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Diffstat (limited to 'crypto/secp256k1/libsecp256k1/include/secp256k1.h')
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diff --git a/crypto/secp256k1/libsecp256k1/include/secp256k1.h b/crypto/secp256k1/libsecp256k1/include/secp256k1.h new file mode 100644 index 000000000..23378de1f --- /dev/null +++ b/crypto/secp256k1/libsecp256k1/include/secp256k1.h @@ -0,0 +1,547 @@ +#ifndef _SECP256K1_ +# define _SECP256K1_ + +# ifdef __cplusplus +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) \ + ((__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 + +/** Flags to pass to secp256k1_context_create. */ +# define SECP256K1_CONTEXT_VERIFY (1 << 0) +# define SECP256K1_CONTEXT_SIGN (1 << 1) + +/** Flag to pass to secp256k1_ec_pubkey_serialize and secp256k1_ec_privkey_export. */ +# define SECP256K1_EC_COMPRESSED (1 << 0) + +/** Create a secp256k1 context object. + * + * Returns: a newly created context object. + * In: flags: which parts of the context to initialize. + */ +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. + * 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. + * + * 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. + */ +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 interal 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. + * outputlen: a pointer to an integer which will contain the serialized + * size. + * In: pubkey: a pointer to a secp256k1_pubkey containing an initialized + * public key. + * flags: SECP256K1_EC_COMPRESSED if serialization should be in + * compressed format. + */ +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 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 + * + * Note that this function also supports some violations of DER and even BER. + */ +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); + +/** Verify an ECDSA signature. + * + * Returns: 1: correct 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) + */ +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); + +/** An implementation of RFC6979 (using HMAC-SHA256) as nonce generation function. + * If a data pointer is passed, it is assumed to be a pointer to 32 bytes of + * extra entropy. + */ +extern const secp256k1_nonce_function secp256k1_nonce_function_rfc6979; + +/** A default safe nonce generation function (currently equal to secp256k1_nonce_function_rfc6979). */ +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 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. + */ +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); + +/** Export a private key in BER format. + * + * Returns: 1 if the private key was valid. + * Args: ctx: pointer to a context object, initialized for signing (cannot + * be NULL) + * Out: privkey: pointer to an array for storing the private key in BER. + * Should have space for 279 bytes, and cannot be NULL. + * privkeylen: Pointer to an int where the length of the private key in + * privkey will be stored. + * In: seckey: pointer to a 32-byte secret key to export. + * flags: SECP256K1_EC_COMPRESSED if the key should be exported in + * compressed format. + * + * This function is purely meant for compatibility with applications that + * require BER encoded keys. When working with secp256k1-specific code, the + * simple 32-byte private keys are sufficient. + * + * Note that this function does not guarantee correct DER output. It is + * guaranteed to be parsable by secp256k1_ec_privkey_import. + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_export( + const secp256k1_context* ctx, + unsigned char *privkey, + size_t *privkeylen, + const unsigned char *seckey, + unsigned int flags +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); + +/** Import a private key in DER format. + * Returns: 1 if a private key was extracted. + * Args: ctx: pointer to a context object (cannot be NULL). + * Out: seckey: pointer to a 32-byte array for storing the private key. + * (cannot be NULL). + * In: privkey: pointer to a private key in DER format (cannot be NULL). + * privkeylen: length of the DER private key pointed to be privkey. + * + * This function will accept more than just strict DER, and even allow some BER + * violations. The public key stored inside the DER-encoded private key is not + * verified for correctness, nor are the curve parameters. Use this function + * only if you know in advance it is supposed to contain a secp256k1 private + * key. + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_privkey_import( + const secp256k1_context* ctx, + unsigned char *seckey, + const unsigned char *privkey, + size_t privkeylen +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +/** Tweak a private key by adding tweak to it. + * Returns: 0 if the tweak was out of range (chance of around 1 in 2^128 for + * uniformly random 32-byte arrays, or if the resulting private key + * 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. + * Returns: 1: randomization successfully updated + * 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) + */ +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 pubkey for placing the resulting public key + * (cannot be NULL) + * In: ins: pointer to array of pointers to public keys (cannot be NULL) + * n: the number of public keys to add together (must be at least 1) + * Use secp256k1_ec_pubkey_compress and secp256k1_ec_pubkey_decompress if the + * uncompressed format is needed. + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ec_pubkey_combine( + const secp256k1_context* ctx, + secp256k1_pubkey *out, + const secp256k1_pubkey * const * ins, + int n +) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3); + +# ifdef __cplusplus +} +# endif + +#endif |