tomFlowee
c63519fa47
The leveldb and univalue 3rd party libraries are not installed and not needed by anyone outside of the Hub. So move them there, making it easier for 3rd party usage.
92 lines
3.9 KiB
C
92 lines
3.9 KiB
C
/**********************************************************************
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* Copyright (c) 2015 Pieter Wuille *
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* Distributed under the MIT software license, see the accompanying *
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* file COPYING or http://www.opensource.org/licenses/mit-license.php.*
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**********************************************************************/
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/****
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* Please do not link this file directly. It is not part of the libsecp256k1
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* project and does not promise any stability in its API, functionality or
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* presence. Projects which use this code should instead copy this header
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* and its accompanying .c file directly into their codebase.
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****/
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/* This file defines a function that parses DER with various errors and
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* violations. This is not a part of the library itself, because the allowed
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* violations are chosen arbitrarily and do not follow or establish any
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* standard.
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*
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* In many places it matters that different implementations do not only accept
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* the same set of valid signatures, but also reject the same set of signatures.
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* The only means to accomplish that is by strictly obeying a standard, and not
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* accepting anything else.
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*
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* Nonetheless, sometimes there is a need for compatibility with systems that
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* use signatures which do not strictly obey DER. The snippet below shows how
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* certain violations are easily supported. You may need to adapt it.
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*
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* Do not use this for new systems. Use well-defined DER or compact signatures
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* instead if you have the choice (see secp256k1_ecdsa_signature_parse_der and
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* secp256k1_ecdsa_signature_parse_compact).
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*
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* The supported violations are:
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* - All numbers are parsed as nonnegative integers, even though X.609-0207
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* section 8.3.3 specifies that integers are always encoded as two's
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* complement.
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* - Integers can have length 0, even though section 8.3.1 says they can't.
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* - Integers with overly long padding are accepted, violation section
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* 8.3.2.
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* - 127-byte long length descriptors are accepted, even though section
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* 8.1.3.5.c says that they are not.
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* - Trailing garbage data inside or after the signature is ignored.
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* - The length descriptor of the sequence is ignored.
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*
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* Compared to for example OpenSSL, many violations are NOT supported:
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* - Using overly long tag descriptors for the sequence or integers inside,
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* violating section 8.1.2.2.
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* - Encoding primitive integers as constructed values, violating section
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* 8.3.1.
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*/
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#ifndef SECP256K1_CONTRIB_LAX_DER_PARSING_H
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#define SECP256K1_CONTRIB_LAX_DER_PARSING_H
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#include <secp256k1.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** Parse a signature in "lax DER" format
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*
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* Returns: 1 when the signature could be parsed, 0 otherwise.
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* Args: ctx: a secp256k1 context object
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* Out: sig: a pointer to a signature object
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* In: input: a pointer to the signature to be parsed
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* inputlen: the length of the array pointed to be input
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*
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* This function will accept any valid DER encoded signature, even if the
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* encoded numbers are out of range. In addition, it will accept signatures
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* which violate the DER spec in various ways. Its purpose is to allow
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* validation of the Bitcoin blockchain, which includes non-DER signatures
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* from before the network rules were updated to enforce DER. Note that
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* the set of supported violations is a strict subset of what OpenSSL will
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* accept.
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*
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* After the call, sig will always be initialized. If parsing failed or the
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* encoded numbers are out of range, signature validation with it is
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* guaranteed to fail for every message and public key.
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*/
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int ecdsa_signature_parse_der_lax(
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const secp256k1_context* ctx,
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secp256k1_ecdsa_signature* sig,
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const unsigned char *input,
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size_t inputlen
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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#ifdef __cplusplus
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}
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#endif
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#endif /* SECP256K1_CONTRIB_LAX_DER_PARSING_H */
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