NUL <clientfp> NUL *startdata*
90 // check if client would get accepted; if not, do "reject" now
91 // require non-control packets to be encrypted require non-control packets to be encrypted
92 // d0_blind_id_authenticate_with_private_id_challenge() = 1
93 // < d0pk\cnt\5\aes\<aesenabled> NUL *challengedata*
95 // IF clientfp AND serverfp:
96 // RESET to clientfp RESET to clientfp
97 // d0_blind_id_authenticate_with_private_id_start() = 1
98 // d0pk\cnt\4 NUL *startdata* >
99 // d0_blind_id_authenticate_with_private_id_challenge() = 1
100 // < d0pk\cnt\5 NUL *challengedata*
103 // d0_blind_id_authenticate_with_private_id_response() = 0
104 // d0pk\cnt\6 NUL *responsedata* >
105 // d0_blind_id_authenticate_with_private_id_verify() = 1
106 // store client's fingerprint NOW
107 // d0_blind_id_sessionkey_public_id() = 1 d0_blind_id_sessionkey_public_id() = 1
108 // note: the ... is the "connect" message, except without the challenge. Reinterpret as regular connect message on server side
110 // enforce encrypted transmission (key is XOR of the two DH keys)
113 // < challenge (mere sync message)
116 // < accept (ALWAYS accept if connection is encrypted, ignore challenge as it had been checked before)
118 // commence with ingame protocol
122 // getchallenge NUL d0_blind_id: reply with challenge with added fingerprints
123 // cnt=0: IF server will auth, cnt=1, ELSE cnt=5
126 // cnt=6: send "challenge"
128 // challenge with added fingerprints: cnt=0; if client will auth but not server, append client auth start
130 // cnt=3: IF client will auth, cnt=4, ELSE rewrite as "challenge"
131 // cnt=5: cnt=6, server will continue by sending "challenge" (let's avoid sending two packets as response to one)
133 // accept empty "challenge", and challenge-less connect in case crypto protocol has executed and finished
134 // statusResponse and infoResponse get an added d0_blind_id key that lists
135 // the keys the server can auth with and to in key@ca SPACE key@ca notation
136 // any d0pk\ message has an appended "id" parameter; messages with an unexpected "id" are ignored to prevent errors from multiple concurrent auth runs
139 // comparison to OTR:
141 // - authentication: yes
142 // - deniability: no (attacker requires the temporary session key to prove you
143 // have sent a specific message, the private key itself does not suffice), no
144 // measures are taken to provide forgeability to even provide deniability
145 // against an attacker who knows the temporary session key, as using CTR mode
146 // for the encryption - which, together with deriving the MAC key from the
147 // encryption key, and MACing the ciphertexts instead of the plaintexts,
148 // would provide forgeability and thus deniability - requires longer
149 // encrypted packets and deniability was not a goal of this, as we may e.g.
150 // reserve the right to capture packet dumps + extra state info to prove a
151 // client/server has sent specific packets to prove cheating)
152 // - perfect forward secrecy: yes (session key is derived via DH key exchange)