crypto/secp256k1: update to github.com/bitcoin-core/secp256k1 @ 9d560f9 (#3544)

- Use defined constants instead of hard-coding their integer value.
- Allocate secp256k1 structs on the C stack instead of converting []byte
- Remove dead code
This commit is contained in:
Felix Lange
2017-01-12 21:29:11 +01:00
committed by GitHub
parent 93077c98e4
commit e0ceeab0d1
79 changed files with 8242 additions and 2011 deletions

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@ -47,11 +47,8 @@ typedef struct secp256k1_context_struct secp256k1_context;
* 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 or transmission, use
* secp256k1_ec_pubkey_serialize and secp256k1_ec_pubkey_parse.
*
* Furthermore, it is guaranteed that identical public keys (ignoring
* compression) will have identical representation, so they can be memcmp'ed.
* If you need to convert to a format suitable for storage, transmission, or
* comparison, use secp256k1_ec_pubkey_serialize and secp256k1_ec_pubkey_parse.
*/
typedef struct {
unsigned char data[64];
@ -62,12 +59,9 @@ typedef struct {
* 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 or transmission, use
* the secp256k1_ecdsa_signature_serialize_* and
* If you need to convert to a format suitable for storage, transmission, or
* comparison, use the secp256k1_ecdsa_signature_serialize_* and
* secp256k1_ecdsa_signature_serialize_* functions.
*
* Furthermore, it is guaranteed to identical signatures will have identical
* representation, so they can be memcmp'ed.
*/
typedef struct {
unsigned char data[64];
@ -147,12 +141,23 @@ typedef int (*secp256k1_nonce_function)(
# define SECP256K1_ARG_NONNULL(_x)
# endif
/** All flags' lower 8 bits indicate what they're for. Do not use directly. */
#define SECP256K1_FLAGS_TYPE_MASK ((1 << 8) - 1)
#define SECP256K1_FLAGS_TYPE_CONTEXT (1 << 0)
#define SECP256K1_FLAGS_TYPE_COMPRESSION (1 << 1)
/** The higher bits contain the actual data. Do not use directly. */
#define SECP256K1_FLAGS_BIT_CONTEXT_VERIFY (1 << 8)
#define SECP256K1_FLAGS_BIT_CONTEXT_SIGN (1 << 9)
#define SECP256K1_FLAGS_BIT_COMPRESSION (1 << 8)
/** Flags to pass to secp256k1_context_create. */
# define SECP256K1_CONTEXT_VERIFY (1 << 0)
# define SECP256K1_CONTEXT_SIGN (1 << 1)
#define SECP256K1_CONTEXT_VERIFY (SECP256K1_FLAGS_TYPE_CONTEXT | SECP256K1_FLAGS_BIT_CONTEXT_VERIFY)
#define SECP256K1_CONTEXT_SIGN (SECP256K1_FLAGS_TYPE_CONTEXT | SECP256K1_FLAGS_BIT_CONTEXT_SIGN)
#define SECP256K1_CONTEXT_NONE (SECP256K1_FLAGS_TYPE_CONTEXT)
/** Flag to pass to secp256k1_ec_pubkey_serialize and secp256k1_ec_privkey_export. */
# define SECP256K1_EC_COMPRESSED (1 << 0)
#define SECP256K1_EC_COMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION | SECP256K1_FLAGS_BIT_COMPRESSION)
#define SECP256K1_EC_UNCOMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION)
/** Create a secp256k1 context object.
*
@ -218,7 +223,7 @@ SECP256K1_API void secp256k1_context_set_illegal_callback(
* crashing.
*
* Args: ctx: an existing context object (cannot be NULL)
* In: fun: a pointer to a function to call when an interal error occurs,
* In: fun: a pointer to a function to call when an internal error occurs,
* taking a message and an opaque pointer (NULL restores a default
* handler that calls abort).
* data: the opaque pointer to pass to fun above.
@ -253,15 +258,17 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_parse(
/** Serialize a pubkey object into a serialized byte sequence.
*
* Returns: 1 always.
* Args: ctx: a secp256k1 context object.
* Out: output: a pointer to a 65-byte (if compressed==0) or 33-byte (if
* compressed==1) byte array to place the serialized key in.
* outputlen: a pointer to an integer which will contain the serialized
* size.
* In: pubkey: a pointer to a secp256k1_pubkey containing an initialized
* public key.
* flags: SECP256K1_EC_COMPRESSED if serialization should be in
* compressed format.
* Args: ctx: a secp256k1 context object.
* Out: output: a pointer to a 65-byte (if compressed==0) or 33-byte (if
* compressed==1) byte array to place the serialized key
* in.
* In/Out: outputlen: a pointer to an integer which is initially set to the
* size of output, and is overwritten with the written
* size.
* In: pubkey: a pointer to a secp256k1_pubkey containing an
* initialized public key.
* flags: SECP256K1_EC_COMPRESSED if serialization should be in
* compressed format, otherwise SECP256K1_EC_UNCOMPRESSED.
*/
SECP256K1_API int secp256k1_ec_pubkey_serialize(
const secp256k1_context* ctx,
@ -271,6 +278,27 @@ SECP256K1_API int secp256k1_ec_pubkey_serialize(
unsigned int flags
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Parse an ECDSA signature in compact (64 bytes) format.
*
* Returns: 1 when the signature could be parsed, 0 otherwise.
* Args: ctx: a secp256k1 context object
* Out: sig: a pointer to a signature object
* In: input64: a pointer to the 64-byte array to parse
*
* The signature must consist of a 32-byte big endian R value, followed by a
* 32-byte big endian S value. If R or S fall outside of [0..order-1], the
* encoding is invalid. R and S with value 0 are allowed in the encoding.
*
* After the call, sig will always be initialized. If parsing failed or R or
* S are zero, the resulting sig value is guaranteed to fail validation for any
* message and public key.
*/
SECP256K1_API int secp256k1_ecdsa_signature_parse_compact(
const secp256k1_context* ctx,
secp256k1_ecdsa_signature* sig,
const unsigned char *input64
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Parse a DER ECDSA signature.
*
* Returns: 1 when the signature could be parsed, 0 otherwise.
@ -279,7 +307,12 @@ SECP256K1_API int secp256k1_ec_pubkey_serialize(
* In: input: a pointer to the signature to be parsed
* inputlen: the length of the array pointed to be input
*
* Note that this function also supports some violations of DER and even BER.
* This function will accept any valid DER encoded signature, even if the
* encoded numbers are out of range.
*
* After the call, sig will always be initialized. If parsing failed or the
* encoded numbers are out of range, signature validation with it is
* guaranteed to fail for every message and public key.
*/
SECP256K1_API int secp256k1_ecdsa_signature_parse_der(
const secp256k1_context* ctx,
@ -306,6 +339,21 @@ SECP256K1_API int secp256k1_ecdsa_signature_serialize_der(
const secp256k1_ecdsa_signature* sig
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Serialize an ECDSA signature in compact (64 byte) format.
*
* Returns: 1
* Args: ctx: a secp256k1 context object
* Out: output64: a pointer to a 64-byte array to store the compact serialization
* In: sig: a pointer to an initialized signature object
*
* See secp256k1_ecdsa_signature_parse_compact for details about the encoding.
*/
SECP256K1_API int secp256k1_ecdsa_signature_serialize_compact(
const secp256k1_context* ctx,
unsigned char *output64,
const secp256k1_ecdsa_signature* sig
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Verify an ECDSA signature.
*
* Returns: 1: correct signature
@ -314,6 +362,15 @@ SECP256K1_API int secp256k1_ecdsa_signature_serialize_der(
* In: sig: the signature being verified (cannot be NULL)
* msg32: the 32-byte message hash being verified (cannot be NULL)
* pubkey: pointer to an initialized public key to verify with (cannot be NULL)
*
* To avoid accepting malleable signatures, only ECDSA signatures in lower-S
* form are accepted.
*
* If you need to accept ECDSA signatures from sources that do not obey this
* rule, apply secp256k1_ecdsa_signature_normalize to the signature prior to
* validation, but be aware that doing so results in malleable signatures.
*
* For details, see the comments for that function.
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
const secp256k1_context* ctx,
@ -322,14 +379,62 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
const secp256k1_pubkey *pubkey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Convert a signature to a normalized lower-S form.
*
* Returns: 1 if sigin was not normalized, 0 if it already was.
* Args: ctx: a secp256k1 context object
* Out: sigout: a pointer to a signature to fill with the normalized form,
* or copy if the input was already normalized. (can be NULL if
* you're only interested in whether the input was already
* normalized).
* In: sigin: a pointer to a signature to check/normalize (cannot be NULL,
* can be identical to sigout)
*
* With ECDSA a third-party can forge a second distinct signature of the same
* message, given a single initial signature, but without knowing the key. This
* is done by negating the S value modulo the order of the curve, 'flipping'
* the sign of the random point R which is not included in the signature.
*
* Forgery of the same message isn't universally problematic, but in systems
* where message malleability or uniqueness of signatures is important this can
* cause issues. This forgery can be blocked by all verifiers forcing signers
* to use a normalized form.
*
* The lower-S form reduces the size of signatures slightly on average when
* variable length encodings (such as DER) are used and is cheap to verify,
* making it a good choice. Security of always using lower-S is assured because
* anyone can trivially modify a signature after the fact to enforce this
* property anyway.
*
* The lower S value is always between 0x1 and
* 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
* inclusive.
*
* No other forms of ECDSA malleability are known and none seem likely, but
* there is no formal proof that ECDSA, even with this additional restriction,
* is free of other malleability. Commonly used serialization schemes will also
* accept various non-unique encodings, so care should be taken when this
* property is required for an application.
*
* The secp256k1_ecdsa_sign function will by default create signatures in the
* lower-S form, and secp256k1_ecdsa_verify will not accept others. In case
* signatures come from a system that cannot enforce this property,
* secp256k1_ecdsa_signature_normalize must be called before verification.
*/
SECP256K1_API int secp256k1_ecdsa_signature_normalize(
const secp256k1_context* ctx,
secp256k1_ecdsa_signature *sigout,
const secp256k1_ecdsa_signature *sigin
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(3);
/** An implementation of RFC6979 (using HMAC-SHA256) as nonce generation function.
* If a data pointer is passed, it is assumed to be a pointer to 32 bytes of
* extra entropy.
*/
extern const secp256k1_nonce_function secp256k1_nonce_function_rfc6979;
SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_rfc6979;
/** A default safe nonce generation function (currently equal to secp256k1_nonce_function_rfc6979). */
extern const secp256k1_nonce_function secp256k1_nonce_function_default;
SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_default;
/** Create an ECDSA signature.
*
@ -342,32 +447,8 @@ extern const secp256k1_nonce_function secp256k1_nonce_function_default;
* noncefp:pointer to a nonce generation function. If NULL, secp256k1_nonce_function_default is used
* ndata: pointer to arbitrary data used by the nonce generation function (can be NULL)
*
* The sig always has an s value in the lower half of the range (From 0x1
* to 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0,
* inclusive), unlike many other implementations.
*
* With ECDSA a third-party can can forge a second distinct signature
* of the same message given a single initial signature without knowing
* the key by setting s to its additive inverse mod-order, 'flipping' the
* sign of the random point R which is not included in the signature.
* Since the forgery is of the same message this isn't universally
* problematic, but in systems where message malleability or uniqueness
* of signatures is important this can cause issues. This forgery can be
* blocked by all verifiers forcing signers to use a canonical form. The
* lower-S form reduces the size of signatures slightly on average when
* variable length encodings (such as DER) are used and is cheap to
* verify, making it a good choice. Security of always using lower-S is
* assured because anyone can trivially modify a signature after the
* fact to enforce this property. Adjusting it inside the signing
* function avoids the need to re-serialize or have curve specific
* constants outside of the library. By always using a canonical form
* even in applications where it isn't needed it becomes possible to
* impose a requirement later if a need is discovered.
* No other forms of ECDSA malleability are known and none seem likely,
* but there is no formal proof that ECDSA, even with this additional
* restriction, is free of other malleability. Commonly used serialization
* schemes will also accept various non-unique encodings, so care should
* be taken when this property is required for an application.
* The created signature is always in lower-S form. See
* secp256k1_ecdsa_signature_normalize for more details.
*/
SECP256K1_API int secp256k1_ecdsa_sign(
const secp256k1_context* ctx,
@ -404,55 +485,6 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create(
const unsigned char *seckey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Export a private key in BER format.
*
* Returns: 1 if the private key was valid.
* Args: ctx: pointer to a context object, initialized for signing (cannot
* be NULL)
* Out: privkey: pointer to an array for storing the private key in BER.
* Should have space for 279 bytes, and cannot be NULL.
* privkeylen: Pointer to an int where the length of the private key in
* privkey will be stored.
* In: seckey: pointer to a 32-byte secret key to export.
* flags: SECP256K1_EC_COMPRESSED if the key should be exported in
* compressed format.
*
* This function is purely meant for compatibility with applications that
* require BER encoded keys. When working with secp256k1-specific code, the
* simple 32-byte private keys are sufficient.
*
* Note that this function does not guarantee correct DER output. It is
* guaranteed to be parsable by secp256k1_ec_privkey_import.
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_export(
const secp256k1_context* ctx,
unsigned char *privkey,
size_t *privkeylen,
const unsigned char *seckey,
unsigned int flags
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Import a private key in DER format.
* Returns: 1 if a private key was extracted.
* Args: ctx: pointer to a context object (cannot be NULL).
* Out: seckey: pointer to a 32-byte array for storing the private key.
* (cannot be NULL).
* In: privkey: pointer to a private key in DER format (cannot be NULL).
* privkeylen: length of the DER private key pointed to be privkey.
*
* This function will accept more than just strict DER, and even allow some BER
* violations. The public key stored inside the DER-encoded private key is not
* verified for correctness, nor are the curve parameters. Use this function
* only if you know in advance it is supposed to contain a secp256k1 private
* key.
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_import(
const secp256k1_context* ctx,
unsigned char *seckey,
const unsigned char *privkey,
size_t privkeylen
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Tweak a private key by adding tweak to it.
* Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for
* uniformly random 32-byte arrays, or if the resulting private key
@ -526,18 +558,16 @@ SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_context_randomize(
* Returns: 1: the sum of the public keys is valid.
* 0: the sum of the public keys is not valid.
* Args: ctx: pointer to a context object
* Out: out: pointer to pubkey for placing the resulting public key
* Out: out: pointer to a public key object for placing the resulting public key
* (cannot be NULL)
* In: ins: pointer to array of pointers to public keys (cannot be NULL)
* n: the number of public keys to add together (must be at least 1)
* Use secp256k1_ec_pubkey_compress and secp256k1_ec_pubkey_decompress if the
* uncompressed format is needed.
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_combine(
const secp256k1_context* ctx,
secp256k1_pubkey *out,
const secp256k1_pubkey * const * ins,
int n
size_t n
) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
# ifdef __cplusplus

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@ -10,17 +10,18 @@ extern "C" {
/** Compute an EC Diffie-Hellman secret in constant time
* Returns: 1: exponentiation was successful
* 0: scalar was invalid (zero or overflow)
* Args: ctx: pointer to a context object (cannot be NULL)
* Out: result: a 32-byte array which will be populated by an ECDH
* secret computed from the point and scalar
* In: point: pointer to a public point
* scalar: a 32-byte scalar with which to multiply the point
* Args: ctx: pointer to a context object (cannot be NULL)
* Out: result: a 32-byte array which will be populated by an ECDH
* secret computed from the point and scalar
* In: pubkey: a pointer to a secp256k1_pubkey containing an
* initialized public key
* privkey: a 32-byte scalar with which to multiply the point
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdh(
const secp256k1_context* ctx,
unsigned char *result,
const secp256k1_pubkey *point,
const unsigned char *scalar
const secp256k1_pubkey *pubkey,
const unsigned char *privkey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
# ifdef __cplusplus

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@ -65,7 +65,7 @@ SECP256K1_API int secp256k1_ecdsa_recoverable_signature_serialize_compact(
unsigned char *output64,
int *recid,
const secp256k1_ecdsa_recoverable_signature* sig
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4);
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Create a recoverable ECDSA signature.
*
@ -92,7 +92,7 @@ SECP256K1_API int secp256k1_ecdsa_sign_recoverable(
* Returns: 1: public key successfully recovered (which guarantees a correct signature).
* 0: otherwise.
* Args: ctx: pointer to a context object, initialized for verification (cannot be NULL)
* Out: pubkey: pointer to the recoved public key (cannot be NULL)
* Out: pubkey: pointer to the recovered public key (cannot be NULL)
* In: sig: pointer to initialized signature that supports pubkey recovery (cannot be NULL)
* msg32: the 32-byte message hash assumed to be signed (cannot be NULL)
*/

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@ -1,173 +0,0 @@
#ifndef _SECP256K1_SCHNORR_
# define _SECP256K1_SCHNORR_
# include "secp256k1.h"
# ifdef __cplusplus
extern "C" {
# endif
/** Create a signature using a custom EC-Schnorr-SHA256 construction. It
* produces non-malleable 64-byte signatures which support public key recovery
* batch validation, and multiparty signing.
* Returns: 1: signature created
* 0: the nonce generation function failed, or the private key was
* invalid.
* Args: ctx: pointer to a context object, initialized for signing
* (cannot be NULL)
* Out: sig64: pointer to a 64-byte array where the signature will be
* placed (cannot be NULL)
* In: msg32: the 32-byte message hash being signed (cannot be NULL)
* seckey: pointer to a 32-byte secret key (cannot be NULL)
* noncefp:pointer to a nonce generation function. If NULL,
* secp256k1_nonce_function_default is used
* ndata: pointer to arbitrary data used by the nonce generation
* function (can be NULL)
*/
SECP256K1_API int secp256k1_schnorr_sign(
const secp256k1_context* ctx,
unsigned char *sig64,
const unsigned char *msg32,
const unsigned char *seckey,
secp256k1_nonce_function noncefp,
const void *ndata
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Verify a signature created by secp256k1_schnorr_sign.
* Returns: 1: correct signature
* 0: incorrect signature
* Args: ctx: a secp256k1 context object, initialized for verification.
* In: sig64: the 64-byte signature being verified (cannot be NULL)
* msg32: the 32-byte message hash being verified (cannot be NULL)
* pubkey: the public key to verify with (cannot be NULL)
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_schnorr_verify(
const secp256k1_context* ctx,
const unsigned char *sig64,
const unsigned char *msg32,
const secp256k1_pubkey *pubkey
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Recover an EC public key from a Schnorr signature created using
* secp256k1_schnorr_sign.
* Returns: 1: public key successfully recovered (which guarantees a correct
* signature).
* 0: otherwise.
* Args: ctx: pointer to a context object, initialized for
* verification (cannot be NULL)
* Out: pubkey: pointer to a pubkey to set to the recovered public key
* (cannot be NULL).
* In: sig64: signature as 64 byte array (cannot be NULL)
* msg32: the 32-byte message hash assumed to be signed (cannot
* be NULL)
*/
SECP256K1_API int secp256k1_schnorr_recover(
const secp256k1_context* ctx,
secp256k1_pubkey *pubkey,
const unsigned char *sig64,
const unsigned char *msg32
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
/** Generate a nonce pair deterministically for use with
* secp256k1_schnorr_partial_sign.
* Returns: 1: valid nonce pair was generated.
* 0: otherwise (nonce generation function failed)
* Args: ctx: pointer to a context object, initialized for signing
* (cannot be NULL)
* Out: pubnonce: public side of the nonce (cannot be NULL)
* privnonce32: private side of the nonce (32 byte) (cannot be NULL)
* In: msg32: the 32-byte message hash assumed to be signed (cannot
* be NULL)
* sec32: the 32-byte private key (cannot be NULL)
* noncefp: pointer to a nonce generation function. If NULL,
* secp256k1_nonce_function_default is used
* noncedata: pointer to arbitrary data used by the nonce generation
* function (can be NULL)
*
* Do not use the output as a private/public key pair for signing/validation.
*/
SECP256K1_API int secp256k1_schnorr_generate_nonce_pair(
const secp256k1_context* ctx,
secp256k1_pubkey *pubnonce,
unsigned char *privnonce32,
const unsigned char *msg32,
const unsigned char *sec32,
secp256k1_nonce_function noncefp,
const void* noncedata
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
/** Produce a partial Schnorr signature, which can be combined using
* secp256k1_schnorr_partial_combine, to end up with a full signature that is
* verifiable using secp256k1_schnorr_verify.
* Returns: 1: signature created successfully.
* 0: no valid signature exists with this combination of keys, nonces
* and message (chance around 1 in 2^128)
* -1: invalid private key, nonce, or public nonces.
* Args: ctx: pointer to context object, initialized for signing (cannot
* be NULL)
* Out: sig64: pointer to 64-byte array to put partial signature in
* In: msg32: pointer to 32-byte message to sign
* sec32: pointer to 32-byte private key
* pubnonce_others: pointer to pubkey containing the sum of the other's
* nonces (see secp256k1_ec_pubkey_combine)
* secnonce32: pointer to 32-byte array containing our nonce
*
* The intended procedure for creating a multiparty signature is:
* - Each signer S[i] with private key x[i] and public key Q[i] runs
* secp256k1_schnorr_generate_nonce_pair to produce a pair (k[i],R[i]) of
* private/public nonces.
* - All signers communicate their public nonces to each other (revealing your
* private nonce can lead to discovery of your private key, so it should be
* considered secret).
* - All signers combine all the public nonces they received (excluding their
* own) using secp256k1_ec_pubkey_combine to obtain an
* Rall[i] = sum(R[0..i-1,i+1..n]).
* - All signers produce a partial signature using
* secp256k1_schnorr_partial_sign, passing in their own private key x[i],
* their own private nonce k[i], and the sum of the others' public nonces
* Rall[i].
* - All signers communicate their partial signatures to each other.
* - Someone combines all partial signatures using
* secp256k1_schnorr_partial_combine, to obtain a full signature.
* - The resulting signature is validatable using secp256k1_schnorr_verify, with
* public key equal to the result of secp256k1_ec_pubkey_combine of the
* signers' public keys (sum(Q[0..n])).
*
* Note that secp256k1_schnorr_partial_combine and secp256k1_ec_pubkey_combine
* function take their arguments in any order, and it is possible to
* pre-combine several inputs already with one call, and add more inputs later
* by calling the function again (they are commutative and associative).
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_schnorr_partial_sign(
const secp256k1_context* ctx,
unsigned char *sig64,
const unsigned char *msg32,
const unsigned char *sec32,
const secp256k1_pubkey *pubnonce_others,
const unsigned char *secnonce32
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5) SECP256K1_ARG_NONNULL(6);
/** Combine multiple Schnorr partial signatures.
* Returns: 1: the passed signatures were successfully combined.
* 0: the resulting signature is not valid (chance of 1 in 2^256)
* -1: some inputs were invalid, or the signatures were not created
* using the same set of nonces
* Args: ctx: pointer to a context object
* Out: sig64: pointer to a 64-byte array to place the combined signature
* (cannot be NULL)
* In: sig64sin: pointer to an array of n pointers to 64-byte input
* signatures
* n: the number of signatures to combine (at least 1)
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_schnorr_partial_combine(
const secp256k1_context* ctx,
unsigned char *sig64,
const unsigned char * const * sig64sin,
int n
) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
# ifdef __cplusplus
}
# endif
#endif