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101 lines
2.7 KiB
101 lines
2.7 KiB
#include <bitcoin/privkey.h>
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#include <bitcoin/pubkey.h>
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#include <ccan/cast/cast.h>
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#include <common/blindedpath.h>
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#include <common/blinding.h>
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#include <common/bolt11.h>
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#include <common/hmac.h>
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#include <common/node_id.h>
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#include <common/utils.h>
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#include <secp256k1_ecdh.h>
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#include <sodium.h>
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#include <wire/onion_wire.h>
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/* FIXME: Pad with dummy nodes, but make sure to check them on recv! */
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struct onionmsg_path **make_blindedpath(const tal_t *ctx,
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const struct pubkey *route,
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struct pubkey *initial_blinding,
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struct pubkey *final_blinding)
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{
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struct privkey e;
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struct pubkey *pk_e, *b;
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struct secret *rho;
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struct onionmsg_path **path;
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size_t num = tal_count(route);
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if (!num)
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abort();
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/* E(i) */
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pk_e = tal_arr(tmpctx, struct pubkey, num);
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/* B(i) */
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b = tal_arr(tmpctx, struct pubkey, num);
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/* rho(i) */
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rho = tal_arr(tmpctx, struct secret, num);
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randombytes_buf(&e, sizeof(e));
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if (!pubkey_from_privkey(&e, &pk_e[0]))
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abort();
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for (size_t i = 0; i < num; i++) {
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struct secret ss;
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struct secret hmac;
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struct sha256 h;
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if (secp256k1_ecdh(secp256k1_ctx, ss.data,
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&route[i].pubkey, e.secret.data,
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NULL, NULL) != 1)
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abort();
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subkey_from_hmac("blinded_node_id", &ss, &hmac);
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b[i] = route[i];
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if (i != 0) {
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if (secp256k1_ec_pubkey_tweak_mul(secp256k1_ctx,
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&b[i].pubkey, hmac.data) != 1)
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abort();
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}
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subkey_from_hmac("rho", &ss, &rho[i]);
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blinding_hash_e_and_ss(&pk_e[i], &ss, &h);
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if (i != num-1)
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blinding_next_pubkey(&pk_e[i], &h, &pk_e[i+1]);
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blinding_next_privkey(&e, &h, &e);
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}
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*initial_blinding = pk_e[0];
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*final_blinding = pk_e[num-1];
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path = tal_arr(ctx, struct onionmsg_path *, num);
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for (size_t i = 0; i < num; i++) {
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path[i] = tal(path, struct onionmsg_path);
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path[i]->node_id = b[i];
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}
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for (size_t i = 0; i < num - 1; i++) {
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const unsigned char npub[crypto_aead_chacha20poly1305_ietf_NPUBBYTES] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
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struct tlv_encmsg_tlvs *inner;
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int ret;
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/* Inner is encrypted */
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inner = tlv_encmsg_tlvs_new(tmpctx);
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/* FIXME: We could support scids, too */
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inner->next_node_id = cast_const(struct pubkey *, &route[i+1]);
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path[i]->enctlv = tal_arr(path, u8, 0);
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towire_encmsg_tlvs(&path[i]->enctlv, inner);
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towire_pad(&path[i]->enctlv,
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crypto_aead_chacha20poly1305_ietf_ABYTES);
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ret = crypto_aead_chacha20poly1305_ietf_encrypt(path[i]->enctlv, NULL,
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path[i]->enctlv,
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tal_bytelen(path[i]->enctlv) - crypto_aead_chacha20poly1305_ietf_ABYTES,
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NULL, 0,
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NULL, npub,
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rho[i].data);
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assert(ret == 0);
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}
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/* Final one has no enctlv */
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path[num-1]->enctlv = NULL;
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return path;
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}
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