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[ECDH API change] Support custom hash function

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This commit is contained in:
Kirill Fomichev
2015-11-12 11:43:06 +03:00
parent 452d8e4d2a
commit b00be65056
5 changed files with 93 additions and 35 deletions
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28
include/secp256k1_ecdh.h
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@@ -7,21 +7,41 @@
extern "C" {
#endif
/** A pointer to a function that applies hash function to a point
*
* Returns: 1 if a point was successfully hashed. 0 will cause ecdh to fail
* Out: output: pointer to an array to be filled by the function
* In: x: pointer to a 32-byte x coordinate
* y: pointer to a 32-byte y coordinate
*/
typedef int (*secp256k1_ecdh_hash_function)(
unsigned char *output,
const unsigned char *x,
const unsigned char *y
);
/** An implementation of SHA256 hash function that applies to compressed public key. */
SECP256K1_API extern const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_sha256;
/** A default ecdh hash function (currently equal to secp256k1_ecdh_hash_function_sha256). */
SECP256K1_API extern const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_default;
/** Compute an EC Diffie-Hellman secret in constant time
* Returns: 1: exponentiation was successful
* 0: scalar was invalid (zero or overflow)
* Args: ctx: pointer to a context object (cannot be NULL)
* Out: result: a 32-byte array which will be populated by an ECDH
* secret computed from the point and scalar
* Out: output: pointer to an array to be filled by the function
* In: pubkey: a pointer to a secp256k1_pubkey containing an
* initialized public key
* privkey: a 32-byte scalar with which to multiply the point
* hashfp: pointer to a hash function. If NULL, secp256k1_ecdh_hash_function_sha256 is used
*/
SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdh(
const secp256k1_context* ctx,
unsigned char *result,
unsigned char *output,
const secp256k1_pubkey *pubkey,
const unsigned char *privkey
const unsigned char *privkey,
secp256k1_ecdh_hash_function hashfp
) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4);
#ifdef __cplusplus