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-rw-r--r--main.c29
1 files changed, 19 insertions, 10 deletions
diff --git a/main.c b/main.c
index b083887..2226b52 100644
--- a/main.c
+++ b/main.c
@@ -50,6 +50,7 @@ static bool strtol_safe(long *, const char *);
static bool totp(struct totp_config, uint32_t *);
static uint32_t pow32(uint32_t, uint32_t);
static bool uri_parse(struct totp_config *, const char *);
+static bool big_endian(void);
void
usage(void)
@@ -191,9 +192,9 @@ totp(struct totp_config conf, uint32_t *code)
char *enc_sec;
uchar *mac;
time_t epoch;
- size_t keylen, enc_sec_len, old;
- uint8_t buf[sizeof(time_t)]; /* Enough for a 64bit num */
+ uint8_t buf[sizeof(time_t)];
uint32_t binc;
+ size_t keylen, enc_sec_len, old;
/* conf.enc_sec needs to be ‘=’ padded to a multiple of 8 */
old = enc_sec_len = strlen(conf.enc_sec);
@@ -219,14 +220,12 @@ totp(struct totp_config conf, uint32_t *code)
epoch /= conf.p;
- buf[0] = (epoch >> 56) & 0xFF;
- buf[1] = (epoch >> 48) & 0xFF;
- buf[2] = (epoch >> 40) & 0xFF;
- buf[3] = (epoch >> 32) & 0xFF;
- buf[4] = (epoch >> 24) & 0xFF;
- buf[5] = (epoch >> 16) & 0xFF;
- buf[6] = (epoch >> 8) & 0xFF;
- buf[7] = (epoch >> 0) & 0xFF;
+ if (big_endian())
+ memcpy(buf, &epoch, sizeof(time_t));
+ else {
+ for (size_t i = 0; i < sizeof(buf); i++)
+ buf[i] = (epoch >> (8 * (sizeof(buf) - 1 - i))) & 0xFF;
+ }
mac = HMAC(EVP_sha1(), key, keylen, buf, sizeof(buf), NULL, NULL);
if (mac == NULL)
@@ -234,6 +233,7 @@ totp(struct totp_config conf, uint32_t *code)
/* SHA1 hashes are 20 bytes long */
off = mac[19] & 0x0F;
+ printf("%d\n", off);
binc = (mac[off + 0] & 0x7F) << 24
| (mac[off + 1] & 0xFF) << 16
| (mac[off + 2] & 0xFF) << 8
@@ -265,3 +265,12 @@ pow32(uint32_t x, uint32_t y)
x *= n;
return x;
}
+
+bool
+big_endian(void)
+{
+ unsigned n = 0x01020304;
+ uchar *ptr = (uchar *)&n;
+
+ return *ptr == 1;
+}