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bitcoin/include/secp256k1.h

151 lines
6.5 KiB

#ifndef _SECP256K1_
#define _SECP256K1_
#ifdef __cplusplus
extern "C" {
#endif
/** Flags to pass to secp256k1_start. */
#define SECP256K1_START_VERIFY (1 << 0)
#define SECP256K1_START_SIGN (1 << 1)
/** 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.
*/
void secp256k1_start(unsigned int flags);
/** Free all memory associated with this library. After this, no
* functions can be called anymore, except secp256k1_start()
*/
void secp256k1_stop(void);
/** Verify an ECDSA signature.
* Returns: 1: correct signature
* 0: incorrect signature
* -1: invalid public key
* -2: invalid signature
* Requires starting using SECP256K1_START_VERIFY.
*/
int secp256k1_ecdsa_verify(const unsigned char *msg, int msglen,
const unsigned char *sig, int siglen,
const unsigned char *pubkey, int pubkeylen);
/** 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).
* Requires starting using SECP256K1_START_SIGN.
*/
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.
* Requires starting using SECP256K1_START_SIGN.
*/
int secp256k1_ecdsa_sign_compact(const unsigned char *msg, int msglen,
unsigned char *sig64,
const unsigned char *seckey,
const unsigned char *nonce,
int *recid);
/** Recover an ECDSA public key from a compact signature.
* Returns: 1: public key succesfully recovered (which guarantees a correct signature).
* 0: otherwise.
* In: msg: the message assumed to be signed
* msglen: the length of the message
* sig64: signature as 64 byte array
* compressed: whether to recover a compressed or uncompressed pubkey
* recid: the recovery id (as returned by ecdsa_sign_compact)
* Out: pubkey: pointer to a 33 or 65 byte array to put the pubkey.
* pubkeylen: pointer to an int that will contain the pubkey length.
* Requires starting using SECP256K1_START_VERIFY.
*/
int secp256k1_ecdsa_recover_compact(const unsigned char *msg, int msglen,
const unsigned char *sig64,
unsigned char *pubkey, int *pubkeylen,
int compressed, int recid);
/** 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
*/
int secp256k1_ec_seckey_verify(const unsigned char *seckey);
/** Just validate a public key.
* Returns: 1: valid public key
* 0: invalid public key
*/
int secp256k1_ec_pubkey_verify(const unsigned char *pubkey, int pubkeylen);
/** 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.
* Requires starting using SECP256K1_START_SIGN.
*/
int secp256k1_ec_pubkey_create(unsigned char *pubkey, int *pubkeylen, const unsigned char *seckey, int compressed);
/** Decompress a public key.
* In/Out: pubkey: pointer to a 65-byte array to put the decompressed public key.
It must contain a 33-byte or 65-byte public key already.
* pubkeylen: pointer to the size of the public key pointed to be pubkey.
It will be updated to reflect the new size.
* Returns: 0 if the passed public key was invalid, 1 otherwise. If 1 is returned, the
pubkey is replaced with its decompressed version.
*/
int secp256k1_ec_pubkey_decompress(unsigned char *pubkey, int *pubkeylen);
/** Export a private key in DER format. */
int secp256k1_ec_privkey_export(const unsigned char *seckey,
unsigned char *privkey, int *privkeylen,
int compressed);
/** Import a private key in DER format. */
int secp256k1_ec_privkey_import(unsigned char *seckey,
const unsigned char *privkey, int privkeylen);
/** Tweak a private key by adding tweak to it. */
int secp256k1_ec_privkey_tweak_add(unsigned char *seckey, const unsigned char *tweak);
/** Tweak a public key by adding tweak times the generator to it.
* Requires starting with SECP256K1_START_VERIFY.
*/
int secp256k1_ec_pubkey_tweak_add(unsigned char *pubkey, int pubkeylen, const unsigned char *tweak);
/** Tweak a private key by multiplying it with tweak. */
int secp256k1_ec_privkey_tweak_mul(unsigned char *seckey, const unsigned char *tweak);
/** Tweak a public key by multiplying it with tweak.
* Requires starting with SECP256K1_START_VERIFY.
*/
int secp256k1_ec_pubkey_tweak_mul(unsigned char *pubkey, int pubkeylen, const unsigned char *tweak);
#ifdef __cplusplus
}
#endif
#endif