ssh.h

#include <stdio.h>
#include <string.h>

#include "puttymem.h"
#include "tree234.h"
#include "network.h"
#include "int64.h"
#include "misc.h"

struct ssh_channel;
typedef struct ssh_tag *Ssh;

extern int sshfwd_write(struct ssh_channel *c, char *, int);
extern void sshfwd_write_eof(struct ssh_channel *c);
extern void sshfwd_unclean_close(struct ssh_channel *c, const char *err);
extern void sshfwd_unthrottle(struct ssh_channel *c, int bufsize);
Conf *sshfwd_get_conf(struct ssh_channel *c);
void sshfwd_x11_sharing_handover(struct ssh_channel *c,
                                 void *share_cs,
                                 void *share_chan,
                                 const char *peer_addr,
                                 int peer_port,
                                 int endian,
                                 int protomajor,
                                 int protominor,
                                 const void *initial_data,
                                 int initial_len);
void sshfwd_x11_is_local(struct ssh_channel *c);

extern Socket ssh_connection_sharing_init(
    const char *host, int port, Conf *conf, Ssh ssh, void **state);
int ssh_share_test_for_upstream(const char *host, int port, Conf *conf);
void share_got_pkt_from_server(void *ctx,
                               int type,
                               unsigned char *pkt,
                               int pktlen);
void share_activate(void *state, const char *server_verstring);
void sharestate_free(void *state);
int share_ndownstreams(void *state);

void ssh_connshare_log(Ssh ssh,
                       int event,
                       const char *logtext,
                       const char *ds_err,
                       const char *us_err);
unsigned ssh_alloc_sharing_channel(Ssh ssh, void *sharing_ctx);
void ssh_delete_sharing_channel(Ssh ssh, unsigned localid);
int ssh_alloc_sharing_rportfwd(Ssh ssh,
                               const char *shost,
                               int sport,
                               void *share_ctx);
void ssh_sharing_queue_global_request(Ssh ssh, void *share_ctx);
struct X11FakeAuth *ssh_sharing_add_x11_display(Ssh ssh,
                                                int authtype,
                                                void *share_cs,
                                                void *share_chan);
void ssh_sharing_remove_x11_display(Ssh ssh, struct X11FakeAuth *auth);
void ssh_send_packet_from_downstream(Ssh ssh,
                                     unsigned id,
                                     int type,
                                     const void *pkt,
                                     int pktlen,
                                     const char *additional_log_text);
void ssh_sharing_downstream_connected(Ssh ssh,
                                      unsigned id,
                                      const char *peerinfo);
void ssh_sharing_downstream_disconnected(Ssh ssh, unsigned id);
void ssh_sharing_logf(Ssh ssh, unsigned id, const char *logfmt, ...);
int ssh_agent_forwarding_permitted(Ssh ssh);
void share_setup_x11_channel(void *csv,
                             void *chanv,
                             unsigned upstream_id,
                             unsigned server_id,
                             unsigned server_currwin,
                             unsigned server_maxpkt,
                             unsigned client_adjusted_window,
                             const char *peer_addr,
                             int peer_port,
                             int endian,
                             int protomajor,
                             int protominor,
                             const void *initial_data,
                             int initial_len);

/*
 * Useful thing.
 */
#ifndef lenof
#define lenof(x) ((sizeof((x))) / (sizeof(*(x))))
#endif

#define SSH_CIPHER_IDEA 1
#define SSH_CIPHER_DES 2
#define SSH_CIPHER_3DES 3
#define SSH_CIPHER_BLOWFISH 6

#ifdef MSCRYPTOAPI
#define APIEXTRA 8
#else
#define APIEXTRA 0
#endif

#ifndef BIGNUM_INTERNAL
typedef void *Bignum;
#endif

struct RSAKey {
  int bits;
  int bytes;
#ifdef MSCRYPTOAPI
  unsigned long exponent;
  unsigned char *modulus;
#else
  Bignum modulus;
  Bignum exponent;
  Bignum private_exponent;
  Bignum p;
  Bignum q;
  Bignum iqmp;
#endif
  char *comment;
};

struct dss_key {
  Bignum p, q, g, y, x;
};

struct ec_curve;

struct ec_point {
  const struct ec_curve *curve;
  Bignum x, y;
  Bignum z; /* Jacobian denominator */
  unsigned char infinity;
};

void ec_point_free(struct ec_point *point);

/* Weierstrass form curve */
struct ec_wcurve {
  Bignum a, b, n;
  struct ec_point G;
};

/* Montgomery form curve */
struct ec_mcurve {
  Bignum a, b;
  struct ec_point G;
};

/* Edwards form curve */
struct ec_ecurve {
  Bignum l, d;
  struct ec_point B;
};

struct ec_curve {
  enum
  {
    EC_WEIERSTRASS,
    EC_MONTGOMERY,
    EC_EDWARDS
  } type;
  /* 'name' is the identifier of the curve when it has to appear in
   * wire protocol encodings, as it does in e.g. the public key and
   * signature formats for NIST curves. Curves which do not format
   * their keys or signatures in this way just have name==NULL.
   *
   * 'textname' is non-NULL for all curves, and is a human-readable
   * identification suitable for putting in log messages. */
  const char *name, *textname;
  unsigned int fieldBits;
  Bignum p;
  union {
    struct ec_wcurve w;
    struct ec_mcurve m;
    struct ec_ecurve e;
  };
};

const struct ssh_signkey *ec_alg_by_oid(int len,
                                        const void *oid,
                                        const struct ec_curve **curve);
const unsigned char *ec_alg_oid(const struct ssh_signkey *alg, int *oidlen);
extern const int ec_nist_curve_lengths[], n_ec_nist_curve_lengths;
int ec_nist_alg_and_curve_by_bits(int bits,
                                  const struct ec_curve **curve,
                                  const struct ssh_signkey **alg);
int ec_ed_alg_and_curve_by_bits(int bits,
                                const struct ec_curve **curve,
                                const struct ssh_signkey **alg);

struct ssh_signkey;

struct ec_key {
  const struct ssh_signkey *signalg;
  struct ec_point publicKey;
  Bignum privateKey;
};

struct ec_point *ec_public(const Bignum privateKey,
                           const struct ec_curve *curve);

int makekey(const unsigned char *data,
            int len,
            struct RSAKey *result,
            const unsigned char **keystr,
            int order);
int makeprivate(const unsigned char *data, int len, struct RSAKey *result);
int rsaencrypt(unsigned char *data, int length, struct RSAKey *key);
Bignum rsadecrypt(Bignum input, struct RSAKey *key);
void rsasign(unsigned char *data, int length, struct RSAKey *key);
void rsasanitise(struct RSAKey *key);
int rsastr_len(struct RSAKey *key);
void rsastr_fmt(char *str, struct RSAKey *key);
void rsa_fingerprint(char *str, int len, struct RSAKey *key);
int rsa_verify(struct RSAKey *key);
unsigned char *rsa_public_blob(struct RSAKey *key, int *len);
int rsa_public_blob_len(void *data, int maxlen);
void freersakey(struct RSAKey *key);

#ifndef PUTTY_UINT32_DEFINED
/* This makes assumptions about the int type. */
typedef unsigned int uint32;
#define PUTTY_UINT32_DEFINED
#endif
typedef uint32 word32;

unsigned long crc32_compute(const void *s, size_t len);
unsigned long crc32_update(unsigned long crc_input, const void *s, size_t len);

/* SSH CRC compensation attack detector */
void *crcda_make_context(void);
void crcda_free_context(void *handle);
int detect_attack(void *handle,
                  unsigned char *buf,
                  uint32 len,
                  unsigned char *IV);

/*
 * SSH2 RSA key exchange functions
 */
struct ssh_hash;
void *ssh_rsakex_newkey(char *data, int len);
void ssh_rsakex_freekey(void *key);
int ssh_rsakex_klen(void *key);
void ssh_rsakex_encrypt(const struct ssh_hash *h,
                        unsigned char *in,
                        int inlen,
                        unsigned char *out,
                        int outlen,
                        void *key);

/*
 * SSH2 ECDH key exchange functions
 */
struct ssh_kex;
const char *ssh_ecdhkex_curve_textname(const struct ssh_kex *kex);
void *ssh_ecdhkex_newkey(const struct ssh_kex *kex);
void ssh_ecdhkex_freekey(void *key);
char *ssh_ecdhkex_getpublic(void *key, int *len);
Bignum ssh_ecdhkex_getkey(void *key, char *remoteKey, int remoteKeyLen);

/*
 * Helper function for k generation in DSA, reused in ECDSA
 */
Bignum *dss_gen_k(const char *id_string,
                  Bignum modulus,
                  Bignum private_key,
                  unsigned char *digest,
                  int digest_len);

typedef struct {
  uint32 h[4];
} MD5_Core_State;

struct MD5Context {
#ifdef MSCRYPTOAPI
  unsigned long hHash;
#else
  MD5_Core_State core;
  unsigned char block[64];
  int blkused;
  uint32 lenhi, lenlo;
#endif
};

void MD5Init(struct MD5Context *context);
void MD5Update(struct MD5Context *context,
               unsigned char const *buf,
               unsigned len);
void MD5Final(unsigned char digest[16], struct MD5Context *context);
void MD5Simple(void const *p, unsigned len, unsigned char output[16]);

void *hmacmd5_make_context(void *);
void hmacmd5_free_context(void *handle);
void hmacmd5_key(void *handle, void const *key, int len);
void hmacmd5_do_hmac(void *handle,
                     unsigned char const *blk,
                     int len,
                     unsigned char *hmac);

typedef struct {
  uint32 h[5];
  unsigned char block[64];
  int blkused;
  uint32 lenhi, lenlo;
} SHA_State;
void SHA_Init(SHA_State *s);
void SHA_Bytes(SHA_State *s, const void *p, int len);
void SHA_Final(SHA_State *s, unsigned char *output);
void SHA_Simple(const void *p, int len, unsigned char *output);

void hmac_sha1_simple(
    void *key, int keylen, void *data, int datalen, unsigned char *output);
typedef struct {
  uint32 h[8];
  unsigned char block[64];
  int blkused;
  uint32 lenhi, lenlo;
} SHA256_State;
void SHA256_Init(SHA256_State *s);
void SHA256_Bytes(SHA256_State *s, const void *p, int len);
void SHA256_Final(SHA256_State *s, unsigned char *output);
void SHA256_Simple(const void *p, int len, unsigned char *output);

typedef struct {
  uint64 h[8];
  unsigned char block[128];
  int blkused;
  uint32 len[4];
} SHA512_State;
#define SHA384_State SHA512_State
void SHA512_Init(SHA512_State *s);
void SHA512_Bytes(SHA512_State *s, const void *p, int len);
void SHA512_Final(SHA512_State *s, unsigned char *output);
void SHA512_Simple(const void *p, int len, unsigned char *output);
void SHA384_Init(SHA384_State *s);
#define SHA384_Bytes(s, p, len) SHA512_Bytes(s, p, len)
void SHA384_Final(SHA384_State *s, unsigned char *output);
void SHA384_Simple(const void *p, int len, unsigned char *output);

struct ssh_mac;
struct ssh_cipher {
  void *(*make_context)(void);
  void (*free_context)(void *);
  void (*sesskey)(void *, unsigned char *key); /* for SSH-1 */
  void (*encrypt)(void *, unsigned char *blk, int len);
  void (*decrypt)(void *, unsigned char *blk, int len);
  int blksize;
  const char *text_name;
};

struct ssh2_cipher {
  void *(*make_context)(void);
  void (*free_context)(void *);
  void (*setiv)(void *, unsigned char *key);  /* for SSH-2 */
  void (*setkey)(void *, unsigned char *key); /* for SSH-2 */
  void (*encrypt)(void *, unsigned char *blk, int len);
  void (*decrypt)(void *, unsigned char *blk, int len);
  /* Ignored unless SSH_CIPHER_SEPARATE_LENGTH flag set */
  void (*encrypt_length)(void *,
                         unsigned char *blk,
                         int len,
                         unsigned long seq);
  void (*decrypt_length)(void *,
                         unsigned char *blk,
                         int len,
                         unsigned long seq);
  const char *name;
  int blksize;
  /* real_keybits is the number of bits of entropy genuinely used by
   * the cipher scheme; it's used for deciding how big a
   * Diffie-Hellman group is needed to exchange a key for the
   * cipher. */
  int real_keybits;
  /* padded_keybytes is the number of bytes of key data expected as
   * input to the setkey function; it's used for deciding how much
   * data needs to be generated from the post-kex generation of key
   * material. In a sensible cipher which uses all its key bytes for
   * real work, this will just be real_keybits/8, but in DES-type
   * ciphers which ignore one bit in each byte, it'll be slightly
   * different. */
  int padded_keybytes;
  unsigned int flags;
#define SSH_CIPHER_IS_CBC 1
#define SSH_CIPHER_SEPARATE_LENGTH 2
  const char *text_name;
  /* If set, this takes priority over other MAC. */
  const struct ssh_mac *required_mac;
};

struct ssh2_ciphers {
  int nciphers;
  const struct ssh2_cipher *const *list;
};

struct ssh_mac {
  /* Passes in the cipher context */
  void *(*make_context)(void *);
  void (*free_context)(void *);
  void (*setkey)(void *, unsigned char *key);
  /* whole-packet operations */
  void (*generate)(void *, unsigned char *blk, int len, unsigned long seq);
  int (*verify)(void *, unsigned char *blk, int len, unsigned long seq);
  /* partial-packet operations */
  void (*start)(void *);
  void (*bytes)(void *, unsigned char const *, int);
  void (*genresult)(void *, unsigned char *);
  int (*verresult)(void *, unsigned char const *);
  const char *name, *etm_name;
  int len, keylen;
  const char *text_name;
};

struct ssh_hash {
  void *(*init)(void); /* also allocates context */
  void *(*copy)(const void *);
  void (*bytes)(void *, const void *, int);
  void (*final)(void *, unsigned char *); /* also frees context */
  void (*free)(void *);
  int hlen; /* output length in bytes */
  const char *text_name;
};

struct ssh_kex {
  const char *name, *groupname;
  enum
  {
    KEXTYPE_DH,
    KEXTYPE_RSA,
    KEXTYPE_ECDH
  } main_type;
  const struct ssh_hash *hash;
  const void *extra; /* private to the kex methods */
};

struct ssh_kexes {
  int nkexes;
  const struct ssh_kex *const *list;
};

struct ssh_signkey {
  void *(*newkey)(const struct ssh_signkey *self, const char *data, int len);
  void (*freekey)(void *key);
  char *(*fmtkey)(void *key);
  unsigned char *(*public_blob)(void *key, int *len);
  unsigned char *(*private_blob)(void *key, int *len);
  void *(*createkey)(const struct ssh_signkey *self,
                     const unsigned char *pub_blob,
                     int pub_len,
                     const unsigned char *priv_blob,
                     int priv_len);
  void *(*openssh_createkey)(const struct ssh_signkey *self,
                             const unsigned char **blob,
                             int *len);
  int (*openssh_fmtkey)(void *key, unsigned char *blob, int len);
  /* OpenSSH private key blobs, as created by openssh_fmtkey and
   * consumed by openssh_createkey, always (at least so far...) take
   * the form of a number of SSH-2 strings / mpints concatenated
   * end-to-end. Because the new-style OpenSSH private key format
   * stores those blobs without a containing string wrapper, we need
   * to know how many strings each one consists of, so that we can
   * skip over the right number to find the next key in the file.
   * openssh_private_npieces gives that information. */
  int openssh_private_npieces;
  int (*pubkey_bits)(const struct ssh_signkey *self, const void *blob, int len);
  int (*verifysig)(
      void *key, const char *sig, int siglen, const char *data, int datalen);
  unsigned char *(*sign)(void *key, const char *data, int datalen, int *siglen);
  const char *name;
  const char *keytype; /* for host key cache */
  const void *extra;   /* private to the public key methods */
};

struct ssh_compress {
  const char *name;
  /* For zlib@openssh.com: if non-NULL, this name will be considered once
   * userauth has completed successfully. */
  const char *delayed_name;
  void *(*compress_init)(void);
  void (*compress_cleanup)(void *);
  int (*compress)(void *,
                  unsigned char *block,
                  int len,
                  unsigned char **outblock,
                  int *outlen);
  void *(*decompress_init)(void);
  void (*decompress_cleanup)(void *);
  int (*decompress)(void *,
                    unsigned char *block,
                    int len,
                    unsigned char **outblock,
                    int *outlen);
  int (*disable_compression)(void *);
  const char *text_name;
};

struct ssh2_userkey {
  const struct ssh_signkey *alg; /* the key algorithm */
  void *data;                    /* the key data */
  char *comment;                 /* the key comment */
};

/* The maximum length of any hash algorithm used in kex. (bytes) */
#define SSH2_KEX_MAX_HASH_LEN (64) /* SHA-512 */

extern const struct ssh_cipher ssh_3des;
extern const struct ssh_cipher ssh_des;
extern const struct ssh_cipher ssh_blowfish_ssh1;
extern const struct ssh2_ciphers ssh2_3des;
extern const struct ssh2_ciphers ssh2_des;
extern const struct ssh2_ciphers ssh2_aes;
extern const struct ssh2_ciphers ssh2_blowfish;
extern const struct ssh2_ciphers ssh2_arcfour;
extern const struct ssh2_ciphers ssh2_ccp;
extern const struct ssh_hash ssh_sha1;
extern const struct ssh_hash ssh_sha256;
extern const struct ssh_hash ssh_sha384;
extern const struct ssh_hash ssh_sha512;
extern const struct ssh_kexes ssh_diffiehellman_group1;
extern const struct ssh_kexes ssh_diffiehellman_group14;
extern const struct ssh_kexes ssh_diffiehellman_gex;
extern const struct ssh_kexes ssh_rsa_kex;
extern const struct ssh_kexes ssh_ecdh_kex;
extern const struct ssh_signkey ssh_dss;
extern const struct ssh_signkey ssh_rsa;
extern const struct ssh_signkey ssh_ecdsa_ed25519;
extern const struct ssh_signkey ssh_ecdsa_nistp256;
extern const struct ssh_signkey ssh_ecdsa_nistp384;
extern const struct ssh_signkey ssh_ecdsa_nistp521;
extern const struct ssh_mac ssh_hmac_md5;
extern const struct ssh_mac ssh_hmac_sha1;
extern const struct ssh_mac ssh_hmac_sha1_buggy;
extern const struct ssh_mac ssh_hmac_sha1_96;
extern const struct ssh_mac ssh_hmac_sha1_96_buggy;
extern const struct ssh_mac ssh_hmac_sha256;

void *aes_make_context(void);
void aes_free_context(void *handle);
void aes128_key(void *handle, unsigned char *key);
void aes192_key(void *handle, unsigned char *key);
void aes256_key(void *handle, unsigned char *key);
void aes_iv(void *handle, unsigned char *iv);
void aes_ssh2_encrypt_blk(void *handle, unsigned char *blk, int len);
void aes_ssh2_decrypt_blk(void *handle, unsigned char *blk, int len);

/*
 * PuTTY version number formatted as an SSH version string.
 */
extern const char sshver[];

/*
 * Gross hack: pscp will try to start SFTP but fall back to scp1 if
 * that fails. This variable is the means by which scp.c can reach
 * into the SSH code and find out which one it got.
 */
extern int ssh_fallback_cmd(void *handle);

#ifndef MSCRYPTOAPI
void SHATransform(word32 *digest, word32 *data);
#endif

int random_byte(void);
void random_add_noise(void *noise, int length);
void random_add_heavynoise(void *noise, int length);

void logevent(void *, const char *);

struct PortForwarding;

/* Allocate and register a new channel for port forwarding */
void *new_sock_channel(void *handle, struct PortForwarding *pf);
void ssh_send_port_open(void *channel,
                        const char *hostname,
                        int port,
                        const char *org);

/* Exports from portfwd.c */
extern char *pfd_connect(struct PortForwarding **pf,
                         char *hostname,
                         int port,
                         void *c,
                         Conf *conf,
                         int addressfamily);
extern void pfd_close(struct PortForwarding *);
extern int pfd_send(struct PortForwarding *, char *data, int len);
extern void pfd_send_eof(struct PortForwarding *);
extern void pfd_confirm(struct PortForwarding *);
extern void pfd_unthrottle(struct PortForwarding *);
extern void pfd_override_throttle(struct PortForwarding *, int enable);
struct PortListener;
/* desthost == NULL indicates dynamic (SOCKS) port forwarding */
extern char *pfl_listen(char *desthost,
                        int destport,
                        char *srcaddr,
                        int port,
                        void *backhandle,
                        Conf *conf,
                        struct PortListener **pl,
                        int address_family);
extern void pfl_terminate(struct PortListener *);

/* Exports from x11fwd.c */
enum
{
  X11_TRANS_IPV4 = 0,
  X11_TRANS_IPV6 = 6,
  X11_TRANS_UNIX = 256
};
struct X11Display {
  /* Broken-down components of the display name itself */
  int unixdomain;
  char *hostname;
  int displaynum;
  int screennum;
  /* OSX sometimes replaces all the above with a full Unix-socket pathname */
  char *unixsocketpath;

  /* PuTTY networking SockAddr to connect to the display, and associated
   * gubbins */
  SockAddr addr;
  int port;
  char *realhost;

  /* Our local auth details for talking to the real X display. */
  int localauthproto;
  unsigned char *localauthdata;
  int localauthdatalen;
};
struct X11FakeAuth {
  /* Auth details we invented for a virtual display on the SSH server. */
  int proto;
  unsigned char *data;
  int datalen;
  char *protoname;
  char *datastring;

  /* The encrypted form of the first block, in XDM-AUTHORIZATION-1.
   * Used as part of the key when these structures are organised
   * into a tree. See x11_invent_fake_auth for explanation. */
  unsigned char *xa1_firstblock;

  /*
   * Used inside x11fwd.c to remember recently seen
   * XDM-AUTHORIZATION-1 strings, to avoid replay attacks.
   */
  tree234 *xdmseen;

  /*
   * What to do with an X connection matching this auth data.
   */
  struct X11Display *disp;
  void *share_cs, *share_chan;
};
void *x11_make_greeting(int endian,
                        int protomajor,
                        int protominor,
                        int auth_proto,
                        const void *auth_data,
                        int auth_len,
                        const char *peer_ip,
                        int peer_port,
                        int *outlen);
int x11_authcmp(void *av, void *bv); /* for putting X11FakeAuth in a tree234 */
/*
 * x11_setup_display() parses the display variable and fills in an
 * X11Display structure. Some remote auth details are invented;
 * the supplied authtype parameter configures the preferred
 * authorisation protocol to use at the remote end. The local auth
 * details are looked up by calling platform_get_x11_auth.
 */
extern struct X11Display *x11_setup_display(const char *display, Conf *);
void x11_free_display(struct X11Display *disp);
struct X11FakeAuth *x11_invent_fake_auth(tree234 *t, int authtype);
void x11_free_fake_auth(struct X11FakeAuth *auth);
struct X11Connection; /* opaque outside x11fwd.c */
struct X11Connection *x11_init(tree234 *authtree, void *, const char *, int);
extern void x11_close(struct X11Connection *);
extern int x11_send(struct X11Connection *, char *, int);
extern void x11_send_eof(struct X11Connection *s);
extern void x11_unthrottle(struct X11Connection *s);
extern void x11_override_throttle(struct X11Connection *s, int enable);
char *x11_display(const char *display);
/* Platform-dependent X11 functions */
extern void platform_get_x11_auth(struct X11Display *display, Conf *);
/* examine a mostly-filled-in X11Display and fill in localauth* */
extern const int platform_uses_x11_unix_by_default;
/* choose default X transport in the absence of a specified one */
SockAddr platform_get_x11_unix_address(const char *path, int displaynum);
/* make up a SockAddr naming the address for displaynum */
char *platform_get_x_display(void);
/* allocated local X display string, if any */
/* Callbacks in x11.c usable _by_ platform X11 functions */
/*
 * This function does the job of platform_get_x11_auth, provided
 * it is told where to find a normally formatted .Xauthority file:
 * it opens that file, parses it to find an auth record which
 * matches the display details in "display", and fills in the
 * localauth fields.
 *
 * It is expected that most implementations of
 * platform_get_x11_auth() will work by finding their system's
 * .Xauthority file, adjusting the display details if necessary
 * for local oddities like Unix-domain socket transport, and
 * calling this function to do the rest of the work.
 */
void x11_get_auth_from_authfile(struct X11Display *display,
                                const char *authfilename);
int x11_identify_auth_proto(const char *proto);
void *x11_dehexify(const char *hex, int *outlen);

Bignum copybn(Bignum b);
Bignum bn_power_2(int n);
void bn_restore_invariant(Bignum b);
Bignum bignum_from_long(unsigned long n);
void freebn(Bignum b);
Bignum modpow(Bignum base, Bignum exp, Bignum mod);
Bignum modmul(Bignum a, Bignum b, Bignum mod);
Bignum modsub(const Bignum a, const Bignum b, const Bignum n);
void decbn(Bignum n);
extern Bignum Zero, One;
Bignum bignum_from_bytes(const unsigned char *data, int nbytes);
Bignum bignum_from_bytes_le(const unsigned char *data, int nbytes);
Bignum bignum_random_in_range(const Bignum lower, const Bignum upper);
int ssh1_read_bignum(const unsigned char *data, int len, Bignum *result);
int bignum_bitcount(Bignum bn);
int ssh1_bignum_length(Bignum bn);
int ssh2_bignum_length(Bignum bn);
int bignum_byte(Bignum bn, int i);
int bignum_bit(Bignum bn, int i);
void bignum_set_bit(Bignum bn, int i, int value);
int ssh1_write_bignum(void *data, Bignum bn);
Bignum biggcd(Bignum a, Bignum b);
unsigned short bignum_mod_short(Bignum number, unsigned short modulus);
Bignum bignum_add_long(Bignum number, unsigned long addend);
Bignum bigadd(Bignum a, Bignum b);
Bignum bigsub(Bignum a, Bignum b);
Bignum bigmul(Bignum a, Bignum b);
Bignum bigmuladd(Bignum a, Bignum b, Bignum addend);
Bignum bigdiv(Bignum a, Bignum b);
Bignum bigmod(Bignum a, Bignum b);
Bignum modinv(Bignum number, Bignum modulus);
Bignum bignum_bitmask(Bignum number);
Bignum bignum_rshift(Bignum number, int shift);
Bignum bignum_lshift(Bignum number, int shift);
int bignum_cmp(Bignum a, Bignum b);
char *bignum_decimal(Bignum x);
Bignum bignum_from_decimal(const char *decimal);

#ifdef DEBUG
void diagbn(char *prefix, Bignum md);
#endif

int dh_is_gex(const struct ssh_kex *kex);
void *dh_setup_group(const struct ssh_kex *kex);
void *dh_setup_gex(Bignum pval, Bignum gval);
void dh_cleanup(void *);
Bignum dh_create_e(void *, int nbits);
const char *dh_validate_f(void *handle, Bignum f);
Bignum dh_find_K(void *, Bignum f);

int loadrsakey(const Filename *filename,
               struct RSAKey *key,
               const char *passphrase,
               const char **errorstr);
int rsakey_encrypted(const Filename *filename, char **comment);
int rsakey_pubblob(const Filename *filename,
                   void **blob,
                   int *bloblen,
                   char **commentptr,
                   const char **errorstr);

int saversakey(const Filename *filename, struct RSAKey *key, char *passphrase);

extern int base64_decode_atom(const char *atom, unsigned char *out);
extern int base64_lines(int datalen);
extern void base64_encode_atom(const unsigned char *data, int n, char *out);
extern void base64_encode(FILE *fp,
                          const unsigned char *data,
                          int datalen,
                          int cpl);

/* ssh2_load_userkey can return this as an error */
extern struct ssh2_userkey ssh2_wrong_passphrase;
#define SSH2_WRONG_PASSPHRASE (&ssh2_wrong_passphrase)

int ssh2_userkey_encrypted(const Filename *filename, char **comment);
struct ssh2_userkey *ssh2_load_userkey(const Filename *filename,
                                       const char *passphrase,
                                       const char **errorstr);
unsigned char *ssh2_userkey_loadpub(const Filename *filename,
                                    char **algorithm,
                                    int *pub_blob_len,
                                    char **commentptr,
                                    const char **errorstr);
int ssh2_save_userkey(const Filename *filename,
                      struct ssh2_userkey *key,
                      char *passphrase);
const struct ssh_signkey *find_pubkey_alg(const char *name);
const struct ssh_signkey *find_pubkey_alg_len(int namelen, const char *name);

enum
{
  SSH_KEYTYPE_UNOPENABLE,
  SSH_KEYTYPE_UNKNOWN,
  SSH_KEYTYPE_SSH1,
  SSH_KEYTYPE_SSH2,
  /*
   * The OpenSSH key types deserve a little explanation. OpenSSH has
   * two physical formats for private key storage: an old PEM-based
   * one largely dictated by their use of OpenSSL and full of ASN.1,
   * and a new one using the same private key formats used over the
   * wire for talking to ssh-agent. The old format can only support
   * a subset of the key types, because it needs redesign for each
   * key type, and after a while they decided to move to the new
   * format so as not to have to do that.
   *
   * On input, key files are identified as either
   * SSH_KEYTYPE_OPENSSH_PEM or SSH_KEYTYPE_OPENSSH_NEW, describing
   * accurately which actual format the keys are stored in.
   *
   * On output, however, we default to following OpenSSH's own
   * policy of writing out PEM-style keys for maximum backwards
   * compatibility if the key type supports it, and otherwise
   * switching to the new format. So the formats you can select for
   * output are SSH_KEYTYPE_OPENSSH_NEW (forcing the new format for
   * any key type), and SSH_KEYTYPE_OPENSSH_AUTO to use the oldest
   * format supported by whatever key type you're writing out.
   *
   * So we have three type codes, but only two of them usable in any
   * given circumstance. An input key file will never be identified
   * as AUTO, only PEM or NEW; key export UIs should not be able to
   * select PEM, only AUTO or NEW.
   */
  SSH_KEYTYPE_OPENSSH_AUTO,
  SSH_KEYTYPE_OPENSSH_PEM,
  SSH_KEYTYPE_OPENSSH_NEW,
  SSH_KEYTYPE_SSHCOM,
  /*
   * Public-key-only formats, which we still want to be able to read
   * for various purposes.
   */
  SSH_KEYTYPE_SSH1_PUBLIC,
  SSH_KEYTYPE_SSH2_PUBLIC_RFC4716,
  SSH_KEYTYPE_SSH2_PUBLIC_OPENSSH
};
char *ssh1_pubkey_str(struct RSAKey *ssh1key);
void ssh1_write_pubkey(FILE *fp, struct RSAKey *ssh1key);
char *ssh2_pubkey_openssh_str(struct ssh2_userkey *key);
void ssh2_write_pubkey(FILE *fp,
                       const char *comment,
                       const void *v_pub_blob,
                       int pub_len,
                       int keytype);
char *ssh2_fingerprint_blob(const void *blob, int bloblen);
char *ssh2_fingerprint(const struct ssh_signkey *alg, void *data);
int key_type(const Filename *filename);
const char *key_type_to_str(int type);

int import_possible(int type);
int import_target_type(int type);
int import_encrypted(const Filename *filename, int type, char **comment);
int import_ssh1(const Filename *filename,
                int type,
                struct RSAKey *key,
                char *passphrase,
                const char **errmsg_p);
struct ssh2_userkey *import_ssh2(const Filename *filename,
                                 int type,
                                 char *passphrase,
                                 const char **errmsg_p);
int export_ssh1(const Filename *filename,
                int type,
                struct RSAKey *key,
                char *passphrase);
int export_ssh2(const Filename *filename,
                int type,
                struct ssh2_userkey *key,
                char *passphrase);

void des3_decrypt_pubkey(unsigned char *key, unsigned char *blk, int len);
void des3_encrypt_pubkey(unsigned char *key, unsigned char *blk, int len);
void des3_decrypt_pubkey_ossh(unsigned char *key,
                              unsigned char *iv,
                              unsigned char *blk,
                              int len);
void des3_encrypt_pubkey_ossh(unsigned char *key,
                              unsigned char *iv,
                              unsigned char *blk,
                              int len);
void aes256_encrypt_pubkey(unsigned char *key, unsigned char *blk, int len);
void aes256_decrypt_pubkey(unsigned char *key, unsigned char *blk, int len);

void des_encrypt_xdmauth(const unsigned char *key, unsigned char *blk, int len);
void des_decrypt_xdmauth(const unsigned char *key, unsigned char *blk, int len);

void openssh_bcrypt(const char *passphrase,
                    const unsigned char *salt,
                    int saltbytes,
                    int rounds,
                    unsigned char *out,
                    int outbytes);

/*
 * For progress updates in the key generation utility.
 */
#define PROGFN_INITIALISE 1
#define PROGFN_LIN_PHASE 2
#define PROGFN_EXP_PHASE 3
#define PROGFN_PHASE_EXTENT 4
#define PROGFN_READY 5
#define PROGFN_PROGRESS 6
typedef void (*progfn_t)(void *param, int action, int phase, int progress);

int rsa_generate(struct RSAKey *key, int bits, progfn_t pfn, void *pfnparam);
int dsa_generate(struct dss_key *key, int bits, progfn_t pfn, void *pfnparam);
int ec_generate(struct ec_key *key, int bits, progfn_t pfn, void *pfnparam);
int ec_edgenerate(struct ec_key *key, int bits, progfn_t pfn, void *pfnparam);
Bignum primegen(int bits,
                int modulus,
                int residue,
                Bignum factor,
                int phase,
                progfn_t pfn,
                void *pfnparam,
                unsigned firstbits);
void invent_firstbits(unsigned *one, unsigned *two);

/*
 * zlib compression.
 */
void *zlib_compress_init(void);
void zlib_compress_cleanup(void *);
void *zlib_decompress_init(void);
void zlib_decompress_cleanup(void *);
int zlib_compress_block(void *,
                        unsigned char *block,
                        int len,
                        unsigned char **outblock,
                        int *outlen);
int zlib_decompress_block(void *,
                          unsigned char *block,
                          int len,
                          unsigned char **outblock,
                          int *outlen);

/*
 * Connection-sharing API provided by platforms. This function must
 * either:
 *  - return SHARE_NONE and do nothing
 *  - return SHARE_DOWNSTREAM and set *sock to a Socket connected to
 *    downplug
 *  - return SHARE_UPSTREAM and set *sock to a Socket connected to
 *    upplug.
 */
enum
{
  SHARE_NONE,
  SHARE_DOWNSTREAM,
  SHARE_UPSTREAM
};
int platform_ssh_share(const char *name,
                       Conf *conf,
                       Plug downplug,
                       Plug upplug,
                       Socket *sock,
                       char **logtext,
                       char **ds_err,
                       char **us_err,
                       int can_upstream,
                       int can_downstream);
void platform_ssh_share_cleanup(const char *name);

/*
 * SSH-1 message type codes.
 */
#define SSH1_MSG_DISCONNECT 1                  /* 0x1 */
#define SSH1_SMSG_PUBLIC_KEY 2                 /* 0x2 */
#define SSH1_CMSG_SESSION_KEY 3                /* 0x3 */
#define SSH1_CMSG_USER 4                       /* 0x4 */
#define SSH1_CMSG_AUTH_RSA 6                   /* 0x6 */
#define SSH1_SMSG_AUTH_RSA_CHALLENGE 7         /* 0x7 */
#define SSH1_CMSG_AUTH_RSA_RESPONSE 8          /* 0x8 */
#define SSH1_CMSG_AUTH_PASSWORD 9              /* 0x9 */
#define SSH1_CMSG_REQUEST_PTY 10               /* 0xa */
#define SSH1_CMSG_WINDOW_SIZE 11               /* 0xb */
#define SSH1_CMSG_EXEC_SHELL 12                /* 0xc */
#define SSH1_CMSG_EXEC_CMD 13                  /* 0xd */
#define SSH1_SMSG_SUCCESS 14                   /* 0xe */
#define SSH1_SMSG_FAILURE 15                   /* 0xf */
#define SSH1_CMSG_STDIN_DATA 16                /* 0x10 */
#define SSH1_SMSG_STDOUT_DATA 17               /* 0x11 */
#define SSH1_SMSG_STDERR_DATA 18               /* 0x12 */
#define SSH1_CMSG_EOF 19                       /* 0x13 */
#define SSH1_SMSG_EXIT_STATUS 20               /* 0x14 */
#define SSH1_MSG_CHANNEL_OPEN_CONFIRMATION 21  /* 0x15 */
#define SSH1_MSG_CHANNEL_OPEN_FAILURE 22       /* 0x16 */
#define SSH1_MSG_CHANNEL_DATA 23               /* 0x17 */
#define SSH1_MSG_CHANNEL_CLOSE 24              /* 0x18 */
#define SSH1_MSG_CHANNEL_CLOSE_CONFIRMATION 25 /* 0x19 */
#define SSH1_SMSG_X11_OPEN 27                  /* 0x1b */
#define SSH1_CMSG_PORT_FORWARD_REQUEST 28      /* 0x1c */
#define SSH1_MSG_PORT_OPEN 29                  /* 0x1d */
#define SSH1_CMSG_AGENT_REQUEST_FORWARDING 30  /* 0x1e */
#define SSH1_SMSG_AGENT_OPEN 31                /* 0x1f */
#define SSH1_MSG_IGNORE 32                     /* 0x20 */
#define SSH1_CMSG_EXIT_CONFIRMATION 33         /* 0x21 */
#define SSH1_CMSG_X11_REQUEST_FORWARDING 34    /* 0x22 */
#define SSH1_CMSG_AUTH_RHOSTS_RSA 35           /* 0x23 */
#define SSH1_MSG_DEBUG 36                      /* 0x24 */
#define SSH1_CMSG_REQUEST_COMPRESSION 37       /* 0x25 */
#define SSH1_CMSG_AUTH_TIS 39                  /* 0x27 */
#define SSH1_SMSG_AUTH_TIS_CHALLENGE 40        /* 0x28 */
#define SSH1_CMSG_AUTH_TIS_RESPONSE 41         /* 0x29 */
#define SSH1_CMSG_AUTH_CCARD 70                /* 0x46 */
#define SSH1_SMSG_AUTH_CCARD_CHALLENGE 71      /* 0x47 */
#define SSH1_CMSG_AUTH_CCARD_RESPONSE 72       /* 0x48 */

#define SSH1_AUTH_RHOSTS 1     /* 0x1 */
#define SSH1_AUTH_RSA 2        /* 0x2 */
#define SSH1_AUTH_PASSWORD 3   /* 0x3 */
#define SSH1_AUTH_RHOSTS_RSA 4 /* 0x4 */
#define SSH1_AUTH_TIS 5        /* 0x5 */
#define SSH1_AUTH_CCARD 16     /* 0x10 */

#define SSH1_PROTOFLAG_SCREEN_NUMBER 1 /* 0x1 */
/* Mask for protoflags we will echo back to server if seen */
#define SSH1_PROTOFLAGS_SUPPORTED 0 /* 0x1 */

/*
 * SSH-2 message type codes.
 */
#define SSH2_MSG_DISCONNECT 1                 /* 0x1 */
#define SSH2_MSG_IGNORE 2                     /* 0x2 */
#define SSH2_MSG_UNIMPLEMENTED 3              /* 0x3 */
#define SSH2_MSG_DEBUG 4                      /* 0x4 */
#define SSH2_MSG_SERVICE_REQUEST 5            /* 0x5 */
#define SSH2_MSG_SERVICE_ACCEPT 6             /* 0x6 */
#define SSH2_MSG_KEXINIT 20                   /* 0x14 */
#define SSH2_MSG_NEWKEYS 21                   /* 0x15 */
#define SSH2_MSG_KEXDH_INIT 30                /* 0x1e */
#define SSH2_MSG_KEXDH_REPLY 31               /* 0x1f */
#define SSH2_MSG_KEX_DH_GEX_REQUEST_OLD 30    /* 0x1e */
#define SSH2_MSG_KEX_DH_GEX_REQUEST 34        /* 0x22 */
#define SSH2_MSG_KEX_DH_GEX_GROUP 31          /* 0x1f */
#define SSH2_MSG_KEX_DH_GEX_INIT 32           /* 0x20 */
#define SSH2_MSG_KEX_DH_GEX_REPLY 33          /* 0x21 */
#define SSH2_MSG_KEXRSA_PUBKEY 30             /* 0x1e */
#define SSH2_MSG_KEXRSA_SECRET 31             /* 0x1f */
#define SSH2_MSG_KEXRSA_DONE 32               /* 0x20 */
#define SSH2_MSG_KEX_ECDH_INIT 30             /* 0x1e */
#define SSH2_MSG_KEX_ECDH_REPLY 31            /* 0x1f */
#define SSH2_MSG_KEX_ECMQV_INIT 30            /* 0x1e */
#define SSH2_MSG_KEX_ECMQV_REPLY 31           /* 0x1f */
#define SSH2_MSG_USERAUTH_REQUEST 50          /* 0x32 */
#define SSH2_MSG_USERAUTH_FAILURE 51          /* 0x33 */
#define SSH2_MSG_USERAUTH_SUCCESS 52          /* 0x34 */
#define SSH2_MSG_USERAUTH_BANNER 53           /* 0x35 */
#define SSH2_MSG_USERAUTH_PK_OK 60            /* 0x3c */
#define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ 60 /* 0x3c */
#define SSH2_MSG_USERAUTH_INFO_REQUEST 60     /* 0x3c */
#define SSH2_MSG_USERAUTH_INFO_RESPONSE 61    /* 0x3d */
#define SSH2_MSG_GLOBAL_REQUEST 80            /* 0x50 */
#define SSH2_MSG_REQUEST_SUCCESS 81           /* 0x51 */
#define SSH2_MSG_REQUEST_FAILURE 82           /* 0x52 */
#define SSH2_MSG_CHANNEL_OPEN 90              /* 0x5a */
#define SSH2_MSG_CHANNEL_OPEN_CONFIRMATION 91 /* 0x5b */
#define SSH2_MSG_CHANNEL_OPEN_FAILURE 92      /* 0x5c */
#define SSH2_MSG_CHANNEL_WINDOW_ADJUST 93     /* 0x5d */
#define SSH2_MSG_CHANNEL_DATA 94              /* 0x5e */
#define SSH2_MSG_CHANNEL_EXTENDED_DATA 95     /* 0x5f */
#define SSH2_MSG_CHANNEL_EOF 96               /* 0x60 */
#define SSH2_MSG_CHANNEL_CLOSE 97             /* 0x61 */
#define SSH2_MSG_CHANNEL_REQUEST 98           /* 0x62 */
#define SSH2_MSG_CHANNEL_SUCCESS 99           /* 0x63 */
#define SSH2_MSG_CHANNEL_FAILURE 100          /* 0x64 */
#define SSH2_MSG_USERAUTH_GSSAPI_RESPONSE 60
#define SSH2_MSG_USERAUTH_GSSAPI_TOKEN 61
#define SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE 63
#define SSH2_MSG_USERAUTH_GSSAPI_ERROR 64
#define SSH2_MSG_USERAUTH_GSSAPI_ERRTOK 65
#define SSH2_MSG_USERAUTH_GSSAPI_MIC 66

/*
 * SSH-1 agent messages.
 */
#define SSH1_AGENTC_REQUEST_RSA_IDENTITIES 1
#define SSH1_AGENT_RSA_IDENTITIES_ANSWER 2
#define SSH1_AGENTC_RSA_CHALLENGE 3
#define SSH1_AGENT_RSA_RESPONSE 4
#define SSH1_AGENTC_ADD_RSA_IDENTITY 7
#define SSH1_AGENTC_REMOVE_RSA_IDENTITY 8
#define SSH1_AGENTC_REMOVE_ALL_RSA_IDENTITIES 9 /* openssh private? */

/*
 * Messages common to SSH-1 and OpenSSH's SSH-2.
 */
#define SSH_AGENT_FAILURE 5
#define SSH_AGENT_SUCCESS 6

/*
 * OpenSSH's SSH-2 agent messages.
 */
#define SSH2_AGENTC_REQUEST_IDENTITIES 11
#define SSH2_AGENT_IDENTITIES_ANSWER 12
#define SSH2_AGENTC_SIGN_REQUEST 13
#define SSH2_AGENT_SIGN_RESPONSE 14
#define SSH2_AGENTC_ADD_IDENTITY 17
#define SSH2_AGENTC_REMOVE_IDENTITY 18
#define SSH2_AGENTC_REMOVE_ALL_IDENTITIES 19

/*
 * Assorted other SSH-related enumerations.
 */
#define SSH2_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1     /* 0x1 */
#define SSH2_DISCONNECT_PROTOCOL_ERROR 2                  /* 0x2 */
#define SSH2_DISCONNECT_KEY_EXCHANGE_FAILED 3             /* 0x3 */
#define SSH2_DISCONNECT_HOST_AUTHENTICATION_FAILED 4      /* 0x4 */
#define SSH2_DISCONNECT_MAC_ERROR 5                       /* 0x5 */
#define SSH2_DISCONNECT_COMPRESSION_ERROR 6               /* 0x6 */
#define SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE 7           /* 0x7 */
#define SSH2_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8  /* 0x8 */
#define SSH2_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9         /* 0x9 */
#define SSH2_DISCONNECT_CONNECTION_LOST 10                /* 0xa */
#define SSH2_DISCONNECT_BY_APPLICATION 11                 /* 0xb */
#define SSH2_DISCONNECT_TOO_MANY_CONNECTIONS 12           /* 0xc */
#define SSH2_DISCONNECT_AUTH_CANCELLED_BY_USER 13         /* 0xd */
#define SSH2_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14 /* 0xe */
#define SSH2_DISCONNECT_ILLEGAL_USER_NAME 15              /* 0xf */

#define SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED 1 /* 0x1 */
#define SSH2_OPEN_CONNECT_FAILED 2              /* 0x2 */
#define SSH2_OPEN_UNKNOWN_CHANNEL_TYPE 3        /* 0x3 */
#define SSH2_OPEN_RESOURCE_SHORTAGE 4           /* 0x4 */

#define SSH2_EXTENDED_DATA_STDERR 1 /* 0x1 */

/*
 * Need this to warn about support for the original SSH-2 keyfile
 * format.
 */
void old_keyfile_warning(void);