642 lines
29 KiB
C
642 lines
29 KiB
C
#ifndef SECP256K1_H
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#define SECP256K1_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <stddef.h>
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/* These rules specify the order of arguments in API calls:
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*
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* 1. Context pointers go first, followed by output arguments, combined
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* output/input arguments, and finally input-only arguments.
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* 2. Array lengths always immediately the follow the argument whose length
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* they describe, even if this violates rule 1.
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* 3. Within the OUT/OUTIN/IN groups, pointers to data that is typically generated
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* later go first. This means: signatures, public nonces, private nonces,
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* messages, public keys, secret keys, tweaks.
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* 4. Arguments that are not data pointers go last, from more complex to less
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* complex: function pointers, algorithm names, messages, void pointers,
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* counts, flags, booleans.
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* 5. Opaque data pointers follow the function pointer they are to be passed to.
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*/
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/** Opaque data structure that holds context information (precomputed tables etc.).
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*
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* The purpose of context structures is to cache large precomputed data tables
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* that are expensive to construct, and also to maintain the randomization data
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* for blinding.
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*
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* Do not create a new context object for each operation, as construction is
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* far slower than all other API calls (~100 times slower than an ECDSA
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* verification).
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*
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* A constructed context can safely be used from multiple threads
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* simultaneously, but API calls that take a non-const pointer to a context
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* need exclusive access to it. In particular this is the case for
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* secp256k1_context_destroy, secp256k1_context_preallocated_destroy,
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* and secp256k1_context_randomize.
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*
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* Regarding randomization, either do it once at creation time (in which case
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* you do not need any locking for the other calls), or use a read-write lock.
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*/
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typedef struct secp256k1_context_struct secp256k1_context;
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/** Opaque data structure that holds rewriteable "scratch space"
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*
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* The purpose of this structure is to replace dynamic memory allocations,
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* because we target architectures where this may not be available. It is
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* essentially a resizable (within specified parameters) block of bytes,
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* which is initially created either by memory allocation or TODO as a pointer
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* into some fixed rewritable space.
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*
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* Unlike the context object, this cannot safely be shared between threads
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* without additional synchronization logic.
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*/
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typedef struct secp256k1_scratch_space_struct secp256k1_scratch_space;
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/** Opaque data structure that holds a parsed and valid public key.
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*
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* The exact representation of data inside is implementation defined and not
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* guaranteed to be portable between different platforms or versions. It is
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* however guaranteed to be 64 bytes in size, and can be safely copied/moved.
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* If you need to convert to a format suitable for storage, transmission, or
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* comparison, use secp256k1_ec_pubkey_serialize and secp256k1_ec_pubkey_parse.
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*/
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typedef struct {
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unsigned char data[64];
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} secp256k1_pubkey;
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/** Opaque data structured that holds a parsed ECDSA signature.
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*
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* The exact representation of data inside is implementation defined and not
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* guaranteed to be portable between different platforms or versions. It is
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* however guaranteed to be 64 bytes in size, and can be safely copied/moved.
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* If you need to convert to a format suitable for storage, transmission, or
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* comparison, use the secp256k1_ecdsa_signature_serialize_* and
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* secp256k1_ecdsa_signature_parse_* functions.
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*/
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typedef struct {
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unsigned char data[64];
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} secp256k1_ecdsa_signature;
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/** A pointer to a function to deterministically generate a nonce.
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*
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* Returns: 1 if a nonce was successfully generated. 0 will cause signing to fail.
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* Out: nonce32: pointer to a 32-byte array to be filled by the function.
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* In: msg32: the 32-byte message hash being verified (will not be NULL)
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* key32: pointer to a 32-byte secret key (will not be NULL)
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* algo16: pointer to a 16-byte array describing the signature
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* algorithm (will be NULL for ECDSA for compatibility).
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* data: Arbitrary data pointer that is passed through.
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* attempt: how many iterations we have tried to find a nonce.
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* This will almost always be 0, but different attempt values
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* are required to result in a different nonce.
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*
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* Except for test cases, this function should compute some cryptographic hash of
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* the message, the algorithm, the key and the attempt.
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*/
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typedef int (*secp256k1_nonce_function)(
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unsigned char *nonce32,
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const unsigned char *msg32,
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const unsigned char *key32,
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const unsigned char *algo16,
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void *data,
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unsigned int attempt
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);
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# if !defined(SECP256K1_GNUC_PREREQ)
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# if defined(__GNUC__)&&defined(__GNUC_MINOR__)
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# define SECP256K1_GNUC_PREREQ(_maj,_min) \
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((__GNUC__<<16)+__GNUC_MINOR__>=((_maj)<<16)+(_min))
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# else
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# define SECP256K1_GNUC_PREREQ(_maj,_min) 0
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# endif
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# endif
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# if (!defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L) )
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# if SECP256K1_GNUC_PREREQ(2,7)
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# define SECP256K1_INLINE __inline__
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# elif (defined(_MSC_VER))
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# define SECP256K1_INLINE __inline
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# else
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# define SECP256K1_INLINE
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# endif
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# else
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# define SECP256K1_INLINE inline
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# endif
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#ifndef SECP256K1_API
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# if defined(_WIN32)
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# ifdef SECP256K1_BUILD
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# define SECP256K1_API __declspec(dllexport)
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# else
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# define SECP256K1_API
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# endif
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# elif defined(__GNUC__) && defined(SECP256K1_BUILD)
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# define SECP256K1_API __attribute__ ((visibility ("default")))
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# else
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# define SECP256K1_API
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# endif
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#endif
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/**Warning attributes
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* NONNULL is not used if SECP256K1_BUILD is set to avoid the compiler optimizing out
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* some paranoid null checks. */
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# if defined(__GNUC__) && SECP256K1_GNUC_PREREQ(3, 4)
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# define SECP256K1_WARN_UNUSED_RESULT __attribute__ ((__warn_unused_result__))
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# else
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# define SECP256K1_WARN_UNUSED_RESULT
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# endif
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# if !defined(SECP256K1_BUILD) && defined(__GNUC__) && SECP256K1_GNUC_PREREQ(3, 4)
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# define SECP256K1_ARG_NONNULL(_x) __attribute__ ((__nonnull__(_x)))
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# else
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# define SECP256K1_ARG_NONNULL(_x)
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# endif
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/** All flags' lower 8 bits indicate what they're for. Do not use directly. */
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#define SECP256K1_FLAGS_TYPE_MASK ((1 << 8) - 1)
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#define SECP256K1_FLAGS_TYPE_CONTEXT (1 << 0)
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#define SECP256K1_FLAGS_TYPE_COMPRESSION (1 << 1)
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/** The higher bits contain the actual data. Do not use directly. */
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#define SECP256K1_FLAGS_BIT_CONTEXT_VERIFY (1 << 8)
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#define SECP256K1_FLAGS_BIT_CONTEXT_SIGN (1 << 9)
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#define SECP256K1_FLAGS_BIT_COMPRESSION (1 << 8)
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/** Flags to pass to secp256k1_context_create, secp256k1_context_preallocated_size, and
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* secp256k1_context_preallocated_create. */
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#define SECP256K1_CONTEXT_VERIFY (SECP256K1_FLAGS_TYPE_CONTEXT | SECP256K1_FLAGS_BIT_CONTEXT_VERIFY)
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#define SECP256K1_CONTEXT_SIGN (SECP256K1_FLAGS_TYPE_CONTEXT | SECP256K1_FLAGS_BIT_CONTEXT_SIGN)
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#define SECP256K1_CONTEXT_NONE (SECP256K1_FLAGS_TYPE_CONTEXT)
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/** Flag to pass to secp256k1_ec_pubkey_serialize and secp256k1_ec_privkey_export. */
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#define SECP256K1_EC_COMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION | SECP256K1_FLAGS_BIT_COMPRESSION)
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#define SECP256K1_EC_UNCOMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION)
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/** Prefix byte used to tag various encoded curvepoints for specific purposes */
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#define SECP256K1_TAG_PUBKEY_EVEN 0x02
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#define SECP256K1_TAG_PUBKEY_ODD 0x03
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#define SECP256K1_TAG_PUBKEY_UNCOMPRESSED 0x04
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#define SECP256K1_TAG_PUBKEY_HYBRID_EVEN 0x06
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#define SECP256K1_TAG_PUBKEY_HYBRID_ODD 0x07
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/** A simple secp256k1 context object with no precomputed tables. These are useful for
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* type serialization/parsing functions which require a context object to maintain
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* API consistency, but currently do not require expensive precomputations or dynamic
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* allocations.
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*/
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SECP256K1_API extern const secp256k1_context *secp256k1_context_no_precomp;
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/** Set a callback function to be called when an illegal argument is passed to
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* an API call. It will only trigger for violations that are mentioned
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* explicitly in the header.
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*
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* The philosophy is that these shouldn't be dealt with through a
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* specific return value, as calling code should not have branches to deal with
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* the case that this code itself is broken.
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*
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* On the other hand, during debug stage, one would want to be informed about
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* such mistakes, and the default (crashing) may be inadvisable.
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* When this callback is triggered, the API function called is guaranteed not
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* to cause a crash, though its return value and output arguments are
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* undefined.
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*
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* When this function has not been called (or called with fn==NULL), then the
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* default handler will be used. The library provides a default handler which
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* writes the message to stderr and calls abort. This default handler can be
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* replaced at link time if the preprocessor macro
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* USE_EXTERNAL_DEFAULT_CALLBACKS is defined, which is the case if the build
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* has been configured with --enable-external-default-callbacks. Then the
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* following two symbols must be provided to link against:
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* - void secp256k1_default_illegal_callback_fn(const char* message, void* data);
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* - void secp256k1_default_error_callback_fn(const char* message, void* data);
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* The library can call these default handlers even before a proper callback data
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* pointer could have been set using secp256k1_context_set_illegal_callback or
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* secp256k1_context_set_illegal_callback, e.g., when the creation of a context
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* fails. In this case, the corresponding default handler will be called with
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* the data pointer argument set to NULL.
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*
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* Args: ctx: an existing context object (cannot be NULL)
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* In: fun: a pointer to a function to call when an illegal argument is
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* passed to the API, taking a message and an opaque pointer.
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* (NULL restores the default handler.)
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* data: the opaque pointer to pass to fun above.
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*
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* See also secp256k1_context_set_error_callback.
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*/
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SECP256K1_API void secp256k1_context_set_illegal_callback(
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secp256k1_context* ctx,
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void (*fun)(const char* message, void* data),
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const void* data
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) SECP256K1_ARG_NONNULL(1);
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/** Set a callback function to be called when an internal consistency check
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* fails. The default is crashing.
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*
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* This can only trigger in case of a hardware failure, miscompilation,
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* memory corruption, serious bug in the library, or other error would can
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* otherwise result in undefined behaviour. It will not trigger due to mere
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* incorrect usage of the API (see secp256k1_context_set_illegal_callback
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* for that). After this callback returns, anything may happen, including
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* crashing.
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*
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* Args: ctx: an existing context object (cannot be NULL)
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* In: fun: a pointer to a function to call when an internal error occurs,
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* taking a message and an opaque pointer (NULL restores the
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* default handler, see secp256k1_context_set_illegal_callback
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* for details).
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* data: the opaque pointer to pass to fun above.
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*
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* See also secp256k1_context_set_illegal_callback.
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*/
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SECP256K1_API void secp256k1_context_set_error_callback(
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secp256k1_context* ctx,
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void (*fun)(const char* message, void* data),
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const void* data
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) SECP256K1_ARG_NONNULL(1);
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/** Parse a variable-length public key into the pubkey object.
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*
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* Returns: 1 if the public key was fully valid.
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* 0 if the public key could not be parsed or is invalid.
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* Args: ctx: a secp256k1 context object.
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* Out: pubkey: pointer to a pubkey object. If 1 is returned, it is set to a
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* parsed version of input. If not, its value is undefined.
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* In: input: pointer to a serialized public key
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* inputlen: length of the array pointed to by input
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*
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* This function supports parsing compressed (33 bytes, header byte 0x02 or
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* 0x03), uncompressed (65 bytes, header byte 0x04), or hybrid (65 bytes, header
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* byte 0x06 or 0x07) format public keys.
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_parse(
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const secp256k1_context* ctx,
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secp256k1_pubkey* pubkey,
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const unsigned char *input,
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size_t inputlen
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Serialize a pubkey object into a serialized byte sequence.
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*
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* Returns: 1 always.
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* Args: ctx: a secp256k1 context object.
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* Out: output: a pointer to a 65-byte (if compressed==0) or 33-byte (if
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* compressed==1) byte array to place the serialized key
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* in.
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* In/Out: outputlen: a pointer to an integer which is initially set to the
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* size of output, and is overwritten with the written
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* size.
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* In: pubkey: a pointer to a secp256k1_pubkey containing an
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* initialized public key.
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* flags: SECP256K1_EC_COMPRESSED if serialization should be in
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* compressed format, otherwise SECP256K1_EC_UNCOMPRESSED.
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*/
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SECP256K1_API int secp256k1_ec_pubkey_serialize(
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const secp256k1_context* ctx,
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unsigned char *output,
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size_t *outputlen,
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const secp256k1_pubkey* pubkey,
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unsigned int flags
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
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/** Parse an ECDSA signature in compact (64 bytes) format.
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*
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* Returns: 1 when the signature could be parsed, 0 otherwise.
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* Args: ctx: a secp256k1 context object
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* Out: sig: a pointer to a signature object
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* In: input64: a pointer to the 64-byte array to parse
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*
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* The signature must consist of a 32-byte big endian R value, followed by a
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* 32-byte big endian S value. If R or S fall outside of [0..order-1], the
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* encoding is invalid. R and S with value 0 are allowed in the encoding.
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*
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* After the call, sig will always be initialized. If parsing failed or R or
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* S are zero, the resulting sig value is guaranteed to fail validation for any
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* message and public key.
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*/
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SECP256K1_API int secp256k1_ecdsa_signature_parse_compact(
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const secp256k1_context* ctx,
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secp256k1_ecdsa_signature* sig,
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const unsigned char *input64
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Parse a DER ECDSA signature.
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*
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* Returns: 1 when the signature could be parsed, 0 otherwise.
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* Args: ctx: a secp256k1 context object
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* Out: sig: a pointer to a signature object
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* In: input: a pointer to the signature to be parsed
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* inputlen: the length of the array pointed to be input
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*
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* This function will accept any valid DER encoded signature, even if the
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* encoded numbers are out of range.
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*
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* After the call, sig will always be initialized. If parsing failed or the
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* encoded numbers are out of range, signature validation with it is
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* guaranteed to fail for every message and public key.
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*/
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SECP256K1_API int secp256k1_ecdsa_signature_parse_der(
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const secp256k1_context* ctx,
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secp256k1_ecdsa_signature* sig,
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const unsigned char *input,
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size_t inputlen
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Serialize an ECDSA signature in DER format.
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*
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* Returns: 1 if enough space was available to serialize, 0 otherwise
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* Args: ctx: a secp256k1 context object
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* Out: output: a pointer to an array to store the DER serialization
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* In/Out: outputlen: a pointer to a length integer. Initially, this integer
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* should be set to the length of output. After the call
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* it will be set to the length of the serialization (even
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* if 0 was returned).
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* In: sig: a pointer to an initialized signature object
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*/
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SECP256K1_API int secp256k1_ecdsa_signature_serialize_der(
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const secp256k1_context* ctx,
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unsigned char *output,
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size_t *outputlen,
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const secp256k1_ecdsa_signature* sig
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
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/** Serialize an ECDSA signature in compact (64 byte) format.
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*
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* Returns: 1
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* Args: ctx: a secp256k1 context object
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* Out: output64: a pointer to a 64-byte array to store the compact serialization
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* In: sig: a pointer to an initialized signature object
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*
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* See secp256k1_ecdsa_signature_parse_compact for details about the encoding.
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*/
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SECP256K1_API int secp256k1_ecdsa_signature_serialize_compact(
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const secp256k1_context* ctx,
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unsigned char *output64,
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const secp256k1_ecdsa_signature* sig
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3);
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/** Verify an ECDSA signature.
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*
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* Returns: 1: correct signature
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* 0: incorrect or unparseable signature
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* Args: ctx: a secp256k1 context object, initialized for verification.
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* In: sig: the signature being verified (cannot be NULL)
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* msg32: the 32-byte message hash being verified (cannot be NULL)
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* pubkey: pointer to an initialized public key to verify with (cannot be NULL)
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*
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* To avoid accepting malleable signatures, only ECDSA signatures in lower-S
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* form are accepted.
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*
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* If you need to accept ECDSA signatures from sources that do not obey this
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* rule, apply secp256k1_ecdsa_signature_normalize to the signature prior to
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* validation, but be aware that doing so results in malleable signatures.
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*
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* For details, see the comments for that function.
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*/
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SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdsa_verify(
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const secp256k1_context* ctx,
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const secp256k1_ecdsa_signature *sig,
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const unsigned char *msg32,
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const secp256k1_pubkey *pubkey
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) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
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/** Convert a signature to a normalized lower-S form.
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*
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* Returns: 1 if sigin was not normalized, 0 if it already was.
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* Args: ctx: a secp256k1 context object
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* Out: sigout: a pointer to a signature to fill with the normalized form,
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* or copy if the input was already normalized. (can be NULL if
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* you're only interested in whether the input was already
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* 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.
|
||
*/
|
||
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: 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
|
||
* Args: ctx: pointer to a context object (cannot be NULL)
|
||
* In: seckey: pointer to a 32-byte secret key (cannot be NULL)
|
||
*/
|
||
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.
|
||
*
|
||
* 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_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);
|
||
|
||
/** 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 obkect.
|
||
* 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 /* SECP256K1_H */
|