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