lukechilds
/
lightning
mirror of https://github.com/lukechilds/lightning.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
Browse Source

Move DER encoding into bitcoin/signature.c 

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
ppa-0.6.1
Rusty Russell 9 years ago
parent
20624c049f
commit
fbe63124f6
3 changed files with 119 additions and 109 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 111
      bitcoin/script.c
  2. 114
      bitcoin/signature.c
  3. 3
      bitcoin/signature.h

111
bitcoin/script.c
View File

@ -85,121 +85,14 @@ static void add_push_key(u8 **scriptp, const struct pubkey *key)
add_push_bytes(scriptp, key->key, pubkey_len(key));
}
/* Stolen direct from bitcoin/src/script/sign.cpp:
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
*/
static bool IsValidSignatureEncoding(const unsigned char sig[], size_t len)
{
// Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S] [sighash]
// * total-length: 1-byte length descriptor of everything that follows,
// excluding the sighash byte.
// * R-length: 1-byte length descriptor of the R value that follows.
// * R: arbitrary-length big-endian encoded R value. It must use the shortest
// possible encoding for a positive integers (which means no null bytes at
// the start, except a single one when the next byte has its highest bit set).
// * S-length: 1-byte length descriptor of the S value that follows.
// * S: arbitrary-length big-endian encoded S value. The same rules apply.
// * sighash: 1-byte value indicating what data is hashed (not part of the DER
// signature)
// Minimum and maximum size constraints.
if (len < 9) return false;
if (len > 73) return false;
// A signature is of type 0x30 (compound).
if (sig[0] != 0x30) return false;
// Make sure the length covers the entire signature.
if (sig[1] != len - 3) return false;
// Extract the length of the R element.
unsigned int lenR = sig[3];
// Make sure the length of the S element is still inside the signature.
if (5 + lenR >= len) return false;
// Extract the length of the S element.
unsigned int lenS = sig[5 + lenR];
// Verify that the length of the signature matches the sum of the length
// of the elements.
if ((size_t)(lenR + lenS + 7) != len) return false;
// Check whether the R element is an integer.
if (sig[2] != 0x02) return false;
// Zero-length integers are not allowed for R.
if (lenR == 0) return false;
// Negative numbers are not allowed for R.
if (sig[4] & 0x80) return false;
// Null bytes at the start of R are not allowed, unless R would
// otherwise be interpreted as a negative number.
if (lenR > 1 && (sig[4] == 0x00) && !(sig[5] & 0x80)) return false;
// Check whether the S element is an integer.
if (sig[lenR + 4] != 0x02) return false;
// Zero-length integers are not allowed for S.
if (lenS == 0) return false;
// Negative numbers are not allowed for S.
if (sig[lenR + 6] & 0x80) return false;
// Null bytes at the start of S are not allowed, unless S would otherwise be
// interpreted as a negative number.
if (lenS > 1 && (sig[lenR + 6] == 0x00) && !(sig[lenR + 7] & 0x80)) return false;
return true;
}
/* DER encode a value, return length used. */
static size_t der_encode_val(const u8 *val, u8 *der)
{
size_t len = 0, val_len = 32;
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. */
if (val[0] & 0x80) {
der[len++] = 1 + val_len; /* value length */
der[len++] = 0;
} else
der[len++] = val_len; /* value length */
memcpy(der + len, val, val_len);
return len + val_len;
}
/* Bitcoin wants DER encoding. */
static void add_push_sig(u8 **scriptp, const struct bitcoin_signature *sig)
{
u8 der[2 + 2 + 1 + sizeof(sig->sig.r) + 2 + 1 + sizeof(sig->sig.s) + 1];
size_t len = 0;
der[len++] = 0x30; /* Type */
der[len++] = 0; /* Total length after this: fill it at end. */
len += der_encode_val(sig->sig.r, der + len);
len += der_encode_val(sig->sig.s, der + len);
/* Fix up total length */
der[1] = len - 2;
u8 der[73];
size_t len = signature_to_der(der, &sig->sig);
/* Append sighash type */
der[len++] = sig->stype;
assert(IsValidSignatureEncoding(der, len));
add_push_bytes(scriptp, der, len);
}

114
bitcoin/signature.c
View File

@ -238,3 +238,117 @@ bool check_2of2_sig(struct bitcoin_tx *tx, size_t input_num,
return check_signed_hash(&hash, &sig1->sig, key1)
&& check_signed_hash(&hash, &sig2->sig, key2);
}
/* Stolen direct from bitcoin/src/script/sign.cpp:
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
*/
static bool IsValidSignatureEncoding(const unsigned char sig[], size_t len)
{
// Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S] [sighash]
// * total-length: 1-byte length descriptor of everything that follows,
// excluding the sighash byte.
// * R-length: 1-byte length descriptor of the R value that follows.
// * R: arbitrary-length big-endian encoded R value. It must use the shortest
// possible encoding for a positive integers (which means no null bytes at
// the start, except a single one when the next byte has its highest bit set).
// * S-length: 1-byte length descriptor of the S value that follows.
// * S: arbitrary-length big-endian encoded S value. The same rules apply.
// * sighash: 1-byte value indicating what data is hashed (not part of the DER
// signature)
// Minimum and maximum size constraints.
if (len < 9) return false;
if (len > 73) return false;
// A signature is of type 0x30 (compound).
if (sig[0] != 0x30) return false;
// Make sure the length covers the entire signature.
if (sig[1] != len - 3) return false;
// Extract the length of the R element.
unsigned int lenR = sig[3];
// Make sure the length of the S element is still inside the signature.
if (5 + lenR >= len) return false;
// Extract the length of the S element.
unsigned int lenS = sig[5 + lenR];
// Verify that the length of the signature matches the sum of the length
// of the elements.
if ((size_t)(lenR + lenS + 7) != len) return false;
// Check whether the R element is an integer.
if (sig[2] != 0x02) return false;
// Zero-length integers are not allowed for R.
if (lenR == 0) return false;
// Negative numbers are not allowed for R.
if (sig[4] & 0x80) return false;
// Null bytes at the start of R are not allowed, unless R would
// otherwise be interpreted as a negative number.
if (lenR > 1 && (sig[4] == 0x00) && !(sig[5] & 0x80)) return false;
// Check whether the S element is an integer.
if (sig[lenR + 4] != 0x02) return false;
// Zero-length integers are not allowed for S.
if (lenS == 0) return false;
// Negative numbers are not allowed for S.
if (sig[lenR + 6] & 0x80) return false;
// Null bytes at the start of S are not allowed, unless S would otherwise be
// interpreted as a negative number.
if (lenS > 1 && (sig[lenR + 6] == 0x00) && !(sig[lenR + 7] & 0x80)) return false;
return true;
}
/* DER encode a value, return length used. */
static size_t der_encode_val(const u8 *val, u8 *der)
{
size_t len = 0, val_len = 32;
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. */
if (val[0] & 0x80) {
der[len++] = 1 + val_len; /* value length */
der[len++] = 0;
} else
der[len++] = val_len; /* value length */
memcpy(der + len, val, val_len);
return len + val_len;
}
size_t signature_to_der(u8 der[72], const struct signature *sig)
{
size_t len = 0;
der[len++] = 0x30; /* Type */
der[len++] = 0; /* Total length after this: fill it at end. */
len += der_encode_val(sig->r, der + len);
len += der_encode_val(sig->s, der + len);
/* Fix up total length */
der[1] = len - 2;
/* IsValidSignatureEncoding() expect extra byte for sighash */
assert(IsValidSignatureEncoding(der, len + 1));
return len;
}

3
bitcoin/signature.h
View File

@ -46,4 +46,7 @@ bool check_2of2_sig(struct bitcoin_tx *tx, size_t input_num,
const struct bitcoin_signature *sig1,
const struct bitcoin_signature *sig2);
/* Give DER encoding of signature: returns length used (<= 72). */
size_t signature_to_der(u8 der[72], const struct signature *s);
#endif /* LIGHTNING_BITCOIN_SIGNATURE_H */

Write Preview
Loading…
Cancel
Save