8 extern struct cvar_s crypto_developer;
9 extern struct cvar_s crypto_aeslevel;
10 #define ENCRYPTION_REQUIRED (crypto_aeslevel.integer >= 3)
12 extern int crypto_keyfp_recommended_length; // applies to LOCAL IDs, and to ALL keys
14 #define CRYPTO_HEADERSIZE 31
15 // AES case causes 16 to 31 bytes overhead
16 // SHA256 case causes 16 bytes overhead as we truncate to 128bit
23 unsigned char dhkey[DHKEY_SIZE]; // shared key, not NUL terminated
24 char client_idfp[FP64_SIZE+1];
25 char client_keyfp[FP64_SIZE+1];
26 qbool client_issigned;
27 char server_idfp[FP64_SIZE+1];
28 char server_keyfp[FP64_SIZE+1];
29 qbool server_issigned;
36 void Crypto_Init(void);
37 void Crypto_Init_Commands(void);
38 void Crypto_LoadKeys(void); // NOTE: when this is called, the SV_LockThreadMutex MUST be active
39 void Crypto_Shutdown(void);
40 qbool Crypto_Available(void);
41 void sha256(unsigned char *out, const unsigned char *in, int n); // may ONLY be called if Crypto_Available()
42 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);
43 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);
44 #define CRYPTO_NOMATCH 0 // process as usual (packet was not used)
45 #define CRYPTO_MATCH 1 // process as usual (packet was used)
46 #define CRYPTO_DISCARD 2 // discard this packet
47 #define CRYPTO_REPLACE 3 // make the buffer the current packet
48 int Crypto_ClientParsePacket(const char *data_in, size_t len_in, char *data_out, size_t *len_out, struct lhnetaddress_s *peeraddress);
49 int Crypto_ServerParsePacket(const char *data_in, size_t len_in, char *data_out, size_t *len_out, struct lhnetaddress_s *peeraddress);
51 // if len_out is nonzero, the packet is to be sent to the client
53 qbool Crypto_ServerAppendToChallenge(const char *data_in, size_t len_in, char *data_out, size_t *len_out, size_t maxlen);
54 crypto_t *Crypto_ServerGetInstance(struct lhnetaddress_s *peeraddress);
55 qbool Crypto_FinishInstance(crypto_t *out, crypto_t *in); // also clears allocated memory, and frees the instance received by ServerGetInstance
56 const char *Crypto_GetInfoResponseDataString(void);
58 // 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)
59 // pointers may be NULL
60 qbool Crypto_RetrieveHostKey(struct lhnetaddress_s *peeraddress, int *keyid, char *keyfp, size_t keyfplen, char *idfp, size_t idfplen, int *aeslevel, qbool *issigned);
61 int Crypto_RetrieveLocalKey(int keyid, char *keyfp, size_t keyfplen, char *idfp, size_t idfplen, qbool *issigned); // return value: -1 if more to come, +1 if valid, 0 if end of list
63 size_t Crypto_SignData(const void *data, size_t datasize, int keyid, void *signed_data, size_t signed_size);
64 size_t Crypto_SignDataDetached(const void *data, size_t datasize, int keyid, void *signed_data, size_t signed_size);
71 // < accept (or: reject)
74 // < challenge SP <challenge> NUL vlen <size> d0pk <fingerprints I can auth to> NUL NUL <other fingerprints I accept>
77 // d0pk\cnt\0\challenge\<challenge>\aeslevel\<level> NUL <serverfp> NUL <clientfp>
79 // check if client would get accepted; if not, do "reject" now
80 // require non-control packets to be encrypted require non-control packets to be encrypted
81 // do not send anything yet do not send anything yet
82 // RESET to serverfp RESET to serverfp
83 // d0_blind_id_authenticate_with_private_id_start() = 1
84 // < d0pk\cnt\1\aes\<aesenabled> NUL *startdata*
85 // d0_blind_id_authenticate_with_private_id_challenge() = 1
86 // d0pk\cnt\2 NUL *challengedata* >
87 // d0_blind_id_authenticate_with_private_id_response() = 0
88 // < d0pk\cnt\3 NUL *responsedata*
89 // d0_blind_id_authenticate_with_private_id_verify() = 1
90 // store server's fingerprint NOW
91 // d0_blind_id_sessionkey_public_id() = 1 d0_blind_id_sessionkey_public_id() = 1
93 // IF clientfp AND NOT serverfp:
94 // RESET to clientfp RESET to clientfp
95 // d0_blind_id_authenticate_with_private_id_start() = 1
96 // d0pk\cnt\0\challenge\<challenge>\aeslevel\<level> NUL NUL <clientfp> NUL *startdata*
98 // check if client would get accepted; if not, do "reject" now
99 // require non-control packets to be encrypted require non-control packets to be encrypted
100 // d0_blind_id_authenticate_with_private_id_challenge() = 1
101 // < d0pk\cnt\5\aes\<aesenabled> NUL *challengedata*
103 // IF clientfp AND serverfp:
104 // RESET to clientfp RESET to clientfp
105 // d0_blind_id_authenticate_with_private_id_start() = 1
106 // d0pk\cnt\4 NUL *startdata* >
107 // d0_blind_id_authenticate_with_private_id_challenge() = 1
108 // < d0pk\cnt\5 NUL *challengedata*
111 // d0_blind_id_authenticate_with_private_id_response() = 0
112 // d0pk\cnt\6 NUL *responsedata* >
113 // d0_blind_id_authenticate_with_private_id_verify() = 1
114 // store client's fingerprint NOW
115 // d0_blind_id_sessionkey_public_id() = 1 d0_blind_id_sessionkey_public_id() = 1
116 // note: the ... is the "connect" message, except without the challenge. Reinterpret as regular connect message on server side
118 // enforce encrypted transmission (key is XOR of the two DH keys)
121 // < challenge (mere sync message)
124 // < accept (ALWAYS accept if connection is encrypted, ignore challenge as it had been checked before)
126 // commence with ingame protocol
130 // getchallenge NUL d0_blind_id: reply with challenge with added fingerprints
131 // cnt=0: IF server will auth, cnt=1, ELSE cnt=5
134 // cnt=6: send "challenge"
136 // challenge with added fingerprints: cnt=0; if client will auth but not server, append client auth start
138 // cnt=3: IF client will auth, cnt=4, ELSE rewrite as "challenge"
139 // cnt=5: cnt=6, server will continue by sending "challenge" (let's avoid sending two packets as response to one)
141 // accept empty "challenge", and challenge-less connect in case crypto protocol has executed and finished
142 // statusResponse and infoResponse get an added d0_blind_id key that lists
143 // the keys the server can auth with and to in key@ca SPACE key@ca notation
144 // any d0pk\ message has an appended "id" parameter; messages with an unexpected "id" are ignored to prevent errors from multiple concurrent auth runs
147 // comparison to OTR:
149 // - authentication: yes
150 // - deniability: no (attacker requires the temporary session key to prove you
151 // have sent a specific message, the private key itself does not suffice), no
152 // measures are taken to provide forgeability to even provide deniability
153 // against an attacker who knows the temporary session key, as using CTR mode
154 // for the encryption - which, together with deriving the MAC key from the
155 // encryption key, and MACing the ciphertexts instead of the plaintexts,
156 // would provide forgeability and thus deniability - requires longer
157 // encrypted packets and deniability was not a goal of this, as we may e.g.
158 // reserve the right to capture packet dumps + extra state info to prove a
159 // client/server has sent specific packets to prove cheating)
160 // - perfect forward secrecy: yes (session key is derived via DH key exchange)