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#include <ccan/crypto/hkdf_sha256/hkdf_sha256.h>
#include <ccan/crypto/sha256/sha256.h>
#include <common/derive_basepoints.h>
#include <common/utils.h>
bool derive_basepoints(const struct privkey *seed,
struct pubkey *funding_pubkey,
struct basepoints *basepoints,
struct secrets *secrets,
struct sha256 *shaseed)
{
struct keys {
struct privkey f, r, h, p, d;
struct sha256 shaseed;
} keys;
hkdf_sha256(&keys, sizeof(keys), NULL, 0, seed, sizeof(*seed),
"c-lightning", strlen("c-lightning"));
if (secrets) {
secrets->funding_privkey = keys.f;
secrets->revocation_basepoint_secret = keys.r.secret;
secrets->payment_basepoint_secret = keys.p.secret;
secrets->htlc_basepoint_secret = keys.h.secret;
secrets->delayed_payment_basepoint_secret = keys.d.secret;
}
if (funding_pubkey) {
if (!pubkey_from_privkey(&keys.f, funding_pubkey))
return false;
}
if (basepoints) {
if (!pubkey_from_privkey(&keys.r, &basepoints->revocation)
|| !pubkey_from_privkey(&keys.p, &basepoints->payment)
|| !pubkey_from_privkey(&keys.h, &basepoints->htlc)
|| !pubkey_from_privkey(&keys.d, &basepoints->delayed_payment))
return false;
}
/* BOLT #3:
*
* A node:
* - MUST select an unguessable 256-bit seed for each connection,
* - MUST NOT reveal the seed.
*/
if (shaseed)
*shaseed = keys.shaseed;
return true;
}
void per_commit_secret(const struct sha256 *shaseed,
struct sha256 *commit_secret,
u64 per_commit_index)
{
shachain_from_seed(shaseed, shachain_index(per_commit_index),
commit_secret);
}
bool per_commit_point(const struct sha256 *shaseed,
struct pubkey *commit_point,
u64 per_commit_index)
{
struct sha256 per_commit_secret;
/* Derive new per-commitment-point. */
shachain_from_seed(shaseed, shachain_index(per_commit_index),
&per_commit_secret);
/* BOLT #3:
*
* The `per_commitment_point` is generated using elliptic-curve
* multiplication:
*
* per_commitment_point = per_commitment_secret * G
*/
if (secp256k1_ec_pubkey_create(secp256k1_ctx,
&commit_point->pubkey,
per_commit_secret.u.u8) != 1)
return false;
return true;
}