[u/mdw/catacomb] / key / key-data.h

/* -*-c-*-
 *
 * Manipulating key data
 *
 * (c) 1999 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * Catacomb is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

#ifndef CATACOMB_KEY_DATA_H
#define CATACOMB_KEY_DATA_H

#ifdef __cplusplus
  extern "C" {
#endif

/*----- Header files ------------------------------------------------------*/

#include <stddef.h>

#include <mLib/bits.h>
#include <mLib/dstr.h>
#include <mLib/sym.h>

#ifndef CATACOMB_KEY_ERROR_H
#  include "key-error.h"
#endif

#ifndef CATACOMB_MP_H
#  include "mp.h"
#endif

#ifndef CATACOMB_EC_H
#  include "ec.h"
#endif

/*----- Data structures ---------------------------------------------------*/

/* --- Key binary data --- */

typedef struct key_bin {
  octet *k;                             /* Pointer to key data */
  size_t sz;                            /* Size of the key data (in bytes) */
} key_bin;

/* --- Key data structure --- */

typedef struct key_data {
  unsigned e;                           /* Encoding type for key data */
  unsigned ref;                         /* Reference counter */
  union {
    key_bin k;                          /* Binary key data */
    mp *m;                              /* Multiprecision integer */
    sym_table s;                        /* Structured key data */
    char *p;                            /* String pointer */
    ec e;                               /* Elliptic curve point */
  } u;
} key_data;

typedef struct key_struct {
  sym_base _b;
  key_data *k;
} key_struct;

typedef struct key_subkeyiter { sym_iter i; } key_subkeyiter;

/* --- Packing and unpacking --- */

typedef struct key_packdef {
  unsigned e;                           /* Key data encoding type */
  void *p;                              /* Pointer to the destination */
  key_data *kd;                         /* Key data block */
} key_packdef;

typedef struct key_packstruct {
  char *name;                           /* Pointer to name string */
  key_packdef kp;                       /* Packing structure */
} key_packstruct;

/* --- Key binary encoding --- *
 *
 * The binary encoding consists of a header containing a 16-bit encoding type
 * and a 16-bit length, followed immediately by the key data, followed by
 * between zero and three zero bytes to make the total length a multiple of
 * four.  The format of the following data depends on the encoding type:
 *
 * @KENC_BINARY@        Binary data.
 *
 * @KENC_MP@            Octet array interpreted in big-endian byte order.
 *
 * @KENC_STRUCT@        An array of pairs, each containing a string (8-bit
 *                      length followed by data and zero-padding to 4-byte
 *                      boundary) and key binary encodings.
 *
 * @KENC_ENCRYPT@       Binary data, format
 */

/* --- Key encoding methods and other flags--- */

enum {

  /* --- Bottom two bits are the encoding type --- */

  KF_ENCMASK    = 0x83,                 /* Encoding mask */
  KENC_BINARY   = 0x00,                 /* Plain binary key (@k@) */
  KENC_MP       = 0x01,                 /* Multiprecision integer (@i@) */
  KENC_STRUCT   = 0x02,                 /* Structured key data (@s@) */
  KENC_ENCRYPT  = 0x03,                 /* Encrypted key type (@k@) */
  KENC_STRING   = 0x80,                 /* ASCII string (@p@) */
  KENC_EC       = 0x81,                 /* Elliptic curve point (@e@) */

  /* --- Key category bits --- */

  KF_CATMASK    = 0x0c,                 /* Category mask */
  KCAT_SYMM     = 0x00,                 /* Symmetric encryption key */
  KCAT_PRIV     = 0x04,                 /* Private (asymmetric) key */
  KCAT_PUB      = 0x08,                 /* Public (asymmetric) key */
  KCAT_SHARE    = 0x0c,                 /* Shared (asymmetric) key */
  KF_NONSECRET  = 0x08,                 /* Bit flag for non-secret keys */

  /* --- Other flags --- */

  KF_BURN       = 0x10,                 /* Burn key after use */
  KF_OPT        = 0x20,                 /* Optional key (for @key_unpack@) */

  /* --- Tag end --- */

  KENC_MAX                              /* Dummy limit constant */
};

/* --- Key locking return codes --- */

#define KL_OK 0                         /* All good */
#define KL_IOERR -1                     /* I/O problem (e.g., getting pp) */
#define KL_KEYERR -2                    /* Wrong key supplied */
#define KL_DATAERR -3                   /* Data format error */

/* --- Key flag filtering --- */

typedef struct key_filter {
  unsigned f;
  unsigned m;
} key_filter;

/* --- Matching aginst key selection --- *
 *
 * GCC will warn about constant addresses in this test, which is rather
 * unfortunate.  Muffle the warning.  This is rather hideous because of the
 * way GCC's parser handles pragmata.
 */

#if __GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
#  define KEY_MATCH_MUFFLE_WARNING(x) __extension__ ({                  \
        _Pragma("GCC diagnostic push")                                  \
        _Pragma("GCC diagnostic ignored \"-Waddress\"")                 \
        (x);                                                            \
        _Pragma("GCC diagnostic pop")                                   \
   })
#else
#  define KEY_MATCH_MUFFLE_WARNING(x) (x)
#endif

#define KEY_MATCH(kd, kf)                                               \
  (KEY_MATCH_MUFFLE_WARNING(!(kf)) ||                                   \
   ((kd)->e & KF_ENCMASK) == KENC_STRUCT ||                             \
   ((kd)->e & (kf)->m) == (kf)->f)

/*----- Key flags and filtering -------------------------------------------*/

/* --- @key_readflags@ --- *
 *
 * Arguments:   @const char *p@ = pointer to string to read
 *              @char **pp@ = where to store the end pointer
 *              @unsigned *ff@ = where to store the flags
 *              @unsigned *mm@ = where to store the mask
 *
 * Returns:     Zero if all went well, nonzero if there was an error.
 *
 * Use:         Reads a flag string.
 */

extern int key_readflags(const char */*p*/, char **/*pp*/,
                         unsigned */*ff*/, unsigned */*mm*/);

/* --- @key_writeflags@ --- *
 *
 * Arguments:   @unsigned f@ = flags to write
 *              @dstr *d@ = pointer to destination string
 *
 * Returns:     ---
 *
 * Use:         Emits a flags word as a string representation.
 */

extern void key_writeflags(unsigned /*f*/, dstr */*d*/);

/* --- @key_match@ --- *
 *
 * Arguments:   @key_data *k@ = pointer to key data block
 *              @const key_filter *kf@ = pointer to filter block
 *
 * Returns:     Nonzero if the key matches the filter.
 *
 * Use:         Checks whether a key matches a filter.
 */

extern int key_match(key_data */*k*/, const key_filter */*kf*/);

/*----- Setting new key data ----------------------------------------------*/

/* --- @key_newraw@ --- *
 *
 * Arguments:   @unsigned e@ = encoding type to set
 *
 * Returns:     New key block, not filled in.
 */

extern key_data *key_newraw(unsigned /*e*/);

/* --- @key_newbinary@ --- *
 *
 * Arguments:   @unsigned e@ = other encoding flags
 *              @const void *p@ = pointer to key data
 *              @size_t sz@ = size of the key data
 *
 * Returns:     New key data object.
 */

extern key_data *key_newbinary(unsigned /*e*/,
                               const void */*p*/, size_t /*sz*/);

/* --- @key_newencrypted@ --- *
 *
 * Arguments:   @unsigned e@ = other encoding flags
 *              @const void *p@ = pointer to key data
 *              @size_t sz@ = size of the key data
 *
 * Returns:     New key data object.
 */

extern key_data *key_newencrypted(unsigned /*e*/,
                                  const void */*p*/, size_t /*sz*/);

/* --- @key_newmp@ --- *
 *
 * Arguments:   @unsigned e@ = other encoding flags
 *              @mp *m@ = pointer to the value to set
 *
 * Returns:     New key data object.
 */

extern key_data *key_newmp(unsigned /*e*/, mp */*m*/);

/* --- @key_newstring@ --- *
 *
 * Arguments:   @unsigned e@ = other encoding flags
 *              @const char *p@ = pointer to the value to set
 *
 * Returns:     New key data object.
 */

extern key_data *key_newstring(unsigned /*e*/, const char */*p*/);

/* --- @key_newec@ --- *
 *
 * Arguments:   @unsigned e@ = other encoding flags
 *              @const ec *pt@ = pointer to the value to set
 *
 * Returns:     New key data object.
 */

extern key_data *key_newec(unsigned /*e*/, const ec */*pt*/);

/* --- @key_newstruct@ --- *
 *
 * Arguments:   ---
 *
 * Returns:     New key data object.
 */

extern key_data *key_newstruct(void);

/* --- @key_structfind@ --- *
 *
 * Arguments:   @key_data *k@ = pointer to key data block
 *              @const char *tag@ = pointer to tag string
 *
 * Returns:     Pointer to key data block, or null.
 *
 * Use:         Looks up the tag in a structured key.
 */

extern key_data *key_structfind(key_data */*k*/, const char */*tag*/);

/* --- @key_mksubkeyiter@ --- *
 *
 * Arguments:   @key_subkeyiter *i@ = pointer to iterator block
 *              @key_data *k@ = pointer to key data block
 *
 * Returns:     ---
 *
 * Use:         Initializes a subkey iterator.
 */

extern void key_mksubkeyiter(key_subkeyiter */*i*/, key_data */*k*/);

/* --- @key_nextsubkey@ --- *
 *
 * Arguments:   @key_structiter *i@ = pointer to iterator block
 *              @const char **tag@ = where to put the tag pointer, or null
 *              @key_data **kd@ = where to put the key data pointer, or null
 *
 * Returns:     Nonzero if there was another item, zero if we hit the
 *              end-stop.
 *
 * Use:         Collects the next subkey of a structured key.
 */

extern int key_nextsubkey(key_subkeyiter */*i*/,
                          const char **/*tag*/, key_data **/*kd*/);

/* --- @key_structset@, @key_structsteal@ --- *
 *
 * Arguments:   @key_data *k@ = pointer to key data block
 *              @const char *tag@ = pointer to tag string
 *              @key_data *kd@ = new key data to store
 *
 * Returns:     ---
 *
 * Use:         Creates a new subkey.  Stealing doesn't affect @kd@'s
 *              refcount.  If @kd@ is null, the subkey is deleted.
 */

extern void key_structset(key_data */*k*/,
                          const char */*tag*/, key_data */*kd*/);
extern void key_structsteal(key_data */*k*/,
                            const char */*tag*/, key_data */*kd*/);

/* --- @key_split@ --- *
 *
 * Arguments:   @key_data **kk@ = address of pointer to key data block
 *
 * Returns:     ---
 *
 * Use:         Replaces @*kk@ with a pointer to the same key data, but with
 *              just one reference.
 */

extern void key_split(key_data **/*kk*/);

/*----- Miscellaneous operations ------------------------------------------*/

/* --- @key_incref@ --- *
 *
 * Arguments:   @key_data *k@ = pointer to key data
 *
 * Returns:     ---
 *
 * Use:         Increments the refcount on a key data block.
 */

#define KEY_INCREF(k) ((k)->ref++)
extern void key_incref(key_data */*k*/);

/* --- @key_destroy@ --- *
 *
 * Arguments:   @key_data *k@ = pointer to key data to destroy
 *
 * Returns:     ---
 *
 * Use:         Destroys a block of key data, regardless of reference count.
 *              Don't use this unless you know what you're doing.
 */

extern void key_destroy(key_data */*k*/);

/* --- @key_drop@ --- *
 *
 * Arguments:   @key_data *k@ = pointer to key data to destroy
 *
 * Returns:     ---
 *
 * Use:         Drops a reference to key data, destroying it if necessary.
 */

#define KEY_DROP(k) do {                                                \
  key_data *_k = k;                                                     \
  _k->ref--;                                                            \
  if (_k->ref == 0)                                                     \
    key_destroy(_k);                                                    \
} while (0)

extern void key_drop(key_data */*k*/);

/* --- @key_do@ --- *
 *
 * Arguments:   @key_data *k@ = pointer to key data block
 *              @const key_filter *kf@ = pointer to filter block
 *              @dstr *d@ = pointer to base string
 *              @int (*func)(key_data *kd, dstr *d, void *p@ = function
 *              @void *p@ = argument to function
 *
 * Returns:     Nonzero return code from function, or zero.
 *
 * Use:         Runs a function over all the leaves of a key.
 */

extern int key_do(key_data */*k*/, const key_filter */*kf*/, dstr */*d*/,
                  int (*/*func*/)(key_data */*kd*/,
                                  dstr */*d*/, void */*p*/),
                  void */*p*/);

/* --- @key_copydata@ --- *
 *
 * Arguments:   @key_data *k@ = key data to copy
 *              @const key_filter *kf@ = pointer to filter block
 *
 * Returns:     Pointer to a copy of the data, or null if the root subkey
 *              didn't match the filter.
 *
 * Use:         Copies a chunk of key data.  Subkeys, whether they're
 *              structured or leaves, which don't match the filter aren't
 *              copied.  The copy may or may not have structure in common
 *              with the original.
 */

extern key_data *key_copydata(key_data */*k*/, const key_filter */*kf*/);

/*----- Textual encoding --------------------------------------------------*/

/* --- @key_read@ --- *
 *
 * Arguments:   @const char *p@ = pointer to textual key representation
 *              @char **pp@ = where to store the end pointer
 *
 * Returns:     The newly-read key data, or null if it failed.
 *
 * Use:         Parses a textual key description.
 */

extern key_data *key_read(const char */*p*/, char **/*pp*/);

/* --- @key_write@ --- *
 *
 * Arguments:   @key_data *k@ = pointer to key data
 *              @dstr *d@ = destination string to write on
 *              @const key_filter *kf@ = pointer to key selection block
 *
 * Returns:     Nonzero if any items were actually written.
 *
 * Use:         Writes a key in a textual encoding.
 */

extern int key_write(key_data */*k*/, dstr */*d*/, const key_filter */*kf*/);

/*----- Key binary encoding -----------------------------------------------*/

/* --- @key_decode@ --- *
 *
 * Arguments:   @const void *p@ = pointer to buffer to read
 *              @size_t sz@ = size of the buffer
 *
 * Returns:     The newly-read key data, or null if it failed.
 *
 * Use:         Decodes a binary representation of a key.
 */

extern key_data *key_decode(const void */*p*/, size_t /*sz*/);

/* --- @key_encode@ --- *
 *
 * Arguments:   @key_data *k@ = pointer to key data block
 *              @dstr *d@ = pointer to destination string
 *              @const key_filter *kf@ = pointer to key selection block
 *
 * Returns:     Nonzero if any items were actually written.
 *
 * Use:         Encodes a key block as binary data.
 */

extern int key_encode(key_data */*k*/, dstr */*d*/,
                      const key_filter */*kf*/);

/*----- Packing and unpacking keys ----------------------------------------*/

/* --- @key_pack@ --- *
 *
 * Arguments:   @key_packdef *kp@ = pointer to packing structure
 *              @key_data **kd@ = where to put the key data pointer
 *              @dstr *d@ = pointer to tag string for the key data
 *
 * Returns:     Error code, or zero.
 *
 * Use:         Packs a key from a data structure.
 */

extern int key_pack(key_packdef */*kp*/, key_data **/*kd*/, dstr */*d*/);

/* --- @key_unpack@ --- *
 *
 * Arguments:   @key_packdef *kp@ = pointer to packing structure
 *              @key_data *kd@ = pointer to source key data
 *              @dstr *d@ = pointer to tag string for the key data
 *
 * Returns:     Error code, or zero.
 *
 * Use:         Unpacks a key into an appropriate data structure.
 */

extern int key_unpack(key_packdef */*kp*/, key_data */*kd*/, dstr */*d*/);

/* --- @key_unpackdone@ --- *
 *
 * Arguments:   @key_packdef *kp@ = pointer to packing definition
 *
 * Returns:     ---
 *
 * Use:         Frees the key components contained within a packing
 *              definition, created during key unpacking.
 */

extern void key_unpackdone(key_packdef */*kp*/);

/*----- Key encryption ----------------------------------------------------*/

/* --- @key_lock@ --- *
 *
 * Arguments:   @key_data **kt@ = where to store the destination pointer
 *              @key_data *k@ = source key data block or null to use @*kt@
 *              @const void *e@ = secret to encrypt key with
 *              @size_t esz@ = size of the secret
 *
 * Returns:     ---
 *
 * Use:         Encrypts a key data block using a secret.
 */

extern void key_lock(key_data **/*kt*/, key_data */*k*/,
                     const void */*e*/, size_t /*esz*/);

/* --- @key_unlock@ --- *
 *
 * Arguments:   @key_data **kt@ = where to store the destination pointer
 *              @key_data *k@ = source key data block or null to use @*kt@
 *              @const void *e@ = secret to decrypt the block with
 *              @size_t esz@ = size of the secret
 *
 * Returns:     Zero for success, or a @KERR_@ error code.
 *
 * Use:         Unlocks a key using a secret.
 */

extern int key_unlock(key_data **/*kt*/, key_data */*k*/,
                      const void */*e*/, size_t /*esz*/);

/* --- @key_plock@ --- *
 *
 * Arguments:   @key_data **kt@ = where to store the destination pointer
 *              @key_data *k@ = source key data block or null to use @*kt@
 *              @const char *tag@ = tag to use for passphrase
 *
 * Returns:     Zero if successful, a @KERR@ error code on failure.
 *
 * Use:         Locks a key by encrypting it with a passphrase.
 */

extern int key_plock(key_data **/*kt*/, key_data */*k*/,
                     const char */*tag*/);

/* --- @key_punlock@ --- *
 *
 * Arguments:   @key_data **kt@ = where to store the destination pointer
 *              @key_data *k@ = source key data block or null to use @*kt@
 *              @const char *tag@ = tag to use for passphrase
 *
 * Returns:     Zero if successful, a @KERR@ error code on failure.
 *
 * Use:         Unlocks a passphrase-locked key.
 */

extern int key_punlock(key_data **/*kt*/, key_data */*k*/,
                       const char */*tag*/);

/*----- That's all, folks -------------------------------------------------*/

#ifdef __cplusplus
  }
#endif

#endif