common/blindedpath: enctlv creation primitives.

And test vector generation!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2021-09-22 06:47:16 +09:30
parent f2a4bd6ad8
commit b98e8a099d
4 changed files with 356 additions and 1 deletions

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@ -7,7 +7,11 @@
#include <sodium.h>
#include <wire/onion_wire.h>
/* FIXME: Pad with dummy nodes, but make sure to check them on recv! */
#ifndef SUPERVERBOSE
#define SUPERVERBOSE(...)
#endif
/* Obsolete version: use enctlv() helper. */
struct onionmsg_path **make_blindedpath(const tal_t *ctx,
const struct pubkey *route,
struct pubkey *initial_blinding,
@ -95,3 +99,145 @@ struct onionmsg_path **make_blindedpath(const tal_t *ctx,
return path;
}
/* Blinds node_id and calculates next blinding factor. */
static bool blind_node(const struct privkey *blinding,
const struct secret *ss,
const struct pubkey *node,
struct pubkey *node_alias,
struct privkey *next_blinding)
{
struct secret node_id_blinding;
struct pubkey blinding_pubkey;
struct sha256 h;
/*
* Blinded node_id for N(i), private key known only by N(i):
* B(i) = HMAC256("blinded_node_id", ss(i)) * P(i)
*/
subkey_from_hmac("blinded_node_id", ss, &node_id_blinding);
SUPERVERBOSE("\t\"HMAC256('blinded_node_id', ss)\": \"%s\",\n",
type_to_string(tmpctx, struct secret,
&node_id_blinding));
*node_alias = *node;
if (secp256k1_ec_pubkey_tweak_mul(secp256k1_ctx,
&node_alias->pubkey,
node_id_blinding.data) != 1)
return false;
SUPERVERBOSE("\t\"blinded_node_id\": \"%s\",\n",
type_to_string(tmpctx, struct pubkey, node_alias));
/*
* Ephemeral private key, only known by N(r):
* e(i+1) = H(E(i) || ss(i)) * e(i)
*/
if (!pubkey_from_privkey(blinding, &blinding_pubkey))
return false;
SUPERVERBOSE("\t\"E\": \"%s\",\n",
type_to_string(tmpctx, struct pubkey, &blinding_pubkey));
blinding_hash_e_and_ss(&blinding_pubkey, ss, &h);
SUPERVERBOSE("\t\"H(E || ss)\": \"%s\",\n",
type_to_string(tmpctx, struct sha256, &h));
blinding_next_privkey(blinding, &h, next_blinding);
SUPERVERBOSE("\t\"next_e\": \"%s\",\n",
type_to_string(tmpctx, struct privkey, next_blinding));
return true;
}
static u8 *enctlv_from_encmsg(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *node,
const struct tlv_encmsg_tlvs *encmsg,
struct privkey *next_blinding,
struct pubkey *node_alias)
{
/* https://github.com/lightningnetwork/lightning-rfc/blob/route-blinding/proposals/route-blinding.md */
struct secret ss, rho;
u8 *ret;
int ok;
/* All-zero npub */
static const unsigned char npub[crypto_aead_chacha20poly1305_ietf_NPUBBYTES];
/*
* shared secret known only by N(r) and N(i):
* ss(i) = H(e(i) * P(i)) = H(k(i) * E(i))
*/
if (secp256k1_ecdh(secp256k1_ctx, ss.data,
&node->pubkey, blinding->secret.data,
NULL, NULL) != 1)
return NULL;
SUPERVERBOSE("\t\"ss\": \"%s\",\n",
type_to_string(tmpctx, struct secret, &ss));
/* This calculates the node's alias, and next blinding */
if (!blind_node(blinding, &ss, node, node_alias, next_blinding))
return NULL;
/* Marshall */
ret = tal_arr(ctx, u8, 0);
towire_encmsg_tlvs(&ret, encmsg);
SUPERVERBOSE("\t\"encmsg_hex\": \"%s\",\n", tal_hex(tmpctx, ret));
/*
* Key used to encrypt payload for N(i) by N(r):
* rho(i) = HMAC256("rho", ss(i))
*/
subkey_from_hmac("rho", &ss, &rho);
SUPERVERBOSE("\t\"rho\": \"%s\",\n",
type_to_string(tmpctx, struct secret, &rho));
/* Encrypt in place */
towire_pad(&ret, crypto_aead_chacha20poly1305_ietf_ABYTES);
ok = crypto_aead_chacha20poly1305_ietf_encrypt(ret, NULL,
ret,
tal_bytelen(ret)
- crypto_aead_chacha20poly1305_ietf_ABYTES,
NULL, 0,
NULL, npub,
rho.data);
assert(ok == 0);
return ret;
}
u8 *create_enctlv(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *node,
const struct pubkey *next_node,
size_t padlen,
const struct pubkey *override_blinding,
struct privkey *next_blinding,
struct pubkey *node_alias)
{
struct tlv_encmsg_tlvs *encmsg = tlv_encmsg_tlvs_new(tmpctx);
if (padlen)
encmsg->padding = tal_arrz(encmsg, u8, padlen);
encmsg->next_node_id = cast_const(struct pubkey *, next_node);
encmsg->next_blinding = cast_const(struct pubkey *, override_blinding);
return enctlv_from_encmsg(ctx, blinding, node, encmsg,
next_blinding, node_alias);
}
u8 *create_final_enctlv(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *final_node,
size_t padlen,
const struct secret *self_id,
struct pubkey *node_alias)
{
struct tlv_encmsg_tlvs *encmsg = tlv_encmsg_tlvs_new(tmpctx);
struct privkey unused_next_blinding;
if (padlen)
encmsg->padding = tal_arrz(encmsg, u8, padlen);
if (self_id)
encmsg->self_id = (u8 *)tal_dup(encmsg, struct secret, self_id);
return enctlv_from_encmsg(ctx, blinding, final_node, encmsg,
&unused_next_blinding, node_alias);
}

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@ -1,10 +1,14 @@
#ifndef LIGHTNING_COMMON_BLINDEDPATH_H
#define LIGHTNING_COMMON_BLINDEDPATH_H
#include "config.h"
#include <ccan/compiler/compiler.h>
#include <ccan/short_types/short_types.h>
#include <ccan/tal/tal.h>
struct route_info;
struct pubkey;
struct privkey;
struct secret;
/* Fills in *initial_blinding and *final_blinding and returns
* onionmsg_path array for this route */
@ -12,4 +16,47 @@ struct onionmsg_path **make_blindedpath(const tal_t *ctx,
const struct pubkey *route,
struct pubkey *initial_blinding,
struct pubkey *final_blinding);
/**
* create_enctlv - Encrypt an encmsg to form an enctlv.
* @ctx: tal context
* @blinding: e(i), the blinding secret
* @node: the pubkey of the node to encrypt for
* @next_node: the pubkey of the next node, to place in enctlv
* @padlen: if non-zero, the bytes of padding to add (also adds 2 byte padding hdr)
* @override_blinding: the optional blinding point to place in enctlv
* @next_blinding: (out) e(i+1), the next blinding secret.
* @node_alias: (out) the blinded pubkey of the node to tell the recipient.
*
* Returns the enctlv blob, or NULL if the secret is invalid.
*/
u8 *create_enctlv(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *node,
const struct pubkey *next_node,
size_t padlen,
const struct pubkey *override_blinding,
struct privkey *next_blinding,
struct pubkey *node_alias)
NON_NULL_ARGS(2, 3, 4, 7, 8);
/**
* create_final_enctlv - Encrypt an encmsg to form the final enctlv.
* @ctx: tal context
* @blinding: e(i), the blinding secret
* @final_node: the pubkey of the node to encrypt for
* @padlen: if non-zero, the bytes of padding to add (also adds 2 byte padding hdr)
* @self_id: secret to include in enctlv, if not NULL.
* @node_alias: (out) the blinded pubkey of the node to tell the recipient.
*
* If it fails, it means one of the privkeys is bad.
*/
u8 *create_final_enctlv(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *final_node,
size_t padlen,
const struct secret *self_id,
struct pubkey *node_alias)
NON_NULL_ARGS(2, 3, 6);
#endif /* LIGHTNING_COMMON_BLINDEDPATH_H */

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@ -20,6 +20,7 @@ ALL_TEST_PROGRAMS += $(COMMON_TEST_PROGRAMS)
# Sphinx test wants to decode TLVs.
common/test/run-sphinx: wire/onion$(EXP)_wiregen.o wire/towire.o wire/fromwire.o
common/test/run-blindedpath_enctlv: wire/onion$(EXP)_wiregen.o wire/towire.o wire/fromwire.o wire/tlvstream.o
common/test/run-param \
common/test/run-json: \

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@ -0,0 +1,161 @@
#include "../bigsize.c"
#include "../blinding.c"
#include "../hmac.c"
#include "../type_to_string.c"
#include <common/setup.h>
#include <stdio.h>
#undef SUPERVERBOSE
#define SUPERVERBOSE printf
#include "../blindedpath.c"
/* AUTOGENERATED MOCKS START */
/* Generated stub for amount_asset_is_main */
bool amount_asset_is_main(struct amount_asset *asset UNNEEDED)
{ fprintf(stderr, "amount_asset_is_main called!\n"); abort(); }
/* Generated stub for amount_asset_to_sat */
struct amount_sat amount_asset_to_sat(struct amount_asset *asset UNNEEDED)
{ fprintf(stderr, "amount_asset_to_sat called!\n"); abort(); }
/* Generated stub for amount_sat */
struct amount_sat amount_sat(u64 satoshis UNNEEDED)
{ fprintf(stderr, "amount_sat called!\n"); abort(); }
/* Generated stub for amount_sat_add */
bool amount_sat_add(struct amount_sat *val UNNEEDED,
struct amount_sat a UNNEEDED,
struct amount_sat b UNNEEDED)
{ fprintf(stderr, "amount_sat_add called!\n"); abort(); }
/* Generated stub for amount_sat_eq */
bool amount_sat_eq(struct amount_sat a UNNEEDED, struct amount_sat b UNNEEDED)
{ fprintf(stderr, "amount_sat_eq called!\n"); abort(); }
/* Generated stub for amount_sat_greater_eq */
bool amount_sat_greater_eq(struct amount_sat a UNNEEDED, struct amount_sat b UNNEEDED)
{ fprintf(stderr, "amount_sat_greater_eq called!\n"); abort(); }
/* Generated stub for amount_sat_sub */
bool amount_sat_sub(struct amount_sat *val UNNEEDED,
struct amount_sat a UNNEEDED,
struct amount_sat b UNNEEDED)
{ fprintf(stderr, "amount_sat_sub called!\n"); abort(); }
/* Generated stub for amount_sat_to_asset */
struct amount_asset amount_sat_to_asset(struct amount_sat *sat UNNEEDED, const u8 *asset UNNEEDED)
{ fprintf(stderr, "amount_sat_to_asset called!\n"); abort(); }
/* Generated stub for amount_tx_fee */
struct amount_sat amount_tx_fee(u32 fee_per_kw UNNEEDED, size_t weight UNNEEDED)
{ fprintf(stderr, "amount_tx_fee called!\n"); abort(); }
/* Generated stub for fromwire_amount_msat */
struct amount_msat fromwire_amount_msat(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
{ fprintf(stderr, "fromwire_amount_msat called!\n"); abort(); }
/* Generated stub for fromwire_amount_sat */
struct amount_sat fromwire_amount_sat(const u8 **cursor UNNEEDED, size_t *max UNNEEDED)
{ fprintf(stderr, "fromwire_amount_sat called!\n"); abort(); }
/* Generated stub for towire_amount_msat */
void towire_amount_msat(u8 **pptr UNNEEDED, const struct amount_msat msat UNNEEDED)
{ fprintf(stderr, "towire_amount_msat called!\n"); abort(); }
/* Generated stub for towire_amount_sat */
void towire_amount_sat(u8 **pptr UNNEEDED, const struct amount_sat sat UNNEEDED)
{ fprintf(stderr, "towire_amount_sat called!\n"); abort(); }
/* AUTOGENERATED MOCKS END */
static void json_strfield(const char *name, const char *val)
{
printf("\t\"%s\": \"%s\",\n", name, val);
}
int main(int argc, char *argv[])
{
struct privkey alice, bob, carol, dave, blinding, override_blinding;
struct pubkey alice_id, bob_id, carol_id, dave_id, blinding_pub, override_blinding_pub, alias;
u8 *enctlv;
common_setup(argv[0]);
memset(&alice, 'A', sizeof(alice));
memset(&bob, 'B', sizeof(bob));
memset(&carol, 'C', sizeof(carol));
memset(&dave, 'D', sizeof(dave));
pubkey_from_privkey(&alice, &alice_id);
pubkey_from_privkey(&bob, &bob_id);
pubkey_from_privkey(&carol, &carol_id);
pubkey_from_privkey(&dave, &dave_id);
memset(&blinding, 5, sizeof(blinding));
pubkey_from_privkey(&blinding, &blinding_pub);
/* We output the JSON test vectors. */
printf("[{");
json_strfield("test name", "Simple enctlv for Alice, next is Bob");
json_strfield("node_privkey",
type_to_string(tmpctx, struct privkey, &alice));
json_strfield("node_id",
type_to_string(tmpctx, struct pubkey, &alice_id));
json_strfield("blinding_secret",
type_to_string(tmpctx, struct privkey, &blinding));
json_strfield("blinding",
type_to_string(tmpctx, struct pubkey, &blinding_pub));
printf("\t\"encmsg\": {\n"
"\t\t\"next_node_id\": \"%s\"\n"
"\t},\n",
type_to_string(tmpctx, struct pubkey, &bob_id));
enctlv = create_enctlv(tmpctx, &blinding, &alice_id, &bob_id,
0, NULL, &blinding, &alias);
printf("\t\"enctlv_hex\": \"%s\"\n"
"},\n",
tal_hex(tmpctx, enctlv));
pubkey_from_privkey(&blinding, &blinding_pub);
memset(&override_blinding, 7, sizeof(override_blinding));
pubkey_from_privkey(&override_blinding, &override_blinding_pub);
printf("{");
json_strfield("test name",
"Blinding-key-override enctlv for Bob, next is Carol");
json_strfield("node_privkey",
type_to_string(tmpctx, struct privkey, &bob));
json_strfield("node_id",
type_to_string(tmpctx, struct pubkey, &bob_id));
json_strfield("blinding_secret",
type_to_string(tmpctx, struct privkey, &blinding));
json_strfield("blinding",
type_to_string(tmpctx, struct pubkey, &blinding_pub));
printf("\t\"encmsg\": {\n"
"\t\t\"next_node_id\": \"%s\",\n"
"\t\t\"blinding\": \"%s\"\n"
"\t},\n",
type_to_string(tmpctx, struct pubkey, &carol_id),
type_to_string(tmpctx, struct privkey, &override_blinding));
enctlv = create_enctlv(tmpctx, &blinding, &bob_id, &carol_id,
0, &override_blinding_pub, &blinding, &alias);
printf("\t\"enctlv_hex\": \"%s\"\n"
"},\n",
tal_hex(tmpctx, enctlv));
/* That replaced the blinding */
blinding = override_blinding;
blinding_pub = override_blinding_pub;
printf("{");
json_strfield("test name", "Padded enctlv for Carol, next is Dave");
json_strfield("node_privkey",
type_to_string(tmpctx, struct privkey, &carol));
json_strfield("node_id",
type_to_string(tmpctx, struct pubkey, &carol_id));
json_strfield("blinding_secret",
type_to_string(tmpctx, struct privkey, &blinding));
json_strfield("blinding",
type_to_string(tmpctx, struct pubkey, &blinding_pub));
printf("\t\"encmsg\": {\n"
"\t\t\"next_node_id\": \"%s\",\n"
"\t\t\"padding\": \"%s\"\n"
"\t},\n",
type_to_string(tmpctx, struct pubkey, &dave_id),
tal_hex(tmpctx, tal_arrz(tmpctx, u8, 35)));
enctlv = create_enctlv(tmpctx, &blinding, &carol_id, &dave_id,
35, NULL, &blinding, &alias);
printf("\t\"enctlv_hex\": \"%s\"\n"
"}]\n",
tal_hex(tmpctx, enctlv));
common_shutdown();
}