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wg: constanter time encoding 

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2018-05-30 21:32:27 +02:00
parent 206e8f08e2
commit 2bca99893f
2 changed files with 28 additions and 22 deletions
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14
contrib/embeddable-wg-library/wireguard.c
View File

@ -1559,25 +1559,25 @@ int wg_key_from_base64(wg_key key, const wg_key_b64_string base64)
{ {
unsigned int i; unsigned int i;
int val; int val;
volatile uint8_t ret = 0;
errno = EINVAL; if (strlen(base64) != sizeof(wg_key_b64_string) - 1 || base64[sizeof(wg_key_b64_string) - 2] != '=') {
if (strlen(base64) != sizeof(wg_key_b64_string) - 1 || base64[sizeof(wg_key_b64_string) - 2] != '=') errno = EINVAL;
goto out; goto out;
}
for (i = 0; i < 32 / 3; ++i) { for (i = 0; i < 32 / 3; ++i) {
val = decode_base64(&base64[i * 4]); val = decode_base64(&base64[i * 4]);
if (val < 0) ret |= (uint32_t)val >> 31;
goto out;
key[i * 3 + 0] = (val >> 16) & 0xff; key[i * 3 + 0] = (val >> 16) & 0xff;
key[i * 3 + 1] = (val >> 8) & 0xff; key[i * 3 + 1] = (val >> 8) & 0xff;
key[i * 3 + 2] = val & 0xff; key[i * 3 + 2] = val & 0xff;
} }
val = decode_base64((const char[]){ base64[i * 4 + 0], base64[i * 4 + 1], base64[i * 4 + 2], 'A' }); val = decode_base64((const char[]){ base64[i * 4 + 0], base64[i * 4 + 1], base64[i * 4 + 2], 'A' });
if (val < 0 || val & 0xff) ret |= ((uint32_t)val >> 31) | (val & 0xff);
goto out;
key[i * 3 + 0] = (val >> 16) & 0xff; key[i * 3 + 0] = (val >> 16) & 0xff;
key[i * 3 + 1] = (val >> 8) & 0xff; key[i * 3 + 1] = (val >> 8) & 0xff;
errno = 0; errno = EINVAL & ~((ret - 1) >> 8);
out: out:
return -errno; return -errno;
} }

36
src/encoding.c
View File

@ -50,6 +50,7 @@ static inline int decode_base64(const char src[4])
bool key_from_base64(uint8_t key[static WG_KEY_LEN], const char *base64) bool key_from_base64(uint8_t key[static WG_KEY_LEN], const char *base64)
{ {
unsigned int i; unsigned int i;
volatile uint8_t ret = 0;
int val; int val;
if (strlen(base64) != WG_KEY_LEN_BASE64 - 1 || base64[WG_KEY_LEN_BASE64 - 2] != '=') if (strlen(base64) != WG_KEY_LEN_BASE64 - 1 || base64[WG_KEY_LEN_BASE64 - 2] != '=')
@ -57,18 +58,17 @@ bool key_from_base64(uint8_t key[static WG_KEY_LEN], const char *base64)
for (i = 0; i < WG_KEY_LEN / 3; ++i) { for (i = 0; i < WG_KEY_LEN / 3; ++i) {
val = decode_base64(&base64[i * 4]); val = decode_base64(&base64[i * 4]);
if (val < 0) ret |= (uint32_t)val >> 31;
return false;
key[i * 3 + 0] = (val >> 16) & 0xff; key[i * 3 + 0] = (val >> 16) & 0xff;
key[i * 3 + 1] = (val >> 8) & 0xff; key[i * 3 + 1] = (val >> 8) & 0xff;
key[i * 3 + 2] = val & 0xff; key[i * 3 + 2] = val & 0xff;
} }
val = decode_base64((const char[]){ base64[i * 4 + 0], base64[i * 4 + 1], base64[i * 4 + 2], 'A' }); val = decode_base64((const char[]){ base64[i * 4 + 0], base64[i * 4 + 1], base64[i * 4 + 2], 'A' });
if (val < 0 || val & 0xff) ret |= ((uint32_t)val >> 31) | (val & 0xff);
return false;
key[i * 3 + 0] = (val >> 16) & 0xff; key[i * 3 + 0] = (val >> 16) & 0xff;
key[i * 3 + 1] = (val >> 8) & 0xff; key[i * 3 + 1] = (val >> 8) & 0xff;
return true;
return 1 & ((ret - 1) >> 8);
} }
void key_to_hex(char hex[static WG_KEY_LEN_HEX], const uint8_t key[static WG_KEY_LEN]) void key_to_hex(char hex[static WG_KEY_LEN_HEX], const uint8_t key[static WG_KEY_LEN])
@ -84,27 +84,33 @@ void key_to_hex(char hex[static WG_KEY_LEN_HEX], const uint8_t key[static WG_KEY
bool key_from_hex(uint8_t key[static WG_KEY_LEN], const char *hex) bool key_from_hex(uint8_t key[static WG_KEY_LEN], const char *hex)
{ {
uint8_t c, c_acc = 0, c_alpha0, c_alpha, c_num0, c_num, c_val, state = 0; uint8_t c, c_acc = 0, c_alpha0, c_alpha, c_num0, c_num, c_val;
volatile uint8_t ret = 0;
if (strlen(hex) != WG_KEY_LEN_HEX - 1) if (strlen(hex) != WG_KEY_LEN_HEX - 1)
return false; return false;
for (unsigned int i = 0; i < WG_KEY_LEN_HEX - 1; ++i) { for (unsigned int i = 0; i < WG_KEY_LEN_HEX - 1; i += 2) {
c = (uint8_t)hex[i]; c = (uint8_t)hex[i];
c_num = c ^ 48U; c_num = c ^ 48U;
c_num0 = (c_num - 10U) >> 8; c_num0 = (c_num - 10U) >> 8;
c_alpha = (c & ~32U) - 55U; c_alpha = (c & ~32U) - 55U;
c_alpha0 = ((c_alpha - 10U) ^ (c_alpha - 16U)) >> 8; c_alpha0 = ((c_alpha - 10U) ^ (c_alpha - 16U)) >> 8;
if (!(c_num0 | c_alpha0)) ret |= ((c_num0 | c_alpha0) - 1) >> 8;
return false;
c_val = (c_num0 & c_num) | (c_alpha0 & c_alpha); c_val = (c_num0 & c_num) | (c_alpha0 & c_alpha);
if (!state) c_acc = c_val * 16U;
c_acc = c_val * 16U;
else c = (uint8_t)hex[i + 1];
key[i / 2] = c_acc | c_val; c_num = c ^ 48U;
state = ~state; c_num0 = (c_num - 10U) >> 8;
c_alpha = (c & ~32U) - 55U;
c_alpha0 = ((c_alpha - 10U) ^ (c_alpha - 16U)) >> 8;
ret |= ((c_num0 | c_alpha0) - 1) >> 8;
c_val = (c_num0 & c_num) | (c_alpha0 & c_alpha);
key[i / 2] = c_acc | c_val;
} }
return true;
return 1 & ((ret - 1) >> 8);
} }
bool key_is_zero(const uint8_t key[static WG_KEY_LEN]) bool key_is_zero(const uint8_t key[static WG_KEY_LEN])