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+#ifndef _SECP256K1_
+# define _SECP256K1_
+
+# ifdef __cplusplus
+extern "C" {
+# endif
+
+#include <stddef.h>
+
+/* These rules specify the order of arguments in API calls:
+ *
+ * 1. Context pointers go first, followed by output arguments, combined
+ * output/input arguments, and finally input-only arguments.
+ * 2. Array lengths always immediately the follow the argument whose length
+ * they describe, even if this violates rule 1.
+ * 3. Within the OUT/OUTIN/IN groups, pointers to data that is typically generated
+ * later go first. This means: signatures, public nonces, private nonces,
+ * messages, public keys, secret keys, tweaks.
+ * 4. Arguments that are not data pointers go last, from more complex to less
+ * complex: function pointers, algorithm names, messages, void pointers,
+ * counts, flags, booleans.
+ * 5. Opaque data pointers follow the function pointer they are to be passed to.
+ */
+
+/** Opaque data structure that holds context information (precomputed tables etc.).
+ *
+ * The purpose of context structures is to cache large precomputed data tables
+ * that are expensive to construct, and also to maintain the randomization data
+ * for blinding.
+ *
+ * Do not create a new context object for each operation, as construction is
+ * far slower than all other API calls (~100 times slower than an ECDSA
+ * verification).
+ *
+ * A constructed context can safely be used from multiple threads
+ * simultaneously, but API call that take a non-const pointer to a context
+ * need exclusive access to it. In particular this is the case for
+ * secp256k1_context_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.
+ *
+ * Furthermore, it is guaranteed that identical public keys (ignoring
+ * compression) will have identical representation, so they can be memcmp'ed.
+ */
+typedef struct {
+ unsigned char data[64];
+} secp256k1_pubkey;
+
+/** Opaque data structured 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 or transmission, use
+ * the secp256k1_ecdsa_signature_serialize_* and
+ * secp256k1_ecdsa_signature_serialize_* functions.
+ *
+ * Furthermore, it is guaranteed to identical signatures will have identical
+ * representation, so they can be memcmp'ed.
+ */
+typedef struct {
+ 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
+
+# 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
+
+#ifndef SECP256K1_API
+# if defined(_WIN32)
+# ifdef SECP256K1_BUILD
+# define SECP256K1_API __declspec(dllexport)
+# else
+# define SECP256K1_API
+# endif
+# elif defined(__GNUC__) && defined(SECP256K1_BUILD)
+# define SECP256K1_API __attribute__ ((visibility ("default")))
+# else
+# define SECP256K1_API
+# endif
+#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_context_create. */
+# define SECP256K1_CONTEXT_VERIFY (1 << 0)
+# define SECP256K1_CONTEXT_SIGN (1 << 1)
+
+/** Flag to pass to secp256k1_ec_pubkey_serialize and secp256k1_ec_privkey_export. */
+# define SECP256K1_EC_COMPRESSED (1 << 0)
+
+/** Create a secp256k1 context object.
+ *
+ * Returns: a newly created context object.
+ * In: flags: which parts of the context to initialize.
+ */
+SECP256K1_API secp256k1_context* secp256k1_context_create(
+ unsigned int flags
+) SECP256K1_WARN_UNUSED_RESULT;
+
+/** Copies a secp256k1 context object.
+ *
+ * Returns: a newly created context object.
+ * Args: ctx: an existing context to copy (cannot be NULL)
+ */
+SECP256K1_API secp256k1_context* secp256k1_context_clone(
+ const secp256k1_context* ctx
+) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT;
+
+/** Destroy a secp256k1 context object.
+ *
+ * The context pointer may not be used afterwards.
+ * Args: ctx: an existing context to destroy (cannot be NULL)
+ */
+SECP256K1_API void secp256k1_context_destroy(
+ secp256k1_context* ctx
+);
+
+/** Set a callback function to be called when an illegal argument is passed to
+ * an API call. It will only trigger for violations that are mentioned
+ * explicitly in the header.
+ *
+ * The philosophy is that these shouldn't be dealt with through a
+ * specific return value, as calling code should not have branches to deal with
+ * the case that this code itself is broken.
+ *
+ * On the other hand, during debug stage, one would want to be informed about
+ * such mistakes, and the default (crashing) may be inadvisable.
+ * When this callback is triggered, the API function called is guaranteed not
+ * to cause a crash, though its return value and output arguments are
+ * undefined.
+ *
+ * Args: ctx: an existing context object (cannot be NULL)
+ * In: fun: a pointer to a function to call when an illegal argument is
+ * passed to the API, taking a message and an opaque pointer
+ * (NULL restores a default handler that calls abort).
+ * data: the opaque pointer to pass to fun above.
+ */
+SECP256K1_API void secp256k1_context_set_illegal_callback(
+ secp256k1_context* ctx,
+ void (*fun)(const char* message, void* data),
+ const void* data
+) SECP256K1_ARG_NONNULL(1);
+
+/** Set a callback function to be called when an internal consistency check
+ * fails. The default is crashing.
+ *
+ * This can only trigger in case of a hardware failure, miscompilation,
+ * memory corruption, serious bug in the library, or other error would can
+ * otherwise result in undefined behaviour. It will not trigger due to mere
+ * incorrect usage of the API (see secp256k1_context_set_illegal_callback
+ * for that). After this callback returns, anything may happen, including
+ * crashing.
+ *
+ * Args: ctx: an existing context object (cannot be NULL)
+ * In: fun: a pointer to a function to call when an interal error occurs,
+ * taking a message and an opaque pointer (NULL restores a default
+ * handler that calls abort).
+ * data: the opaque pointer to pass to fun above.
+ */
+SECP256K1_API void secp256k1_context_set_error_callback(
+ secp256k1_context* ctx,
+ void (*fun)(const char* message, void* data),
+ const void* data
+) SECP256K1_ARG_NONNULL(1);
+
+/** Parse a variable-length public key into the pubkey object.
+ *
+ * Returns: 1 if the public key was fully valid.
+ * 0 if the public key could not be parsed or is invalid.
+ * Args: ctx: a secp256k1 context object.
+ * Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to a
+ * parsed version of input. If not, its value is undefined.
+ * In: input: pointer to a serialized public key
+ * inputlen: length of the array pointed to by input
+ *
+ * This function supports parsing compressed (33 bytes, header byte 0x02 or
+ * 0x03), uncompressed (65 bytes, header byte 0x04), or hybrid (65 bytes, header
+ * byte 0x06 or 0x07) format public keys.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_parse(
+ const secp256k1_context* ctx,
+ secp256k1_pubkey* pubkey,
+ const unsigned char *input,
+ size_t inputlen
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Serialize a pubkey object into a serialized byte sequence.
+ *
+ * Returns: 1 always.
+ * Args: ctx: a secp256k1 context object.
+ * Out: output: a pointer to a 65-byte (if compressed==0) or 33-byte (if
+ * compressed==1) byte array to place the serialized key in.
+ * outputlen: a pointer to an integer which will contain the serialized
+ * size.
+ * In: pubkey: a pointer to a secp256k1_pubkey containing an initialized
+ * public key.
+ * flags: SECP256K1_EC_COMPRESSED if serialization should be in
+ * compressed format.
+ */
+SECP256K1_API int secp256k1_ec_pubkey_serialize(
+ const secp256k1_context* ctx,
+ unsigned char *output,
+ size_t *outputlen,
+ const secp256k1_pubkey* pubkey,
+ unsigned int flags
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+/** Parse a DER ECDSA signature.
+ *
+ * Returns: 1 when the signature could be parsed, 0 otherwise.
+ * Args: ctx: a secp256k1 context object
+ * Out: sig: a pointer to a signature object
+ * In: input: a pointer to the signature to be parsed
+ * inputlen: the length of the array pointed to be input
+ *
+ * Note that this function also supports some violations of DER and even BER.
+ */
+SECP256K1_API int secp256k1_ecdsa_signature_parse_der(
+ const secp256k1_context* ctx,
+ secp256k1_ecdsa_signature* sig,
+ const unsigned char *input,
+ size_t inputlen
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Serialize an ECDSA signature in DER format.
+ *
+ * Returns: 1 if enough space was available to serialize, 0 otherwise
+ * Args: ctx: a secp256k1 context object
+ * Out: output: a pointer to an array to store the DER serialization
+ * In/Out: outputlen: a pointer to a length integer. Initially, this integer
+ * should be set to the length of output. After the call
+ * it will be set to the length of the serialization (even
+ * if 0 was returned).
+ * In: sig: a pointer to an initialized signature object
+ */
+SECP256K1_API int secp256k1_ecdsa_signature_serialize_der(
+ const secp256k1_context* ctx,
+ unsigned char *output,
+ size_t *outputlen,
+ const secp256k1_ecdsa_signature* sig
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+/** Verify an ECDSA signature.
+ *
+ * Returns: 1: correct signature
+ * 0: incorrect or unparseable signature
+ * Args: ctx: a secp256k1 context object, initialized for verification.
+ * In: sig: the signature being verified (cannot be NULL)
+ * msg32: the 32-byte message hash being verified (cannot be NULL)
+ * pubkey: pointer to an initialized public key to verify with (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
+ const secp256k1_context* ctx,
+ const secp256k1_ecdsa_signature *sig,
+ const unsigned char *msg32,
+ const secp256k1_pubkey *pubkey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+/** An implementation of RFC6979 (using HMAC-SHA256) as nonce generation function.
+ * If a data pointer is passed, it is assumed to be a pointer to 32 bytes of
+ * extra entropy.
+ */
+extern const secp256k1_nonce_function secp256k1_nonce_function_rfc6979;
+
+/** A default safe nonce generation function (currently equal to secp256k1_nonce_function_rfc6979). */
+extern const secp256k1_nonce_function secp256k1_nonce_function_default;
+
+/** Create an ECDSA signature.
+ *
+ * Returns: 1: signature created
+ * 0: the nonce generation function failed, or the private key was invalid.
+ * Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
+ * Out: sig: pointer to an array where the signature will be placed (cannot be NULL)
+ * 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)
+ *
+ * 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.
+ */
+SECP256K1_API int secp256k1_ecdsa_sign(
+ const secp256k1_context* ctx,
+ secp256k1_ecdsa_signature *sig,
+ const unsigned char *msg32,
+ const unsigned char *seckey,
+ secp256k1_nonce_function noncefp,
+ const void *ndata
+) 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
+ * Args: ctx: pointer to a context object (cannot be NULL)
+ * In: seckey: pointer to a 32-byte secret key (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify(
+ const secp256k1_context* ctx,
+ const unsigned char *seckey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
+
+/** Compute the public key for a secret key.
+ *
+ * Returns: 1: secret was valid, public key stores
+ * 0: secret was invalid, try again
+ * Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
+ * Out: pubkey: pointer to the created public key (cannot be NULL)
+ * In: seckey: pointer to a 32-byte private key (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
+ const secp256k1_context* ctx,
+ secp256k1_pubkey *pubkey,
+ const unsigned char *seckey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Export a private key in BER format.
+ *
+ * Returns: 1 if the private key was valid.
+ * Args: ctx: pointer to a context object, initialized for signing (cannot
+ * be NULL)
+ * Out: privkey: pointer to an array for storing the private key in BER.
+ * Should have space for 279 bytes, and cannot be NULL.
+ * privkeylen: Pointer to an int where the length of the private key in
+ * privkey will be stored.
+ * In: seckey: pointer to a 32-byte secret key to export.
+ * flags: SECP256K1_EC_COMPRESSED if the key should be exported in
+ * compressed format.
+ *
+ * This function is purely meant for compatibility with applications that
+ * require BER encoded keys. When working with secp256k1-specific code, the
+ * simple 32-byte private keys are sufficient.
+ *
+ * Note that this function does not guarantee correct DER output. It is
+ * guaranteed to be parsable by secp256k1_ec_privkey_import.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_export(
+ const secp256k1_context* ctx,
+ unsigned char *privkey,
+ size_t *privkeylen,
+ const unsigned char *seckey,
+ unsigned int flags
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
+
+/** Import a private key in DER format.
+ * Returns: 1 if a private key was extracted.
+ * Args: ctx: pointer to a context object (cannot be NULL).
+ * Out: seckey: pointer to a 32-byte array for storing the private key.
+ * (cannot be NULL).
+ * In: privkey: pointer to a private key in DER format (cannot be NULL).
+ * privkeylen: length of the DER private key pointed to be privkey.
+ *
+ * This function will accept more than just strict DER, and even allow some BER
+ * violations. The public key stored inside the DER-encoded private key is not
+ * verified for correctness, nor are the curve parameters. Use this function
+ * only if you know in advance it is supposed to contain a secp256k1 private
+ * key.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_import(
+ const secp256k1_context* ctx,
+ unsigned char *seckey,
+ const unsigned char *privkey,
+ size_t privkeylen
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Tweak a private key by adding tweak to it.
+ * Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
+ * uniformly random 32-byte arrays, or if the resulting private key
+ * would be invalid (only when the tweak is the complement of the
+ * private key). 1 otherwise.
+ * Args: ctx: pointer to a context object (cannot be NULL).
+ * In/Out: seckey: pointer to a 32-byte private key.
+ * In: tweak: pointer to a 32-byte tweak.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add(
+ const secp256k1_context* ctx,
+ unsigned char *seckey,
+ const unsigned char *tweak
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Tweak a public key by adding tweak times the generator to it.
+ * Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
+ * uniformly random 32-byte arrays, or if the resulting public key
+ * would be invalid (only when the tweak is the complement of the
+ * corresponding private key). 1 otherwise.
+ * Args: ctx: pointer to a context object initialized for validation
+ * (cannot be NULL).
+ * In/Out: pubkey: pointer to a public key object.
+ * In: tweak: pointer to a 32-byte tweak.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add(
+ const secp256k1_context* ctx,
+ secp256k1_pubkey *pubkey,
+ const unsigned char *tweak
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Tweak a private key by multiplying it by a tweak.
+ * Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
+ * uniformly random 32-byte arrays, or equal to zero. 1 otherwise.
+ * Args: ctx: pointer to a context object (cannot be NULL).
+ * In/Out: seckey: pointer to a 32-byte private key.
+ * In: tweak: pointer to a 32-byte tweak.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul(
+ const secp256k1_context* ctx,
+ unsigned char *seckey,
+ const unsigned char *tweak
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Tweak a public key by multiplying it by a tweak value.
+ * Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
+ * uniformly random 32-byte arrays, or equal to zero. 1 otherwise.
+ * Args: ctx: pointer to a context object initialized for validation
+ * (cannot be NULL).
+ * In/Out: pubkey: pointer to a public key obkect.
+ * In: tweak: pointer to a 32-byte tweak.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul(
+ const secp256k1_context* ctx,
+ secp256k1_pubkey *pubkey,
+ const unsigned char *tweak
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+/** Updates the context randomization.
+ * Returns: 1: randomization successfully updated
+ * 0: error
+ * Args: ctx: pointer to a context object (cannot be NULL)
+ * In: seed32: pointer to a 32-byte random seed (NULL resets to initial state)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_context_randomize(
+ secp256k1_context* ctx,
+ const unsigned char *seed32
+) SECP256K1_ARG_NONNULL(1);
+
+/** Add a number of public keys together.
+ * Returns: 1: the sum of the public keys is valid.
+ * 0: the sum of the public keys is not valid.
+ * Args: ctx: pointer to a context object
+ * Out: out: pointer to pubkey for placing the resulting public key
+ * (cannot be NULL)
+ * In: ins: pointer to array of pointers to public keys (cannot be NULL)
+ * n: the number of public keys to add together (must be at least 1)
+ * Use secp256k1_ec_pubkey_compress and secp256k1_ec_pubkey_decompress if the
+ * uncompressed format is needed.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_combine(
+ const secp256k1_context* ctx,
+ secp256k1_pubkey *out,
+ const secp256k1_pubkey * const * ins,
+ int n
+) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
+
+# ifdef __cplusplus
+}
+# endif
+
+#endif