abe.c

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/*
     This file is part of GNUnet.  Copyright (C) 2001-2018 Christian Grothoff
     (and other contributing authors)

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later

 */

#include "platform.h"
#include <pbc/pbc.h>
#include <gabe.h>

#include "gnunet_crypto_lib.h"
#include "gnunet_abe_lib.h"

struct GNUNET_ABE_AbeMasterKey {
  gabe_pub_t* pub;
  gabe_msk_t* msk;
};

struct GNUNET_ABE_AbeKey {
  gabe_pub_t* pub;
  gabe_prv_t* prv;
};

static int
init_aes(element_t k, int enc,
         gcry_cipher_hd_t* handle,
         struct GNUNET_CRYPTO_SymmetricSessionKey *key,
         unsigned char* iv)
{
  int rc;
  int key_len;
  unsigned char* key_buf;

  key_len = element_length_in_bytes(k) < 33 ? 3 : element_length_in_bytes(k);
  key_buf = (unsigned char*)malloc(key_len);
  element_to_bytes(key_buf, k);

  GNUNET_memcpy(key->aes_key, key_buf, GNUNET_CRYPTO_AES_KEY_LENGTH);
  GNUNET_assert(0 ==
                gcry_cipher_open(handle, GCRY_CIPHER_AES256,
                                 GCRY_CIPHER_MODE_CFB, 0));
  rc = gcry_cipher_setkey(*handle,
                          key->aes_key,
                          sizeof(key->aes_key));
  GNUNET_assert((0 == rc) || ((char)rc == GPG_ERR_WEAK_KEY));
  memset(iv, 0, 16);  //TODO make reasonable
  rc = gcry_cipher_setiv(*handle,
                         iv,
                         16);
  GNUNET_assert((0 == rc) || ((char)rc == GPG_ERR_WEAK_KEY));

  free(key_buf);
  return rc;
}

static int
aes_128_cbc_encrypt(char* pt,
                    int size,
                    element_t k,
                    char **ct)
{
  gcry_cipher_hd_t handle;
  struct GNUNET_CRYPTO_SymmetricSessionKey skey;
  unsigned char iv[16];
  char* buf;
  int padding;
  int buf_size;
  uint8_t len[4];

  init_aes(k, 1, &handle, &skey, iv);

  /* TODO make less crufty */

  /* stuff in real length (big endian) before padding */
  len[0] = (size & 0xff000000) >> 24;
  len[1] = (size & 0xff0000) >> 16;
  len[2] = (size & 0xff00) >> 8;
  len[3] = (size & 0xff) >> 0;
  padding = 16 - ((4 + size) % 16);
  buf_size = 4 + size + padding;
  buf = GNUNET_malloc(buf_size);
  GNUNET_memcpy(buf, len, 4);
  GNUNET_memcpy(buf + 4, pt, size);
  *ct = GNUNET_malloc(buf_size);

  GNUNET_assert(0 == gcry_cipher_encrypt(handle, *ct, buf_size, buf, buf_size));
  gcry_cipher_close(handle);
  //AES_cbc_encrypt(pt->data, ct->data, pt->len, &key, iv, AES_ENCRYPT);
  GNUNET_free(buf);
  return buf_size;
}

static int
aes_128_cbc_decrypt(char* ct,
                    int size,
                    element_t k,
                    char **pt)
{
  struct GNUNET_CRYPTO_SymmetricSessionKey skey;
  gcry_cipher_hd_t handle;
  unsigned char iv[16];
  char* tmp;
  uint32_t len;

  init_aes(k, 1, &handle, &skey, iv);

  tmp = GNUNET_malloc(size);

  //AES_cbc_encrypt(ct->data, pt->data, ct->len, &key, iv, AES_DECRYPT);
  GNUNET_assert(0 == gcry_cipher_decrypt(handle, tmp, size, ct, size));
  gcry_cipher_close(handle);
  /* TODO make less crufty */

  /* get real length */
  len = 0;
  len = len
        | ((tmp[0]) << 24) | ((tmp[1]) << 16)
        | ((tmp[2]) << 8) | ((tmp[3]) << 0);
  /* truncate any garbage from the padding */
  *pt = GNUNET_malloc(len);
  GNUNET_memcpy(*pt, tmp + 4, len);
  GNUNET_free(tmp);
  return len;
}

struct GNUNET_ABE_AbeMasterKey*
GNUNET_ABE_cpabe_create_master_key(void)
{
  struct GNUNET_ABE_AbeMasterKey* key;

  key = GNUNET_new(struct GNUNET_ABE_AbeMasterKey);
  gabe_setup(&key->pub, &key->msk);
  GNUNET_assert(NULL != key->pub);
  GNUNET_assert(NULL != key->msk);
  return key;
}

void
GNUNET_ABE_cpabe_delete_master_key(struct GNUNET_ABE_AbeMasterKey *key)
{
  gabe_msk_free(key->msk);
  gabe_pub_free(key->pub);
  //GNUNET_free (key->msk);
  //gabe_msk_free (key->msk); //For some reason free of pub implicit?
  GNUNET_free(key);
}

struct GNUNET_ABE_AbeKey*
GNUNET_ABE_cpabe_create_key(struct GNUNET_ABE_AbeMasterKey *key,
                            char **attrs)
{
  struct GNUNET_ABE_AbeKey *prv_key;
  int size;
  char *tmp;

  prv_key = GNUNET_new(struct GNUNET_ABE_AbeKey);
  prv_key->prv = gabe_keygen(key->pub, key->msk, attrs);
  size = gabe_pub_serialize(key->pub, &tmp);
  prv_key->pub = gabe_pub_unserialize(tmp, size);
  GNUNET_free(tmp);
  GNUNET_assert(NULL != prv_key->prv);
  return prv_key;
}

void
GNUNET_ABE_cpabe_delete_key(struct GNUNET_ABE_AbeKey *key,
                            int delete_pub)
{
  //Memory management in gabe is buggy
  gabe_prv_free(key->prv);
  if (GNUNET_YES == delete_pub)
    gabe_pub_free(key->pub);
  GNUNET_free(key);
}

static ssize_t
write_cpabe(void **result,
            uint32_t file_len,
            char* cph_buf,
            int cph_buf_len,
            char* aes_buf,
            int aes_buf_len)
{
  char *ptr;
  uint32_t *len;

  *result = GNUNET_malloc(12 + cph_buf_len + aes_buf_len);
  ptr = *result;
  len = (uint32_t*)ptr;
  *len = htonl(file_len);
  ptr += 4;
  len = (uint32_t*)ptr;
  *len = htonl(aes_buf_len);
  ptr += 4;
  GNUNET_memcpy(ptr, aes_buf, aes_buf_len);
  ptr += aes_buf_len;
  len = (uint32_t*)ptr;
  *len = htonl(cph_buf_len);
  ptr += 4;
  GNUNET_memcpy(ptr, cph_buf, cph_buf_len);
  return 12 + cph_buf_len + aes_buf_len;
}

static ssize_t
read_cpabe(const void *data,
           char** cph_buf,
           int *cph_buf_len,
           char** aes_buf,
           int *aes_buf_len)
{
  int buf_len;
  char *ptr;
  uint32_t *len;

  ptr = (char*)data;
  len = (uint32_t*)ptr;
  buf_len = ntohl(*len);
  ptr += 4;
  len = (uint32_t*)ptr;
  *aes_buf_len = ntohl(*len);
  ptr += 4;
  *aes_buf = GNUNET_malloc(*aes_buf_len);
  GNUNET_memcpy(*aes_buf, ptr, *aes_buf_len);
  ptr += *aes_buf_len;
  len = (uint32_t*)ptr;
  *cph_buf_len = ntohl(*len);
  ptr += 4;
  *cph_buf = GNUNET_malloc(*cph_buf_len);
  GNUNET_memcpy(*cph_buf, ptr, *cph_buf_len);

  return buf_len;
}

ssize_t
GNUNET_ABE_cpabe_encrypt(const void *block,
                         size_t size,
                         const char *policy,
                         const struct GNUNET_ABE_AbeMasterKey *key,
                         void **result)
{
  gabe_cph_t* cph;
  char* plt;
  char* cph_buf;
  char* aes_buf;
  element_t m;
  int cph_buf_len;
  int aes_buf_len;
  ssize_t result_len;

  if (!(cph = gabe_enc(key->pub, m, (char*)policy)))
    return GNUNET_SYSERR;
  cph_buf_len = gabe_cph_serialize(cph,
                                   &cph_buf);
  gabe_cph_free(cph);
  GNUNET_free(cph);
  plt = GNUNET_memdup(block, size);
  aes_buf_len = aes_128_cbc_encrypt(plt, size, m, &aes_buf);
  GNUNET_free(plt);
  element_clear(m);
  result_len = write_cpabe(result, size, cph_buf, cph_buf_len, aes_buf, aes_buf_len);
  GNUNET_free(cph_buf);
  GNUNET_free(aes_buf);
  return result_len;
}

ssize_t
GNUNET_ABE_cpabe_decrypt(const void *block,
                         size_t size,
                         const struct GNUNET_ABE_AbeKey *key,
                         void **result)
{
  char* aes_buf;
  char* cph_buf;
  gabe_cph_t* cph;
  element_t m;
  int cph_buf_size;
  int aes_buf_size;
  int plt_len;

  read_cpabe(block, &cph_buf, &cph_buf_size, &aes_buf, &aes_buf_size);
  cph = gabe_cph_unserialize(key->pub, cph_buf, cph_buf_size);
  if (!gabe_dec(key->pub, key->prv, cph, m))
    {
      GNUNET_log(GNUNET_ERROR_TYPE_DEBUG,
                 "%s\n", gabe_error());
      GNUNET_free(aes_buf);
      GNUNET_free(cph_buf);
      gabe_cph_free(cph);
      GNUNET_free(cph);
      element_clear(m);
      return GNUNET_SYSERR;
    }
  gabe_cph_free(cph);
  GNUNET_free(cph);
  plt_len = aes_128_cbc_decrypt(aes_buf, aes_buf_size, m, (char**)result);
  GNUNET_free(cph_buf);
  GNUNET_free(aes_buf);
  element_clear(m);
  //freeing is buggy in gabe
  //gabe_prv_free (prv);
  //gabe_pub_free (pub);
  return plt_len;
}

ssize_t
GNUNET_ABE_cpabe_serialize_key(const struct GNUNET_ABE_AbeKey *key,
                               void **result)
{
  ssize_t len;
  char *pub;
  char *prv;
  int pub_len;
  int prv_len;

  pub_len = gabe_pub_serialize(key->pub, &pub);
  prv_len = gabe_prv_serialize(key->prv, &prv);

  len = pub_len + prv_len + 12;
  write_cpabe(result, len, pub, pub_len, prv, prv_len);

  GNUNET_free(pub);
  GNUNET_free(prv);

  return len;
}

struct GNUNET_ABE_AbeKey*
GNUNET_ABE_cpabe_deserialize_key(const void *data,
                                 size_t len)
{
  struct GNUNET_ABE_AbeKey *key;
  char *pub;
  char *prv;
  int prv_len;
  int pub_len;

  key = GNUNET_new(struct GNUNET_ABE_AbeKey);
  read_cpabe(data,
             &pub,
             &pub_len,
             &prv,
             &prv_len);
  key->pub = gabe_pub_unserialize(pub, pub_len);
  key->prv = gabe_prv_unserialize(key->pub, prv, prv_len);

  GNUNET_free(pub);
  GNUNET_free(prv);
  return key;
}

ssize_t
GNUNET_ABE_cpabe_serialize_master_key(const struct GNUNET_ABE_AbeMasterKey *key,
                                      void **result)
{
  ssize_t len;
  char *pub;
  char *msk;
  int pub_len;
  int msk_len;

  pub_len = gabe_pub_serialize(key->pub, &pub);
  msk_len = gabe_msk_serialize(key->msk, &msk);

  len = pub_len + msk_len + 12;
  write_cpabe(result, len, pub, pub_len, msk, msk_len);

  GNUNET_free(pub);
  GNUNET_free(msk);

  return len;
}

struct GNUNET_ABE_AbeMasterKey*
GNUNET_ABE_cpabe_deserialize_master_key(const void *data,
                                        size_t len)
{
  struct GNUNET_ABE_AbeMasterKey *key;
  char *msk;
  char *pub;
  int msk_len;
  int pub_len;

  key = GNUNET_new(struct GNUNET_ABE_AbeMasterKey);
  read_cpabe(data,
             &pub,
             &pub_len,
             &msk,
             &msk_len);
  key->pub = gabe_pub_unserialize(pub, pub_len);
  key->msk = gabe_msk_unserialize(key->pub, msk, msk_len);

  GNUNET_free(pub);
  GNUNET_free(msk);

  return key;
}