path: root/hash.c

/* 
 * hashes.c
 * --------
 *
 * HAL interface to Cryptech hash cores.
 * 
 * Authors: Joachim Strömbergson, Paul Selkirk, Rob Austein
 * Copyright (c) 2014-2015, SUNET
 * 
 * Redistribution and use in source and binary forms, with or 
 * without modification, are permitted provided that the following 
 * conditions are met: 
 * 
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 * 
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in 
 *    the documentation and/or other materials provided with the 
 *    distribution. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>

#include "cryptech.h"

/*
 * Longest block and digest we support at the moment.
 */

#define MAX_BLOCK_LEN           SHA512_BLOCK_LEN
#define	MAX_DIGEST_LEN		SHA512_DIGEST_LEN

/*
 * HMAC magic numbers.
 */

#define HMAC_IPAD 0x36
#define HMAC_OPAD 0x5c

/*
 * Driver.  This encapsulates whatever per-algorithm voodoo we need
 * this week.  At the moment, this is mostly Cryptech core addresses,
 * but this is subject to change without notice.
 *
 * Most of the addresses in the current version could be calculated
 * from a single address (the core base address), but this week's
 * theory prefers the precomputed composite addresses, and doing it
 * this way saves some microscopic bit of addition at runtime.
 * Whatever.  It'll probably all change again once we have a dynamic
 * memory map, so it's not really worth overthinking at the moment.
 */

typedef struct {
  size_t length_length;                 /* Length of the length field */
  off_t block_addr;                     /* Where to write hash blocks */
  off_t ctrl_addr;                      /* Control register */
  off_t status_addr;                    /* Status register */
  off_t digest_addr;                    /* Where to read digest */
  off_t name_addr;                      /* Where to read core name */
  char core_name[8];                    /* Expected name of core */
  uint8_t ctrl_mode;                    /* Digest mode, for cores that have modes */
} driver_t;

/*
 * Hash state.
 */

typedef struct {
  const hal_hash_descriptor_t *descriptor;
  const driver_t *driver;
  uint64_t msg_length_high;             /* Total data hashed in this message */
  uint64_t msg_length_low;              /* (128 bits in SHA-512 cases) */
  uint8_t block[MAX_BLOCK_LEN];         /* Block we're accumulating */
  size_t block_used;                    /* How much of the block we've used */
  unsigned block_count;                 /* Blocks sent */
} internal_hash_state_t;

/*
 * HMAC state.
 */

typedef struct {
  internal_hash_state_t hash_state;     /* Hash state */
  uint8_t keybuf[MAX_BLOCK_LEN];        /* HMAC key */
} internal_hmac_state_t;

/*
 * Drivers for known digest algorithms.
 *
 * Initialization of the core_name field is not a typo, we're
 * concatenating two string constants and trusting the compiler to
 * whine if the resulting string doesn't fit into the field.
 */

static const driver_t sha1_driver = {
  SHA1_LENGTH_LEN,
  SHA1_ADDR_BLOCK, SHA1_ADDR_CTRL, SHA1_ADDR_STATUS, SHA1_ADDR_DIGEST,
  SHA1_ADDR_NAME0, (SHA1_NAME0 SHA1_NAME1),
  0
};

static const driver_t sha256_driver = {
  SHA256_LENGTH_LEN,
  SHA256_ADDR_BLOCK, SHA256_ADDR_CTRL, SHA256_ADDR_STATUS, SHA256_ADDR_DIGEST,
  SHA256_ADDR_NAME0, (SHA256_NAME0 SHA256_NAME1),
  0
};

static const driver_t sha512_224_driver = {
  SHA512_LENGTH_LEN,
  SHA512_ADDR_BLOCK, SHA512_ADDR_CTRL, SHA512_ADDR_STATUS, SHA512_ADDR_DIGEST,
  SHA512_ADDR_NAME0, (SHA512_NAME0 SHA512_NAME1),
  MODE_SHA_512_224
};

static const driver_t sha512_256_driver = {
  SHA512_LENGTH_LEN,
  SHA512_ADDR_BLOCK, SHA512_ADDR_CTRL, SHA512_ADDR_STATUS, SHA512_ADDR_DIGEST,
  SHA512_ADDR_NAME0, (SHA512_NAME0 SHA512_NAME1),
  MODE_SHA_512_256
};

static const driver_t sha384_driver = {
  SHA512_LENGTH_LEN,
  SHA512_ADDR_BLOCK, SHA512_ADDR_CTRL, SHA512_ADDR_STATUS, SHA512_ADDR_DIGEST,
  SHA512_ADDR_NAME0, (SHA512_NAME0 SHA512_NAME1),
  MODE_SHA_384
};

static const driver_t sha512_driver = {
  SHA512_LENGTH_LEN,
  SHA512_ADDR_BLOCK, SHA512_ADDR_CTRL, SHA512_ADDR_STATUS, SHA512_ADDR_DIGEST,
  SHA512_ADDR_NAME0, (SHA512_NAME0 SHA512_NAME1),
  MODE_SHA_512
};

/*
 * Descriptors.  Yes, the {hash,hmac}_state_length fields are a bit
 * repetitive given that they (currently) have the same value
 * regardless of algorithm, but we don't want to wire in that
 * assumption, so it's simplest to be explicit.
 */

const hal_hash_descriptor_t hal_hash_sha1 = {
  SHA1_BLOCK_LEN, SHA1_DIGEST_LEN,
  sizeof(internal_hash_state_t), sizeof(internal_hmac_state_t),
  &sha1_driver
};

const hal_hash_descriptor_t hal_hash_sha256 = {
  SHA256_BLOCK_LEN, SHA256_DIGEST_LEN,
  sizeof(internal_hash_state_t), sizeof(internal_hmac_state_t),
  &sha256_driver
};

const hal_hash_descriptor_t hal_hash_sha512_224 = {
  SHA512_BLOCK_LEN, SHA512_DIGEST_LEN,
  sizeof(internal_hash_state_t), sizeof(internal_hmac_state_t),
  &sha512_224_driver
};

const hal_hash_descriptor_t hal_hash_sha512_256 = {
  SHA512_BLOCK_LEN, SHA512_DIGEST_LEN,
  sizeof(internal_hash_state_t), sizeof(internal_hmac_state_t),
  &sha512_256_driver
};

const hal_hash_descriptor_t hal_hash_sha384 = {
  SHA512_BLOCK_LEN, SHA512_DIGEST_LEN,
  sizeof(internal_hash_state_t), sizeof(internal_hmac_state_t),
  &sha384_driver
};

const hal_hash_descriptor_t hal_hash_sha512 = {
  SHA512_BLOCK_LEN, SHA512_DIGEST_LEN,
  sizeof(internal_hash_state_t), sizeof(internal_hmac_state_t),
  &sha512_driver
};

/*
 * Debugging control.
 */

static int debug = 0;

void hal_hash_set_debug(int onoff)
{
  debug = onoff;
}

/*
 * Internal utility to do whatever checking we need of a descriptor,
 * then extract the driver pointer in a way that works nicely with
 * initialization of an automatic const pointer.
 *
 * Returns the driver pointer on success, NULL on failure.
 */

static const driver_t *check_driver(const hal_hash_descriptor_t * const descriptor)
{
  return descriptor == NULL ? NULL : descriptor->driver;
}

/*
 * Report whether cores are present.
 */

hal_error_t hal_hash_core_present(const hal_hash_descriptor_t * const descriptor)
{
  const driver_t * const driver = check_driver(descriptor);

  if (driver == NULL)
    return HAL_ERROR_BAD_ARGUMENTS;

  return hal_io_expected(driver->name_addr,
                         (const uint8_t *) driver->core_name,
                         sizeof(driver->core_name));
}

/*
 * Initialize hash state.
 */

hal_error_t hal_hash_initialize(const hal_hash_descriptor_t * const descriptor,
                                hal_hash_state_t *opaque_state,
                                void *state_buffer, const size_t state_length)
{
  const driver_t * const driver = check_driver(descriptor);
  internal_hash_state_t *state = state_buffer;

  if (driver == NULL || state == NULL || opaque_state == NULL ||
      state_length < descriptor->hash_state_length)
    return HAL_ERROR_BAD_ARGUMENTS;

  memset(state, 0, sizeof(*state));
  state->descriptor = descriptor;
  state->driver = driver;

  opaque_state->state = state;

  return HAL_OK;
}

/*
 * Send one block to a core.
 */

static hal_error_t hash_write_block(const internal_hash_state_t * const state)
{
  uint8_t ctrl_cmd[4];
  hal_error_t err;

  assert(state != NULL && state->descriptor != NULL && state->driver != NULL);
  assert(state->descriptor->block_length % 4 == 0);

  if (debug)
    fprintf(stderr, "[ %s ]\n", state->block_count == 0 ? "init" : "next");

  if ((err = hal_io_write(state->driver->block_addr, state->block, state->descriptor->block_length)) != HAL_OK)
    return err;

  ctrl_cmd[0] = ctrl_cmd[1] = ctrl_cmd[2] = 0;
  ctrl_cmd[3] = state->block_count == 0 ? CTRL_INIT : CTRL_NEXT;  
  ctrl_cmd[3] |= state->driver->ctrl_mode;

  /*
   * Not sure why we're waiting for ready here, but it's what the old
   * (read: tested) code did, so keep that behavior for now.
   */

  if ((err = hal_io_write(state->driver->ctrl_addr, ctrl_cmd, sizeof(ctrl_cmd))) != HAL_OK)
    return err;

  return hal_io_wait_valid(state->driver->status_addr);
}

/*
 * Read hash result from core.
 */

static hal_error_t hash_read_digest(const driver_t * const driver,
                                    uint8_t *digest,
                                    const size_t digest_length)
{
  hal_error_t err;

  assert(digest != NULL && digest_length % 4 == 0);

  if ((err = hal_io_wait_valid(driver->status_addr)) != HAL_OK)
    return err;

  return hal_io_read(driver->digest_addr, digest, digest_length);
}

/*
 * Add data to hash.
 */

hal_error_t hal_hash_update(hal_hash_state_t opaque_state,      /* Opaque state block */
                            const uint8_t * const data_buffer,  /* Data to be hashed */
                            size_t data_buffer_length)          /* Length of data_buffer */
{
  internal_hash_state_t *state = opaque_state.state;
  const uint8_t *p = data_buffer;
  hal_error_t err;
  size_t n;

  if (state == NULL || data_buffer == NULL)
    return HAL_ERROR_BAD_ARGUMENTS;

  if (data_buffer_length == 0)
    return HAL_OK;

  assert(state->descriptor != NULL && state->driver != NULL);
  assert(state->descriptor->block_length <= sizeof(state->block));

  while ((n = state->descriptor->block_length - state->block_used) <= data_buffer_length) {
    /*
     * We have enough data for another complete block.
     */
    if (debug)
      fprintf(stderr, "[ Full block, data_buffer_length %lu, used %lu, n %lu, msg_length %llu ]\n",
              (unsigned long) data_buffer_length, (unsigned long) state->block_used, (unsigned long) n, state->msg_length_low);
    memcpy(state->block + state->block_used, p, n);
    if ((state->msg_length_low += n) < n)
      state->msg_length_high++;
    state->block_used = 0;
    data_buffer_length -= n;
    p += n;
    if ((err = hash_write_block(state)) != HAL_OK)
      return err;
    state->block_count++;
  }

  if (data_buffer_length > 0) {
    /*
     * Data left over, but not enough for a full block, stash it.
     */
    if (debug)
      fprintf(stderr, "[ Partial block, data_buffer_length %lu, used %lu, n %lu, msg_length %llu ]\n",
              (unsigned long) data_buffer_length, (unsigned long) state->block_used, (unsigned long) n, state->msg_length_low);
    assert(data_buffer_length < n);
    memcpy(state->block + state->block_used, p, data_buffer_length);
    if ((state->msg_length_low += data_buffer_length) < data_buffer_length)
      state->msg_length_high++;
    state->block_used += data_buffer_length;
  }

  return HAL_OK;
}

/*
 * Finish hash and return digest.
 */

hal_error_t hal_hash_finalize(hal_hash_state_t opaque_state,            /* Opaque state block */
                              uint8_t *digest_buffer,                   /* Returned digest */
                              const size_t digest_buffer_length)        /* Length of digest_buffer */
{
  internal_hash_state_t *state = opaque_state.state;
  uint64_t bit_length_high, bit_length_low;
  hal_error_t err;
  uint8_t *p;
  size_t n;
  int i;

  if (state == NULL || digest_buffer == NULL)
    return HAL_ERROR_BAD_ARGUMENTS;

  assert(state->descriptor != NULL && state->driver != NULL);

  if (digest_buffer_length < state->descriptor->digest_length)
    return HAL_ERROR_BAD_ARGUMENTS;

  assert(state->descriptor->block_length <= sizeof(state->block));

  /*
   * Add padding, then pull result from the core
   */

  bit_length_low  = (state->msg_length_low  << 3);
  bit_length_high = (state->msg_length_high << 3) | (state->msg_length_low >> 61);

  /* Initial pad byte */
  assert(state->block_used < state->descriptor->block_length);
  state->block[state->block_used++] = 0x80;

  /* If not enough room for bit count, zero and push current block */
  if ((n = state->descriptor->block_length - state->block_used) < state->driver->length_length) {
    if (debug)
      fprintf(stderr, "[ Overflow block, used %lu, n %lu, msg_length %llu ]\n",
              (unsigned long) state->block_used, (unsigned long) n, state->msg_length_low);
    if (n > 0)
      memset(state->block + state->block_used, 0, n);
    if ((err = hash_write_block(state)) != HAL_OK)
      return err;
    state->block_count++;
    state->block_used = 0;
  }

  /* Pad final block */
  n = state->descriptor->block_length - state->block_used;
  assert(n >= state->driver->length_length);
  if (n > 0)
    memset(state->block + state->block_used, 0, n);
  if (debug)
    fprintf(stderr, "[ Final block, used %lu, n %lu, msg_length %llu ]\n",
            (unsigned long) state->block_used, (unsigned long) n, state->msg_length_low);
  p = state->block + state->descriptor->block_length;
  for (i = 0; (bit_length_low || bit_length_high) && i < state->driver->length_length; i++) {
    *--p = (uint8_t) (bit_length_low & 0xFF);
    bit_length_low >>= 8;
    if (bit_length_high) {
      bit_length_low |= ((bit_length_high & 0xFF) << 56);
      bit_length_high >>= 8;
    }
  }

  /* Push final block */
  if ((err = hash_write_block(state)) != HAL_OK)
    return err;
  state->block_count++;

  /* All data pushed to core, now we just need to read back the result */
  if ((err = hash_read_digest(state->driver, digest_buffer, state->descriptor->digest_length)) != HAL_OK)
    return err;

  return HAL_OK;
}

/*
 * Initialize HMAC state.
 */

hal_error_t hal_hmac_initialize(const hal_hash_descriptor_t * const descriptor,
                                hal_hmac_state_t *opaque_state,
                                void *state_buffer, const size_t state_length,
                                const uint8_t * const key, const size_t key_length)
{
  const driver_t * const driver = check_driver(descriptor);
  internal_hmac_state_t *state = state_buffer;
  internal_hash_state_t *h = &state->hash_state;
  hal_hash_state_t oh;
  hal_error_t err;
  int i;

  if (descriptor == NULL || driver == NULL || state == NULL || opaque_state == NULL ||
      state_length < descriptor->hmac_state_length)
    return HAL_ERROR_BAD_ARGUMENTS;

  assert(descriptor->block_length <= sizeof(state->keybuf));

#if 0
  /*
   * RFC 2104 frowns upon keys shorter than the digest length.
   * ... but most of the test vectors fail this test!
   */

  if (key_length < descriptor->digest_length)
    return HAL_ERROR_UNSUPPORTED_KEY;
#endif

  if ((err = hal_hash_initialize(descriptor, &oh, h, sizeof(*h))) != HAL_OK)
    return err;

  /*
   * If the supplied HMAC key is longer than the hash block length, we
   * need to hash the supplied HMAC key to get the real HMAC key.
   * Otherwise, we just use the supplied HMAC key directly.
   */

  memset(state->keybuf, 0, sizeof(state->keybuf));

  if (key_length <= descriptor->block_length)
    memcpy(state->keybuf, key, key_length);

  else if ((err = hal_hash_update(oh, key, key_length))                        != HAL_OK ||
           (err = hal_hash_finalize(oh, state->keybuf, sizeof(state->keybuf))) != HAL_OK ||
           (err = hal_hash_initialize(descriptor, &oh, h, sizeof(*h)))         != HAL_OK)
    return err;

  /*
   * XOR the key with the IPAD value, then start the inner hash.
   */

  for (i = 0; i < descriptor->block_length; i++)
    state->keybuf[i] ^= HMAC_IPAD;

  if ((err = hal_hash_update(oh, state->keybuf, descriptor->block_length)) != HAL_OK)
    return err;

  /*
   * Prepare the key for the final hash.  Since we just XORed key with
   * IPAD, we need to XOR with both IPAD and OPAD to get key XOR OPAD.
   */

  for (i = 0; i < descriptor->block_length; i++)
    state->keybuf[i] ^= HMAC_IPAD ^ HMAC_OPAD;

  /*
   * If we had some good way of saving all of our state (including
   * state internal to the hash core), this would be a good place to
   * do it, since it might speed up algorithms like PBKDF2 which do
   * repeated HMAC operations using the same key.  Revisit this if and
   * when the hash cores support such a thing.
   */

  opaque_state->state = state;

  return HAL_OK;
}

/*
 * Add data to HMAC.
 */

hal_error_t hal_hmac_update(const hal_hmac_state_t opaque_state,
                            const uint8_t * data, const size_t length)
{
  internal_hmac_state_t *state = opaque_state.state;
  internal_hash_state_t *h = &state->hash_state;
  hal_hash_state_t oh = { h };

  if (state == NULL || data == NULL)
    return HAL_ERROR_BAD_ARGUMENTS;

  return hal_hash_update(oh, data, length);
}

/*
 * Finish and return HMAC.
 */

hal_error_t hal_hmac_finalize(const hal_hmac_state_t opaque_state,
                              uint8_t *hmac, const size_t length)
{
  internal_hmac_state_t *state = opaque_state.state;
  internal_hash_state_t *h = &state->hash_state;
  const hal_hash_descriptor_t *descriptor;
  hal_hash_state_t oh = { h };
  uint8_t d[MAX_DIGEST_LEN];
  hal_error_t err;

  if (state == NULL || hmac == NULL)
    return HAL_ERROR_BAD_ARGUMENTS;

  descriptor = h->descriptor;
  assert(descriptor != NULL && descriptor->digest_length <= sizeof(d));

  /*
   * Finish up inner hash and extract digest, then perform outer hash
   * to get HMAC.  Key was prepared for this in hal_hmac_initialize().
   */

  if ((err = hal_hash_finalize(oh, d, sizeof(d)))                          != HAL_OK ||
      (err = hal_hash_initialize(descriptor, &oh, h, sizeof(*h)))          != HAL_OK ||
      (err = hal_hash_update(oh, state->keybuf, descriptor->block_length)) != HAL_OK ||
      (err = hal_hash_update(oh, d, descriptor->digest_length))            != HAL_OK ||
      (err = hal_hash_finalize(oh, hmac, length))                          != HAL_OK)
    return err;

  return HAL_OK;
}

/*
 * "Any programmer who fails to comply with the standard naming, formatting,
 *  or commenting conventions should be shot.  If it so happens that it is
 *  inconvenient to shoot him, then he is to be politely requested to recode
 *  his program in adherence to the above standard."
 *                      -- Michael Spier, Digital Equipment Corporation
 *
 * Local variables:
 * indent-tabs-mode: nil
 * End:
 */