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bitcoin_script: DER correctly when we have leading zeroes.

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Happens one in 128 times, I guess...

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2015-06-08 09:21:38 +09:30
parent a25ba452f3
commit 3c7e11fd65
1 changed files with 12 additions and 5 deletions
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17
bitcoin_script.c
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@@ -154,18 +154,25 @@ static bool IsValidSignatureEncoding(const unsigned char sig[], size_t len)
/* DER encode a value, return length used. */ /* DER encode a value, return length used. */
static size_t der_encode_val(const u8 *val, u8 *der) static size_t der_encode_val(const u8 *val, u8 *der)
{ {
size_t len = 0; size_t len = 0, val_len = 32;
der[len++] = 0x2; /* value type. */ der[len++] = 0x2; /* value type. */
/* Strip leading zeroes. */
while (val_len && val[0] == 0) {
val++;
val_len--;
}
/* Add zero byte if it would otherwise be signed. */ /* Add zero byte if it would otherwise be signed. */
if (val[0] & 0x80) { if (val[0] & 0x80) {
der[len++] = 33; /* value length */ der[len++] = 1 + val_len; /* value length */
der[len++] = 0; der[len++] = 0;
} else } else
der[len++] = 32; /* value length */ der[len++] = val_len; /* value length */
memcpy(der + len, val, 32); memcpy(der + len, val, val_len);
return len + 32; return len + val_len;
} }
/* Bitcoin wants DER encoding. */ /* Bitcoin wants DER encoding. */