contrib: embedded-wg-library: add key generation functions

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2018-02-21 19:19:50 +01:00
parent 295c9ff274
commit 0e6fe9a548
3 changed files with 205 additions and 2 deletions

View File

@ -50,9 +50,11 @@ int main(int argc, char *argv[])
.first_peer = &new_peer,
.last_peer = &new_peer
};
wg_key temp_private_key;
wg_key_from_base64(new_device.private_key, "SFLKy56SOiFoAvQDSCBRrH/nyYonuAQnyr/JTQRPDlU=");
wg_key_from_base64(new_peer.public_key, "aNoLvvCfgbtTf4f2Eb/CWVNvIc5AJt/4C4pKrxMUZlM=");
wg_generate_private_key(temp_private_key);
wg_generate_public_key(new_peer.public_key, temp_private_key);
wg_generate_private_key(new_device.private_key);
if (wg_add_device(new_device.name) < 0) {
perror("Unable to add device");

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@ -19,6 +19,8 @@
#include <sys/socket.h>
#include <time.h>
#include <unistd.h>
#include <fcntl.h>
#include <assert.h>
#include "wireguard.h"
@ -1575,3 +1577,199 @@ int wg_key_from_base64(wg_key key, const wg_key_b64_string base64)
out:
return -errno;
}
typedef int64_t fe[16];
static __attribute__((noinline)) void memzero_explicit(void *s, size_t count)
{
memset(s, 0, count);
__asm__ __volatile__("": :"r"(s) :"memory");
}
static void carry(fe o)
{
int i;
int64_t c;
for (i = 0; i < 16; ++i) {
o[i] += (1LL << 16);
c = o[i] >> 16;
o[(i + 1) * (i < 15)] += c - 1 + 37 * (c - 1) * (i == 15);
o[i] -= c << 16;
}
memzero_explicit(&c, sizeof(c));
}
static void cswap(fe p, fe q, int b)
{
int i;
int64_t t, c = ~(b - 1);
for (i = 0; i < 16; ++i) {
t = c & (p[i] ^ q[i]);
p[i] ^= t;
q[i] ^= t;
}
memzero_explicit(&t, sizeof(t));
memzero_explicit(&c, sizeof(c));
memzero_explicit(&b, sizeof(b));
}
static void pack(uint8_t *o, const fe n)
{
int i, j, b;
fe m, t;
memcpy(t, n, sizeof(t));
carry(t);
carry(t);
carry(t);
for (j = 0; j < 2; ++j) {
m[0] = t[0] - 0xffed;
for (i = 1; i < 15; ++i) {
m[i] = t[i] - 0xffff - ((m[i - 1] >> 16) & 1);
m[i - 1] &= 0xffff;
}
m[15] = t[15] - 0x7fff - ((m[14] >> 16) & 1);
b = (m[15] >> 16) & 1;
m[14] &= 0xffff;
cswap(t, m, 1 - b);
}
for (i = 0; i < 16; ++i) {
o[2 * i] = t[i] & 0xff;
o[2 * i + 1] = t[i] >> 8;
}
memzero_explicit(m, sizeof(m));
memzero_explicit(t, sizeof(t));
memzero_explicit(&b, sizeof(b));
}
static void add(fe o, const fe a, const fe b)
{
int i;
for (i = 0; i < 16; ++i)
o[i] = a[i] + b[i];
}
static void subtract(fe o, const fe a, const fe b)
{
int i;
for (i = 0; i < 16; ++i)
o[i] = a[i] - b[i];
}
static void multmod(fe o, const fe a, const fe b)
{
int i, j;
int64_t t[31] = { 0 };
for (i = 0; i < 16; ++i) {
for (j = 0; j < 16; ++j)
t[i + j] += a[i] * b[j];
}
for (i = 0; i < 15; ++i)
t[i] += 38 * t[i + 16];
memcpy(o, t, sizeof(fe));
carry(o);
carry(o);
memzero_explicit(t, sizeof(t));
}
static void invert(fe o, const fe i)
{
fe c;
int a;
memcpy(c, i, sizeof(c));
for (a = 253; a >= 0; --a) {
multmod(c, c, c);
if (a != 2 && a != 4)
multmod(c, c, i);
}
memcpy(o, c, sizeof(fe));
memzero_explicit(c, sizeof(c));
}
static void normalize_key(uint8_t *z)
{
z[31] = (z[31] & 127) | 64;
z[0] &= 248;
}
void wg_generate_public_key(wg_key public_key, const wg_key private_key)
{
int i, r;
uint8_t z[32];
fe a = { 1 }, b = { 9 }, c = { 0 }, d = { 1 }, e, f;
memcpy(z, private_key, sizeof(z));
normalize_key(z);
for (i = 254; i >= 0; --i) {
r = (z[i >> 3] >> (i & 7)) & 1;
cswap(a, b, r);
cswap(c, d, r);
add(e, a, c);
subtract(a, a, c);
add(c, b, d);
subtract(b, b, d);
multmod(d, e, e);
multmod(f, a, a);
multmod(a, c, a);
multmod(c, b, e);
add(e, a, c);
subtract(a, a, c);
multmod(b, a, a);
subtract(c, d, f);
multmod(a, c, (const fe){ 0xdb41, 1 });
add(a, a, d);
multmod(c, c, a);
multmod(a, d, f);
multmod(d, b, (const fe){ 9 });
multmod(b, e, e);
cswap(a, b, r);
cswap(c, d, r);
}
invert(c, c);
multmod(a, a, c);
pack(public_key, a);
memzero_explicit(&r, sizeof(r));
memzero_explicit(z, sizeof(z));
memzero_explicit(a, sizeof(a));
memzero_explicit(b, sizeof(b));
memzero_explicit(c, sizeof(c));
memzero_explicit(d, sizeof(d));
memzero_explicit(e, sizeof(e));
memzero_explicit(f, sizeof(f));
}
void wg_generate_private_key(wg_key private_key)
{
wg_generate_preshared_key(private_key);
normalize_key(private_key);
}
void wg_generate_preshared_key(wg_key preshared_key)
{
ssize_t ret;
int fd;
#if defined(__NR_getrandom)
ret = syscall(__NR_getrandom, preshared_key, sizeof(wg_key), 0);
if (ret == sizeof(wg_key))
return;
#endif
fd = open("/dev/urandom", O_RDONLY);
assert(fd >= 0);
ret = read(fd, preshared_key, sizeof(wg_key));
close(fd);
assert(ret == sizeof(wg_key));
}

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@ -90,5 +90,8 @@ char *wg_list_device_names(void); /* first\0second\0third\0forth\0last\0\0 */
void wg_key_to_base64(wg_key_b64_string base64, const wg_key key);
int wg_key_from_base64(wg_key key, const wg_key_b64_string base64);
bool wg_key_is_zero(const wg_key key);
void wg_generate_public_key(wg_key public_key, const wg_key private_key);
void wg_generate_private_key(wg_key private_key);
void wg_generate_preshared_key(wg_key preshared_key);
#endif