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295 lines
13 KiB
295 lines
13 KiB
#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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/** Just validate a public key. |
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* Returns: 1: valid public key |
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* 0: invalid public key |
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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 if the passed public key was invalid, 1 otherwise. If 1 is returned, the |
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pubkey is 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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