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common/blindedpath: expose API at a lower level.
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We actually want lightningd to create these, since it wants to put the
path_id secret in the last element.  So best API is actually a generic
one, rather than separate APIs to create first and last ones.

And really, the more explicit initialization makes the users clearer.

Signed-off-by: Rusty Russell <[email protected]>
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@rustyrussell @cdecker
rustyrussell authored and cdecker committed Nov 9, 2022
1 parent 01a4772 commit 4cfd972
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Showing 7 changed files with 124 additions and 159 deletions.
66 changes: 11 additions & 55 deletions common/blindedpath.c
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Original file line number Diff line number Diff line change
Expand Up @@ -107,15 +107,20 @@ static u8 *enctlv_from_encmsg_raw(const tal_t *ctx,
return ret;
}

static u8 *enctlv_from_encmsg(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *node,
const struct tlv_encrypted_data_tlv *encmsg,
struct privkey *next_blinding,
struct pubkey *node_alias)
u8 *encrypt_tlv_encrypted_data(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *node,
const struct tlv_encrypted_data_tlv *encmsg,
struct privkey *next_blinding,
struct pubkey *node_alias)
{
struct privkey unused;
u8 *encmsg_raw = tal_arr(NULL, u8, 0);
towire_tlv_encrypted_data_tlv(&encmsg_raw, encmsg);

/* last hop doesn't care about next_blinding */
if (!next_blinding)
next_blinding = &unused;
return enctlv_from_encmsg_raw(ctx, blinding, node, take(encmsg_raw),
next_blinding, node_alias);
}
Expand Down Expand Up @@ -253,52 +258,3 @@ void blindedpath_next_blinding(const struct tlv_encrypted_data_tlv *enc,
blinding_next_pubkey(blinding, &h, next_blinding);
}
}

u8 *create_enctlv(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *node,
const struct pubkey *next_node,
const struct short_channel_id *next_scid,
size_t padlen,
const struct pubkey *next_blinding_override,
const struct tlv_encrypted_data_tlv_payment_relay *payment_relay TAKES,
const struct tlv_encrypted_data_tlv_payment_constraints *payment_constraints TAKES,
const u8 *allowed_features TAKES,
struct privkey *next_blinding,
struct pubkey *node_alias)
{
struct tlv_encrypted_data_tlv *encmsg = tlv_encrypted_data_tlv_new(tmpctx);
if (padlen)
encmsg->padding = tal_arrz(encmsg, u8, padlen);
encmsg->next_node_id = cast_const(struct pubkey *, next_node);
encmsg->next_blinding_override = cast_const(struct pubkey *, next_blinding_override);
encmsg->payment_relay = tal_dup_or_null(encmsg, struct tlv_encrypted_data_tlv_payment_relay,
payment_relay);
encmsg->payment_constraints = tal_dup_or_null(encmsg, struct tlv_encrypted_data_tlv_payment_constraints,
payment_constraints);
encmsg->allowed_features = tal_dup_talarr(encmsg, u8, allowed_features);

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 *path_id,
const u8 *allowed_features TAKES,
struct pubkey *node_alias)
{
struct tlv_encrypted_data_tlv *encmsg = tlv_encrypted_data_tlv_new(tmpctx);
struct privkey unused_next_blinding;

if (padlen)
encmsg->padding = tal_arrz(encmsg, u8, padlen);
if (path_id)
encmsg->path_id = (u8 *)tal_dup(encmsg, struct secret, path_id);
encmsg->allowed_features = tal_dup_talarr(encmsg, u8, allowed_features);

return enctlv_from_encmsg(ctx, blinding, final_node, encmsg,
&unused_next_blinding, node_alias);
}
58 changes: 13 additions & 45 deletions common/blindedpath.h
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Original file line number Diff line number Diff line change
Expand Up @@ -10,61 +10,29 @@ struct pubkey;
struct privkey;
struct secret;
struct short_channel_id;
struct tlv_encrypted_data_tlv;
struct tlv_encrypted_data_tlv_payment_constraints;
struct tlv_encrypted_data_tlv_payment_relay;

/**
* create_enctlv - Encrypt an encmsg to form an enctlv.
* encrypt_tlv_encrypted_data - Encrypt a tlv_encrypted_data_tlv.
* @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
* @next_scid: the short_channel_id to the next node, to place in enctlv
* @padlen: if non-zero, the bytes of padding to add (also adds 2 byte padding hdr)
* @next_blinding_override: the optional blinding point to place in enctlv
* @payment_relay: optional payment_relay tlv
* @payment_constraints: optional payment_constraints tlv
* @allowed_features: optional allowed_features array
* @next_blinding: (out) e(i+1), the next blinding secret.
* @tlv: the message to encrypt.
* @next_blinding: (out) e(i+1), the next blinding secret (optional)
* @node_alias: (out) the blinded pubkey of the node to tell the recipient.
*
* Exactly one of next_node and next_scid must be non-NULL.
* Returns the enctlv blob, or NULL if the secret is invalid.
* You create a blinding secret using randombytes_buf(), then call this
* iteratively for each node in the path.
*/
u8 *create_enctlv(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *node,
const struct pubkey *next_node,
const struct short_channel_id *next_scid,
size_t padlen,
const struct pubkey *next_blinding_override,
const struct tlv_encrypted_data_tlv_payment_relay *payment_relay TAKES,
const struct tlv_encrypted_data_tlv_payment_constraints *payment_constraints TAKES,
const u8 *allowed_features TAKES,
struct privkey *next_blinding,
struct pubkey *node_alias)
NON_NULL_ARGS(2, 3, 11, 12);

/**
* 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)
* @allowed_features: optional allowed_features array
* @path_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 *path_id,
const u8 *allowed_features TAKES,
struct pubkey *node_alias)
NON_NULL_ARGS(2, 3, 7);
u8 *encrypt_tlv_encrypted_data(const tal_t *ctx,
const struct privkey *blinding,
const struct pubkey *node,
const struct tlv_encrypted_data_tlv *tlv,
struct privkey *next_blinding,
struct pubkey *node_alias)
NON_NULL_ARGS(2, 3, 4, 6);

/**
* unblind_onion - tweak onion epheremeral key so we can decode it with ours.
Expand Down
1 change: 0 additions & 1 deletion common/onion_decode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -373,4 +373,3 @@ struct onion_payload *onion_decode(const tal_t *ctx,
*failtlvtype);
return tal_free(p);
}

29 changes: 20 additions & 9 deletions common/test/run-blindedpath_enctlv.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -140,6 +140,7 @@ int main(int argc, char *argv[])
struct pubkey alice_id, bob_id, carol_id, dave_id, blinding_pub, override_blinding_pub, alias;
struct secret self_id;
u8 *enctlv;
struct tlv_encrypted_data_tlv *tlv;

common_setup(argv[0]);

Expand Down Expand Up @@ -171,8 +172,10 @@ int main(int argc, char *argv[])
"\t},\n",
type_to_string(tmpctx, struct pubkey, &bob_id));

enctlv = create_enctlv(tmpctx, &blinding, &alice_id, &bob_id, NULL,
0, NULL, NULL, NULL, NULL, &blinding, &alias);
tlv = tlv_encrypted_data_tlv_new(tmpctx);
tlv->next_node_id = &bob_id;
enctlv = encrypt_tlv_encrypted_data(tmpctx, &blinding, &alice_id, tlv,
&blinding, &alias);
printf("\t\"encrypted_recipient_data_hex\": \"%s\"\n"
"},\n",
tal_hex(tmpctx, enctlv));
Expand Down Expand Up @@ -201,9 +204,11 @@ int main(int argc, char *argv[])
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, NULL,
0, &override_blinding_pub, NULL, NULL, NULL,
&blinding, &alias);
tlv = tlv_encrypted_data_tlv_new(tmpctx);
tlv->next_node_id = &carol_id;
tlv->next_blinding_override = &override_blinding_pub;
enctlv = encrypt_tlv_encrypted_data(tmpctx, &blinding, &bob_id, tlv,
&blinding, &alias);
printf("\t\"encrypted_recipient_data_hex\": \"%s\"\n"
"},\n",
tal_hex(tmpctx, enctlv));
Expand Down Expand Up @@ -231,8 +236,11 @@ int main(int argc, char *argv[])
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, NULL,
35, NULL, NULL, NULL, NULL, &blinding, &alias);
tlv = tlv_encrypted_data_tlv_new(tmpctx);
tlv->padding = tal_arrz(tlv, u8, 35);
tlv->next_node_id = &dave_id;
enctlv = encrypt_tlv_encrypted_data(tmpctx, &blinding, &carol_id, tlv,
&blinding, &alias);
printf("\t\"encrypted_recipient_data_hex\": \"%s\"\n"
"},\n",
tal_hex(tmpctx, enctlv));
Expand All @@ -256,8 +264,11 @@ int main(int argc, char *argv[])
"\t},\n",
type_to_string(tmpctx, struct secret, &self_id));

enctlv = create_final_enctlv(tmpctx, &blinding, &dave_id,
0, &self_id, NULL, &alias);
tlv = tlv_encrypted_data_tlv_new(tmpctx);
tlv->path_id = tal_dup_arr(tlv, u8,
self_id.data, ARRAY_SIZE(self_id.data), 0);
enctlv = encrypt_tlv_encrypted_data(tmpctx, &blinding, &dave_id, tlv,
NULL, &alias);

printf("\t\"encrypted_recipient_data_hex\": \"%s\"\n",
tal_hex(tmpctx, enctlv));
Expand Down
48 changes: 34 additions & 14 deletions common/test/run-blindedpath_onion.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -154,6 +154,7 @@ int main(int argc, char *argv[])
struct privkey nodekey[4], blinding[4], override_blinding;
struct pubkey id[4], blinding_pub[4], override_blinding_pub, alias[4];
struct secret self_id;
struct tlv_encrypted_data_tlv *tlv[4];
u8 *enctlv[4];
u8 *onionmsg_tlv[4];
u8 *omsg;
Expand All @@ -173,35 +174,54 @@ int main(int argc, char *argv[])
memset(&blinding[ALICE], 5, sizeof(blinding[ALICE]));
pubkey_from_privkey(&blinding[ALICE], &blinding_pub[ALICE]);

enctlv[ALICE] = create_enctlv(tmpctx, &blinding[ALICE],
&id[ALICE], &id[BOB], NULL,
0, NULL, NULL, NULL, NULL,
&blinding[BOB], &alias[ALICE]);
tlv[ALICE] = tlv_encrypted_data_tlv_new(tmpctx);
tlv[ALICE]->next_node_id = &id[BOB];
enctlv[ALICE] = encrypt_tlv_encrypted_data(tmpctx,
&blinding[ALICE],
&id[ALICE], tlv[ALICE],
&blinding[BOB],
&alias[ALICE]);

pubkey_from_privkey(&blinding[BOB], &blinding_pub[BOB]);

/* We override blinding for Carol. */
memset(&override_blinding, 7, sizeof(override_blinding));
pubkey_from_privkey(&override_blinding, &override_blinding_pub);
enctlv[BOB] = create_enctlv(tmpctx, &blinding[BOB],
&id[BOB], &id[CAROL], NULL,
0, &override_blinding_pub, NULL, NULL, NULL,
&blinding[CAROL], &alias[BOB]);

tlv[BOB] = tlv_encrypted_data_tlv_new(tmpctx);
tlv[BOB]->next_node_id = &id[CAROL];
tlv[BOB]->next_blinding_override = &override_blinding_pub;
enctlv[BOB] = encrypt_tlv_encrypted_data(tmpctx,
&blinding[BOB],
&id[BOB], tlv[BOB],
&blinding[CAROL],
&alias[BOB]);

/* That replaced the blinding */
blinding[CAROL] = override_blinding;
blinding_pub[CAROL] = override_blinding_pub;

enctlv[CAROL] = create_enctlv(tmpctx, &blinding[CAROL],
&id[CAROL], &id[DAVE], NULL,
35, NULL, NULL, NULL, NULL,
&blinding[DAVE], &alias[CAROL]);
tlv[CAROL] = tlv_encrypted_data_tlv_new(tmpctx);
tlv[CAROL]->next_node_id = &id[DAVE];
tlv[CAROL]->padding = tal_arrz(tlv[CAROL], u8, 35);
enctlv[CAROL] = encrypt_tlv_encrypted_data(tmpctx,
&blinding[CAROL],
&id[CAROL], tlv[CAROL],
&blinding[DAVE],
&alias[CAROL]);

for (size_t i = 0; i < sizeof(self_id); i++)
self_id.data[i] = i+1;

enctlv[DAVE] = create_final_enctlv(tmpctx, &blinding[DAVE], &id[DAVE],
0, &self_id, NULL, &alias[DAVE]);
tlv[DAVE] = tlv_encrypted_data_tlv_new(tmpctx);
tlv[DAVE]->path_id = tal_dup_arr(tlv[DAVE], u8,
self_id.data, ARRAY_SIZE(self_id.data),
0);
enctlv[DAVE] = encrypt_tlv_encrypted_data(tmpctx,
&blinding[DAVE],
&id[DAVE], tlv[DAVE],
NULL,
&alias[DAVE]);
pubkey_from_privkey(&blinding[DAVE], &blinding_pub[DAVE]);

/* Create an onion which encodes this. */
Expand Down
39 changes: 22 additions & 17 deletions lightningd/onion_message.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -285,6 +285,7 @@ static struct command_result *json_blindedpath(struct command *cmd,
struct blinded_path *path;
size_t nhops;
struct json_stream *response;
struct tlv_encrypted_data_tlv *tlv;

if (!param(cmd, buffer, params,
p_req("ids", param_pubkeys, &ids),
Expand Down Expand Up @@ -319,29 +320,33 @@ static struct command_result *json_blindedpath(struct command *cmd,
blinding_iter = first_blinding;
for (size_t i = 0; i < nhops - 1; i++) {
path->path[i] = tal(path->path, struct onionmsg_hop);

tlv = tlv_encrypted_data_tlv_new(tmpctx);
tlv->next_node_id = &ids[i+1];
/* FIXME: Pad? */

path->path[i]->encrypted_recipient_data
= create_enctlv(path->path[i],
&blinding_iter,
&ids[i],
&ids[i+1], NULL,
/* FIXME: Pad? */
0,
NULL, NULL, NULL, NULL,
&blinding_iter,
&path->path[i]->blinded_node_id);
= encrypt_tlv_encrypted_data(path->path[i],
&blinding_iter,
&ids[i],
tlv,
&blinding_iter,
&path->path[i]->blinded_node_id);
}

/* FIXME: Add padding! */
path->path[nhops-1] = tal(path->path, struct onionmsg_hop);

tlv = tlv_encrypted_data_tlv_new(tmpctx);
tlv->path_id = (u8 *)tal_dup(tlv, struct secret,
&cmd->ld->onion_reply_secret);
path->path[nhops-1]->encrypted_recipient_data
= create_final_enctlv(path->path[nhops-1],
&blinding_iter,
&ids[nhops-1],
/* FIXME: Pad? */
0,
&cmd->ld->onion_reply_secret,
NULL,
&path->path[nhops-1]->blinded_node_id);
= encrypt_tlv_encrypted_data(path->path[nhops-1],
&blinding_iter,
&ids[nhops-1],
tlv,
NULL,
&path->path[nhops-1]->blinded_node_id);

response = json_stream_success(cmd);
json_add_blindedpath(response, "blindedpath", path);
Expand Down
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