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#include "ec.h"
#include "bn.h"
#ifdef HAVE_EC
static EC_KEY* ec_key_new(ErlNifEnv* env, ERL_NIF_TERM curve_arg);
static ERL_NIF_TERM point2term(ErlNifEnv* env,
const EC_GROUP *group,
const EC_POINT *point,
point_conversion_form_t form);
ERL_NIF_TERM make_badarg_maybe(ErlNifEnv* env)
{
ERL_NIF_TERM reason;
if (enif_has_pending_exception(env, &reason))
return reason; /* dummy return value ignored */
else
return enif_make_badarg(env);
}
static EC_KEY* ec_key_new(ErlNifEnv* env, ERL_NIF_TERM curve_arg)
{
EC_KEY *key = NULL;
int c_arity = -1;
const ERL_NIF_TERM* curve;
ErlNifBinary seed;
BIGNUM *p = NULL;
BIGNUM *a = NULL;
BIGNUM *b = NULL;
BIGNUM *bn_order = NULL;
BIGNUM *cofactor = NULL;
EC_GROUP *group = NULL;
EC_POINT *point = NULL;
/* {Field, Prime, Point, Order, CoFactor} = Curve */
if (enif_get_tuple(env,curve_arg,&c_arity,&curve)
&& c_arity == 5
&& get_bn_from_bin(env, curve[3], &bn_order)
&& (curve[4] != atom_none && get_bn_from_bin(env, curve[4], &cofactor))) {
int f_arity = -1;
const ERL_NIF_TERM* field;
int p_arity = -1;
const ERL_NIF_TERM* prime;
long field_bits;
/* {A, B, Seed} = Prime */
if (!enif_get_tuple(env,curve[1],&p_arity,&prime)
|| !get_bn_from_bin(env, prime[0], &a)
|| !get_bn_from_bin(env, prime[1], &b))
goto out_err;
if (!enif_get_tuple(env,curve[0],&f_arity,&field))
goto out_err;
if (f_arity == 2 && field[0] == atom_prime_field) {
/* {prime_field, Prime} */
if (!get_bn_from_bin(env, field[1], &p))
goto out_err;
if (BN_is_negative(p) || BN_is_zero(p))
goto out_err;
field_bits = BN_num_bits(p);
if (field_bits > OPENSSL_ECC_MAX_FIELD_BITS)
goto out_err;
/* create the EC_GROUP structure */
group = EC_GROUP_new_curve_GFp(p, a, b, NULL);
} else if (f_arity == 3 && field[0] == atom_characteristic_two_field) {
#if defined(OPENSSL_NO_EC2M)
enif_raise_exception(env, atom_notsup);
goto out_err;
#else
/* {characteristic_two_field, M, Basis} */
int b_arity = -1;
const ERL_NIF_TERM* basis;
unsigned int k1, k2, k3;
if ((p = BN_new()) == NULL)
goto out_err;
if (!enif_get_long(env, field[1], &field_bits)
|| field_bits > OPENSSL_ECC_MAX_FIELD_BITS)
goto out_err;
if (enif_get_tuple(env,field[2],&b_arity,&basis)) {
if (b_arity == 2
&& basis[0] == atom_tpbasis
&& enif_get_uint(env, basis[1], &k1)) {
/* {tpbasis, k} = Basis */
if (!(field_bits > k1 && k1 > 0))
goto out_err;
/* create the polynomial */
if (!BN_set_bit(p, (int)field_bits)
|| !BN_set_bit(p, (int)k1)
|| !BN_set_bit(p, 0))
goto out_err;
} else if (b_arity == 4
&& basis[0] == atom_ppbasis
&& enif_get_uint(env, basis[1], &k1)
&& enif_get_uint(env, basis[2], &k2)
&& enif_get_uint(env, basis[3], &k3)) {
/* {ppbasis, k1, k2, k3} = Basis */
if (!(field_bits > k3 && k3 > k2 && k2 > k1 && k1 > 0))
goto out_err;
/* create the polynomial */
if (!BN_set_bit(p, (int)field_bits)
|| !BN_set_bit(p, (int)k1)
|| !BN_set_bit(p, (int)k2)
|| !BN_set_bit(p, (int)k3)
|| !BN_set_bit(p, 0))
goto out_err;
} else
goto out_err;
} else if (field[2] == atom_onbasis) {
/* onbasis = Basis */
/* no parameters */
goto out_err;
} else
goto out_err;
group = EC_GROUP_new_curve_GF2m(p, a, b, NULL);
#endif
} else
goto out_err;
if (!group)
goto out_err;
if (enif_inspect_binary(env, prime[2], &seed)) {
EC_GROUP_set_seed(group, seed.data, seed.size);
}
if (!term2point(env, curve[2], group, &point))
goto out_err;
if (BN_is_negative(bn_order)
|| BN_is_zero(bn_order)
|| BN_num_bits(bn_order) > (int)field_bits + 1)
goto out_err;
if (!EC_GROUP_set_generator(group, point, bn_order, cofactor))
goto out_err;
EC_GROUP_set_asn1_flag(group, 0x0);
key = EC_KEY_new();
if (!key)
goto out_err;
EC_KEY_set_group(key, group);
}
else {
goto out_err;
}
goto out;
out_err:
if (key) EC_KEY_free(key);
key = NULL;
out:
/* some OpenSSL structures are mem-dup'ed into the key,
so we have to free our copies here */
if (p) BN_free(p);
if (a) BN_free(a);
if (b) BN_free(b);
if (bn_order) BN_free(bn_order);
if (cofactor) BN_free(cofactor);
if (group) EC_GROUP_free(group);
if (point) EC_POINT_free(point);
return key;
}
static ERL_NIF_TERM point2term(ErlNifEnv* env,
const EC_GROUP *group,
const EC_POINT *point,
point_conversion_form_t form)
{
unsigned dlen;
ErlNifBinary bin;
dlen = EC_POINT_point2oct(group, point, form, NULL, 0, NULL);
if (dlen == 0)
return atom_undefined;
if (!enif_alloc_binary(dlen, &bin))
return enif_make_badarg(env);
if (!EC_POINT_point2oct(group, point, form, bin.data, bin.size, NULL)) {
enif_release_binary(&bin);
return enif_make_badarg(env);
}
ERL_VALGRIND_MAKE_MEM_DEFINED(bin.data, bin.size);
return enif_make_binary(env, &bin);
}
int term2point(ErlNifEnv* env, ERL_NIF_TERM term, EC_GROUP *group, EC_POINT **pptr)
{
int ret = 0;
ErlNifBinary bin;
EC_POINT *point;
if (!enif_inspect_binary(env,term,&bin)) {
return 0;
}
if ((*pptr = point = EC_POINT_new(group)) == NULL) {
return 0;
}
/* set the point conversion form */
EC_GROUP_set_point_conversion_form(group, (point_conversion_form_t)(bin.data[0] & ~0x01));
/* extract the ec point */
if (!EC_POINT_oct2point(group, point, bin.data, bin.size, NULL)) {
EC_POINT_free(point);
*pptr = NULL;
} else
ret = 1;
return ret;
}
int get_ec_key(ErlNifEnv* env,
ERL_NIF_TERM curve, ERL_NIF_TERM priv, ERL_NIF_TERM pub,
EC_KEY** res)
{
EC_KEY *key = NULL;
BIGNUM *priv_key = NULL;
EC_POINT *pub_key = NULL;
EC_GROUP *group = NULL;
if (!(priv == atom_undefined || get_bn_from_bin(env, priv, &priv_key))
|| !(pub == atom_undefined || enif_is_binary(env, pub))) {
goto out_err;
}
key = ec_key_new(env, curve);
if (!key) {
goto out_err;
}
if (!group)
group = EC_GROUP_dup(EC_KEY_get0_group(key));
if (term2point(env, pub, group, &pub_key)) {
if (!EC_KEY_set_public_key(key, pub_key)) {
goto out_err;
}
}
if (priv != atom_undefined
&& !BN_is_zero(priv_key)) {
if (!EC_KEY_set_private_key(key, priv_key))
goto out_err;
/* calculate public key (if necessary) */
if (EC_KEY_get0_public_key(key) == NULL)
{
/* the public key was not included in the SEC1 private
* key => calculate the public key */
pub_key = EC_POINT_new(group);
if (pub_key == NULL
|| !EC_POINT_copy(pub_key, EC_GROUP_get0_generator(group))
|| !EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, NULL)
|| !EC_KEY_set_public_key(key, pub_key))
goto out_err;
}
}
goto out;
out_err:
if (key) EC_KEY_free(key);
key = NULL;
out:
/* some OpenSSL structures are mem-dup'ed into the key,
so we have to free our copies here */
if (priv_key) BN_clear_free(priv_key);
if (pub_key) EC_POINT_free(pub_key);
if (group) EC_GROUP_free(group);
if (!key)
return 0;
*res = key;
return 1;
}
#endif /* HAVE_EC */
ERL_NIF_TERM ec_key_generate(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
#if defined(HAVE_EC)
EC_KEY *key = NULL;
const EC_GROUP *group;
const EC_POINT *public_key;
ERL_NIF_TERM priv_key;
ERL_NIF_TERM pub_key = atom_undefined;
if (!get_ec_key(env, argv[0], argv[1], atom_undefined, &key))
goto badarg;
if (argv[1] == atom_undefined) {
if (!EC_KEY_generate_key(key))
goto badarg;
}
group = EC_KEY_get0_group(key);
public_key = EC_KEY_get0_public_key(key);
if (group && public_key) {
pub_key = point2term(env, group, public_key,
EC_KEY_get_conv_form(key));
}
priv_key = bn2term(env, EC_KEY_get0_private_key(key));
EC_KEY_free(key);
return enif_make_tuple2(env, pub_key, priv_key);
badarg:
if (key)
EC_KEY_free(key);
return make_badarg_maybe(env);
#else
return atom_notsup;
#endif
}
|
