core-lightning/common/bolt12_id.h
Rusty Russell 09401e34b6 common/bolt12_id: generate alias tweak.
For now we only use a fake id for requesting invoices (as a payer_key), but we
will eventually use this generically, and we want plugins to be able to map them
too, so use the same scheme as path_id: a generated secret using the makesecret
API.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2024-08-01 12:31:48 +09:30

55 lines
1.9 KiB
C

#ifndef LIGHTNING_COMMON_BOLT12_ID_H
#define LIGHTNING_COMMON_BOLT12_ID_H
#include "config.h"
#include <ccan/short_types/short_types.h>
#include <ccan/tal/tal.h>
struct secret;
struct sha256;
/* String to use with makesecret to get the bolt12 base secret */
#define BOLT12_ID_BASE_STRING "bolt12-invoice-base"
/* String to use with makesecret to get node aliases */
#define NODE_ALIAS_BASE_STRING "node-alias-base"
/**
* bolt12_path_secret: generate the "path_" field for the tlv_encrypted_data_tlv
* @base_secret: the node-specific secret makesecret(BOLT12_ID_BASE_STRING)
* @payment_hash: the invoice payment hash
* @path_secret: the path_secret to populate.
*
* Receiving a blinded, encrypted tlv_encrypted_data_tlv containing
* the correct path_id is how we know this blinded path is the correct
* one for this invoice payment.
*
* It's exposed here as plugins may want to generate blinded paths.
*/
void bolt12_path_secret(const struct secret *base_secret,
const struct sha256 *payment_hash,
struct secret *path_secret);
/* This variant gives the result as a u8 talarr, as expected by
* the tlv interface */
u8 *bolt12_path_id(const tal_t *ctx,
const struct secret *base_secret,
const struct sha256 *payment_hash);
/**
* bolt12_alias_tweak: generate a tweak to disguise our node id for this offer/invoice_request
* @base_secret: the node-specific secret makesecret(NODE_ALIAS_BASE_STRING)
* @input: the byte array to use to generate the tweak.
* @input_len: the length of @input.
* @tweak: the resulting tweak.
*
* We use this tweak to disguise our node_id when we want a temporary id for a specific
* purpose. The "input" can be shared publicly, as the base_secret prevents
* others from linking the tweak (or the resulting pubkey) to us.
*/
void bolt12_alias_tweak(const struct secret *base_secret,
const void *input,
size_t input_len,
struct sha256 *tweak);
#endif /* LIGHTNING_COMMON_BOLT12_ID_H */