250 lines
11 KiB
C
250 lines
11 KiB
C
#ifndef SECP256K1_EXTRAKEYS_H
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#define SECP256K1_EXTRAKEYS_H
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#include "secp256k1.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** Opaque data structure that holds a parsed and valid "x-only" public key.
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* An x-only pubkey encodes a point whose Y coordinate is even. It is
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* serialized using only its X coordinate (32 bytes). See BIP-340 for more
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* information about x-only pubkeys.
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*
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* The exact representation of data inside is implementation defined and not
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* guaranteed to be portable between different platforms or versions. It is
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* however guaranteed to be 64 bytes in size, and can be safely copied/moved.
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* If you need to convert to a format suitable for storage, transmission, use
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* use secp256k1_xonly_pubkey_serialize and secp256k1_xonly_pubkey_parse. To
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* compare keys, use secp256k1_xonly_pubkey_cmp.
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*/
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typedef struct {
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unsigned char data[64];
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} secp256k1_xonly_pubkey;
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/** Opaque data structure that holds a keypair consisting of a secret and a
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* public key.
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*
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* The exact representation of data inside is implementation defined and not
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* guaranteed to be portable between different platforms or versions. It is
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* however guaranteed to be 96 bytes in size, and can be safely copied/moved.
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*/
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typedef struct {
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unsigned char data[96];
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} secp256k1_keypair;
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/** Parse a 32-byte sequence into a xonly_pubkey object.
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*
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* Returns: 1 if the public key was fully valid.
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* 0 if the public key could not be parsed or is invalid.
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*
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* Args: ctx: a secp256k1 context object.
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* Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to a
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* parsed version of input. If not, it's set to an invalid value.
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* In: input32: pointer to a serialized xonly_pubkey.
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_parse(
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const secp256k1_context* ctx,
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secp256k1_xonly_pubkey* pubkey,
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const unsigned char *input32
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Serialize an xonly_pubkey object into a 32-byte sequence.
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*
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* Returns: 1 always.
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*
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* Args: ctx: a secp256k1 context object.
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* Out: output32: a pointer to a 32-byte array to place the serialized key in.
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* In: pubkey: a pointer to a secp256k1_xonly_pubkey containing an initialized public key.
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*/
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SECP256K1_API int secp256k1_xonly_pubkey_serialize(
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const secp256k1_context* ctx,
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unsigned char *output32,
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const secp256k1_xonly_pubkey* pubkey
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Compare two x-only public keys using lexicographic order
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*
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* Returns: <0 if the first public key is less than the second
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* >0 if the first public key is greater than the second
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* 0 if the two public keys are equal
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* Args: ctx: a secp256k1 context object.
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* In: pubkey1: first public key to compare
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* pubkey2: second public key to compare
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*/
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SECP256K1_API int secp256k1_xonly_pubkey_cmp(
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const secp256k1_context* ctx,
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const secp256k1_xonly_pubkey* pk1,
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const secp256k1_xonly_pubkey* pk2
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Converts a secp256k1_pubkey into a secp256k1_xonly_pubkey.
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*
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* Returns: 1 always.
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*
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* Args: ctx: pointer to a context object.
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* Out: xonly_pubkey: pointer to an x-only public key object for placing the converted public key.
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* pk_parity: Ignored if NULL. Otherwise, pointer to an integer that
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* will be set to 1 if the point encoded by xonly_pubkey is
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* the negation of the pubkey and set to 0 otherwise.
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* In: pubkey: pointer to a public key that is converted.
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_from_pubkey(
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const secp256k1_context* ctx,
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secp256k1_xonly_pubkey *xonly_pubkey,
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int *pk_parity,
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const secp256k1_pubkey *pubkey
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
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/** Tweak an x-only public key by adding the generator multiplied with tweak32
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* to it.
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*
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* Note that the resulting point can not in general be represented by an x-only
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* pubkey because it may have an odd Y coordinate. Instead, the output_pubkey
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* is a normal secp256k1_pubkey.
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*
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* Returns: 0 if the arguments are invalid or the resulting public key would be
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* invalid (only when the tweak is the negation of the corresponding
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* secret key). 1 otherwise.
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*
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* Args: ctx: pointer to a context object.
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* Out: output_pubkey: pointer to a public key to store the result. Will be set
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* to an invalid value if this function returns 0.
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* In: internal_pubkey: pointer to an x-only pubkey to apply the tweak to.
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* tweak32: pointer to a 32-byte tweak. If the tweak is invalid
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* according to secp256k1_ec_seckey_verify, this function
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* returns 0. For uniformly random 32-byte arrays the
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* chance of being invalid is negligible (around 1 in 2^128).
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add(
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const secp256k1_context* ctx,
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secp256k1_pubkey *output_pubkey,
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const secp256k1_xonly_pubkey *internal_pubkey,
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const unsigned char *tweak32
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
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/** Checks that a tweaked pubkey is the result of calling
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* secp256k1_xonly_pubkey_tweak_add with internal_pubkey and tweak32.
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*
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* The tweaked pubkey is represented by its 32-byte x-only serialization and
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* its pk_parity, which can both be obtained by converting the result of
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* tweak_add to a secp256k1_xonly_pubkey.
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*
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* Note that this alone does _not_ verify that the tweaked pubkey is a
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* commitment. If the tweak is not chosen in a specific way, the tweaked pubkey
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* can easily be the result of a different internal_pubkey and tweak.
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*
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* Returns: 0 if the arguments are invalid or the tweaked pubkey is not the
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* result of tweaking the internal_pubkey with tweak32. 1 otherwise.
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* Args: ctx: pointer to a context object.
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* In: tweaked_pubkey32: pointer to a serialized xonly_pubkey.
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* tweaked_pk_parity: the parity of the tweaked pubkey (whose serialization
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* is passed in as tweaked_pubkey32). This must match the
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* pk_parity value that is returned when calling
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* secp256k1_xonly_pubkey with the tweaked pubkey, or
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* this function will fail.
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* internal_pubkey: pointer to an x-only public key object to apply the tweak to.
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* tweak32: pointer to a 32-byte tweak.
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_tweak_add_check(
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const secp256k1_context* ctx,
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const unsigned char *tweaked_pubkey32,
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int tweaked_pk_parity,
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const secp256k1_xonly_pubkey *internal_pubkey,
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const unsigned char *tweak32
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5);
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/** Compute the keypair for a secret key.
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*
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* Returns: 1: secret was valid, keypair is ready to use
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* 0: secret was invalid, try again with a different secret
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* Args: ctx: pointer to a context object (not secp256k1_context_static).
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* Out: keypair: pointer to the created keypair.
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* In: seckey: pointer to a 32-byte secret key.
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_create(
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const secp256k1_context* ctx,
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secp256k1_keypair *keypair,
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const unsigned char *seckey
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Get the secret key from a keypair.
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*
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* Returns: 1 always.
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* Args: ctx: pointer to a context object.
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* Out: seckey: pointer to a 32-byte buffer for the secret key.
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* In: keypair: pointer to a keypair.
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_sec(
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const secp256k1_context* ctx,
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unsigned char *seckey,
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const secp256k1_keypair *keypair
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Get the public key from a keypair.
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*
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* Returns: 1 always.
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* Args: ctx: pointer to a context object.
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* Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to
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* the keypair public key. If not, it's set to an invalid value.
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* In: keypair: pointer to a keypair.
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_pub(
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const secp256k1_context* ctx,
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secp256k1_pubkey *pubkey,
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const secp256k1_keypair *keypair
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Get the x-only public key from a keypair.
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*
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* This is the same as calling secp256k1_keypair_pub and then
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* secp256k1_xonly_pubkey_from_pubkey.
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*
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* Returns: 1 always.
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* Args: ctx: pointer to a context object.
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* Out: pubkey: pointer to an xonly_pubkey object. If 1 is returned, it is set
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* to the keypair public key after converting it to an
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* xonly_pubkey. If not, it's set to an invalid value.
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* pk_parity: Ignored if NULL. Otherwise, pointer to an integer that will be set to the
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* pk_parity argument of secp256k1_xonly_pubkey_from_pubkey.
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* In: keypair: pointer to a keypair.
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_pub(
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const secp256k1_context* ctx,
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secp256k1_xonly_pubkey *pubkey,
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int *pk_parity,
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const secp256k1_keypair *keypair
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
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/** Tweak a keypair by adding tweak32 to the secret key and updating the public
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* key accordingly.
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*
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* Calling this function and then secp256k1_keypair_pub results in the same
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* public key as calling secp256k1_keypair_xonly_pub and then
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* secp256k1_xonly_pubkey_tweak_add.
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*
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* Returns: 0 if the arguments are invalid or the resulting keypair would be
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* invalid (only when the tweak is the negation of the keypair's
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* secret key). 1 otherwise.
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*
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* Args: ctx: pointer to a context object.
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* In/Out: keypair: pointer to a keypair to apply the tweak to. Will be set to
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* an invalid value if this function returns 0.
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* In: tweak32: pointer to a 32-byte tweak. If the tweak is invalid according
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* to secp256k1_ec_seckey_verify, this function returns 0. For
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* uniformly random 32-byte arrays the chance of being invalid
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* is negligible (around 1 in 2^128).
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_tweak_add(
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const secp256k1_context* ctx,
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secp256k1_keypair *keypair,
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const unsigned char *tweak32
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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#ifdef __cplusplus
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}
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#endif
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#endif /* SECP256K1_EXTRAKEYS_H */
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