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tls: implement secp256r1 elliptic curve (aka P256)

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function                                             old     new   delta
sp_256_mod_mul_norm_10                                 -    1439   +1439
sp_256_ecc_mulmod_10                                   -    1363   +1363
sp_256_proj_point_dbl_10                               -     490    +490
p256_base                                              -     244    +244
static.sp_256_mont_sqr_10                              -     234    +234
static.sp_256_mont_mul_10                              -     214    +214
curve_P256_compute_pubkey_and_premaster                -     197    +197
static.sp_256_mont_reduce_10                           -     176    +176
static.sp_256_from_bin                                 -     149    +149
sp_256_to_bin                                          -     148    +148
tls_handshake                                       2046    2146    +100
static.sp_256_mul_add_10                               -      82     +82
.rodata                                           103275  103336     +61
static.sp_256_mont_sub_10                              -      52     +52
static.sp_256_mont_dbl_10                              -      52     +52
static.sp_256_cmp_10                                   -      43     +43
p256_mod                                               -      40     +40
static.sp_256_cond_sub_10                              -      32     +32
p256_mod_2                                             -      32     +32
sp_256_norm_10                                         -      31     +31
sp_256_cmp_equal_10                                    -      30     +30
sp_256_add_10                                          -      22     +22
addr_mask                                              -       8      +8
------------------------------------------------------------------------------
(add/remove: 22/0 grow/shrink: 2/0 up/down: 5239/0)          Total: 5239 bytes
   text	   data	    bss	    dec	    hex	filename
1018192	    559	   5020	1023771	  f9f1b	busybox_old
1023431	    559	   5020	1029010	  fb392	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-04-26 13:25:56 +02:00
parent 121b02d6b6
commit f18a1fd6f3
4 changed files with 1126 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

101
networking/tls.c
View File

@ -18,6 +18,7 @@
//kbuild:lib-$(CONFIG_TLS) += tls_aesgcm.o
//kbuild:lib-$(CONFIG_TLS) += tls_rsa.o
//kbuild:lib-$(CONFIG_TLS) += tls_fe.o
//kbuild:lib-$(CONFIG_TLS) += tls_sp_c32.o
#include "tls.h"
@ -265,8 +266,9 @@ enum {
GOT_CERT_RSA_KEY_ALG = 1 << 1,
GOT_CERT_ECDSA_KEY_ALG = 1 << 2, // so far unused
GOT_EC_KEY = 1 << 3,
ENCRYPTION_AESGCM = 1 << 4, // else AES-SHA (or NULL-SHA if ALLOW_RSA_NULL_SHA256=1)
ENCRYPT_ON_WRITE = 1 << 5,
GOT_EC_CURVE_X25519 = 1 << 4, // else P256
ENCRYPTION_AESGCM = 1 << 5, // else AES-SHA (or NULL-SHA if ALLOW_RSA_NULL_SHA256=1)
ENCRYPT_ON_WRITE = 1 << 6,
};
struct record_hdr {
@ -285,7 +287,11 @@ struct tls_handshake_data {
//TODO: store just the DER key here, parse/use/delete it when sending client key
//this way it will stay key type agnostic here.
psRsaKey_t server_rsa_pub_key;
uint8_t ecc_pub_key32[32];
/* peer's elliptic curve key data */
/* for x25519, it contains one point in first 32 bytes */
/* for P256, it contains x,y point pair, each 32 bytes long */
uint8_t ecc_pub_key32[2 * 32];
/* HANDSHAKE HASH: */
//unsigned saved_client_hello_size;
@ -1526,20 +1532,13 @@ static void send_client_hello_and_alloc_hsd(tls_state_t *tls, const char *sni)
};
static const uint8_t supported_groups[] = {
0x00,0x0a, //extension_type: "supported_groups"
0x00,0x04, //ext len
0x00,0x02, //list len
0x00,0x1d, //curve_x25519 (RFC 7748)
//0x00,0x1e, //curve_x448 (RFC 7748)
//0x00,0x17, //curve_secp256r1
0x00,0x06, //ext len
0x00,0x04, //list len
0x00,0x17, //curve_secp256r1
//0x00,0x18, //curve_secp384r1
//0x00,0x19, //curve_secp521r1
//TODO: implement secp256r1 (at least): dl.fedoraproject.org immediately aborts
//if only x25519/x448 are advertised, seems to support only secpNNNr1 curves:
// openssl s_client -connect dl.fedoraproject.org:443 -debug -tls1_2 -cipher ECDHE-RSA-AES128-GCM-SHA256
//Peer signing digest: SHA512
//Peer signature type: RSA
//Server Temp Key: ECDH, P-256, 256 bits
//TLSv1.2, Cipher is ECDHE-RSA-AES128-GCM-SHA256
0x00,0x1d, //curve_x25519 (RFC 7748)
//0x00,0x1e, //curve_x448 (RFC 7748)
};
//static const uint8_t signature_algorithms[] = {
// 000d
@ -1877,12 +1876,32 @@ static void process_server_key(tls_state_t *tls, int len)
if (len < (1+2+1+32)) tls_error_die(tls);
keybuf += 4;
/* So far we only support curve_x25519 */
#if BB_BIG_ENDIAN
# define _0x03001741 0x03001741
# define _0x03001d20 0x03001d20
#else
# define _0x03001741 0x41170003
# define _0x03001d20 0x201d0003
#endif
move_from_unaligned32(t32, keybuf);
if (t32 != htonl(0x03001d20))
bb_simple_error_msg_and_die("elliptic curve is not x25519");
keybuf += 4;
switch (t32) {
case _0x03001d20: //curve_x25519
tls->flags |= GOT_EC_CURVE_X25519;
memcpy(tls->hsd->ecc_pub_key32, keybuf, 32);
break;
case _0x03001741: //curve_secp256r1
/* P256 point can be transmitted odd- or even-compressed
* (first byte is 3 or 2) or uncompressed (4).
*/
if (*keybuf++ != 4)
bb_simple_error_msg_and_die("compressed EC points not supported");
memcpy(tls->hsd->ecc_pub_key32, keybuf, 2 * 32);
break;
default:
bb_error_msg_and_die("elliptic curve is not x25519 or P256: 0x%08x", t32);
}
memcpy(tls->hsd->ecc_pub_key32, keybuf + 4, 32);
tls->flags |= GOT_EC_KEY;
dbg("got eccPubKey\n");
}
@ -1918,9 +1937,7 @@ static void send_client_key_exchange(tls_state_t *tls)
};
//FIXME: better size estimate
struct client_key_exchange *record = tls_get_zeroed_outbuf(tls, sizeof(*record));
uint8_t rsa_premaster[RSA_PREMASTER_SIZE];
uint8_t x25519_premaster[CURVE25519_KEYSIZE];
uint8_t *premaster;
uint8_t premaster[RSA_PREMASTER_SIZE > EC_CURVE_KEYSIZE ? RSA_PREMASTER_SIZE : EC_CURVE_KEYSIZE];
int premaster_size;
int len;
@ -1929,19 +1946,19 @@ static void send_client_key_exchange(tls_state_t *tls)
if (!(tls->flags & GOT_CERT_RSA_KEY_ALG))
bb_simple_error_msg("server cert is not RSA");
tls_get_random(rsa_premaster, sizeof(rsa_premaster));
tls_get_random(premaster, RSA_PREMASTER_SIZE);
if (TLS_DEBUG_FIXED_SECRETS)
memset(rsa_premaster, 0x44, sizeof(rsa_premaster));
memset(premaster, 0x44, RSA_PREMASTER_SIZE);
// RFC 5246
// "Note: The version number in the PreMasterSecret is the version
// offered by the client in the ClientHello.client_version, not the
// version negotiated for the connection."
rsa_premaster[0] = TLS_MAJ;
rsa_premaster[1] = TLS_MIN;
dump_hex("premaster:%s\n", rsa_premaster, sizeof(rsa_premaster));
premaster[0] = TLS_MAJ;
premaster[1] = TLS_MIN;
dump_hex("premaster:%s\n", premaster, sizeof(premaster));
len = psRsaEncryptPub(/*pool:*/ NULL,
/* psRsaKey_t* */ &tls->hsd->server_rsa_pub_key,
rsa_premaster, /*inlen:*/ sizeof(rsa_premaster),
premaster, /*inlen:*/ RSA_PREMASTER_SIZE,
record->key + 2, sizeof(record->key) - 2,
data_param_ignored
);
@ -1949,10 +1966,10 @@ static void send_client_key_exchange(tls_state_t *tls)
record->key[0] = len >> 8;
record->key[1] = len & 0xff;
len += 2;
premaster = rsa_premaster;
premaster_size = sizeof(rsa_premaster);
} else {
/* ECDHE */
premaster_size = RSA_PREMASTER_SIZE;
} else /* ECDHE */
if (tls->flags & GOT_EC_CURVE_X25519) {
/* ECDHE, curve x25519 */
static const uint8_t basepoint9[CURVE25519_KEYSIZE] ALIGN8 = {9};
uint8_t privkey[CURVE25519_KEYSIZE]; //[32]
@ -1969,13 +1986,27 @@ static void send_client_key_exchange(tls_state_t *tls)
/* Compute premaster using peer's public key */
dbg("computing x25519_premaster\n");
curve25519(x25519_premaster, privkey, tls->hsd->ecc_pub_key32);
curve25519(premaster, privkey, tls->hsd->ecc_pub_key32);
len = CURVE25519_KEYSIZE;
record->key[0] = len;
len++;
premaster = x25519_premaster;
premaster_size = sizeof(x25519_premaster);
premaster_size = CURVE25519_KEYSIZE;
} else {
/* ECDHE, curve P256 */
if (!(tls->flags & GOT_EC_KEY))
bb_simple_error_msg_and_die("server did not provide EC key");
dbg("computing P256_premaster\n");
curve_P256_compute_pubkey_and_premaster(
record->key + 2, premaster,
/*point:*/ tls->hsd->ecc_pub_key32
);
premaster_size = P256_KEYSIZE;
len = 1 + P256_KEYSIZE * 2;
record->key[0] = len;
record->key[1] = 4;
len++;
}
record->type = HANDSHAKE_CLIENT_KEY_EXCHANGE;

8
networking/tls.h
View File

@ -106,3 +106,11 @@ void xorbuf_aligned_AES_BLOCK_SIZE(void* buf, const void* mask) FAST_FUNC;
#include "tls_aesgcm.h"
#include "tls_rsa.h"
#include "tls_fe.h"
#define EC_CURVE_KEYSIZE 32
#define P256_KEYSIZE 32
#define CURVE25519_KEYSIZE 32
void curve_P256_compute_pubkey_and_premaster(
uint8_t *pubkey, uint8_t *premaster,
const uint8_t *peerkey32) FAST_FUNC;

1
networking/tls_fe.h
View File

@ -3,5 +3,4 @@
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
#define CURVE25519_KEYSIZE 32
void curve25519(uint8_t *result, const uint8_t *e, const uint8_t *q) FAST_FUNC;

1052
networking/tls_sp_c32.c Normal file
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