112 lines
5.0 KiB
C
112 lines
5.0 KiB
C
#ifndef SECP256K1_SCHNORRSIG_H
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#define SECP256K1_SCHNORRSIG_H
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#include "secp256k1.h"
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#include "secp256k1_extrakeys.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** This module implements a variant of Schnorr signatures compliant with
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* Bitcoin Improvement Proposal 340 "Schnorr Signatures for secp256k1"
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* (https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki).
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*/
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/** A pointer to a function to deterministically generate a nonce.
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*
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* Same as rustsecp256k1_v0_3_1_nonce function with the exception of accepting an
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* additional pubkey argument and not requiring an attempt argument. The pubkey
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* argument can protect signature schemes with key-prefixed challenge hash
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* inputs against reusing the nonce when signing with the wrong precomputed
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* pubkey.
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*
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* Returns: 1 if a nonce was successfully generated. 0 will cause signing to
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* return an error.
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* Out: nonce32: pointer to a 32-byte array to be filled by the function.
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* In: msg32: the 32-byte message hash being verified (will not be NULL)
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* key32: pointer to a 32-byte secret key (will not be NULL)
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* xonly_pk32: the 32-byte serialized xonly pubkey corresponding to key32
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* (will not be NULL)
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* algo16: pointer to a 16-byte array describing the signature
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* algorithm (will not be NULL).
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* data: Arbitrary data pointer that is passed through.
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*
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* Except for test cases, this function should compute some cryptographic hash of
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* the message, the key, the pubkey, the algorithm description, and data.
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*/
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typedef int (*rustsecp256k1_v0_3_1_nonce_function_hardened)(
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unsigned char *nonce32,
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const unsigned char *msg32,
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const unsigned char *key32,
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const unsigned char *xonly_pk32,
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const unsigned char *algo16,
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void *data
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);
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/** An implementation of the nonce generation function as defined in Bitcoin
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* Improvement Proposal 340 "Schnorr Signatures for secp256k1"
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* (https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki).
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*
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* If a data pointer is passed, it is assumed to be a pointer to 32 bytes of
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* auxiliary random data as defined in BIP-340. If the data pointer is NULL,
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* schnorrsig_sign does not produce BIP-340 compliant signatures. The algo16
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* argument must be non-NULL, otherwise the function will fail and return 0.
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* The hash will be tagged with algo16 after removing all terminating null
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* bytes. Therefore, to create BIP-340 compliant signatures, algo16 must be set
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* to "BIP0340/nonce\0\0\0"
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*/
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SECP256K1_API extern const rustsecp256k1_v0_3_1_nonce_function_hardened rustsecp256k1_v0_3_1_nonce_function_bip340;
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/** Create a Schnorr signature.
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*
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* Does _not_ strictly follow BIP-340 because it does not verify the resulting
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* signature. Instead, you can manually use rustsecp256k1_v0_3_1_schnorrsig_verify and
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* abort if it fails.
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*
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* Otherwise BIP-340 compliant if the noncefp argument is NULL or
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* rustsecp256k1_v0_3_1_nonce_function_bip340 and the ndata argument is 32-byte auxiliary
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* randomness.
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*
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* Returns 1 on success, 0 on failure.
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* Args: ctx: pointer to a context object, initialized for signing (cannot be NULL)
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* Out: sig64: pointer to a 64-byte array to store the serialized signature (cannot be NULL)
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* In: msg32: the 32-byte message being signed (cannot be NULL)
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* keypair: pointer to an initialized keypair (cannot be NULL)
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* noncefp: pointer to a nonce generation function. If NULL, rustsecp256k1_v0_3_1_nonce_function_bip340 is used
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* ndata: pointer to arbitrary data used by the nonce generation
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* function (can be NULL). If it is non-NULL and
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* rustsecp256k1_v0_3_1_nonce_function_bip340 is used, then ndata must be a
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* pointer to 32-byte auxiliary randomness as per BIP-340.
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*/
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SECP256K1_API int rustsecp256k1_v0_3_1_schnorrsig_sign(
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const rustsecp256k1_v0_3_1_context* ctx,
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unsigned char *sig64,
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const unsigned char *msg32,
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const rustsecp256k1_v0_3_1_keypair *keypair,
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rustsecp256k1_v0_3_1_nonce_function_hardened noncefp,
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void *ndata
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
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/** Verify a Schnorr signature.
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*
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* Returns: 1: correct signature
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* 0: incorrect signature
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* Args: ctx: a secp256k1 context object, initialized for verification.
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* In: sig64: pointer to the 64-byte signature to verify (cannot be NULL)
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* msg32: the 32-byte message being verified (cannot be NULL)
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* pubkey: pointer to an x-only public key to verify with (cannot be NULL)
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int rustsecp256k1_v0_3_1_schnorrsig_verify(
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const rustsecp256k1_v0_3_1_context* ctx,
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const unsigned char *sig64,
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const unsigned char *msg32,
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const rustsecp256k1_v0_3_1_xonly_pubkey *pubkey
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
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#ifdef __cplusplus
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}
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#endif
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#endif /* SECP256K1_SCHNORRSIG_H */
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