crypto_symmetric.c File Reference

Symmetric encryption services; combined cipher AES+TWOFISH (256-bit each) More...

#include "platform.h"
#include "gnunet_crypto_lib.h"
#include <gcrypt.h>

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Macros
#define	LOG(kind, ...)   GNUNET_log_from(kind, "util-crypto-symmetric", __VA_ARGS__)

Functions
void	GNUNET_CRYPTO_symmetric_create_session_key (struct GNUNET_CRYPTO_SymmetricSessionKey *key)
	Create a new SessionKey (for symmetric encryption). More...
static int	setup_cipher_aes (gcry_cipher_hd_t *handle, const struct GNUNET_CRYPTO_SymmetricSessionKey *sessionkey, const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv)
	Initialize AES cipher. More...
static int	setup_cipher_twofish (gcry_cipher_hd_t *handle, const struct GNUNET_CRYPTO_SymmetricSessionKey *sessionkey, const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv)
	Initialize TWOFISH cipher. More...
ssize_t	GNUNET_CRYPTO_symmetric_encrypt (const void *block, size_t size, const struct GNUNET_CRYPTO_SymmetricSessionKey *sessionkey, const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv, void *result)
	Encrypt a block with a symmetric session key. More...
ssize_t	GNUNET_CRYPTO_symmetric_decrypt (const void *block, size_t size, const struct GNUNET_CRYPTO_SymmetricSessionKey *sessionkey, const struct GNUNET_CRYPTO_SymmetricInitializationVector *iv, void *result)
	Decrypt a given block with the session key. More...
void	GNUNET_CRYPTO_symmetric_derive_iv (struct GNUNET_CRYPTO_SymmetricInitializationVector *iv, const struct GNUNET_CRYPTO_SymmetricSessionKey *skey, const void *salt, size_t salt_len,...)
	Derive an IV. More...
void	GNUNET_CRYPTO_symmetric_derive_iv_v (struct GNUNET_CRYPTO_SymmetricInitializationVector *iv, const struct GNUNET_CRYPTO_SymmetricSessionKey *skey, const void *salt, size_t salt_len, va_list argp)
	Derive an IV. More...

Detailed Description

Symmetric encryption services; combined cipher AES+TWOFISH (256-bit each)

Author

Christian Grothoff

Ioana Patrascu

Definition in file crypto_symmetric.c.

Macro Definition Documentation

LOG

#define LOG	(		kind,
			...
	)		GNUNET_log_from(kind, "util-crypto-symmetric", __VA_ARGS__)

Definition at line 32 of file crypto_symmetric.c.

Function Documentation

setup_cipher_aes()

static int setup_cipher_aes ( gcry_cipher_hd_t *  handle, const struct GNUNET_CRYPTO_SymmetricSessionKey *  sessionkey, const struct GNUNET_CRYPTO_SymmetricInitializationVector *  iv  )

static

Initialize AES cipher.

Parameters

handle	handle to initialize
sessionkey	session key to use
iv	initialization vector to use

Returns

GNUNET_OK on success, GNUNET_SYSERR on error

Definition at line 60 of file crypto_symmetric.c.

References GNUNET_CRYPTO_SymmetricInitializationVector::aes_iv, GNUNET_CRYPTO_SymmetricSessionKey::aes_key, GNUNET_assert, and GNUNET_OK.

Referenced by GNUNET_CRYPTO_symmetric_decrypt(), and GNUNET_CRYPTO_symmetric_encrypt().

{
  int rc;

  GNUNET_assert(0 ==
                gcry_cipher_open(handle, GCRY_CIPHER_AES256,
                                 GCRY_CIPHER_MODE_CFB, 0));
  rc = gcry_cipher_setkey(*handle,
                          sessionkey->aes_key,
                          sizeof(sessionkey->aes_key));
  GNUNET_assert((0 == rc) || ((char)rc == GPG_ERR_WEAK_KEY));
  rc = gcry_cipher_setiv(*handle,
                         iv->aes_iv,
                         sizeof(iv->aes_iv));
  GNUNET_assert((0 == rc) || ((char)rc == GPG_ERR_WEAK_KEY));
  return GNUNET_OK;
}

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setup_cipher_twofish()

static int setup_cipher_twofish ( gcry_cipher_hd_t *  handle, const struct GNUNET_CRYPTO_SymmetricSessionKey *  sessionkey, const struct GNUNET_CRYPTO_SymmetricInitializationVector *  iv  )

static

Initialize TWOFISH cipher.

Parameters

handle	handle to initialize
sessionkey	session key to use
iv	initialization vector to use

Returns

GNUNET_OK on success, GNUNET_SYSERR on error

Definition at line 90 of file crypto_symmetric.c.

References GNUNET_assert, GNUNET_OK, GNUNET_CRYPTO_SymmetricInitializationVector::twofish_iv, and GNUNET_CRYPTO_SymmetricSessionKey::twofish_key.

Referenced by GNUNET_CRYPTO_symmetric_decrypt(), and GNUNET_CRYPTO_symmetric_encrypt().

{
  int rc;

  GNUNET_assert(0 ==
                gcry_cipher_open(handle, GCRY_CIPHER_TWOFISH,
                                 GCRY_CIPHER_MODE_CFB, 0));
  rc = gcry_cipher_setkey(*handle,
                          sessionkey->twofish_key,
                          sizeof(sessionkey->twofish_key));
  GNUNET_assert((0 == rc) || ((char)rc == GPG_ERR_WEAK_KEY));
  rc = gcry_cipher_setiv(*handle,
                         iv->twofish_iv,
                         sizeof(iv->twofish_iv));
  GNUNET_assert((0 == rc) || ((char)rc == GPG_ERR_WEAK_KEY));
  return GNUNET_OK;
}

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GNUNET_CRYPTO_symmetric_derive_iv_v()

void GNUNET_CRYPTO_symmetric_derive_iv_v	(	struct GNUNET_CRYPTO_SymmetricInitializationVector *	iv,
		const struct GNUNET_CRYPTO_SymmetricSessionKey *	skey,
		const void *	salt,
		size_t	salt_len,
		va_list	argp
	)

Derive an IV.

Parameters

iv	initialization vector
skey	session key
salt	salt for the derivation
salt_len	size of the salt
argp	pairs of void * & size_t for context chunks, terminated by NULL

Definition at line 217 of file crypto_symmetric.c.

References GNUNET_CRYPTO_SymmetricInitializationVector::aes_iv, GNUNET_CRYPTO_SymmetricSessionKey::aes_key, GNUNET_CRYPTO_kdf_v(), GNUNET_memcpy, GNUNET_CRYPTO_SymmetricInitializationVector::twofish_iv, and GNUNET_CRYPTO_SymmetricSessionKey::twofish_key.

Referenced by GNUNET_CRYPTO_symmetric_derive_iv().

{
  char aes_salt[salt_len + 4];
  char twofish_salt[salt_len + 4];

  GNUNET_memcpy(aes_salt, salt, salt_len);
  GNUNET_memcpy(&aes_salt[salt_len], "AES!", 4);
  GNUNET_memcpy(twofish_salt, salt, salt_len);
  GNUNET_memcpy(&twofish_salt[salt_len], "FISH", 4);
  GNUNET_CRYPTO_kdf_v(iv->aes_iv,
                      sizeof(iv->aes_iv),
                      aes_salt,
                      salt_len + 4,
                      skey->aes_key,
                      sizeof(skey->aes_key),
                      argp);
  GNUNET_CRYPTO_kdf_v(iv->twofish_iv,
                      sizeof(iv->twofish_iv),
                      twofish_salt,
                      salt_len + 4,
                      skey->twofish_key,
                      sizeof(skey->twofish_key),
                      argp);
}

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