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/*
* Copyright (C) 2011-2012 Free Software Foundation, Inc.
*
* Author: Nikos Mavrogiannopoulos
*
* This file is part of GnuTLS.
*
* The GnuTLS is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>
*
*/
#include "gnutls_int.h"
#include <algorithms.h>
#include "errors.h"
#include <x509/common.h>
typedef struct {
const char *name;
gnutls_sec_param_t sec_param;
unsigned int bits; /* security level */
unsigned int pk_bits; /* DH, RSA, SRP */
unsigned int dsa_bits; /* bits for DSA. Handled differently since
* choice of key size in DSA is political.
*/
unsigned int subgroup_bits; /* subgroup bits */
unsigned int ecc_bits; /* bits for ECC keys */
} gnutls_sec_params_entry;
static const gnutls_sec_params_entry sec_params[] = {
{"Insecure", GNUTLS_SEC_PARAM_INSECURE, 0, 0, 0, 0, 0},
{"Export", GNUTLS_SEC_PARAM_EXPORT, 42, 512, 0, 84, 0},
{"Very weak", GNUTLS_SEC_PARAM_VERY_WEAK, 64, 767, 0, 128, 0},
{"Weak", GNUTLS_SEC_PARAM_WEAK, 72, 1008, 1008, 160, 160},
#ifdef ENABLE_FIPS140
{"Low", GNUTLS_SEC_PARAM_LOW, 80, 1024, 1024, 160, 160},
{"Legacy", GNUTLS_SEC_PARAM_LEGACY, 96, 1024, 1024, 192, 192},
{"Medium", GNUTLS_SEC_PARAM_MEDIUM, 112, 2048, 2048, 224, 224},
{"High", GNUTLS_SEC_PARAM_HIGH, 128, 3072, 3072, 256, 256},
#else
{"Low", GNUTLS_SEC_PARAM_LOW, 80, 1024, 1024, 160, 160}, /* ENISA-LEGACY */
{"Legacy", GNUTLS_SEC_PARAM_LEGACY, 96, 1776, 2048, 192, 192},
{"Medium", GNUTLS_SEC_PARAM_MEDIUM, 112, 2048, 2048, 256, 224},
{"High", GNUTLS_SEC_PARAM_HIGH, 128, 3072, 3072, 256, 256},
#endif
{"Ultra", GNUTLS_SEC_PARAM_ULTRA, 192, 8192, 8192, 384, 384},
{"Future", GNUTLS_SEC_PARAM_FUTURE, 256, 15360, 15360, 512, 512},
{NULL, 0, 0, 0, 0, 0}
};
#define GNUTLS_SEC_PARAM_LOOP(b) \
{ const gnutls_sec_params_entry *p; \
for(p = sec_params; p->name != NULL; p++) { b ; } }
/**
* gnutls_sec_param_to_pk_bits:
* @algo: is a public key algorithm
* @param: is a security parameter
*
* When generating private and public key pairs a difficult question
* is which size of "bits" the modulus will be in RSA and the group size
* in DSA. The easy answer is 1024, which is also wrong. This function
* will convert a human understandable security parameter to an
* appropriate size for the specific algorithm.
*
* Returns: The number of bits, or (0).
*
* Since: 2.12.0
**/
unsigned int
gnutls_sec_param_to_pk_bits(gnutls_pk_algorithm_t algo,
gnutls_sec_param_t param)
{
unsigned int ret = 0;
/* handle DSA differently */
GNUTLS_SEC_PARAM_LOOP(
if (p->sec_param == param) {
if (algo == GNUTLS_PK_DSA)
ret = p->dsa_bits;
else if (IS_EC(algo)||IS_GOSTEC(algo))
ret = p->ecc_bits;
else
ret = p->pk_bits; break;
}
);
return ret;
}
/**
* gnutls_sec_param_to_symmetric_bits:
* @algo: is a public key algorithm
* @param: is a security parameter
*
* This function will return the number of bits that correspond to
* symmetric cipher strength for the given security parameter.
*
* Returns: The number of bits, or (0).
*
* Since: 3.3.0
**/
unsigned int
gnutls_sec_param_to_symmetric_bits(gnutls_sec_param_t param)
{
unsigned int ret = 0;
/* handle DSA differently */
GNUTLS_SEC_PARAM_LOOP(
if (p->sec_param == param) {
ret = p->bits; break;
}
);
return ret;
}
/* Returns the corresponding size for subgroup bits (q),
* given the group bits (p).
*/
unsigned int _gnutls_pk_bits_to_subgroup_bits(unsigned int pk_bits)
{
unsigned int ret = 0;
GNUTLS_SEC_PARAM_LOOP(
ret = p->subgroup_bits;
if (p->pk_bits >= pk_bits)
break;
);
return ret;
}
/* Returns a corresponding SHA algorithm size for the
* public key bits given. It is based on the NIST mappings.
*/
gnutls_digest_algorithm_t _gnutls_pk_bits_to_sha_hash(unsigned int pk_bits)
{
GNUTLS_SEC_PARAM_LOOP(
if (p->pk_bits >= pk_bits) {
if (p->bits <= 128)
return GNUTLS_DIG_SHA256;
else if (p->bits <= 192)
return GNUTLS_DIG_SHA384;
else
return GNUTLS_DIG_SHA512;
}
);
return GNUTLS_DIG_SHA256;
}
/**
* gnutls_sec_param_get_name:
* @param: is a security parameter
*
* Convert a #gnutls_sec_param_t value to a string.
*
* Returns: a pointer to a string that contains the name of the
* specified security level, or %NULL.
*
* Since: 2.12.0
**/
const char *gnutls_sec_param_get_name(gnutls_sec_param_t param)
{
const char *ret = "Unknown";
GNUTLS_SEC_PARAM_LOOP(
if (p->sec_param == param) {
ret = p->name;
break;
}
);
return ret;
}
/**
* gnutls_pk_bits_to_sec_param:
* @algo: is a public key algorithm
* @bits: is the number of bits
*
* This is the inverse of gnutls_sec_param_to_pk_bits(). Given an algorithm
* and the number of bits, it will return the security parameter. This is
* a rough indication.
*
* Returns: The security parameter.
*
* Since: 2.12.0
**/
gnutls_sec_param_t
gnutls_pk_bits_to_sec_param(gnutls_pk_algorithm_t algo, unsigned int bits)
{
gnutls_sec_param_t ret = GNUTLS_SEC_PARAM_INSECURE;
if (bits == 0)
return GNUTLS_SEC_PARAM_UNKNOWN;
if (IS_EC(algo)||IS_GOSTEC(algo)) {
GNUTLS_SEC_PARAM_LOOP(
if (p->ecc_bits > bits) {
break;
}
ret = p->sec_param;
);
} else {
GNUTLS_SEC_PARAM_LOOP(
if (p->pk_bits > bits) {
break;
}
ret = p->sec_param;
);
}
return ret;
}
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