[Bitcoin-development] The difficulty of writing consensus critical code: the SIGHASH_SINGLE bug

[Peter Todd]

On Fri, Nov 07, 2014 at 11:30:22AM +0000, Clément Elbaz wrote:
> Thinking out loud here : would it make sense to separate the consensus code
> into some kind of "Bitcoin Kernel" (similar to the Linux Kernel) project
> that could be used by anyone ?

That's a pretty old idea, and we're working on it. First step is a
stand-alone script verification library:

https://github.com/theuni/bitcoin/blob/da18a0266c4de76c2a461cc2984aa2fa066c42f5/src/script/bitcoinconsensus.h

#ifndef H_BITCOIN_BITCOINCONSENSUS
#define H_BITCOIN_BITCOINCONSENSUS

#if defined(BUILD_BITCOIN_INTERNAL) && defined(HAVE_CONFIG_H)
#include "config/bitcoin-config.h"
  #if defined(_WIN32)
    #if defined(DLL_EXPORT)
      #if defined(HAVE_FUNC_ATTRIBUTE_DLLEXPORT)
        #define EXPORT_SYMBOL __declspec(dllexport)
      #else
        #define EXPORT_SYMBOL
      #endif
    #endif
  #elif defined(HAVE_FUNC_ATTRIBUTE_VISIBILITY)
    #define EXPORT_SYMBOL __attribute__ ((visibility ("default")))
  #endif
#elif defined(MSC_VER) && !defined(STATIC_LIBBITCOINCONSENSUS)
  #define EXPORT_SYMBOL __declspec(dllimport)
#endif

#ifndef EXPORT_SYMBOL
  #define EXPORT_SYMBOL
#endif

#ifdef __cplusplus
extern "C" {
#else
#include <stdbool.h>
#endif

/** Script verification flags */
enum
{
    bitcoinconsensus_SCRIPT_FLAGS_VERIFY_NONE      = 0,
    bitcoinconsensus_SCRIPT_FLAGS_VERIFY_P2SH      = (1U << 0), // evaluate P2SH (BIP16) subscripts
};

/// Returns true if the input nIn of the serialized transaction pointed to by
/// txTo correctly spends the scriptPubKey pointed to by scriptPubKey under
/// the additional constraints specified by flags.
EXPORT_SYMBOL bool bitcoinconsensus_verify_script(const unsigned char *scriptPubKey, const unsigned int scriptPubKeyLen,
                                    const unsigned char *txTo        , const unsigned int txToLen,
                                    const unsigned int nIn, const unsigned int flags);

EXPORT_SYMBOL unsigned int bitcoinconsensus_version();

#ifdef __cplusplus
} // extern "C"
#endif

#undef EXPORT_SYMBOL

#endif // H_BITCOIN_BITCOINCONSENSUS

-- 
'peter'[:-1]@petertodd.org
000000000000000001208038fd7130083ff118147890dbb37913ffa83c1f48cd
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