secp256k1_extrakeys.h File Reference

#include "secp256k1.h"

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Classes
struct	secp256k1_xonly_pubkey
	Opaque data structure that holds a parsed and valid "x-only" public key. More...
struct	secp256k1_keypair
	Opaque data structure that holds a keypair consisting of a secret and a public key. More...

Typedefs
typedef struct secp256k1_xonly_pubkey	secp256k1_xonly_pubkey
	Opaque data structure that holds a parsed and valid "x-only" public key. More...
typedef struct secp256k1_keypair	secp256k1_keypair
	Opaque data structure that holds a keypair consisting of a secret and a public key. More...

Functions
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)
	Parse a 32-byte sequence into a xonly_pubkey object. More...
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)
	Serialize an xonly_pubkey object into a 32-byte sequence. More...
SECP256K1_API int	secp256k1_xonly_pubkey_cmp (const secp256k1_context *ctx, const secp256k1_xonly_pubkey *pk1, const secp256k1_xonly_pubkey *pk2) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3)
	Compare two x-only public keys using lexicographic order. More...
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)
	Converts a secp256k1_pubkey into a secp256k1_xonly_pubkey. More...
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)
	Tweak an x-only public key by adding the generator multiplied with tweak32 to it. More...
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)
	Checks that a tweaked pubkey is the result of calling secp256k1_xonly_pubkey_tweak_add with internal_pubkey and tweak32. More...
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)
	Compute the keypair for a valid secret key. More...
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int	secp256k1_keypair_sec (const secp256k1_context *ctx, unsigned char *seckey, const secp256k1_keypair *keypair) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3)
	Get the secret key from a keypair. More...
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 public key from a keypair. More...
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)
	Get the x-only public key from a keypair. More...
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)
	Tweak a keypair by adding tweak32 to the secret key and updating the public key accordingly. More...

Typedef Documentation

secp256k1_keypair

typedef struct secp256k1_keypair secp256k1_keypair

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.

secp256k1_xonly_pubkey

typedef struct secp256k1_xonly_pubkey secp256k1_xonly_pubkey

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, use use secp256k1_xonly_pubkey_serialize and secp256k1_xonly_pubkey_parse. To compare keys, use secp256k1_xonly_pubkey_cmp.

Function Documentation

secp256k1_keypair_create()

SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_create	(	const secp256k1_context *	ctx,
		secp256k1_keypair *	keypair,
		const unsigned char *	seckey
	)

Compute the keypair for a valid secret key.

See the documentation of secp256k1_ec_seckey_verify for more information about the validity of secret keys.

Returns: 1: secret key is valid 0: secret key is invalid Args: ctx: pointer to a context object (not secp256k1_context_static). Out: keypair: pointer to the created keypair. In: seckey: pointer to a 32-byte secret key.

Definition at line 196 of file main_impl.h.

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secp256k1_keypair_pub()

SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_pub	(	const secp256k1_context *	ctx,
		secp256k1_pubkey *	pubkey,
		const secp256k1_keypair *	keypair
	)

Get the public key from a keypair.

Returns: 1 always. Args: ctx: pointer to a context object. Out: pubkey: pointer to a pubkey object, set to the keypair public key. In: keypair: pointer to a keypair.

Definition at line 224 of file main_impl.h.

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secp256k1_keypair_sec()

SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_sec	(	const secp256k1_context *	ctx,
		unsigned char *	seckey,
		const secp256k1_keypair *	keypair
	)

Get the secret key from a keypair.

Returns: 1 always. Args: ctx: pointer to a context object. Out: seckey: pointer to a 32-byte buffer for the secret key. In: keypair: pointer to a keypair.

Definition at line 214 of file main_impl.h.

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secp256k1_keypair_xonly_pub()

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
	)

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: 1 always. Args: ctx: pointer to a context object. Out: pubkey: pointer to an xonly_pubkey object, set to the keypair public key after converting it to an xonly_pubkey. pk_parity: Ignored if NULL. Otherwise, pointer to an integer that will be set to the pk_parity argument of secp256k1_xonly_pubkey_from_pubkey. In: keypair: pointer to a keypair.

Definition at line 234 of file main_impl.h.

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secp256k1_keypair_xonly_tweak_add()

SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_keypair_xonly_tweak_add	(	const secp256k1_context *	ctx,
		secp256k1_keypair *	keypair,
		const unsigned char *	tweak32
	)

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. In/Out: keypair: pointer to a keypair to apply the tweak to. Will be set to an invalid value if this function returns 0. In: tweak32: pointer to a 32-byte tweak, which must be valid according to secp256k1_ec_seckey_verify or 32 zero bytes. For uniformly random 32-byte tweaks, the chance of being invalid is negligible (around 1 in 2^128).

Definition at line 255 of file main_impl.h.

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secp256k1_xonly_pubkey_cmp()

SECP256K1_API int secp256k1_xonly_pubkey_cmp	(	const secp256k1_context *	ctx,
		const secp256k1_xonly_pubkey *	pk1,
		const secp256k1_xonly_pubkey *	pk2
	)

Compare two x-only public keys using lexicographic order.

Returns: <0 if the first public key is less than the second >0 if the first public key is greater than the second 0 if the two public keys are equal Args: ctx: pointer to a context object. In: pubkey1: first public key to compare pubkey2: second public key to compare

Definition at line 59 of file main_impl.h.

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secp256k1_xonly_pubkey_from_pubkey()

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
	)

Converts a secp256k1_pubkey into a secp256k1_xonly_pubkey.

Returns: 1 always.

Args: ctx: pointer to a context object. Out: xonly_pubkey: pointer to an x-only public key object for placing the converted public key. pk_parity: Ignored if NULL. Otherwise, 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. In: pubkey: pointer to a public key that is converted.

Definition at line 99 of file main_impl.h.

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secp256k1_xonly_pubkey_parse()

SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_xonly_pubkey_parse	(	const secp256k1_context *	ctx,
		secp256k1_xonly_pubkey *	pubkey,
		const unsigned char *	input32
	)

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: pointer to a context object. 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. In: input32: pointer to a serialized xonly_pubkey.

Definition at line 22 of file main_impl.h.

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secp256k1_xonly_pubkey_serialize()

SECP256K1_API int secp256k1_xonly_pubkey_serialize	(	const secp256k1_context *	ctx,
		unsigned char *	output32,
		const secp256k1_xonly_pubkey *	pubkey
	)

Serialize an xonly_pubkey object into a 32-byte sequence.

Returns: 1 always.

Args: ctx: pointer to a context object. Out: output32: pointer to a 32-byte array to place the serialized key in. In: pubkey: pointer to a secp256k1_xonly_pubkey containing an initialized public key.

Definition at line 44 of file main_impl.h.

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secp256k1_xonly_pubkey_tweak_add()

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
	)

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. Out: output_pubkey: pointer to a public key to store the result. Will be set to an invalid value if this function returns 0. In: internal_pubkey: pointer to an x-only pubkey to apply the tweak to. tweak32: pointer to a 32-byte tweak, which must be valid according to secp256k1_ec_seckey_verify or 32 zero bytes. For uniformly random 32-byte tweaks, the chance of being invalid is negligible (around 1 in 2^128).

Definition at line 118 of file main_impl.h.

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secp256k1_xonly_pubkey_tweak_add_check()

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
	)

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. In: tweaked_pubkey32: pointer to a serialized xonly_pubkey. 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. tweak32: pointer to a 32-byte tweak.

Definition at line 135 of file main_impl.h.

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