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Change contrib/laxder from headers-only to files compilable as standalone C

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Verified that both programs compile with

    gcc -I. -I../include -lsecp256k1 -c -W -Wextra -Wall -Werror -ansi -pedantic lax_der_privatekey_parsing.c
    gcc -I. -I../include -lsecp256k1 -c -W -Wextra -Wall -Werror -ansi -pedantic lax_der_parsing.c
This commit is contained in:
Andrew Poelstra
2015-10-26 15:21:53 -05:00
parent d7eb1ae96d
commit eed87af10a
6 changed files with 326 additions and 249 deletions
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178
contrib/lax_der_parsing.h
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@@ -4,7 +4,14 @@
* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
**********************************************************************/
/* This file contains a code snippet that parses DER with various errors and
/****
* Please do not link this file directly. It is not part of the libsecp256k1
* project and does not promise any stability in its API, functionality or
* presence. Projects which use this code should instead copy this header
* and its accompanying .c file directly into their codebase.
****/
/* This file defines a function that parses DER with various errors and
* violations. This is not a part of the library itself, because the allowed
* violations are chosen arbitrarily and do not follow or establish any
* standard.
@@ -44,148 +51,41 @@
#ifndef _SECP256K1_CONTRIB_LAX_DER_PARSING_H_
#define _SECP256K1_CONTRIB_LAX_DER_PARSING_H_
#include <string.h>
#include <secp256k1.h>
static int secp256k1_ecdsa_signature_parse_der_lax(const secp256k1_context* ctx, secp256k1_ecdsa_signature* sig, const unsigned char *input, size_t inputlen);
# ifdef __cplusplus
extern "C" {
# endif
static int secp256k1_ecdsa_signature_parse_der_lax(const secp256k1_context* ctx, secp256k1_ecdsa_signature* sig, const unsigned char *input, size_t inputlen) {
size_t rpos, rlen, spos, slen;
size_t pos = 0;
size_t lenbyte;
unsigned char tmpsig[64] = {0};
int overflow = 0;
/** Parse a signature in "lax DER" format
*
* Returns: 1 when the signature could be parsed, 0 otherwise.
* Args: ctx: a secp256k1 context object
* Out: sig: a pointer to a signature object
* In: input: a pointer to the signature to be parsed
* inputlen: the length of the array pointed to be input
*
* This function will accept any valid DER encoded signature, even if the
* encoded numbers are out of range. In addition, it will accept signatures
* which violate the DER spec in various ways. Its purpose is to allow
* validation of the Bitcoin blockchain, which includes non-DER signatures
* from before the network rules were updated to enforce DER. Note that
* the set of supported violations is a strict subset of what OpenSSL will
* accept.
*
* After the call, sig will always be initialized. If parsing failed or the
* encoded numbers are out of range, signature validation with it is
* guaranteed to fail for every message and public key.
*/
int ecdsa_signature_parse_der_lax(
const secp256k1_context* ctx,
secp256k1_ecdsa_signature* sig,
const unsigned char *input,
size_t inputlen
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/* Hack to initialize sig with a correctly-parsed but invalid signature. */
secp256k1_ecdsa_signature_parse_compact(ctx, sig, tmpsig);
/* Sequence tag byte */
if (pos == inputlen || input[pos] != 0x30) {
return 0;
}
pos++;
/* Sequence length bytes */
if (pos == inputlen) {
return 0;
}
lenbyte = input[pos++];
if (lenbyte & 0x80) {
lenbyte -= 0x80;
if (pos + lenbyte > inputlen) {
return 0;
}
pos += lenbyte;
}
/* Integer tag byte for R */
if (pos == inputlen || input[pos] != 0x02) {
return 0;
}
pos++;
/* Integer length for R */
if (pos == inputlen) {
return 0;
}
lenbyte = input[pos++];
if (lenbyte & 0x80) {
lenbyte -= 0x80;
if (pos + lenbyte > inputlen) {
return 0;
}
while (lenbyte > 0 && input[pos] == 0) {
pos++;
lenbyte--;
}
if (lenbyte >= sizeof(size_t)) {
return 0;
}
rlen = 0;
while (lenbyte > 0) {
rlen = (rlen << 8) + input[pos];
pos++;
lenbyte--;
}
} else {
rlen = lenbyte;
}
if (rlen > inputlen - pos) {
return 0;
}
rpos = pos;
pos += rlen;
/* Integer tag byte for S */
if (pos == inputlen || input[pos] != 0x02) {
return 0;
}
pos++;
/* Integer length for S */
if (pos == inputlen) {
return 0;
}
lenbyte = input[pos++];
if (lenbyte & 0x80) {
lenbyte -= 0x80;
if (pos + lenbyte > inputlen) {
return 0;
}
while (lenbyte > 0 && input[pos] == 0) {
pos++;
lenbyte--;
}
if (lenbyte >= sizeof(size_t)) {
return 0;
}
slen = 0;
while (lenbyte > 0) {
slen = (slen << 8) + input[pos];
pos++;
lenbyte--;
}
} else {
slen = lenbyte;
}
if (slen > inputlen - pos) {
return 0;
}
spos = pos;
pos += slen;
/* Ignore leading zeroes in R */
while (rlen > 0 && input[rpos] == 0) {
rlen--;
rpos++;
}
/* Copy R value */
if (rlen > 32) {
overflow = 1;
} else {
memcpy(tmpsig + 32 - rlen, input + rpos, rlen);
}
/* Ignore leading zeroes in S */
while (slen > 0 && input[spos] == 0) {
slen--;
spos++;
}
/* Copy S value */
if (slen > 32) {
overflow = 1;
} else {
memcpy(tmpsig + 64 - slen, input + spos, slen);
}
if (!overflow) {
overflow = !secp256k1_ecdsa_signature_parse_compact(ctx, sig, tmpsig);
}
if (overflow) {
memset(tmpsig, 0, 64);
secp256k1_ecdsa_signature_parse_compact(ctx, sig, tmpsig);
}
return 1;
#ifdef __cplusplus
}
#endif
#endif