172 lines
7.4 KiB
C
172 lines
7.4 KiB
C
#ifndef SECP256K1_SCHNORRSIG_H
|
|
#define SECP256K1_SCHNORRSIG_H
|
|
|
|
#include "secp256k1.h"
|
|
#include "secp256k1_extrakeys.h"
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
/** This module implements a variant of Schnorr signatures compliant with
|
|
* Bitcoin Improvement Proposal 340 "Schnorr Signatures for secp256k1"
|
|
* (https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki).
|
|
*/
|
|
|
|
/** A pointer to a function to deterministically generate a nonce.
|
|
*
|
|
* Same as rustsecp256k1_v0_6_1_nonce function with the exception of accepting an
|
|
* additional pubkey argument and not requiring an attempt argument. The pubkey
|
|
* argument can protect signature schemes with key-prefixed challenge hash
|
|
* inputs against reusing the nonce when signing with the wrong precomputed
|
|
* pubkey.
|
|
*
|
|
* Returns: 1 if a nonce was successfully generated. 0 will cause signing to
|
|
* return an error.
|
|
* Out: nonce32: pointer to a 32-byte array to be filled by the function
|
|
* In: msg: the message being verified. Is NULL if and only if msglen
|
|
* is 0.
|
|
* msglen: the length of the message
|
|
* key32: pointer to a 32-byte secret key (will not be NULL)
|
|
* xonly_pk32: the 32-byte serialized xonly pubkey corresponding to key32
|
|
* (will not be NULL)
|
|
* algo: pointer to an array describing the signature
|
|
* algorithm (will not be NULL)
|
|
* algolen: the length of the algo array
|
|
* data: arbitrary data pointer that is passed through
|
|
*
|
|
* Except for test cases, this function should compute some cryptographic hash of
|
|
* the message, the key, the pubkey, the algorithm description, and data.
|
|
*/
|
|
typedef int (*rustsecp256k1_v0_6_1_nonce_function_hardened)(
|
|
unsigned char *nonce32,
|
|
const unsigned char *msg,
|
|
size_t msglen,
|
|
const unsigned char *key32,
|
|
const unsigned char *xonly_pk32,
|
|
const unsigned char *algo,
|
|
size_t algolen,
|
|
void *data
|
|
);
|
|
|
|
/** An implementation of the nonce generation function as defined in Bitcoin
|
|
* Improvement Proposal 340 "Schnorr Signatures for secp256k1"
|
|
* (https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki).
|
|
*
|
|
* If a data pointer is passed, it is assumed to be a pointer to 32 bytes of
|
|
* auxiliary random data as defined in BIP-340. If the data pointer is NULL,
|
|
* the nonce derivation procedure follows BIP-340 by setting the auxiliary
|
|
* random data to zero. The algo argument must be non-NULL, otherwise the
|
|
* function will fail and return 0. The hash will be tagged with algo.
|
|
* Therefore, to create BIP-340 compliant signatures, algo must be set to
|
|
* "BIP0340/nonce" and algolen to 13.
|
|
*/
|
|
SECP256K1_API extern const rustsecp256k1_v0_6_1_nonce_function_hardened rustsecp256k1_v0_6_1_nonce_function_bip340;
|
|
|
|
/** Data structure that contains additional arguments for schnorrsig_sign_custom.
|
|
*
|
|
* A schnorrsig_extraparams structure object can be initialized correctly by
|
|
* setting it to SECP256K1_SCHNORRSIG_EXTRAPARAMS_INIT.
|
|
*
|
|
* Members:
|
|
* magic: set to SECP256K1_SCHNORRSIG_EXTRAPARAMS_MAGIC at initialization
|
|
* and has no other function than making sure the object is
|
|
* initialized.
|
|
* noncefp: pointer to a nonce generation function. If NULL,
|
|
* rustsecp256k1_v0_6_1_nonce_function_bip340 is used
|
|
* ndata: pointer to arbitrary data used by the nonce generation function
|
|
* (can be NULL). If it is non-NULL and
|
|
* rustsecp256k1_v0_6_1_nonce_function_bip340 is used, then ndata must be a
|
|
* pointer to 32-byte auxiliary randomness as per BIP-340.
|
|
*/
|
|
typedef struct {
|
|
unsigned char magic[4];
|
|
rustsecp256k1_v0_6_1_nonce_function_hardened noncefp;
|
|
void* ndata;
|
|
} rustsecp256k1_v0_6_1_schnorrsig_extraparams;
|
|
|
|
#define SECP256K1_SCHNORRSIG_EXTRAPARAMS_MAGIC { 0xda, 0x6f, 0xb3, 0x8c }
|
|
#define SECP256K1_SCHNORRSIG_EXTRAPARAMS_INIT {\
|
|
SECP256K1_SCHNORRSIG_EXTRAPARAMS_MAGIC,\
|
|
NULL,\
|
|
NULL\
|
|
}
|
|
|
|
/** Create a Schnorr signature.
|
|
*
|
|
* Does _not_ strictly follow BIP-340 because it does not verify the resulting
|
|
* signature. Instead, you can manually use rustsecp256k1_v0_6_1_schnorrsig_verify and
|
|
* abort if it fails.
|
|
*
|
|
* This function only signs 32-byte messages. If you have messages of a
|
|
* different size (or the same size but without a context-specific tag
|
|
* prefix), it is recommended to create a 32-byte message hash with
|
|
* rustsecp256k1_v0_6_1_tagged_sha256 and then sign the hash. Tagged hashing allows
|
|
* providing an context-specific tag for domain separation. This prevents
|
|
* signatures from being valid in multiple contexts by accident.
|
|
*
|
|
* Returns 1 on success, 0 on failure.
|
|
* Args: ctx: pointer to a context object, initialized for signing.
|
|
* Out: sig64: pointer to a 64-byte array to store the serialized signature.
|
|
* In: msg32: the 32-byte message being signed.
|
|
* keypair: pointer to an initialized keypair.
|
|
* aux_rand32: 32 bytes of fresh randomness. While recommended to provide
|
|
* this, it is only supplemental to security and can be NULL. A
|
|
* NULL argument is treated the same as an all-zero one. See
|
|
* BIP-340 "Default Signing" for a full explanation of this
|
|
* argument and for guidance if randomness is expensive.
|
|
*/
|
|
SECP256K1_API int rustsecp256k1_v0_6_1_schnorrsig_sign(
|
|
const rustsecp256k1_v0_6_1_context* ctx,
|
|
unsigned char *sig64,
|
|
const unsigned char *msg32,
|
|
const rustsecp256k1_v0_6_1_keypair *keypair,
|
|
const unsigned char *aux_rand32
|
|
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
|
|
|
|
/** Create a Schnorr signature with a more flexible API.
|
|
*
|
|
* Same arguments as rustsecp256k1_v0_6_1_schnorrsig_sign except that it allows signing
|
|
* variable length messages and accepts a pointer to an extraparams object that
|
|
* allows customizing signing by passing additional arguments.
|
|
*
|
|
* Creates the same signatures as schnorrsig_sign if msglen is 32 and the
|
|
* extraparams.ndata is the same as aux_rand32.
|
|
*
|
|
* In: msg: the message being signed. Can only be NULL if msglen is 0.
|
|
* msglen: length of the message
|
|
* extraparams: pointer to a extraparams object (can be NULL)
|
|
*/
|
|
SECP256K1_API int rustsecp256k1_v0_6_1_schnorrsig_sign_custom(
|
|
const rustsecp256k1_v0_6_1_context* ctx,
|
|
unsigned char *sig64,
|
|
const unsigned char *msg,
|
|
size_t msglen,
|
|
const rustsecp256k1_v0_6_1_keypair *keypair,
|
|
rustsecp256k1_v0_6_1_schnorrsig_extraparams *extraparams
|
|
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(5);
|
|
|
|
/** Verify a Schnorr signature.
|
|
*
|
|
* Returns: 1: correct signature
|
|
* 0: incorrect signature
|
|
* Args: ctx: a secp256k1 context object, initialized for verification.
|
|
* In: sig64: pointer to the 64-byte signature to verify.
|
|
* msg: the message being verified. Can only be NULL if msglen is 0.
|
|
* msglen: length of the message
|
|
* pubkey: pointer to an x-only public key to verify with (cannot be NULL)
|
|
*/
|
|
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int rustsecp256k1_v0_6_1_schnorrsig_verify(
|
|
const rustsecp256k1_v0_6_1_context* ctx,
|
|
const unsigned char *sig64,
|
|
const unsigned char *msg,
|
|
size_t msglen,
|
|
const rustsecp256k1_v0_6_1_xonly_pubkey *pubkey
|
|
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(5);
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif /* SECP256K1_SCHNORRSIG_H */
|