diff options
Diffstat (limited to 'src/secp256k1/include')
| -rw-r--r-- | src/secp256k1/include/secp256k1.h | 696 | ||||
| -rw-r--r-- | src/secp256k1/include/secp256k1_ecdh.h | 31 | ||||
| -rw-r--r-- | src/secp256k1/include/secp256k1_recovery.h | 110 | ||||
| -rw-r--r-- | src/secp256k1/include/secp256k1_schnorr.h | 173 |
4 files changed, 780 insertions, 230 deletions
diff --git a/src/secp256k1/include/secp256k1.h b/src/secp256k1/include/secp256k1.h index 06afd4c65b..7145dbcc54 100644 --- a/src/secp256k1/include/secp256k1.h +++ b/src/secp256k1/include/secp256k1.h @@ -5,6 +5,99 @@ extern "C" { # endif +#include <stddef.h> + +/* These rules specify the order of arguments in API calls: + * + * 1. Context pointers go first, followed by output arguments, combined + * output/input arguments, and finally input-only arguments. + * 2. Array lengths always immediately the follow the argument whose length + * they describe, even if this violates rule 1. + * 3. Within the OUT/OUTIN/IN groups, pointers to data that is typically generated + * later go first. This means: signatures, public nonces, private nonces, + * messages, public keys, secret keys, tweaks. + * 4. Arguments that are not data pointers go last, from more complex to less + * complex: function pointers, algorithm names, messages, void pointers, + * counts, flags, booleans. + * 5. Opaque data pointers follow the function pointer they are to be passed to. + */ + +/** Opaque data structure that holds context information (precomputed tables etc.). + * + * The purpose of context structures is to cache large precomputed data tables + * that are expensive to construct, and also to maintain the randomization data + * for blinding. + * + * Do not create a new context object for each operation, as construction is + * far slower than all other API calls (~100 times slower than an ECDSA + * verification). + * + * A constructed context can safely be used from multiple threads + * simultaneously, but API call that take a non-const pointer to a context + * need exclusive access to it. In particular this is the case for + * secp256k1_context_destroy and secp256k1_context_randomize. + * + * Regarding randomization, either do it once at creation time (in which case + * you do not need any locking for the other calls), or use a read-write lock. + */ +typedef struct secp256k1_context_struct secp256k1_context; + +/** Opaque data structure that holds a parsed and valid 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 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. + */ +typedef struct { + unsigned char data[64]; +} secp256k1_pubkey; + +/** Opaque data structured that holds a parsed ECDSA signature. + * + * 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 + * 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]; +} secp256k1_ecdsa_signature; + +/** A pointer to a function to deterministically generate a nonce. + * + * Returns: 1 if a nonce was successfully generated. 0 will cause signing to fail. + * Out: nonce32: pointer to a 32-byte array to be filled by the function. + * In: msg32: the 32-byte message hash being verified (will not be NULL) + * key32: pointer to a 32-byte secret key (will not be NULL) + * algo16: pointer to a 16-byte array describing the signature + * algorithm (will be NULL for ECDSA for compatibility). + * data: Arbitrary data pointer that is passed through. + * attempt: how many iterations we have tried to find a nonce. + * This will almost always be 0, but different attempt values + * are required to result in a different nonce. + * + * Except for test cases, this function should compute some cryptographic hash of + * the message, the algorithm, the key and the attempt. + */ +typedef int (*secp256k1_nonce_function)( + unsigned char *nonce32, + const unsigned char *msg32, + const unsigned char *key32, + const unsigned char *algo16, + void *data, + unsigned int attempt +); + # if !defined(SECP256K1_GNUC_PREREQ) # if defined(__GNUC__)&&defined(__GNUC_MINOR__) # define SECP256K1_GNUC_PREREQ(_maj,_min) \ @@ -26,6 +119,20 @@ extern "C" { # define SECP256K1_INLINE inline # endif +#ifndef SECP256K1_API +# if defined(_WIN32) +# ifdef SECP256K1_BUILD +# define SECP256K1_API __declspec(dllexport) +# else +# define SECP256K1_API +# endif +# elif defined(__GNUC__) && defined(SECP256K1_BUILD) +# define SECP256K1_API __attribute__ ((visibility ("default"))) +# else +# define SECP256K1_API +# endif +#endif + /**Warning attributes * NONNULL is not used if SECP256K1_BUILD is set to avoid the compiler optimizing out * some paranoid null checks. */ @@ -40,305 +147,434 @@ extern "C" { # define SECP256K1_ARG_NONNULL(_x) # endif -/** Opaque data structure that holds context information (precomputed tables etc.). - * Only functions that take a pointer to a non-const context require exclusive - * access to it. Multiple functions that take a pointer to a const context may - * run simultaneously. - */ -typedef struct secp256k1_context_struct secp256k1_context_t; +/** 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 (SECP256K1_FLAGS_TYPE_COMPRESSION | SECP256K1_FLAGS_BIT_COMPRESSION) +#define SECP256K1_EC_UNCOMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION) /** Create a secp256k1 context object. + * * Returns: a newly created context object. * In: flags: which parts of the context to initialize. */ -secp256k1_context_t* secp256k1_context_create( - int flags +SECP256K1_API secp256k1_context* secp256k1_context_create( + unsigned int flags ) SECP256K1_WARN_UNUSED_RESULT; /** Copies a secp256k1 context object. + * * Returns: a newly created context object. - * In: ctx: an existing context to copy + * Args: ctx: an existing context to copy (cannot be NULL) */ -secp256k1_context_t* secp256k1_context_clone( - const secp256k1_context_t* ctx -) SECP256K1_WARN_UNUSED_RESULT; +SECP256K1_API secp256k1_context* secp256k1_context_clone( + const secp256k1_context* ctx +) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT; /** Destroy a secp256k1 context object. + * * The context pointer may not be used afterwards. + * Args: ctx: an existing context to destroy (cannot be NULL) + */ +SECP256K1_API void secp256k1_context_destroy( + secp256k1_context* ctx +); + +/** Set a callback function to be called when an illegal argument is passed to + * an API call. It will only trigger for violations that are mentioned + * explicitly in the header. + * + * The philosophy is that these shouldn't be dealt with through a + * specific return value, as calling code should not have branches to deal with + * the case that this code itself is broken. + * + * On the other hand, during debug stage, one would want to be informed about + * such mistakes, and the default (crashing) may be inadvisable. + * When this callback is triggered, the API function called is guaranteed not + * to cause a crash, though its return value and output arguments are + * undefined. + * + * Args: ctx: an existing context object (cannot be NULL) + * In: fun: a pointer to a function to call when an illegal argument is + * passed to the API, taking a message and an opaque pointer + * (NULL restores a default handler that calls abort). + * data: the opaque pointer to pass to fun above. */ -void secp256k1_context_destroy( - secp256k1_context_t* ctx +SECP256K1_API void secp256k1_context_set_illegal_callback( + secp256k1_context* ctx, + void (*fun)(const char* message, void* data), + const void* data ) SECP256K1_ARG_NONNULL(1); +/** Set a callback function to be called when an internal consistency check + * fails. The default is crashing. + * + * This can only trigger in case of a hardware failure, miscompilation, + * memory corruption, serious bug in the library, or other error would can + * otherwise result in undefined behaviour. It will not trigger due to mere + * incorrect usage of the API (see secp256k1_context_set_illegal_callback + * for that). After this callback returns, anything may happen, including + * crashing. + * + * Args: ctx: an existing context object (cannot be NULL) + * 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. + */ +SECP256K1_API void secp256k1_context_set_error_callback( + secp256k1_context* ctx, + void (*fun)(const char* message, void* data), + const void* data +) SECP256K1_ARG_NONNULL(1); + +/** Parse a variable-length public key into the 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. + * Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to a + * parsed version of input. If not, its value is undefined. + * In: input: pointer to a serialized public key + * inputlen: length of the array pointed to by input + * + * This function supports parsing compressed (33 bytes, header byte 0x02 or + * 0x03), uncompressed (65 bytes, header byte 0x04), or hybrid (65 bytes, header + * byte 0x06 or 0x07) format public keys. + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_parse( + const secp256k1_context* ctx, + secp256k1_pubkey* pubkey, + const unsigned char *input, + size_t inputlen +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +/** 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. + * 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, + unsigned char *output, + size_t *outputlen, + const secp256k1_pubkey* pubkey, + 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. + * Args: ctx: a secp256k1 context object + * Out: sig: a pointer to a signature object + * In: input: a pointer to the signature to be parsed + * inputlen: the length of the array pointed to be input + * + * 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, + secp256k1_ecdsa_signature* sig, + const unsigned char *input, + size_t inputlen +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +/** Serialize an ECDSA signature in DER format. + * + * Returns: 1 if enough space was available to serialize, 0 otherwise + * Args: ctx: a secp256k1 context object + * Out: output: a pointer to an array to store the DER serialization + * In/Out: outputlen: a pointer to a length integer. Initially, this integer + * should be set to the length of output. After the call + * it will be set to the length of the serialization (even + * if 0 was returned). + * In: sig: a pointer to an initialized signature object + */ +SECP256K1_API int secp256k1_ecdsa_signature_serialize_der( + const secp256k1_context* ctx, + unsigned char *output, + size_t *outputlen, + 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 - * 0: incorrect signature - * -1: invalid public key - * -2: invalid signature - * In: ctx: a secp256k1 context object, initialized for verification. + * 0: incorrect or unparseable signature + * Args: ctx: a secp256k1 context object, initialized for verification. + * In: sig: the signature being verified (cannot be NULL) * msg32: the 32-byte message hash being verified (cannot be NULL) - * sig: the signature being verified (cannot be NULL) - * siglen: the length of the signature - * pubkey: the public key to verify with (cannot be NULL) - * pubkeylen: the length of pubkey + * 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_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify( - const secp256k1_context_t* ctx, - const unsigned char *msg32, - const unsigned char *sig, - int siglen, - const unsigned char *pubkey, - int pubkeylen -) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(5); +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify( + const secp256k1_context* ctx, + const secp256k1_ecdsa_signature *sig, + const unsigned char *msg32, + const secp256k1_pubkey *pubkey +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); -/** A pointer to a function to deterministically generate a nonce. - * Returns: 1 if a nonce was successfully generated. 0 will cause signing to fail. - * In: msg32: the 32-byte message hash being verified (will not be NULL) - * key32: pointer to a 32-byte secret key (will not be NULL) - * attempt: how many iterations we have tried to find a nonce. - * This will almost always be 0, but different attempt values - * are required to result in a different nonce. - * data: Arbitrary data pointer that is passed through. - * Out: nonce32: pointer to a 32-byte array to be filled by the function. - * Except for test cases, this function should compute some cryptographic hash of - * the message, the key and the attempt. +/** 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. */ -typedef int (*secp256k1_nonce_function_t)( - unsigned char *nonce32, - const unsigned char *msg32, - const unsigned char *key32, - unsigned int attempt, - const void *data -); +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_t 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_t secp256k1_nonce_function_default; - +SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_default; /** Create an ECDSA signature. + * * Returns: 1: signature created - * 0: the nonce generation function failed, the private key was invalid, or there is not - * enough space in the signature (as indicated by siglen). - * In: ctx: pointer to a context object, initialized for signing (cannot be NULL) - * 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) + * 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: sig: pointer to an array where the signature will be placed (cannot be NULL) - * In/Out: siglen: pointer to an int with the length of sig, which will be updated - * to contain the actual signature length (<=72). - * - * 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. - */ -int secp256k1_ecdsa_sign( - const secp256k1_context_t* ctx, - const unsigned char *msg32, - unsigned char *sig, - int *siglen, - const unsigned char *seckey, - secp256k1_nonce_function_t noncefp, - const void *ndata -) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5); - -/** Create a compact ECDSA signature (64 byte + recovery id). - * Returns: 1: signature created - * 0: the nonce generation function failed, or the secret key was invalid. - * In: ctx: pointer to a context object, initialized for signing (cannot be NULL) - * msg32: the 32-byte message hash being signed (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) - * Out: sig: pointer to a 64-byte array where the signature will be placed (cannot be NULL) - * In case 0 is returned, the returned signature length will be zero. - * recid: pointer to an int, which will be updated to contain the recovery id (can be NULL) + * + * The created signature is always in lower-S form. See + * secp256k1_ecdsa_signature_normalize for more details. */ -int secp256k1_ecdsa_sign_compact( - const secp256k1_context_t* ctx, - const unsigned char *msg32, - unsigned char *sig64, - const unsigned char *seckey, - secp256k1_nonce_function_t noncefp, - const void *ndata, - int *recid +SECP256K1_API int secp256k1_ecdsa_sign( + const secp256k1_context* ctx, + secp256k1_ecdsa_signature *sig, + 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); -/** Recover an ECDSA public key from a compact signature. - * Returns: 1: public key successfully recovered (which guarantees a correct signature). - * 0: otherwise. - * In: ctx: pointer to a context object, initialized for verification (cannot be NULL) - * msg32: the 32-byte message hash assumed to be signed (cannot be NULL) - * sig64: signature as 64 byte array (cannot be NULL) - * compressed: whether to recover a compressed or uncompressed pubkey - * recid: the recovery id (0-3, as returned by ecdsa_sign_compact) - * Out: pubkey: pointer to a 33 or 65 byte array to put the pubkey (cannot be NULL) - * pubkeylen: pointer to an int that will contain the pubkey length (cannot be NULL) - */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_recover_compact( - const secp256k1_context_t* ctx, - const unsigned char *msg32, - const unsigned char *sig64, - unsigned char *pubkey, - int *pubkeylen, - int compressed, - int recid -) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4) SECP256K1_ARG_NONNULL(5); - /** Verify an ECDSA secret key. + * * Returns: 1: secret key is valid * 0: secret key is invalid - * In: ctx: pointer to a context object (cannot be NULL) - * seckey: pointer to a 32-byte secret key (cannot be NULL) + * Args: ctx: pointer to a context object (cannot be NULL) + * In: seckey: pointer to a 32-byte secret key (cannot be NULL) */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify( - const secp256k1_context_t* ctx, - const unsigned char *seckey -) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2); - -/** Just validate a public key. - * Returns: 1: public key is valid - * 0: public key is invalid - * In: ctx: pointer to a context object (cannot be NULL) - * pubkey: pointer to a 33-byte or 65-byte public key (cannot be NULL). - * pubkeylen: length of pubkey - */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_verify( - const secp256k1_context_t* ctx, - const unsigned char *pubkey, - int pubkeylen +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_seckey_verify( + const secp256k1_context* ctx, + const unsigned char *seckey ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2); /** Compute the public key for a secret key. - * In: ctx: pointer to a context object, initialized for signing (cannot be NULL) - * compressed: whether the computed public key should be compressed - * seckey: pointer to a 32-byte private key (cannot be NULL) - * Out: pubkey: pointer to a 33-byte (if compressed) or 65-byte (if uncompressed) - * area to store the public key (cannot be NULL) - * pubkeylen: pointer to int that will be updated to contains the pubkey's - * length (cannot be NULL) + * * Returns: 1: secret was valid, public key stores * 0: secret was invalid, try again + * Args: ctx: pointer to a context object, initialized for signing (cannot be NULL) + * Out: pubkey: pointer to the created public key (cannot be NULL) + * In: seckey: pointer to a 32-byte private key (cannot be NULL) */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create( - const secp256k1_context_t* ctx, - unsigned char *pubkey, - int *pubkeylen, - const unsigned char *seckey, - int compressed -) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); - -/** Decompress a public key. - * In: ctx: pointer to a context object (cannot be NULL) - * In/Out: pubkey: pointer to a 65-byte array to put the decompressed public key. - * It must contain a 33-byte or 65-byte public key already (cannot be NULL) - * pubkeylen: pointer to the size of the public key pointed to by pubkey (cannot be NULL) - * It will be updated to reflect the new size. - * Returns: 0: pubkey was invalid - * 1: pubkey was valid, and was replaced with its decompressed version - */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_decompress( - const secp256k1_context_t* ctx, - unsigned char *pubkey, - int *pubkeylen +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_create( + const secp256k1_context* ctx, + secp256k1_pubkey *pubkey, + const unsigned char *seckey ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); -/** Export a private key in DER format. - * In: ctx: pointer to a context object, initialized for signing (cannot be NULL) +/** 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 + * would be invalid (only when the tweak is the complement of the + * private key). 1 otherwise. + * Args: ctx: pointer to a context object (cannot be NULL). + * In/Out: seckey: pointer to a 32-byte private key. + * In: tweak: pointer to a 32-byte tweak. */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_export( - const secp256k1_context_t* ctx, - const unsigned char *seckey, - unsigned char *privkey, - int *privkeylen, - int compressed -) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); - -/** Import a private key in DER format. */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_import( - const secp256k1_context_t* ctx, - unsigned char *seckey, - const unsigned char *privkey, - int privkeylen +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add( + const secp256k1_context* ctx, + unsigned char *seckey, + const unsigned char *tweak ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); -/** Tweak a private key by adding tweak to it. */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_add( - const secp256k1_context_t* ctx, - unsigned char *seckey, - const unsigned char *tweak +/** Tweak a public key by adding tweak times the generator 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 public key + * would be invalid (only when the tweak is the complement of the + * corresponding private key). 1 otherwise. + * Args: ctx: pointer to a context object initialized for validation + * (cannot be NULL). + * In/Out: pubkey: pointer to a public key object. + * In: tweak: pointer to a 32-byte tweak. + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add( + const secp256k1_context* ctx, + secp256k1_pubkey *pubkey, + const unsigned char *tweak ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); -/** Tweak a public key by adding tweak times the generator to it. - * In: ctx: pointer to a context object, initialized for verification (cannot be NULL) +/** Tweak a private key by multiplying it by a tweak. + * Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for + * uniformly random 32-byte arrays, or equal to zero. 1 otherwise. + * Args: ctx: pointer to a context object (cannot be NULL). + * In/Out: seckey: pointer to a 32-byte private key. + * In: tweak: pointer to a 32-byte tweak. */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_add( - const secp256k1_context_t* ctx, - unsigned char *pubkey, - int pubkeylen, - const unsigned char *tweak -) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4); - -/** Tweak a private key by multiplying it with tweak. */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul( - const secp256k1_context_t* ctx, - unsigned char *seckey, - const unsigned char *tweak +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_tweak_mul( + const secp256k1_context* ctx, + unsigned char *seckey, + const unsigned char *tweak ) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); -/** Tweak a public key by multiplying it with tweak. - * In: ctx: pointer to a context object, initialized for verification (cannot be NULL) +/** Tweak a public key by multiplying it by a tweak value. + * Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for + * uniformly random 32-byte arrays, or equal to zero. 1 otherwise. + * Args: ctx: pointer to a context object initialized for validation + * (cannot be NULL). + * In/Out: pubkey: pointer to a public key obkect. + * In: tweak: pointer to a 32-byte tweak. */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul( - const secp256k1_context_t* ctx, - unsigned char *pubkey, - int pubkeylen, - const unsigned char *tweak -) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(4); +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_tweak_mul( + const secp256k1_context* ctx, + secp256k1_pubkey *pubkey, + const unsigned char *tweak +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); /** Updates the context randomization. * Returns: 1: randomization successfully updated * 0: error - * In: ctx: pointer to a context object (cannot be NULL) - * seed32: pointer to a 32-byte random seed (NULL resets to initial state) + * Args: ctx: pointer to a context object (cannot be NULL) + * In: seed32: pointer to a 32-byte random seed (NULL resets to initial state) */ -SECP256K1_WARN_UNUSED_RESULT int secp256k1_context_randomize( - secp256k1_context_t* ctx, - const unsigned char *seed32 +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_context_randomize( + secp256k1_context* ctx, + const unsigned char *seed32 ) SECP256K1_ARG_NONNULL(1); +/** Add a number of public keys together. + * 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 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) + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_combine( + const secp256k1_context* ctx, + secp256k1_pubkey *out, + const secp256k1_pubkey * const * ins, + size_t n +) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); # ifdef __cplusplus } diff --git a/src/secp256k1/include/secp256k1_ecdh.h b/src/secp256k1/include/secp256k1_ecdh.h new file mode 100644 index 0000000000..4b84d7a963 --- /dev/null +++ b/src/secp256k1/include/secp256k1_ecdh.h @@ -0,0 +1,31 @@ +#ifndef _SECP256K1_ECDH_ +# define _SECP256K1_ECDH_ + +# include "secp256k1.h" + +# ifdef __cplusplus +extern "C" { +# endif + +/** 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: 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 *pubkey, + const unsigned char *privkey +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); + +# ifdef __cplusplus +} +# endif + +#endif diff --git a/src/secp256k1/include/secp256k1_recovery.h b/src/secp256k1/include/secp256k1_recovery.h new file mode 100644 index 0000000000..0553797253 --- /dev/null +++ b/src/secp256k1/include/secp256k1_recovery.h @@ -0,0 +1,110 @@ +#ifndef _SECP256K1_RECOVERY_ +# define _SECP256K1_RECOVERY_ + +# include "secp256k1.h" + +# ifdef __cplusplus +extern "C" { +# endif + +/** Opaque data structured that holds a parsed ECDSA signature, + * supporting pubkey recovery. + * + * 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 65 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 + * secp256k1_ecdsa_signature_parse_* functions. + * + * Furthermore, it is guaranteed that identical signatures (including their + * recoverability) will have identical representation, so they can be + * memcmp'ed. + */ +typedef struct { + unsigned char data[65]; +} secp256k1_ecdsa_recoverable_signature; + +/** Parse a compact ECDSA signature (64 bytes + recovery id). + * + * 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 a 64-byte compact signature + * recid: the recovery id (0, 1, 2 or 3) + */ +SECP256K1_API int secp256k1_ecdsa_recoverable_signature_parse_compact( + const secp256k1_context* ctx, + secp256k1_ecdsa_recoverable_signature* sig, + const unsigned char *input64, + int recid +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +/** Convert a recoverable signature into a normal signature. + * + * Returns: 1 + * Out: sig: a pointer to a normal signature (cannot be NULL). + * In: sigin: a pointer to a recoverable signature (cannot be NULL). + */ +SECP256K1_API int secp256k1_ecdsa_recoverable_signature_convert( + const secp256k1_context* ctx, + secp256k1_ecdsa_signature* sig, + const secp256k1_ecdsa_recoverable_signature* sigin +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +/** Serialize an ECDSA signature in compact format (64 bytes + recovery id). + * + * Returns: 1 + * Args: ctx: a secp256k1 context object + * Out: output64: a pointer to a 64-byte array of the compact signature (cannot be NULL) + * recid: a pointer to an integer to hold the recovery id (can be NULL). + * In: sig: a pointer to an initialized signature object (cannot be NULL) + */ +SECP256K1_API int secp256k1_ecdsa_recoverable_signature_serialize_compact( + const secp256k1_context* ctx, + unsigned char *output64, + int *recid, + const secp256k1_ecdsa_recoverable_signature* sig +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); + +/** Create a recoverable ECDSA signature. + * + * 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: sig: pointer to an 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_ecdsa_sign_recoverable( + const secp256k1_context* ctx, + secp256k1_ecdsa_recoverable_signature *sig, + 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); + +/** Recover an ECDSA public key from a signature. + * + * 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 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) + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_recover( + const secp256k1_context* ctx, + secp256k1_pubkey *pubkey, + const secp256k1_ecdsa_recoverable_signature *sig, + const unsigned char *msg32 +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); + +# ifdef __cplusplus +} +# endif + +#endif diff --git a/src/secp256k1/include/secp256k1_schnorr.h b/src/secp256k1/include/secp256k1_schnorr.h new file mode 100644 index 0000000000..dc32fec1ea --- /dev/null +++ b/src/secp256k1/include/secp256k1_schnorr.h @@ -0,0 +1,173 @@ +#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, + size_t n +) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +# ifdef __cplusplus +} +# endif + +#endif |