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#ifndef _SECP256K1_
# define _SECP256K1_
# ifdef __cplusplus
extern "C" {
# endif
# 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
# if (!defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L) )
# if SECP256K1_GNUC_PREREQ(2,7)
# define SECP256K1_INLINE __inline__
# elif (defined(_MSC_VER))
# define SECP256K1_INLINE __inline
# else
# define SECP256K1_INLINE
# endif
# else
# define SECP256K1_INLINE inline
# endif
/**Warning attributes
* NONNULL is not used if SECP256K1_BUILD is set to avoid the compiler optimizing out
* some paranoid null checks. */
# if defined(__GNUC__) && SECP256K1_GNUC_PREREQ(3, 4)
# define SECP256K1_WARN_UNUSED_RESULT __attribute__ ((__warn_unused_result__))
# else
# define SECP256K1_WARN_UNUSED_RESULT
# endif
# if !defined(SECP256K1_BUILD) && defined(__GNUC__) && SECP256K1_GNUC_PREREQ(3, 4)
# define SECP256K1_ARG_NONNULL(_x) __attribute__ ((__nonnull__(_x)))
# else
# define SECP256K1_ARG_NONNULL(_x)
# endif
/** Flags to pass to secp256k1_start. */
# define SECP256K1_START_VERIFY (1 << 0)
# define SECP256K1_START_SIGN (1 << 1)
/** Initialize the library. This may take some time (10-100 ms).
* You need to call this before calling any other function.
* It cannot run in parallel with any other functions, but once
* secp256k1_start() returns, all other functions are thread-safe.
*/
void secp256k1_start(unsigned int flags);
/** Free all memory associated with this library. After this, no
* functions can be called anymore, except secp256k1_start()
*/
void secp256k1_stop(void);
/** Verify an ECDSA signature.
* Returns: 1: correct signature
* 0: incorrect signature
* -1: invalid public key
* -2: invalid signature
* In: msg32: the 32-byte message hash being verified (cannot be NULL)
* sig: the signature being verified (cannot be NULL)
* siglen: the length of the signature
* pubkey: the public key to verify with (cannot be NULL)
* pubkeylen: the length of pubkey
* Requires starting using SECP256K1_START_VERIFY.
*/
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
const unsigned char *msg32,
const unsigned char *sig,
int siglen,
const unsigned char *pubkey,
int pubkeylen
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
/** A pointer to a function to deterministically generate a nonce.
* Returns: 1 if a nonce was successfully generated. 0 will cause signing to fail.
* 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)
* 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.
* data: Arbitrary data pointer that is passed through.
* Out: nonce32: pointer to a 32-byte array to be filled by the function.
* Except for test cases, this function should compute some cryptographic hash of
* the message, the key and the attempt.
*/
typedef int (*secp256k1_nonce_function_t)(
unsigned char *nonce32,
const unsigned char *msg32,
const unsigned char *key32,
unsigned int attempt,
const void *data
);
/** An implementation of RFC6979 (using HMAC-SHA256) as nonce generation function. */
extern const secp256k1_nonce_function_t secp256k1_nonce_function_rfc6979;
/** A default safe nonce generation function (currently equal to secp256k1_nonce_function_rfc6979). */
extern const secp256k1_nonce_function_t secp256k1_nonce_function_default;
/** Create an ECDSA signature.
* Returns: 1: signature created
* 0: the nonce generation function failed, the private key was invalid, or there is not
* enough space in the signature (as indicated by siglen).
* In: msg32: the 32-byte message hash being signed (cannot be NULL)
* seckey: pointer to a 32-byte secret key (cannot be NULL)
* noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
* ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
* Out: sig: pointer to an array where the signature will be placed (cannot be NULL)
* In/Out: siglen: pointer to an int with the length of sig, which will be updated
* to contain the actual signature length (<=72). If 0 is returned, this will be
* set to zero.
* Requires starting using SECP256K1_START_SIGN.
*
* The sig always has an s value in the lower half of the range (From 0x1
* to 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
* inclusive), unlike many other implementations.
* With ECDSA a third-party can can forge a second distinct signature
* of the same message given a single initial signature without knowing
* the key by setting s to its additive inverse mod-order, 'flipping' the
* sign of the random point R which is not included in the signature.
* Since the forgery is of the same message this isn't universally
* problematic, but in systems where message malleability or uniqueness
* of signatures is important this can cause issues. This forgery can be
* blocked by all verifiers forcing signers to use a canonical form. The
* lower-S form reduces the size of signatures slightly on average when
* variable length encodings (such as DER) are used and is cheap to
* verify, making it a good choice. Security of always using lower-S is
* assured because anyone can trivially modify a signature after the
* fact to enforce this property. Adjusting it inside the signing
* function avoids the need to re-serialize or have curve specific
* constants outside of the library. By always using a canonical form
* even in applications where it isn't needed it becomes possible to
* impose a requirement later if a need is discovered.
* No other forms of ECDSA malleability are known and none seem likely,
* but there is no formal proof that ECDSA, even with this additional
* restriction, is free of other malleability. Commonly used serialization
* schemes will also accept various non-unique encodings, so care should
* be taken when this property is required for an application.
*/
int secp256k1_ecdsa_sign(
const unsigned char *msg32,
unsigned char *sig,
int *siglen,
const unsigned char *seckey,
secp256k1_nonce_function_t noncefp,
const void *ndata
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Create a compact ECDSA signature (64 byte + recovery id).
* Returns: 1: signature created
* 0: the nonce generation function failed, or the secret key was invalid.
* In: msg32: the 32-byte message hash being signed (cannot be NULL)
* seckey: pointer to a 32-byte secret key (cannot be NULL)
* noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
* ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
* Out: sig: pointer to a 64-byte array where the signature will be placed (cannot be NULL)
* In case 0 is returned, the returned signature length will be zero.
* recid: pointer to an int, which will be updated to contain the recovery id (can be NULL)
* Requires starting using SECP256K1_START_SIGN.
*/
int secp256k1_ecdsa_sign_compact(
const unsigned char *msg32,
unsigned char *sig64,
const unsigned char *seckey,
secp256k1_nonce_function_t noncefp,
const void *ndata,
int *recid
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Recover an ECDSA public key from a compact signature.
* Returns: 1: public key successfully recovered (which guarantees a correct signature).
* 0: otherwise.
* In: msg32: the 32-byte message hash assumed to be signed (cannot be NULL)
* sig64: signature as 64 byte array (cannot be NULL)
* compressed: whether to recover a compressed or uncompressed pubkey
* recid: the recovery id (0-3, as returned by ecdsa_sign_compact)
* Out: pubkey: pointer to a 33 or 65 byte array to put the pubkey (cannot be NULL)
* pubkeylen: pointer to an int that will contain the pubkey length (cannot be NULL)
* Requires starting using SECP256K1_START_VERIFY.
*/
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_recover_compact(
const unsigned char *msg32,
const unsigned char *sig64,
unsigned char *pubkey,
int *pubkeylen,
int compressed,
int recid
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Verify an ECDSA secret key.
* Returns: 1: secret key is valid
* 0: secret key is invalid
* In: seckey: pointer to a 32-byte secret key (cannot be NULL)
*/
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify(const unsigned char *seckey) SECP256K1_ARG_NONNULL(1);
/** Just validate a public key.
* Returns: 1: valid public key
* 0: invalid public key
* In: pubkey: pointer to a 33-byte or 65-byte public key (cannot be NULL).
* pubkeylen: length of pubkey
*/
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_verify(const unsigned char *pubkey, int pubkeylen) SECP256K1_ARG_NONNULL(1);
/** Compute the public key for a secret key.
* In: compressed: whether the computed public key should be compressed
* seckey: pointer to a 32-byte private key (cannot be NULL)
* Out: pubkey: pointer to a 33-byte (if compressed) or 65-byte (if uncompressed)
* area to store the public key (cannot be NULL)
* pubkeylen: pointer to int that will be updated to contains the pubkey's
* length (cannot be NULL)
* Returns: 1: secret was valid, public key stores
* 0: secret was invalid, try again.
* Requires starting using SECP256K1_START_SIGN.
*/
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
unsigned char *pubkey,
int *pubkeylen,
const unsigned char *seckey,
int compressed
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Decompress a public key.
* In/Out: pubkey: pointer to a 65-byte array to put the decompressed public key.
It must contain a 33-byte or 65-byte public key already (cannot be NULL)
* pubkeylen: pointer to the size of the public key pointed to by pubkey (cannot be NULL)
It will be updated to reflect the new size.
* Returns: 0 if the passed public key was invalid, 1 otherwise. If 1 is returned, the
pubkey is replaced with its decompressed version.
*/
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_decompress(
unsigned char *pubkey,
int *pubkeylen
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
/** Export a private key in DER format. */
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_export(
const unsigned char *seckey,
unsigned char *privkey,
int *privkeylen,
int compressed
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Import a private key in DER format. */
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_import(
unsigned char *seckey,
const unsigned char *privkey,
int privkeylen
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
/** Tweak a private key by adding tweak to it. */
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
unsigned char *seckey,
const unsigned char *tweak
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
/** Tweak a public key by adding tweak times the generator to it.
* Requires starting with SECP256K1_START_VERIFY.
*/
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
unsigned char *pubkey,
int pubkeylen,
const unsigned char *tweak
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3);
/** Tweak a private key by multiplying it with tweak. */
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
unsigned char *seckey,
const unsigned char *tweak
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
/** Tweak a public key by multiplying it with tweak.
* Requires starting with SECP256K1_START_VERIFY.
*/
SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
unsigned char *pubkey,
int pubkeylen,
const unsigned char *tweak
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3);
# ifdef __cplusplus
}
# endif
#endif