-#ifndef _SECP256K1_
-#define _SECP256K1_
+#ifndef SECP256K1_H
+#define SECP256K1_H
#ifdef __cplusplus
extern "C" {
#endif
-/** Initialize the library. This may take some time (10-100 ms).
- * You need to call this before calling any other function.
- * It cannot run in parallel with any other functions, but once
- * secp256k1_start() returns, all other functions are thread-safe.
+#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 calls that take a non-const pointer to a context
+ * need exclusive access to it. In particular this is the case for
+ * secp256k1_context_destroy, secp256k1_context_preallocated_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 rewriteable "scratch space"
+ *
+ * The purpose of this structure is to replace dynamic memory allocations,
+ * because we target architectures where this may not be available. It is
+ * essentially a resizable (within specified parameters) block of bytes,
+ * which is initially created either by memory allocation or TODO as a pointer
+ * into some fixed rewritable space.
+ *
+ * Unlike the context object, this cannot safely be shared between threads
+ * without additional synchronization logic.
+ */
+typedef struct secp256k1_scratch_space_struct secp256k1_scratch_space;
+
+/** 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, transmission, or
+ * comparison, use secp256k1_ec_pubkey_serialize and secp256k1_ec_pubkey_parse.
+ */
+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, transmission, or
+ * comparison, use the secp256k1_ecdsa_signature_serialize_* and
+ * secp256k1_ecdsa_signature_parse_* functions.
+ */
+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) \
+ ((__GNUC__<<16)+__GNUC_MINOR__>=((_maj)<<16)+(_min))
+# else
+# define SECP256K1_GNUC_PREREQ(_maj,_min) 0
+# endif
+# endif
+
+# if (!defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L) )
+# if SECP256K1_GNUC_PREREQ(2,7)
+# define SECP256K1_INLINE __inline__
+# elif (defined(_MSC_VER))
+# define SECP256K1_INLINE __inline
+# else
+# define SECP256K1_INLINE
+# endif
+# else
+# 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. */
+# if defined(__GNUC__) && SECP256K1_GNUC_PREREQ(3, 4)
+# define SECP256K1_WARN_UNUSED_RESULT __attribute__ ((__warn_unused_result__))
+# else
+# define SECP256K1_WARN_UNUSED_RESULT
+# endif
+# if !defined(SECP256K1_BUILD) && defined(__GNUC__) && SECP256K1_GNUC_PREREQ(3, 4)
+# define SECP256K1_ARG_NONNULL(_x) __attribute__ ((__nonnull__(_x)))
+# else
+# 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_CONTEXT_DECLASSIFY (1 << 10)
+#define SECP256K1_FLAGS_BIT_COMPRESSION (1 << 8)
+
+/** Flags to pass to secp256k1_context_create, secp256k1_context_preallocated_size, and
+ * secp256k1_context_preallocated_create. */
+#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_DECLASSIFY (SECP256K1_FLAGS_TYPE_CONTEXT | SECP256K1_FLAGS_BIT_CONTEXT_DECLASSIFY)
+#define SECP256K1_CONTEXT_NONE (SECP256K1_FLAGS_TYPE_CONTEXT)
+
+/** Flag to pass to secp256k1_ec_pubkey_serialize. */
+#define SECP256K1_EC_COMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION | SECP256K1_FLAGS_BIT_COMPRESSION)
+#define SECP256K1_EC_UNCOMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION)
+
+/** Prefix byte used to tag various encoded curvepoints for specific purposes */
+#define SECP256K1_TAG_PUBKEY_EVEN 0x02
+#define SECP256K1_TAG_PUBKEY_ODD 0x03
+#define SECP256K1_TAG_PUBKEY_UNCOMPRESSED 0x04
+#define SECP256K1_TAG_PUBKEY_HYBRID_EVEN 0x06
+#define SECP256K1_TAG_PUBKEY_HYBRID_ODD 0x07
+
+/** A simple secp256k1 context object with no precomputed tables. These are useful for
+ * type serialization/parsing functions which require a context object to maintain
+ * API consistency, but currently do not require expensive precomputations or dynamic
+ * allocations.
+ */
+SECP256K1_API extern const secp256k1_context *secp256k1_context_no_precomp;
+
+/** Create a secp256k1 context object (in dynamically allocated memory).
+ *
+ * This function uses malloc to allocate memory. It is guaranteed that malloc is
+ * called at most once for every call of this function. If you need to avoid dynamic
+ * memory allocation entirely, see the functions in secp256k1_preallocated.h.
+ *
+ * Returns: a newly created context object.
+ * In: flags: which parts of the context to initialize.
+ *
+ * See also secp256k1_context_randomize.
+ */
+SECP256K1_API secp256k1_context* secp256k1_context_create(
+ unsigned int flags
+) SECP256K1_WARN_UNUSED_RESULT;
+
+/** Copy a secp256k1 context object (into dynamically allocated memory).
+ *
+ * This function uses malloc to allocate memory. It is guaranteed that malloc is
+ * called at most once for every call of this function. If you need to avoid dynamic
+ * memory allocation entirely, see the functions in secp256k1_preallocated.h.
+ *
+ * Returns: a newly created context object.
+ * Args: ctx: an existing context to copy (cannot be NULL)
+ */
+SECP256K1_API secp256k1_context* secp256k1_context_clone(
+ const secp256k1_context* ctx
+) SECP256K1_ARG_NONNULL(1) SECP256K1_WARN_UNUSED_RESULT;
+
+/** Destroy a secp256k1 context object (created in dynamically allocated memory).
+ *
+ * The context pointer may not be used afterwards.
+ *
+ * The context to destroy must have been created using secp256k1_context_create
+ * or secp256k1_context_clone. If the context has instead been created using
+ * secp256k1_context_preallocated_create or secp256k1_context_preallocated_clone, the
+ * behaviour is undefined. In that case, secp256k1_context_preallocated_destroy must
+ * be used instead.
+ *
+ * Args: ctx: an existing context to destroy, constructed using
+ * secp256k1_context_create or secp256k1_context_clone
+ */
+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.
+ *
+ * When this function has not been called (or called with fn==NULL), then the
+ * default handler will be used. The library provides a default handler which
+ * writes the message to stderr and calls abort. This default handler can be
+ * replaced at link time if the preprocessor macro
+ * USE_EXTERNAL_DEFAULT_CALLBACKS is defined, which is the case if the build
+ * has been configured with --enable-external-default-callbacks. Then the
+ * following two symbols must be provided to link against:
+ * - void secp256k1_default_illegal_callback_fn(const char* message, void* data);
+ * - void secp256k1_default_error_callback_fn(const char* message, void* data);
+ * The library can call these default handlers even before a proper callback data
+ * pointer could have been set using secp256k1_context_set_illegal_callback or
+ * secp256k1_context_set_error_callback, e.g., when the creation of a context
+ * fails. In this case, the corresponding default handler will be called with
+ * the data pointer argument set to NULL.
+ *
+ * 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 the default handler.)
+ * data: the opaque pointer to pass to fun above.
+ *
+ * See also secp256k1_context_set_error_callback.
+ */
+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 the
+ * default handler, see secp256k1_context_set_illegal_callback
+ * for details).
+ * data: the opaque pointer to pass to fun above.
+ *
+ * See also secp256k1_context_set_illegal_callback.
+ */
+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);
+
+/** Create a secp256k1 scratch space object.
+ *
+ * Returns: a newly created scratch space.
+ * Args: ctx: an existing context object (cannot be NULL)
+ * In: size: amount of memory to be available as scratch space. Some extra
+ * (<100 bytes) will be allocated for extra accounting.
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT secp256k1_scratch_space* secp256k1_scratch_space_create(
+ const secp256k1_context* ctx,
+ size_t size
+) SECP256K1_ARG_NONNULL(1);
+
+/** Destroy a secp256k1 scratch space.
+ *
+ * The pointer may not be used afterwards.
+ * Args: ctx: a secp256k1 context object.
+ * scratch: space to destroy
*/
-void secp256k1_start(void);
+SECP256K1_API void secp256k1_scratch_space_destroy(
+ const secp256k1_context* ctx,
+ secp256k1_scratch_space* scratch
+) SECP256K1_ARG_NONNULL(1);
-/** Free all memory associated with this library. After this, no
- * functions can be called anymore, except secp256k1_start()
+/** 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.
*/
-void secp256k1_stop(void);
+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
+ * 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)
+ * 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,
+ 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);
+
+/** 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.
*/
-int secp256k1_ecdsa_verify(const unsigned char *msg, int msglen,
- const unsigned char *sig, int siglen,
- const unsigned char *pubkey, int pubkeylen);
+SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_rfc6979;
+
+/** A default safe nonce generation function (currently equal to secp256k1_nonce_function_rfc6979). */
+SECP256K1_API extern const secp256k1_nonce_function secp256k1_nonce_function_default;
/** Create an ECDSA signature.
+ *
* Returns: 1: signature created
- * 0: nonce invalid, try another one
- * In: msg: the message being signed
- * msglen: the length of the message being signed
- * seckey: pointer to a 32-byte secret key (assumed to be valid)
- * nonce: pointer to a 32-byte nonce (generated with a cryptographic PRNG)
- * Out: sig: pointer to a 72-byte array where the signature will be placed.
- * siglen: pointer to an int, which will be updated to the signature length (<=72).
- */
-int secp256k1_ecdsa_sign(const unsigned char *msg, int msglen,
- unsigned char *sig, int *siglen,
- const unsigned char *seckey,
- const unsigned char *nonce);
-
-/** Create a compact ECDSA signature (64 byte + recovery id).
- * Returns: 1: signature created
- * 0: nonce invalid, try another one
- * In: msg: the message being signed
- * msglen: the length of the message being signed
- * seckey: pointer to a 32-byte secret key (assumed to be valid)
- * nonce: pointer to a 32-byte nonce (generated with a cryptographic PRNG)
- * Out: sig: pointer to a 64-byte array where the signature will be placed.
- * recid: pointer to an int, which will be updated to contain the recovery id.
- */
-int secp256k1_ecdsa_sign_compact(const unsigned char *msg, int msglen,
- unsigned char *sig64,
- const unsigned char *seckey,
- const unsigned char *nonce,
- int *recid);
-
-int secp256k1_ecdsa_recover_compact(const unsigned char *msg, int msglen,
- const unsigned char *sig64,
- unsigned char *pubkey, int *pubkeylen,
- int compressed, int recid);
+ * 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)
+ *
+ * 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,
+ 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);
/** Verify an ECDSA secret key.
+ *
* Returns: 1: secret key is valid
* 0: secret key is invalid
- * In: seckey: pointer to a 32-byte secret key
+ * Args: ctx: pointer to a context object (cannot be NULL)
+ * In: seckey: pointer to a 32-byte secret key (cannot be NULL)
*/
-int secp256j1_ecdsa_seckey_verify(const unsigned char *seckey);
-
-/** Just validate a public key.
- * Returns: 1: valid public key
- * 0: invalid public key
- */
-int secp256k1_ecdsa_pubkey_verify(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: compressed: whether the computed public key should be compressed
- * seckey: pointer to a 32-byte private key.
- * Out: pubkey: pointer to a 33-byte (if compressed) or 65-byte (if uncompressed)
- * area to store the public key.
- * pubkeylen: pointer to int that will be updated to contains the pubkey's
- * length.
+ *
* Returns: 1: secret was valid, public key stores
- * 0: secret was invalid, try again.
+ * 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)
*/
-int secp256k1_ecdsa_pubkey_create(unsigned char *pubkey, int *pubkeylen, const unsigned char *seckey, int compressed);
+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);
-int secp256k1_ecdsa_pubkey_decompress(unsigned char *pubkey, int *pubkeylen);
+/** Negates a private key in place.
+ *
+ * Returns: 1 always
+ * Args: ctx: pointer to a context object
+ * In/Out: seckey: pointer to the 32-byte private key to be negated (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_negate(
+ const secp256k1_context* ctx,
+ unsigned char *seckey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
+
+/** Negates a public key in place.
+ *
+ * Returns: 1 always
+ * Args: ctx: pointer to a context object
+ * In/Out: pubkey: pointer to the public key to be negated (cannot be NULL)
+ */
+SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_negate(
+ const secp256k1_context* ctx,
+ secp256k1_pubkey *pubkey
+) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2);
+
+/** 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_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 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 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_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 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 object.
+ * In: tweak: pointer to a 32-byte tweak.
+ */
+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 to protect against side-channel leakage.
+ * Returns: 1: randomization successfully updated or nothing to randomize
+ * 0: error
+ * Args: ctx: pointer to a context object (cannot be NULL)
+ * In: seed32: pointer to a 32-byte random seed (NULL resets to initial state)
+ *
+ * While secp256k1 code is written to be constant-time no matter what secret
+ * values are, it's possible that a future compiler may output code which isn't,
+ * and also that the CPU may not emit the same radio frequencies or draw the same
+ * amount power for all values.
+ *
+ * This function provides a seed which is combined into the blinding value: that
+ * blinding value is added before each multiplication (and removed afterwards) so
+ * that it does not affect function results, but shields against attacks which
+ * rely on any input-dependent behaviour.
+ *
+ * This function has currently an effect only on contexts initialized for signing
+ * because randomization is currently used only for signing. However, this is not
+ * guaranteed and may change in the future. It is safe to call this function on
+ * contexts not initialized for signing; then it will have no effect and return 1.
+ *
+ * You should call this after secp256k1_context_create or
+ * secp256k1_context_clone (and secp256k1_context_preallocated_create or
+ * secp256k1_context_clone, resp.), and you may call this repeatedly afterwards.
+ */
+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
}
#endif
-#endif
+#endif /* SECP256K1_H */
projects / secp256k1.git / blobdiff