mirror of
https://github.com/bitcoin/bitcoin.git
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296 lines
13 KiB
C
296 lines
13 KiB
C
#ifndef _SECP256K1_
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# define _SECP256K1_
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# ifdef __cplusplus
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extern "C" {
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# endif
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# if !defined(SECP256K1_GNUC_PREREQ)
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# if defined(__GNUC__)&&defined(__GNUC_MINOR__)
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# define SECP256K1_GNUC_PREREQ(_maj,_min) \
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((__GNUC__<<16)+__GNUC_MINOR__>=((_maj)<<16)+(_min))
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# else
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# define SECP256K1_GNUC_PREREQ(_maj,_min) 0
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# endif
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# endif
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# if (!defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L) )
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# if SECP256K1_GNUC_PREREQ(2,7)
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# define SECP256K1_INLINE __inline__
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# elif (defined(_MSC_VER))
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# define SECP256K1_INLINE __inline
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# else
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# define SECP256K1_INLINE
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# endif
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# else
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# define SECP256K1_INLINE inline
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# endif
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/**Warning attributes
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* NONNULL is not used if SECP256K1_BUILD is set to avoid the compiler optimizing out
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* some paranoid null checks. */
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# if defined(__GNUC__) && SECP256K1_GNUC_PREREQ(3, 4)
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# define SECP256K1_WARN_UNUSED_RESULT __attribute__ ((__warn_unused_result__))
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# else
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# define SECP256K1_WARN_UNUSED_RESULT
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# endif
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# if !defined(SECP256K1_BUILD) && defined(__GNUC__) && SECP256K1_GNUC_PREREQ(3, 4)
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# define SECP256K1_ARG_NONNULL(_x) __attribute__ ((__nonnull__(_x)))
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# else
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# define SECP256K1_ARG_NONNULL(_x)
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# endif
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/** Flags to pass to secp256k1_start. */
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# define SECP256K1_START_VERIFY (1 << 0)
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# define SECP256K1_START_SIGN (1 << 1)
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/** Initialize the library. This may take some time (10-100 ms).
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* You need to call this before calling any other function.
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* It cannot run in parallel with any other functions, but once
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* secp256k1_start() returns, all other functions are thread-safe.
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*/
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void secp256k1_start(unsigned int flags);
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/** Free all memory associated with this library. After this, no
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* functions can be called anymore, except secp256k1_start()
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*/
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void secp256k1_stop(void);
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/** Verify an ECDSA signature.
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* Returns: 1: correct signature
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* 0: incorrect signature
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* -1: invalid public key
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* -2: invalid signature
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* In: msg32: the 32-byte message hash being verified (cannot be NULL)
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* sig: the signature being verified (cannot be NULL)
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* siglen: the length of the signature
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* pubkey: the public key to verify with (cannot be NULL)
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* pubkeylen: the length of pubkey
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* Requires starting using SECP256K1_START_VERIFY.
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*/
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
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const unsigned char *msg32,
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const unsigned char *sig,
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int siglen,
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const unsigned char *pubkey,
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int pubkeylen
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
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/** A pointer to a function to deterministically generate a nonce.
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* Returns: 1 if a nonce was successfully generated. 0 will cause signing to fail.
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* In: msg32: the 32-byte message hash being verified (will not be NULL)
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* key32: pointer to a 32-byte secret key (will not be NULL)
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* attempt: how many iterations we have tried to find a nonce.
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* This will almost always be 0, but different attempt values
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* are required to result in a different nonce.
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* data: Arbitrary data pointer that is passed through.
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* Out: nonce32: pointer to a 32-byte array to be filled by the function.
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* Except for test cases, this function should compute some cryptographic hash of
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* the message, the key and the attempt.
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*/
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typedef int (*secp256k1_nonce_function_t)(
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unsigned char *nonce32,
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const unsigned char *msg32,
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const unsigned char *key32,
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unsigned int attempt,
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const void *data
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);
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/** An implementation of RFC6979 (using HMAC-SHA256) as nonce generation function.
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* If a data pointer is passed, it is assumed to be a pointer to 32 bytes of
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* extra entropy.
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*/
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extern const secp256k1_nonce_function_t secp256k1_nonce_function_rfc6979;
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/** A default safe nonce generation function (currently equal to secp256k1_nonce_function_rfc6979). */
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extern const secp256k1_nonce_function_t secp256k1_nonce_function_default;
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/** Create an ECDSA signature.
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* Returns: 1: signature created
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* 0: the nonce generation function failed, the private key was invalid, or there is not
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* enough space in the signature (as indicated by siglen).
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* In: msg32: the 32-byte message hash being signed (cannot be NULL)
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* seckey: pointer to a 32-byte secret key (cannot be NULL)
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* noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
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* ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
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* Out: sig: pointer to an array where the signature will be placed (cannot be NULL)
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* In/Out: siglen: pointer to an int with the length of sig, which will be updated
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* to contain the actual signature length (<=72). If 0 is returned, this will be
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* set to zero.
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* Requires starting using SECP256K1_START_SIGN.
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*
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* The sig always has an s value in the lower half of the range (From 0x1
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* to 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
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* inclusive), unlike many other implementations.
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* With ECDSA a third-party can can forge a second distinct signature
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* of the same message given a single initial signature without knowing
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* the key by setting s to its additive inverse mod-order, 'flipping' the
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* sign of the random point R which is not included in the signature.
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* Since the forgery is of the same message this isn't universally
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* problematic, but in systems where message malleability or uniqueness
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* of signatures is important this can cause issues. This forgery can be
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* blocked by all verifiers forcing signers to use a canonical form. The
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* lower-S form reduces the size of signatures slightly on average when
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* variable length encodings (such as DER) are used and is cheap to
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* verify, making it a good choice. Security of always using lower-S is
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* assured because anyone can trivially modify a signature after the
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* fact to enforce this property. Adjusting it inside the signing
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* function avoids the need to re-serialize or have curve specific
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* constants outside of the library. By always using a canonical form
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* even in applications where it isn't needed it becomes possible to
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* impose a requirement later if a need is discovered.
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* No other forms of ECDSA malleability are known and none seem likely,
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* but there is no formal proof that ECDSA, even with this additional
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* restriction, is free of other malleability. Commonly used serialization
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* schemes will also accept various non-unique encodings, so care should
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* be taken when this property is required for an application.
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*/
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int secp256k1_ecdsa_sign(
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const unsigned char *msg32,
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unsigned char *sig,
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int *siglen,
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const unsigned char *seckey,
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secp256k1_nonce_function_t noncefp,
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const void *ndata
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
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/** Create a compact ECDSA signature (64 byte + recovery id).
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* Returns: 1: signature created
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* 0: the nonce generation function failed, or the secret key was invalid.
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* In: msg32: the 32-byte message hash being signed (cannot be NULL)
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* seckey: pointer to a 32-byte secret key (cannot be NULL)
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* noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
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* ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
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* Out: sig: pointer to a 64-byte array where the signature will be placed (cannot be NULL)
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* In case 0 is returned, the returned signature length will be zero.
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* recid: pointer to an int, which will be updated to contain the recovery id (can be NULL)
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* Requires starting using SECP256K1_START_SIGN.
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*/
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int secp256k1_ecdsa_sign_compact(
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const unsigned char *msg32,
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unsigned char *sig64,
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const unsigned char *seckey,
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secp256k1_nonce_function_t noncefp,
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const void *ndata,
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int *recid
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Recover an ECDSA public key from a compact signature.
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* Returns: 1: public key successfully recovered (which guarantees a correct signature).
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* 0: otherwise.
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* In: msg32: the 32-byte message hash assumed to be signed (cannot be NULL)
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* sig64: signature as 64 byte array (cannot be NULL)
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* compressed: whether to recover a compressed or uncompressed pubkey
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* recid: the recovery id (0-3, as returned by ecdsa_sign_compact)
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* Out: pubkey: pointer to a 33 or 65 byte array to put the pubkey (cannot be NULL)
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* pubkeylen: pointer to an int that will contain the pubkey length (cannot be NULL)
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* Requires starting using SECP256K1_START_VERIFY.
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*/
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_recover_compact(
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const unsigned char *msg32,
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const unsigned char *sig64,
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unsigned char *pubkey,
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int *pubkeylen,
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int compressed,
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int recid
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
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/** Verify an ECDSA secret key.
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* Returns: 1: secret key is valid
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* 0: secret key is invalid
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* In: seckey: pointer to a 32-byte secret key (cannot be NULL)
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*/
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify(const unsigned char *seckey) SECP256K1_ARG_NONNULL(1);
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/** Verify an ECDSA public key.
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* Returns: 1: public key is valid
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* 0: public key is invalid
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* In: pubkey: pointer to a 33-byte or 65-byte public key (cannot be NULL).
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* pubkeylen: length of pubkey
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*/
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_verify(const unsigned char *pubkey, int pubkeylen) SECP256K1_ARG_NONNULL(1);
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/** Compute the public key for a secret key.
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* In: compressed: whether the computed public key should be compressed
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* seckey: pointer to a 32-byte private key (cannot be NULL)
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* Out: pubkey: pointer to a 33-byte (if compressed) or 65-byte (if uncompressed)
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* area to store the public key (cannot be NULL)
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* pubkeylen: pointer to int that will be updated to contains the pubkey's
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* length (cannot be NULL)
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* Returns: 1: secret was valid, public key stores
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* 0: secret was invalid, try again
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* Requires starting using SECP256K1_START_SIGN.
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*/
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
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unsigned char *pubkey,
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int *pubkeylen,
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const unsigned char *seckey,
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int compressed
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Decompress a public key.
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* In/Out: pubkey: pointer to a 65-byte array to put the decompressed public key.
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* It must contain a 33-byte or 65-byte public key already (cannot be NULL)
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* pubkeylen: pointer to the size of the public key pointed to by pubkey (cannot be NULL)
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* It will be updated to reflect the new size.
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* Returns: 0: pubkey was invalid
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* 1: pubkey was valid, and was replaced with its decompressed version
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*/
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_decompress(
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unsigned char *pubkey,
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int *pubkeylen
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
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/** Export a private key in DER format. */
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_export(
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const unsigned char *seckey,
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unsigned char *privkey,
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int *privkeylen,
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int compressed
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Import a private key in DER format. */
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_import(
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unsigned char *seckey,
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const unsigned char *privkey,
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int privkeylen
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
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/** Tweak a private key by adding tweak to it. */
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
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unsigned char *seckey,
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const unsigned char *tweak
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
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/** Tweak a public key by adding tweak times the generator to it.
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* Requires starting with SECP256K1_START_VERIFY.
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*/
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
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unsigned char *pubkey,
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int pubkeylen,
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const unsigned char *tweak
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3);
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/** Tweak a private key by multiplying it with tweak. */
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
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unsigned char *seckey,
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const unsigned char *tweak
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
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/** Tweak a public key by multiplying it with tweak.
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* Requires starting with SECP256K1_START_VERIFY.
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*/
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SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
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unsigned char *pubkey,
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int pubkeylen,
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const unsigned char *tweak
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3);
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# ifdef __cplusplus
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}
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# endif
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#endif
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