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libsecp256k1/include/secp256k1.h  view on Meta::CPAN

/** Opaque data structure that holds context information
 *
 *  The primary purpose of context objects is to store randomization data for
 *  enhanced protection against side-channel leakage. This protection is only
 *  effective if the context is randomized after its creation. See
 *  secp256k1_context_create for creation of contexts and
 *  secp256k1_context_randomize for randomization.
 *
 *  A secondary purpose of context objects is to store pointers to callback
 *  functions that the library will call when certain error states arise. See
 *  secp256k1_context_set_error_callback as well as
 *  secp256k1_context_set_illegal_callback for details. Future library versions
 *  may use context objects for additional purposes.
 *
 *  A constructed context can safely be used from multiple threads
 *  simultaneously, but API calls that take a non-const pointer to a context
 *  need exclusive access to it. In particular this is the case for
 *  secp256k1_context_destroy, secp256k1_context_preallocated_destroy,
 *  and secp256k1_context_randomize.
 *
 *  Regarding randomization, either do it once at creation time (in which case
 *  you do not need any locking for the other calls), or use a read-write lock.
 */
typedef struct secp256k1_context_struct secp256k1_context;

/** Opaque data structure that holds a parsed and valid public key.
 *
 *  The exact representation of data inside is implementation defined and not
 *  guaranteed to be portable between different platforms or versions. It is
 *  however guaranteed to be 64 bytes in size, and can be safely copied/moved.
 *  If you need to convert to a format suitable for storage or transmission,
 *  use secp256k1_ec_pubkey_serialize and secp256k1_ec_pubkey_parse. To
 *  compare keys, use secp256k1_ec_pubkey_cmp.
 */
typedef struct secp256k1_pubkey {
    unsigned char data[64];
} secp256k1_pubkey;

/** Opaque data structure that holds a parsed ECDSA signature.
 *
 *  The exact representation of data inside is implementation defined and not
 *  guaranteed to be portable between different platforms or versions. It is
 *  however guaranteed to be 64 bytes in size, and can be safely copied/moved.
 *  If you need to convert to a format suitable for storage, transmission, or
 *  comparison, use the secp256k1_ecdsa_signature_serialize_* and
 *  secp256k1_ecdsa_signature_parse_* functions.
 */
typedef struct secp256k1_ecdsa_signature {
    unsigned char data[64];
} secp256k1_ecdsa_signature;

/** A pointer to a function to deterministically generate a nonce.
 *
 * Returns: 1 if a nonce was successfully generated. 0 will cause signing to fail.
 * Out:     nonce32:   pointer to a 32-byte array to be filled by the function.
 * In:      msg32:     the 32-byte message hash being verified (will not be NULL)
 *          key32:     pointer to a 32-byte secret key (will not be NULL)
 *          algo16:    pointer to a 16-byte array describing the signature
 *                     algorithm (will be NULL for ECDSA for compatibility).
 *          data:      Arbitrary data pointer that is passed through.
 *          attempt:   how many iterations we have tried to find a nonce.
 *                     This will almost always be 0, but different attempt values
 *                     are required to result in a different nonce.
 *
 * Except for test cases, this function should compute some cryptographic hash of
 * the message, the algorithm, the key and the attempt.
 */
typedef int (*secp256k1_nonce_function)(
    unsigned char *nonce32,
    const unsigned char *msg32,
    const unsigned char *key32,
    const unsigned char *algo16,
    void *data,
    unsigned int attempt
);

# if !defined(SECP256K1_GNUC_PREREQ)
#  if defined(__GNUC__)&&defined(__GNUC_MINOR__)
#   define SECP256K1_GNUC_PREREQ(_maj,_min) \
 ((__GNUC__<<16)+__GNUC_MINOR__>=((_maj)<<16)+(_min))
#  else
#   define SECP256K1_GNUC_PREREQ(_maj,_min) 0
#  endif
# endif

/*  When this header is used at build-time the SECP256K1_BUILD define needs to be set
 *  to correctly setup export attributes and nullness checks.  This is normally done
 *  by secp256k1.c but to guard against this header being included before secp256k1.c
 *  has had a chance to set the define (e.g. via test harnesses that just includes
 *  secp256k1.c) we set SECP256K1_NO_BUILD when this header is processed without the
 *  BUILD define so this condition can be caught.
 */
#ifndef SECP256K1_BUILD
# define SECP256K1_NO_BUILD
#endif

/* Symbol visibility. */
#if defined(_WIN32)
  /* GCC for Windows (e.g., MinGW) accepts the __declspec syntax
   * for MSVC compatibility. A __declspec declaration implies (but is not
   * exactly equivalent to) __attribute__ ((visibility("default"))), and so we
   * actually want __declspec even on GCC, see "Microsoft Windows Function
   * Attributes" in the GCC manual and the recommendations in
   * https://gcc.gnu.org/wiki/Visibility. */
# if defined(SECP256K1_BUILD)
#  if defined(DLL_EXPORT) || defined(SECP256K1_DLL_EXPORT)
    /* Building libsecp256k1 as a DLL.
     * 1. If using Libtool, it defines DLL_EXPORT automatically.
     * 2. In other cases, SECP256K1_DLL_EXPORT must be defined. */
#   define SECP256K1_API extern __declspec (dllexport)
#  else
    /* Building libsecp256k1 as a static library on Windows.
     * No declspec is needed, and so we would want the non-Windows-specific
     * logic below take care of this case. However, this may result in setting
     * __attribute__ ((visibility("default"))), which is supposed to be a noop
     * on Windows but may trigger warnings when compiling with -flto due to a
     * bug in GCC, see
     * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116478 . */
#   define SECP256K1_API extern
#  endif
  /* The user must define SECP256K1_STATIC when consuming libsecp256k1 as a static