abe.c File Reference

functions for Attribute-Based Encryption More...

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

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Data Structures
struct	GNUNET_ABE_AbeMasterKey
struct	GNUNET_ABE_AbeKey

Functions
static int	init_aes (element_t k, int enc, gcry_cipher_hd_t *handle, struct GNUNET_CRYPTO_SymmetricSessionKey *key, unsigned char *iv)
static int	aes_128_cbc_encrypt (char *pt, int size, element_t k, char **ct)
static int	aes_128_cbc_decrypt (char *ct, int size, element_t k, char **pt)
struct GNUNET_ABE_AbeMasterKey *	GNUNET_ABE_cpabe_create_master_key (void)
	Create a new CP-ABE master key. More...
void	GNUNET_ABE_cpabe_delete_master_key (struct GNUNET_ABE_AbeMasterKey *key)
	Delete a CP-ABE master key. More...
struct GNUNET_ABE_AbeKey *	GNUNET_ABE_cpabe_create_key (struct GNUNET_ABE_AbeMasterKey *key, char **attrs)
	Create a new CP-ABE key. More...
void	GNUNET_ABE_cpabe_delete_key (struct GNUNET_ABE_AbeKey *key, int delete_pub)
	Delete a CP-ABE key. More...
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)
static ssize_t	read_cpabe (const void *data, char **cph_buf, int *cph_buf_len, char **aes_buf, int *aes_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)
	Encrypt a block using sessionkey. More...
ssize_t	GNUNET_ABE_cpabe_decrypt (const void *block, size_t size, const struct GNUNET_ABE_AbeKey *key, void **result)
	Decrypt a block using the ABE key. More...
ssize_t	GNUNET_ABE_cpabe_serialize_key (const struct GNUNET_ABE_AbeKey *key, void **result)
	Serialize an ABE key. More...
struct GNUNET_ABE_AbeKey *	GNUNET_ABE_cpabe_deserialize_key (const void *data, size_t len)
	Deserialize a serialized ABE key. More...
ssize_t	GNUNET_ABE_cpabe_serialize_master_key (const struct GNUNET_ABE_AbeMasterKey *key, void **result)
	Serialize an ABE master key. More...
struct GNUNET_ABE_AbeMasterKey *	GNUNET_ABE_cpabe_deserialize_master_key (const void *data, size_t len)
	Deserialize an ABE master key. More...

Detailed Description

functions for Attribute-Based Encryption

Author

Martin Schanzenbach

Definition in file abe.c.

Function Documentation

init_aes()

static int init_aes ( element_t  k, int  enc, gcry_cipher_hd_t *  handle, struct GNUNET_CRYPTO_SymmetricSessionKey *  key, unsigned char *  iv  )

static

Definition at line 49 of file abe.c.

References GNUNET_CRYPTO_SymmetricSessionKey::aes_key, GNUNET_assert, GNUNET_CRYPTO_AES_KEY_LENGTH, and GNUNET_memcpy.

Referenced by aes_128_cbc_decrypt(), and aes_128_cbc_encrypt().

{
  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;
}

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aes_128_cbc_encrypt()

static int aes_128_cbc_encrypt ( char *  pt, int  size, element_t  k, char **  ct  )

static

Definition at line 82 of file abe.c.

References buf, GNUNET_assert, GNUNET_free, GNUNET_malloc, GNUNET_memcpy, handle, init_aes(), len, and size.

Referenced by GNUNET_ABE_cpabe_encrypt().

{
  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;
}

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aes_128_cbc_decrypt()

static int aes_128_cbc_decrypt ( char *  ct, int  size, element_t  k, char **  pt  )

static

Definition at line 121 of file abe.c.

References GNUNET_assert, GNUNET_free, GNUNET_malloc, GNUNET_memcpy, handle, init_aes(), and len.

Referenced by GNUNET_ABE_cpabe_decrypt().

{
  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;
}

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write_cpabe()

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  )

static

Definition at line 238 of file abe.c.

References GNUNET_malloc, GNUNET_memcpy, len, and result.

Referenced by GNUNET_ABE_cpabe_encrypt(), GNUNET_ABE_cpabe_serialize_key(), and GNUNET_ABE_cpabe_serialize_master_key().

{
  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;
}

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read_cpabe()

static ssize_t read_cpabe ( const void *  data, char **  cph_buf, int *  cph_buf_len, char **  aes_buf, int *  aes_buf_len  )

static

Definition at line 267 of file abe.c.

References GNUNET_malloc, GNUNET_memcpy, and len.

Referenced by GNUNET_ABE_cpabe_decrypt(), GNUNET_ABE_cpabe_deserialize_key(), and GNUNET_ABE_cpabe_deserialize_master_key().

{
  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;
}

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