From: mdw Date: Fri, 16 Feb 2001 21:41:43 +0000 (+0000) Subject: Major changes. See source files for details. X-Git-Tag: 1.0.0pre1~20 X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/tripe/commitdiff_plain/832a2ab6980070401d02e0143a2bd3ece7a3e9db?hp=3785235941bd2ca64d5730223e52da33f0f7871c;ds=sidebyside Major changes. See source files for details. --- diff --git a/tripe.h b/tripe.h index 587c5d5b..9f7fd5d7 100644 --- a/tripe.h +++ b/tripe.h @@ -1,6 +1,6 @@ /* -*-c-*- * - * $Id: tripe.h,v 1.4 2001/02/05 19:56:37 mdw Exp $ + * $Id: tripe.h,v 1.5 2001/02/16 21:41:43 mdw Exp $ * * Main header file for TrIPE * @@ -29,6 +29,9 @@ /*----- Revision history --------------------------------------------------* * * $Log: tripe.h,v $ + * Revision 1.5 2001/02/16 21:41:43 mdw + * Major changes. See source files for details. + * * Revision 1.4 2001/02/05 19:56:37 mdw * Sequence number protection, and BSD tunnels. * @@ -104,12 +107,8 @@ #include #include -#include -#include #include #include -#include -#include #include #include @@ -153,29 +152,95 @@ /*----- TrIPE protocol ----------------------------------------------------*/ -/* --- TrIPE packet format --- * +/* --- TrIPE message format --- * * - * A packet begins with a single-byte packet type. The remaining data - * depends on the packet type. + * A packet begins with a single-byte message type. The top four bits are a + * category code used to send the message to the right general place in the + * code; the bottom bits identify the actual message type. */ -#define MSG_PACKET 0u -/* Followed by a 64-bit MAC and an encrypted packet. The MAC is used as an - * IV for a 64-bit block cipher in CBC-stealing mode. - */ +#define MSG_CATMASK 0xf0 +#define MSG_TYPEMASK 0x0f -#define MSG_PRECHALLENGE 1u -/* Followed by the challenge only. Useful for bootstrapping the system. +/* --- Encrypted message packets --- * + * + * Messages of category @MSG_PACKET@ contain encrypted network packets. The + * message content is a symmetric-encrypted block (see below). Reception of + * a packet encrypted under a new key implicitly permits that key to be used + * to send further packets. + * + * The only packet type accepted is zero. + * + * Packets may be encrypted under any live keyset, but should use the most + * recent one. */ -#define MSG_CHALLENGE 2u -/* Followed by a response hash and a large-integer challenge. - */ +#define MSG_PACKET 0x00 + +/* --- Key exchange packets --- */ + +#define MSG_KEYEXCH 0x10 + +#define KX_PRECHAL 0u +#define KX_COOKIE 1u +#define KX_CHAL 2u +#define KX_REPLY 3u +#define KX_SWITCH 4u +#define KX_SWITCHOK 5u +#define KX_NMSG 6u -#define MSG_RESPONSE 3u -/* Followed by a large-integer response. +/* --- Symmetric encryption and keysets --- * + * + * Packets consist of a 64-bit MAC, a 32-bit sequence number, and the + * encrypted payload. + * + * The MAC is computed using the HMAC construction with RIPEMD160 over the + * sequence number and the original packet plaintext; the first 64 bits of + * the output are used. + * + * The plaintext is encrypted using Blowfish in CBC mode with ciphertext + * stealing (as described in [Schneier]. The initialization vector is + * precisely the 64-bit MAC computed previously. + * + * A keyset consists of + * + * * an integrity (MAC) key; + * * a confidentiality (encryption) key; and + * * a sequence numbering space + * + * in each direction. The packets sent by a host encrypted under a + * particular keyset are assigned consecutive sequence numbers starting from + * zero. The receiving host must ensure that it only accepts each packet at + * most once. It should maintain a window of sequence numbers: packets with + * numbers beyond the end of the window are accepted and cause the window to + * be advanced; packets with numbers before the start of the window are + * rejected; packets with numbers which appear within the window are accepted + * only if the number has not been seen before. + * + * When a host sends a @KX_SWITCH@ or @KX_SWITCHOK@ message, it installs the + * newly-negotiated keyset in a `listen-only' state: it may not send a packet + * encrypted under the keyset until either it has received a @KX_SWITCH@ or + * @KX_SWITCHOK@ message, or a @MSG_PACKET@ encrypted under the keyset, from + * its peer. */ +/*----- Cipher selections -------------------------------------------------*/ + +#include +#include +#include +#include + +#define CIPHER (&blowfish_cbc) +#define MAC (&rmd160_hmac) + +#define HASH_CTX rmd160_ctx +#define HASH_INIT rmd160_init +#define HASH rmd160_hash +#define HASH_STRING(c, s) HASH((c), s, sizeof(s)) +#define HASH_DONE rmd160_done +#define HASHSZ RMD160_HASHSZ + /*----- Data structures ---------------------------------------------------*/ /* --- Buffers --- * @@ -216,19 +281,22 @@ typedef union addr { typedef struct keyset { struct keyset *next; /* Next active keyset in the list */ + unsigned ref; /* Reference count for keyset */ time_t t_exp; /* Expiry time for this keyset */ unsigned long sz_exp; /* Data limit for the keyset */ -#ifndef NTRACE - unsigned seq; /* Sequence number for tracing */ -#endif - gcipher *c; /* Keyset cipher for encryption */ - gmac *m; /* Keyset MAC for integrity */ + T( unsigned seq; ) /* Sequence number for tracing */ + unsigned f; /* Various useful flags */ + gcipher *cin, *cout; /* Keyset ciphers for encryption */ + gmac *min, *mout; /* Keyset MACs for integrity */ uint32 oseq; /* Outbound sequence number */ uint32 iseq, iwin; /* Inbound sequence number */ } keyset; #define KS_SEQWINSZ 32 /* Bits in sequence number window */ +#define KSF_LISTEN 1u /* Don't encrypt packets yet */ +#define KSF_LINK 2u /* Key is in a linked list */ + /* --- Key exchange --- * * * TrIPE uses the Wrestlers Protocol for its key exchange. The Wrestlers @@ -238,27 +306,48 @@ typedef struct keyset { * Clive Jones. */ +#define KX_NCHAL 16u +#define KX_THRESH 4u + +typedef struct kxchal { + struct keyexch *kx; /* Pointer back to key exchange */ + mp *c; /* Responder's challenge */ + mp *r; /* My reply to the challenge */ + keyset *ks; /* Pointer to temporary keyset */ + unsigned f; /* Various useful flags */ + sel_timer t; /* Response timer for challenge */ + octet hc[HASHSZ]; /* Hash of his challenge */ + octet hrx[HASHSZ]; /* My expected reply hash */ + octet hswrq_in[HASHSZ]; /* Inbound switch request message */ + octet hswok_in[HASHSZ]; /* Inbound switch confirmation */ + octet hswrq_out[HASHSZ]; /* Outbound switch request message */ + octet hswok_out[HASHSZ]; /* Outbound switch confirmation */ +} kxchal; + typedef struct keyexch { - keyset **ks; /* Peer's list of keysets */ struct peer *p; /* Pointer back to the peer */ + keyset **ks; /* Peer's list of keysets */ unsigned f; /* Various useful flags */ + unsigned s; /* Current state in exchange */ sel_timer t; /* Timer for next exchange */ dh_pub kpub; /* Peer's public key */ - mp *my_x, *my_gx, *my_gxy; /* My half of the exchange */ - octet my_h[RMD160_HASHSZ]; /* My challenge hash */ - mp *your_gx, *your_gxy; /* Your half of the exchange */ - octet your_h[RMD160_HASHSZ]; /* Your challenge hash */ + mp *alpha; /* My temporary secret */ + mp *c; /* My challenge */ + mp *rx; /* The expected response */ + unsigned nr; /* Number of extant responses */ time_t t_valid; /* When this exchange goes bad */ - time_t t_qchal, t_qresp; /* Quiet timers for packet types */ - time_t t_newchal; /* When to accept a new challenge */ + octet hc[HASHSZ]; /* Hash of my challenge */ + kxchal *r[KX_NCHAL]; /* Array of challenges */ } keyexch; #define KXF_TIMER 1u /* Waiting for a timer to go off */ -#define KXF_INIT 2u /* Big numbers are initialized */ -#define KXF_MYH 4u /* My hash has been computed */ -#define KXF_YOURH 8u /* Your hash has been received */ -#define KXF_REPLY 16u /* Received your response OK */ -#define KXF_DONE 32u /* Key exchange completed */ + +enum { + KXS_DEAD, /* Uninitialized state (magical) */ + KXS_CHAL, /* Main answer-challenges state */ + KXS_COMMIT, /* Committed: send switch request */ + KXS_SWITCH /* Switched: send confirmation */ +}; /* --- Tunnel structure --- * * @@ -278,6 +367,25 @@ typedef struct tunnel { #endif } tunnel; +/* --- Peer statistics --- * + * + * Contains various interesting and not-so-interesting statistics about a + * peer. This is updated by various parts of the code. The format of the + * structure isn't considered private, and @p_stats@ returns a pointer to the + * statistics block for a given peer. + */ + +typedef struct stats { + unsigned long sz_in, sz_out; /* Size of all data in and out */ + unsigned long sz_kxin, sz_kxout; /* Size of key exchange messages */ + unsigned long sz_ipin, sz_ipout; /* Size of encapsulated IP packets */ + time_t t_start, t_last; /* Time peer created, last recv */ + unsigned long n_reject; /* Number of rejected packets */ + unsigned long n_in, n_out; /* Number of packets in and out */ + unsigned long n_kxin, n_kxout; /* Number of key exchange packets */ + unsigned long n_ipin, n_ipout; /* Number of encrypted packets */ +} stats; + /* --- Peer structure --- * * * The main structure which glues everything else together. @@ -288,10 +396,11 @@ typedef struct peer { char *name; /* Name of this peer */ tunnel t; /* Tunnel for local packets */ keyset *ks; /* List head for keysets */ - keyexch kx; /* Key exchange protocol block */ buf b; /* Buffer for sending packets */ addr peer; /* Peer socket address */ size_t sasz; /* Socket address size */ + stats st; /* Statistics */ + keyexch kx; /* Key exchange protocol block */ } peer; /* --- Admin structure --- */ @@ -316,7 +425,7 @@ typedef struct admin { extern sel_state sel; /* Global I/O event state */ extern dh_priv kpriv; /* Our private key */ extern mpmont mg; /* Montgomery context for DH group */ -extern octet buf_i[PKBUFSZ], buf_o[PKBUFSZ]; /* Big packet buffers */ +extern octet buf_i[PKBUFSZ], buf_o[PKBUFSZ], buf_t[PKBUFSZ]; #ifndef NTRACE extern const trace_opt tr_opts[]; /* Trace options array */ @@ -381,41 +490,19 @@ extern int km_getpubkey(const char */*tag*/, dh_pub */*kpub*/); extern void kx_start(keyexch */*kx*/); -/* --- @kx_prechallenge@ --- * - * - * Arguments: @keyexch *kx@ = pointer to key exhange context - * @buf *b@ = pointer to buffer containing the packet - * - * Returns: --- - * - * Use: Reads a prechallenge packet from the buffer and handles it. - */ - -extern void kx_prechallenge(keyexch */*kx*/, buf */*b*/); - -/* --- @kx_challenge@ --- * - * - * Arguments: @keyexch *kx@ = pointer to key exchange context - * @buf *b@ = a buffer containing the packet to read - * - * Returns: --- - * - * Use: Reads a challenge from the buffer and handles it. - */ - -extern void kx_challenge(keyexch */*kx*/, buf */*b*/); - -/* --- @kx_response@ --- * +/* --- @kx_message@ --- * * * Arguments: @keyexch *kx@ = pointer to key exchange context - * @buf *b@ = a buffer containing the packet to read + * @unsigned msg@ = the message code + * @buf *b@ = pointer to buffer containing the packet * * Returns: --- * - * Use: Reads a response from the buffer and handles it. + * Use: Reads a packet containing key exchange messages and handles + * it. */ -extern void kx_response(keyexch */*kx*/, buf */*b*/); +extern void kx_message(keyexch */*kx*/, unsigned /*msg*/, buf */*b*/); /* --- @kx_free@ --- * * @@ -459,44 +546,134 @@ extern int kx_init(keyexch */*kx*/, peer */*p*/, keyset **/*ks*/); /*----- Keysets and symmetric cryptography --------------------------------*/ -/* --- @ks_free@ --- * +/* --- @ks_drop@ --- * + * + * Arguments: @keyset *ks@ = pointer to a keyset + * + * Returns: --- + * + * Use: Decrements a keyset's reference counter. If the counter hits + * zero, the keyset is freed. + */ + +extern void ks_drop(keyset */*ks*/); + +/* --- @ks_gen@ --- * + * + * Arguments: @const void *k@ = pointer to key material + * @size_t x, y, z@ = offsets into key material (see below) + * + * Returns: A pointer to the new keyset. + * + * Use: Derives a new keyset from the given key material. The + * offsets @x@, @y@ and @z@ separate the key material into three + * parts. Between the @k@ and @k + x@ is `my' contribution to + * the key material; between @k + x@ and @k + y@ is `your' + * contribution; and between @k + y@ and @k + z@ is a shared + * value we made together. These are used to construct two + * pairs of symmetric keys. Each pair consists of an encryption + * key and a message authentication key. One pair is used for + * outgoing messages, the other for incoming messages. + * + * The new key is marked so that it won't be selected for output + * by @ksl_encrypt@. You can still encrypt data with it by + * calling @ks_encrypt@ directly. + */ + +extern keyset *ks_gen(const void */*k*/, + size_t /*x*/, size_t /*y*/, size_t /*z*/); + +/* --- @ks_tregen@ --- * + * + * Arguments: @keyset *ks@ = pointer to a keyset + * + * Returns: The time at which moves ought to be made to replace this key. + */ + +extern time_t ks_tregen(keyset */*ks*/); + +/* --- @ks_activate@ --- * + * + * Arguments: @keyset *ks@ = pointer to a keyset + * + * Returns: --- + * + * Use: Activates a keyset, so that it can be used for encrypting + * outgoing messages. + */ + +extern void ks_activate(keyset */*ks*/); + +/* --- @ks_encrypt@ --- * + * + * Arguments: @keyset *ks@ = pointer to a keyset + * @buf *b@ = pointer to input buffer + * @buf *bb@ = pointer to output buffer + * + * Returns: Zero if OK, nonzero if the key needs replacing. If the + * encryption failed, the output buffer is broken and zero is + * returned. + * + * Use: Encrypts a block of data using the key. Note that the `key + * ought to be replaced' notification is only ever given once + * for each key. Also note that this call forces a keyset to be + * used even if it's marked as not for data output. + */ + +extern int ks_encrypt(keyset */*ks*/, buf */*b*/, buf */*bb*/); + +/* --- @ks_decrypt@ --- * + * + * Arguments: @keyset *ks@ = pointer to a keyset + * @buf *b@ = pointer to an input buffer + * @buf *bb@ = pointer to an output buffer + * + * Returns: Zero on success, or nonzero if there was some problem. + * + * Use: Attempts to decrypt a message using a given key. Note that + * requesting decryption with a key directly won't clear a + * marking that it's not for encryption. + */ + +extern int ks_decrypt(keyset */*ks*/, buf */*b*/, buf */*bb*/); + +/* --- @ksl_free@ --- * * * Arguments: @keyset **ksroot@ = pointer to keyset list head * * Returns: --- * - * Use: Frees all of the keys in a keyset. + * Use: Frees (releases references to) all of the keys in a keyset. */ -extern void ks_free(keyset **/*ksroot*/); +extern void ksl_free(keyset **/*ksroot*/); -/* --- @ks_prune@ --- * +/* --- @ksl_link@ --- * * * Arguments: @keyset **ksroot@ = pointer to keyset list head + * @keyset *ks@ = pointer to a keyset * * Returns: --- * - * Use: Prunes the keyset list by removing keys which mustn't be used - * any more. + * Use: Links a keyset into a list. A keyset can only be on one list + * at a time. Bad things happen otherwise. */ -extern void ks_prune(keyset **/*ksroot*/); +extern void ksl_link(keyset **/*ksroot*/, keyset */*ks*/); -/* --- @ks_gen@ --- * +/* --- @ksl_prune@ --- * * * Arguments: @keyset **ksroot@ = pointer to keyset list head - * @const void *k@ = pointer to key material - * @size_t sz@ = size of the key material * - * Returns: The regeneration time for the new key. + * Returns: --- * - * Use: Derives a keyset from the given key material and adds it to - * the list. + * Use: Prunes the keyset list by removing keys which mustn't be used + * any more. */ -extern time_t ks_gen(keyset **/*ksroot*/, const void */*k*/, size_t /*sz*/); +extern void ksl_prune(keyset **/*ksroot*/); -/* --- @ks_encrypt@ --- * +/* --- @ksl_encrypt@ --- * * * Arguments: @keyset **ksroot@ = pointer to keyset list head * @buf *b@ = pointer to input buffer @@ -507,9 +684,9 @@ extern time_t ks_gen(keyset **/*ksroot*/, const void */*k*/, size_t /*sz*/); * Use: Encrypts a packet. */ -extern int ks_encrypt(keyset **/*ksroot*/, buf */*b*/, buf */*bb*/); +extern int ksl_encrypt(keyset **/*ksroot*/, buf */*b*/, buf */*bb*/); -/* --- @ks_decrypt@ --- * +/* --- @ksl_decrypt@ --- * * * Arguments: @keyset **ksroot@ = pointer to keyset list head * @buf *b@ = pointer to input buffer @@ -520,7 +697,7 @@ extern int ks_encrypt(keyset **/*ksroot*/, buf */*b*/, buf */*bb*/); * Use: Decrypts a packet. */ -extern int ks_decrypt(keyset **/*ksroot*/, buf */*b*/, buf */*bb*/); +extern int ksl_decrypt(keyset **/*ksroot*/, buf */*b*/, buf */*bb*/); /*----- Administration interface ------------------------------------------*/ @@ -629,6 +806,15 @@ extern void p_tun(peer */*p*/, buf */*b*/); extern void p_interval(void); +/* --- @p_stats@ --- * + * + * Arguments: @peer *p@ = pointer to a peer block + * + * Returns: A pointer to the peer's statistics. + */ + +extern stats *p_stats(peer */*p*/); + /* --- @p_ifname@ --- * * * Arguments: @peer *p@ = pointer to a peer block @@ -824,6 +1010,18 @@ extern void buf_init(buf */*b*/, void */*p*/, size_t /*sz*/); extern int buf_break(buf */*b*/); +/* --- @buf_flip@ --- * + * + * Arguments: @buf *b@ = pointer to a buffer block + * + * Returns: --- + * + * Use: Flips a buffer so that if you've just been writing to it, + * you can now read from the bit you've written. + */ + +extern void buf_flip(buf */*b*/); + /* --- @buf_ensure@ --- * * * Arguments: @buf *b@ = pointer to a buffer block @@ -839,15 +1037,15 @@ extern int buf_ensure(buf */*b*/, size_t /*sz*/); /* --- @buf_get@ --- * * * Arguments: @buf *b@ = pointer to a buffer block - * @void *p@ = pointer to a buffer * @size_t sz@ = size of the buffer * - * Returns: Zero if it worked, nonzero if there wasn't enough data. + * Returns: Pointer to the place in the buffer. * - * Use: Fetches data from the buffer into some other place. + * Use: Reserves a space in the buffer of the requested size, and + * returns its start address. */ -extern int buf_get(buf */*b*/, void */*p*/, size_t /*sz*/); +extern void *buf_get(buf */*b*/, size_t /*sz*/); /* --- @buf_put@ --- * * @@ -918,7 +1116,7 @@ extern int buf_putword(buf */*b*/, uint32 /*w*/); * Use: Gets a multiprecision integer from a buffer. */ -extern mp *buf_getmp(buf */*b*/, mp */*d*/); +extern mp *buf_getmp(buf */*b*/); /* --- @buf_putmp@ --- * * @@ -941,11 +1139,23 @@ extern int buf_putmp(buf */*b*/, mp */*m*/); * Returns: A pointer to the integer's textual representation. * * Use: Converts a multiprecision integer to a string. Corrupts - * @buf_o@. + * @buf_t@. */ extern const char *mpstr(mp */*m*/); +/* --- @timestr@ --- * + * + * Arguments: @time_t t@ = a time to convert + * + * Returns: A pointer to a textual representation of the time. + * + * Use: Converts a time to a textual representation. Corrupts + * @buf_t@. + */ + +extern const char *timestr(time_t /*t*/); + /*----- That's all, folks -------------------------------------------------*/ #ifdef __cplusplus