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Refactor to combine ECC-CDH with existing “wc_ecc_shared_secret()” and use flag to perform cofactor computation on private key. Added new API “wc_ecc_set_flags()” and flag “WC_ECC_FLAG_COFACTOR” to indicate key should use cofactor. Added NIST CAVS test vector for ECC CDH Primitive with P-256.

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This commit is contained in:
David Garske
2017-02-16 16:30:30 -08:00
parent 39607984f7
commit d625645338
3 changed files with 113 additions and 127 deletions
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152
wolfcrypt/src/ecc.c
View File

@@ -2579,6 +2579,29 @@ static int wc_ecc_shared_secret_gen_sync(ecc_key* private_key, ecc_point* point,
int err;
ecc_point* result = NULL;
word32 x = 0;
mp_int* k = &private_key->k;
#ifdef HAVE_ECC_CDH
mp_int k_lcl;
/* if cofactor flag has been set */
if (private_key->flags & WC_ECC_FLAG_COFACTOR) {
int cofactor = private_key->dp->cofactor;
/* only perform cofactor calc if not equal to 1 */
if (cofactor != 1) {
k = &k_lcl;
if (mp_init(k) != MP_OKAY)
return MEMORY_E;
/* multiple cofactor times private key "k" */
err = mp_set_int(k, cofactor);
if (err == MP_OKAY)
err = mp_mul(k, &private_key->k, k);
if (err != MP_OKAY) {
mp_clear(k);
return err;
}
}
}
#endif
/* make new point */
result = wc_ecc_new_point_h(private_key->heap);
@@ -2586,7 +2609,7 @@ static int wc_ecc_shared_secret_gen_sync(ecc_key* private_key, ecc_point* point,
return MEMORY_E;
}
err = wc_ecc_mulmod_ex(&private_key->k, point, result,
err = wc_ecc_mulmod_ex(k, point, result,
curve->Af, curve->prime, 1, private_key->heap);
if (err == MP_OKAY) {
x = mp_unsigned_bin_size(curve->prime);
@@ -2603,6 +2626,10 @@ static int wc_ecc_shared_secret_gen_sync(ecc_key* private_key, ecc_point* point,
*outlen = x;
wc_ecc_del_point_h(result, private_key->heap);
#ifdef HAVE_ECC_CDH
if (k == &k_lcl)
mp_clear(k);
#endif
return err;
}
@@ -2695,121 +2722,6 @@ int wc_ecc_shared_secret_ex(ecc_key* private_key, ecc_point* point,
#endif /* HAVE_ECC_DHE */
#ifdef HAVE_ECC_CDH
/*
Elliptic Curve Cryptography Cofactor Diffie-Hellman (ECC CDH)
A shared secret Z is computed using the domain parameters:
(q, FR, a, b{, SEED}, G, n, h), the other party’s public key,
and one’s own private key.
Input:
1. (q, FR, a, b{, SEED}, G, n, h): Domain parameters,
2. dA : One’s own private key, and
3. QB : The other party’s public key.
*/
int wc_ecc_cdh_ex(ecc_key* private_key, ecc_point* public_point,
byte* out, word32 *outlen)
{
int err;
int cofactor;
ecc_point* result = NULL;
mp_int k_lcl;
mp_int* k;
word32 x = 0;
DECLARE_CURVE_SPECS(2)
if (private_key == NULL || public_point == NULL || out == NULL ||
outlen == NULL) {
return BAD_FUNC_ARG;
}
/* type valid? */
if (private_key->type != ECC_PRIVATEKEY) {
return ECC_BAD_ARG_E;
}
/* load curve info */
cofactor = private_key->dp->cofactor;
err = wc_ecc_curve_load(private_key->dp, &curve,
(ECC_CURVE_FIELD_PRIME | ECC_CURVE_FIELD_AF));
if (err != MP_OKAY) {
return err;
}
/* multiple cofactor times private key "k" */
if (cofactor != 1) {
k = &k_lcl;
if (mp_init(k) != MP_OKAY) {
return MEMORY_E;
}
mp_set_int(k, cofactor);
mp_mul(k, &private_key->k, k);
}
else {
k = &private_key->k;
}
/* make new point */
result = wc_ecc_new_point_h(private_key->heap);
if (result == NULL) {
return MEMORY_E;
}
/* multiple public and private points */
err = wc_ecc_mulmod_ex(k, public_point, result,
curve->Af, curve->prime, 1, private_key->heap);
if (err == MP_OKAY) {
x = mp_unsigned_bin_size(curve->prime);
if (*outlen < x) {
err = BUFFER_E;
}
}
/* return output */
if (err == MP_OKAY) {
XMEMSET(out, 0, x);
err = mp_to_unsigned_bin(result->x,
out + (x - mp_unsigned_bin_size(result->x)));
}
*outlen = x;
/* clean up */
wc_ecc_del_point_h(result, private_key->heap);
if (cofactor != 1) {
mp_clear(k);
}
wc_ecc_curve_free(curve);
return err;
}
int wc_ecc_cdh(ecc_key* private_key, ecc_key* public_key,
byte* out, word32* outlen)
{
if (private_key == NULL || public_key == NULL) {
return BAD_FUNC_ARG;
}
/* Verify domain params supplied */
if (wc_ecc_is_valid_idx(private_key->idx) == 0 ||
wc_ecc_is_valid_idx(public_key->idx) == 0) {
return ECC_BAD_ARG_E;
}
/* Verify curve id matches */
if (private_key->dp->id != public_key->dp->id) {
return ECC_BAD_ARG_E;
}
return wc_ecc_cdh_ex(private_key, &public_key->pubkey, out, outlen);
}
#endif /* HAVE_ECC_CDH */
#ifndef WOLFSSL_ATECC508A
/* return 1 if point is at infinity, 0 if not, < 0 on error */
int wc_ecc_point_is_at_infinity(ecc_point* p)
@@ -3141,6 +3053,14 @@ int wc_ecc_init(ecc_key* key)
return wc_ecc_init_ex(key, NULL, INVALID_DEVID);
}
int wc_ecc_set_flags(ecc_key* key, word32 flags)
{
if (key == NULL) {
return BAD_FUNC_ARG;
}
key->flags |= flags;
return 0;
}
#ifdef HAVE_ECC_SIGN

69
wolfcrypt/test/test.c
View File

@@ -8198,6 +8198,56 @@ static int ecc_test_vector(int keySize)
return 0;
}
#ifdef HAVE_ECC_CDH
static int ecc_test_cdh_vectors(void)
{
int ret;
ecc_key pub_key, priv_key;
byte sharedA[32] = {0}, sharedB[32] = {0};
word32 x;
mp_int z;
const char* QCAVSx = "700c48f77f56584c5cc632ca65640db91b6bacce3a4df6b42ce7cc838833d287";
const char* QCAVSy = "db71e509e3fd9b060ddb20ba5c51dcc5948d46fbf640dfe0441782cab85fa4ac";
const char* dIUT = "7d7dc5f71eb29ddaf80d6214632eeae03d9058af1fb6d22ed80badb62bc1a534";
const char* QIUTx = "ead218590119e8876b29146ff89ca61770c4edbbf97d38ce385ed281d8a6b230";
const char* QIUTy = "28af61281fd35e2fa7002523acc85a429cb06ee6648325389f59edfce1405141";
const char* ZIUT = "46fc62106420ff012e54a434fbdd2d25ccc5852060561e68040dd7778997bd7b";
/* setup private and public keys */
wc_ecc_init(&pub_key);
wc_ecc_init(&priv_key);
wc_ecc_set_flags(&pub_key, WC_ECC_FLAG_COFACTOR);
wc_ecc_set_flags(&priv_key, WC_ECC_FLAG_COFACTOR);
ret = wc_ecc_import_raw(&pub_key, QCAVSx, QCAVSy, NULL, "SECP256R1");
if (ret != 0)
goto done;
ret = wc_ecc_import_raw(&priv_key, QIUTx, QIUTy, dIUT, "SECP256R1");
if (ret != 0)
goto done;
/* compute ECC Cofactor shared secret */
x = sizeof(sharedA);
ret = wc_ecc_shared_secret(&priv_key, &pub_key, sharedA, &x);
if (ret != 0) {
goto done;
}
/* read in expected Z */
mp_init(&z);
mp_read_radix(&z, ZIUT, 16);
mp_to_unsigned_bin(&z, sharedB);
mp_clear(&z);
/* compare results */
if (XMEMCMP(sharedA, sharedB, x)) {
ERROR_OUT(-1007, done);
}
done:
return ret;
}
#endif /* HAVE_ECC_CDH */
#endif /* HAVE_ECC_VECTOR_TEST */
#ifdef WOLFSSL_KEY_GEN
@@ -8344,14 +8394,18 @@ static int ecc_test_curve_size(WC_RNG* rng, int keySize, int testVerifyCount,
#endif /* HAVE_ECC_DHE */
#ifdef HAVE_ECC_CDH
/* add cofactor flag */
wc_ecc_set_flags(&userA, WC_ECC_FLAG_COFACTOR);
wc_ecc_set_flags(&userB, WC_ECC_FLAG_COFACTOR);
x = sizeof(sharedA);
ret = wc_ecc_cdh(&userA, &userB, sharedA, &x);
ret = wc_ecc_shared_secret(&userA, &userB, sharedA, &x);
if (ret != 0) {
goto done;
}
y = sizeof(sharedB);
ret = wc_ecc_cdh(&userB, &userA, sharedB, &y);
ret = wc_ecc_shared_secret(&userB, &userA, sharedB, &y);
if (ret != 0)
goto done;
@@ -8360,6 +8414,10 @@ static int ecc_test_curve_size(WC_RNG* rng, int keySize, int testVerifyCount,
if (XMEMCMP(sharedA, sharedB, x))
ERROR_OUT(-1007, done);
/* remove cofactor flag */
wc_ecc_set_flags(&userA, 0);
wc_ecc_set_flags(&userB, 0);
#endif /* HAVE_ECC_CDH */
#ifdef HAVE_ECC_KEY_EXPORT
@@ -8598,6 +8656,13 @@ int ecc_test(void)
#endif
#endif
#ifdef HAVE_ECC_CDH
ret = ecc_test_cdh_vectors();
if (ret != 0) {
printf("ecc_test_cdh_vectors failed! %d\n", ret);
}
#endif
done:
wc_FreeRng(&rng);

19
wolfssl/wolfcrypt/ecc.h
View File

@@ -248,6 +248,13 @@ typedef struct {
#endif
} ecc_point;
/* ECC Flags */
enum {
WC_ECC_FLAG_NONE = 0x00,
#ifdef HAVE_ECC_CDH
WC_ECC_FLAG_COFACTOR = 0x01,
#endif
};
/* An ECC Key */
typedef struct ecc_key {
@@ -256,6 +263,7 @@ typedef struct ecc_key {
this curve if -1, this key is using user supplied
curve in dp */
int state;
word32 flags;
const ecc_set_type* dp; /* domain parameters, either points to NIST
curves (idx >= 0) or user supplied */
void* heap; /* heap hint */
@@ -302,15 +310,6 @@ int wc_ecc_shared_secret_ex(ecc_key* private_key, ecc_point* point,
#define wc_ecc_shared_secret_ssh wc_ecc_shared_secret_ex /* For backwards compat */
#endif /* HAVE_ECC_DHE */
#ifdef HAVE_ECC_CDH
WOLFSSL_API
int wc_ecc_cdh(ecc_key* private_key, ecc_key* public_key,
byte* out, word32* outlen);
WOLFSSL_API
int wc_ecc_cdh_ex(ecc_key* private_key, ecc_point* public_point,
byte* out, word32 *outlen);
#endif /* HAVE_ECC_CDH */
#ifdef HAVE_ECC_SIGN
WOLFSSL_API
int wc_ecc_sign_hash(const byte* in, word32 inlen, byte* out, word32 *outlen,
@@ -336,6 +335,8 @@ int wc_ecc_init_ex(ecc_key* key, void* heap, int devId);
WOLFSSL_API
void wc_ecc_free(ecc_key* key);
WOLFSSL_API
int wc_ecc_set_flags(ecc_key* key, word32 flags);
WOLFSSL_API
void wc_ecc_fp_free(void);
WOLFSSL_API