lukechilds
/
lightning
mirror of https://github.com/lukechilds/lightning.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
4018 Commits
55 Branches
107 Tags
38 MiB
 
 
 
 
 
 
Tree: aeafe4dbe7
Branches Tags
${ item.name }
Create tag ${ searchTerm }
Create branch ${ searchTerm }
from 'aeafe4dbe7'
${ noResults }
lightning/gossipd/handshake.c

1006 lines
30 KiB
Raw Blame History

#include <assert.h>
#include <bitcoin/privkey.h>
#include <bitcoin/pubkey.h>
#include <ccan/build_assert/build_assert.h>
#include <ccan/crypto/hkdf_sha256/hkdf_sha256.h>
#include <ccan/endian/endian.h>
#include <ccan/io/io.h>
#include <ccan/mem/mem.h>
#include <common/crypto_state.h>
#include <common/status.h>
#include <common/type_to_string.h>
#include <common/utils.h>
#include <common/wireaddr.h>
#include <errno.h>
#include <gossipd/handshake.h>
#include <hsmd/client.h>
#include <secp256k1.h>
#include <secp256k1_ecdh.h>
#include <sodium/crypto_aead_chacha20poly1305.h>
#include <sodium/randombytes.h>
#include <stdio.h>
#include <unistd.h>
#include <wire/wire.h>
#ifndef SUPERVERBOSE
#define SUPERVERBOSE(...)
#endif
enum bolt8_side {
INITIATOR,
RESPONDER
};
/* BOLT #8:
*
* Act One is sent from initiator to responder. During Act One, the
* initiator attempts to satisfy an implicit challenge by the responder. To
* complete this challenge, the initiator _must_ know the static public key of
* the responder.
*/
struct act_one {
u8 v;
u8 pubkey[PUBKEY_DER_LEN];
u8 tag[crypto_aead_chacha20poly1305_ietf_ABYTES];
};
/* BOLT #8: The handshake message is _exactly_ 50 bytes */
#define ACT_ONE_SIZE 50 /* ARM's stupid ABI adds padding. */
static inline void check_act_one(const struct act_one *act1)
{
/* BOLT #8:
*
* : 1 byte for the handshake version, 33 bytes for the compressed
* ephemeral public key of the initiator, and 16 bytes for the
* `poly1305` tag.
*/
BUILD_ASSERT(sizeof(act1->v) == 1);
BUILD_ASSERT(sizeof(act1->pubkey) == 33);
BUILD_ASSERT(sizeof(act1->tag) == 16);
}
/* BOLT #8:
*
* Act Two is sent from the responder to the initiator. Act Two will
* _only_ take place if Act One was successful. Act One was successful if
* the responder was able to properly decrypt and check the MAC of the tag
* sent at the end of Act One.
*/
struct act_two {
u8 v;
u8 pubkey[PUBKEY_DER_LEN];
u8 tag[crypto_aead_chacha20poly1305_ietf_ABYTES];
};
/* BOLT #8: The handshake is _exactly_ 50 bytes: */
#define ACT_TWO_SIZE 50 /* ARM's stupid ABI adds padding. */
static inline void check_act_two(const struct act_two *act2)
{
/* BOLT #8:
* 1 byte for the handshake version,
* 33 bytes for the compressed ephemeral public key of the initiator, and
* 16 bytes for the `poly1305` tag.
*/
BUILD_ASSERT(sizeof(act2->v) == 1);
BUILD_ASSERT(sizeof(act2->pubkey) == 33);
BUILD_ASSERT(sizeof(act2->tag) == 16);
}
/* BOLT #8:
*
* Act Three is the final phase in the authenticated key agreement described
* in this section. This act is sent from the initiator to the responder as a
* concluding step. Act Three is executed _if and only if_ Act Two was
* successful. During Act Three, the initiator transports its static public
* key to the responder encrypted with _strong_ forward secrecy, using the
* accumulated `HKDF` derived secret key at this point of the handshake.
*/
struct act_three {
u8 v;
u8 ciphertext[PUBKEY_DER_LEN + crypto_aead_chacha20poly1305_ietf_ABYTES];
u8 tag[crypto_aead_chacha20poly1305_ietf_ABYTES];
};
/* BOLT #8: The handshake is _exactly_ 66 bytes */
#define ACT_THREE_SIZE 66 /* ARM's stupid ABI adds padding. */
static inline void check_act_three(const struct act_three *act3)
{
/* BOLT #8:
*
* 1 byte for the handshake version, 33 bytes for the ephemeral
* public key encrypted with the `ChaCha20` stream cipher, 16 bytes
* for the encrypted public key's tag generated via the AEAD
* construction, and 16 bytes for a final authenticating tag.
*/
BUILD_ASSERT(sizeof(act3->v) == 1);
BUILD_ASSERT(sizeof(act3->ciphertext) == 33 + 16);
BUILD_ASSERT(sizeof(act3->tag) == 16);
}
/* BOLT #8:
*
* * `generateKey()`: generates and returns a fresh `secp256k1` keypair
* * where the object returned by `generateKey` has two attributes:
* * `.pub`, which returns an abstract object representing the
* public key
* * `.priv`, which represents the private key used to generate the
* public key
*/
struct keypair {
struct pubkey pub;
struct privkey priv;
};
/* BOLT #8:
*
* Throughout the handshake process, each side maintains these variables:
*
* * `ck`: The **chaining key**. This value is the accumulated hash of all
* previous ECDH outputs. At the end of the handshake, `ck` is used to
* derive the encryption keys for Lightning messages.
*
* * `h`: The **handshake hash**. This value is the accumulated hash of _all_
* handshake data that has been sent and received so far during the
* handshake process.
*
* * `temp_k1`, `temp_k2`, `temp_k3`: **intermediate keys**. These are used to
* encrypt and decrypt the zero-length AEAD payloads at the end of each
* handshake message.
*
* * `e`: A party's **ephemeral keypair**. For each session a node MUST
* generate a new ephemeral key with strong cryptographic randomness.
*
* * `s`: a party's **static public key** (`ls` for local, `rs` for remote)
*/
struct handshake {
struct secret ck;
struct secret temp_k;
struct sha256 h;
struct keypair e;
struct secret ss;
/* Used between the Acts */
struct pubkey re;
struct act_one act1;
struct act_two act2;
struct act_three act3;
/* Where is connection from/to */
struct wireaddr_internal addr;
/* Who we are */
struct pubkey my_id;
/* Who they are: set already if we're initiator. */
struct pubkey their_id;
/* Are we initiator or responder. */
enum bolt8_side side;
/* Function to call once handshake complete. */
struct io_plan *(*cb)(struct io_conn *conn,
const struct pubkey *their_id,
const struct wireaddr_internal *wireaddr,
const struct crypto_state *cs,
void *cbarg);
void *cbarg;
};
static struct keypair generate_key(void)
{
struct keypair k;
do {
randombytes_buf(k.priv.secret.data, sizeof(k.priv.secret.data));
} while (!secp256k1_ec_pubkey_create(secp256k1_ctx,
&k.pub.pubkey, k.priv.secret.data));
return k;
}
/* h = SHA-256(h || data) */
static void sha_mix_in(struct sha256 *h, const void *data, size_t len)
{
struct sha256_ctx shactx;
sha256_init(&shactx);
sha256_update(&shactx, h, sizeof(*h));
sha256_update(&shactx, data, len);
sha256_done(&shactx, h);
}
/* h = SHA-256(h || pub.serializeCompressed()) */
static void sha_mix_in_key(struct sha256 *h, const struct pubkey *key)
{
u8 der[PUBKEY_DER_LEN];
size_t len = sizeof(der);
secp256k1_ec_pubkey_serialize(secp256k1_ctx, der, &len, &key->pubkey,
SECP256K1_EC_COMPRESSED);
assert(len == sizeof(der));
sha_mix_in(h, der, sizeof(der));
}
/* out1, out2 = HKDF(in1, in2)` */
static void hkdf_two_keys(struct secret *out1, struct secret *out2,
const struct secret *in1,
const void *in2, size_t in2_size)
{
/* BOLT #8:
*
* * `HKDF(salt,ikm)`: a function defined in `RFC 5869`<sup>[3](#reference-3)</sup>,
* evaluated with a zero-length `info` field
* * All invocations of `HKDF` implicitly return 64 bytes
* of cryptographic randomness using the extract-and-expand
* component of the `HKDF`.
*/
struct secret okm[2];
SUPERVERBOSE("# HKDF(0x%s,%s%s)",
tal_hexstr(tmpctx, in1, sizeof(*in1)),
in2_size ? "0x" : "zero",
tal_hexstr(tmpctx, in2, in2_size));
BUILD_ASSERT(sizeof(okm) == 64);
hkdf_sha256(okm, sizeof(okm), in1, sizeof(*in1), in2, in2_size,
NULL, 0);
*out1 = okm[0];
*out2 = okm[1];
}
static void le64_nonce(unsigned char *npub, u64 nonce)
{
/* BOLT #8:
*
* ...with nonce `n` encoded as 32 zero bits, followed by a
* *little-endian* 64-bit value (this follows the Noise Protocol
* convention, rather than our normal endian).
*/
le64 le_nonce = cpu_to_le64(nonce);
const size_t zerolen = crypto_aead_chacha20poly1305_ietf_NPUBBYTES - sizeof(le_nonce);
BUILD_ASSERT(crypto_aead_chacha20poly1305_ietf_NPUBBYTES >= sizeof(le_nonce));
/* First part is 0, followed by nonce. */
memset(npub, 0, zerolen);
memcpy(npub + zerolen, &le_nonce, sizeof(le_nonce));
}
/* BOLT #8:
* * `encryptWithAD(k, n, ad, plaintext)`: outputs `encrypt(k, n, ad,
* plaintext)`
* * where `encrypt` is an evaluation of `ChaCha20-Poly1305` (IETF
* variant) with the passed arguments, with nonce `n`
*/
static void encrypt_ad(const struct secret *k, u64 nonce,
const void *additional_data, size_t additional_data_len,
const void *plaintext, size_t plaintext_len,
void *output, size_t outputlen)
{
unsigned char npub[crypto_aead_chacha20poly1305_ietf_NPUBBYTES];
unsigned long long clen;
int ret;
assert(outputlen == plaintext_len + crypto_aead_chacha20poly1305_ietf_ABYTES);
le64_nonce(npub, nonce);
BUILD_ASSERT(sizeof(*k) == crypto_aead_chacha20poly1305_ietf_KEYBYTES);
SUPERVERBOSE("# encryptWithAD(0x%s, 0x%s, 0x%s, %s%s)",
tal_hexstr(tmpctx, k, sizeof(*k)),
tal_hexstr(tmpctx, npub, sizeof(npub)),
tal_hexstr(tmpctx, additional_data, additional_data_len),
plaintext_len ? "0x" : "<empty>",
tal_hexstr(tmpctx, plaintext, plaintext_len));
ret = crypto_aead_chacha20poly1305_ietf_encrypt(output, &clen,
memcheck(plaintext, plaintext_len),
plaintext_len,
additional_data, additional_data_len,
NULL, npub, k->data);
assert(ret == 0);
assert(clen == plaintext_len + crypto_aead_chacha20poly1305_ietf_ABYTES);
}
/* BOLT #8:
* * `decryptWithAD(k, n, ad, ciphertext)`: outputs `decrypt(k, n, ad,
* ciphertext)`
* * where `decrypt` is an evaluation of `ChaCha20-Poly1305` (IETF
* variant) with the passed arguments, with nonce `n`
*/
static bool decrypt(const struct secret *k, u64 nonce,
const void *additional_data, size_t additional_data_len,
const void *ciphertext, size_t ciphertext_len,
void *output, size_t outputlen)
{
unsigned char npub[crypto_aead_chacha20poly1305_ietf_NPUBBYTES];
unsigned long long mlen;
assert(outputlen == ciphertext_len - crypto_aead_chacha20poly1305_ietf_ABYTES);
le64_nonce(npub, nonce);
BUILD_ASSERT(sizeof(*k) == crypto_aead_chacha20poly1305_ietf_KEYBYTES);
SUPERVERBOSE("# decryptWithAD(0x%s, 0x%s, 0x%s, 0x%s)",
tal_hexstr(tmpctx, k, sizeof(*k)),
tal_hexstr(tmpctx, npub, sizeof(npub)),
tal_hexstr(tmpctx, additional_data, additional_data_len),
tal_hexstr(tmpctx, ciphertext, ciphertext_len));
if (crypto_aead_chacha20poly1305_ietf_decrypt(output, &mlen, NULL,
memcheck(ciphertext, ciphertext_len),
ciphertext_len,
additional_data, additional_data_len,
npub, k->data) != 0)
return false;
assert(mlen == ciphertext_len - crypto_aead_chacha20poly1305_ietf_ABYTES);
return true;
}
static struct io_plan *handshake_failed_(struct io_conn *conn,
struct handshake *h,
const char *function, int line)
{
status_trace("%s: handshake failed %s:%u",
h->side == RESPONDER ? "Responder" : "Initiator",
function, line);
errno = EPROTO;
return io_close(conn);
}
#define handshake_failed(conn, h) \
handshake_failed_((conn), (h), __func__, __LINE__)
static struct io_plan *handshake_succeeded(struct io_conn *conn,
struct handshake *h)
{
struct crypto_state cs;
struct io_plan *(*cb)(struct io_conn *conn,
const struct pubkey *their_id,
const struct wireaddr_internal *addr,
const struct crypto_state *cs,
void *cbarg);
void *cbarg;
struct pubkey their_id;
struct wireaddr_internal addr;
/* BOLT #8:
*
* 9. `rk, sk = HKDF(ck, zero)`
* * where `zero` is a zero-length plaintext, `rk` is the key to
* be used by the responder to decrypt the messages sent by the
* initiator, and `sk` is the key to be used by the responder
* to encrypt messages to the initiator
*
* * The final encryption keys to be used for sending and
* receiving messages for the duration of the session are
* generated.
*/
if (h->side == RESPONDER)
hkdf_two_keys(&cs.rk, &cs.sk, &h->ck, NULL, 0);
else
hkdf_two_keys(&cs.sk, &cs.rk, &h->ck, NULL, 0);
cs.rn = cs.sn = 0;
cs.r_ck = cs.s_ck = h->ck;
cb = h->cb;
cbarg = h->cbarg;
their_id = h->their_id;
addr = h->addr;
tal_free(h);
return cb(conn, &their_id, &addr, &cs, cbarg);
}
static struct handshake *new_handshake(const tal_t *ctx,
const struct pubkey *responder_id)
{
struct handshake *handshake = tal(ctx, struct handshake);
/* BOLT #8:
*
* Before the start of the first act, both sides initialize their
* per-sessions state as follows:
*
* 1. `h = SHA-256(protocolName)`
* * where `protocolName = "Noise_XK_secp256k1_ChaChaPoly_SHA256"`
* encoded as an ASCII string.
*/
sha256(&handshake->h, "Noise_XK_secp256k1_ChaChaPoly_SHA256",
strlen("Noise_XK_secp256k1_ChaChaPoly_SHA256"));
/* BOLT #8:
*
* 2. `ck = h`
*/
BUILD_ASSERT(sizeof(handshake->h) == sizeof(handshake->ck));
memcpy(&handshake->ck, &handshake->h, sizeof(handshake->ck));
SUPERVERBOSE("# ck=%s",
tal_hexstr(tmpctx, &handshake->ck, sizeof(handshake->ck)));
/* BOLT #8:
*
* 3. `h = SHA-256(h || prologue)`
* * where `prologue` is the ASCII string: `lightning`.
*/
sha_mix_in(&handshake->h, "lightning", strlen("lightning"));
/* BOLT #8:
*
* As a concluding step, both sides mix the responder's public key
* into the handshake digest:
*
* * The initiating node mixes in the responding node's static public
* key serialized in Bitcoin's DER-compressed format:
* * `h = SHA-256(h || rs.pub.serializeCompressed())`
*
* * The responding node mixes in their local static public key
* serialized in Bitcoin's DER-compressed format:
* * `h = SHA-256(h || ls.pub.serializeCompressed())`
*/
sha_mix_in_key(&handshake->h, responder_id);
SUPERVERBOSE("# h=%s",
tal_hexstr(tmpctx, &handshake->h, sizeof(handshake->h)));
return handshake;
}
static struct io_plan *act_three_initiator(struct io_conn *conn,
struct handshake *h)
{
u8 spub[PUBKEY_DER_LEN];
size_t len = sizeof(spub);
SUPERVERBOSE("Initiator: Act 3");
/* BOLT #8:
* 1. `c = encryptWithAD(temp_k2, 1, h, s.pub.serializeCompressed())`
* * where `s` is the static public key of the initiator
*/
secp256k1_ec_pubkey_serialize(secp256k1_ctx, spub, &len,
&h->my_id.pubkey,
SECP256K1_EC_COMPRESSED);
encrypt_ad(&h->temp_k, 1, &h->h, sizeof(h->h), spub, sizeof(spub),
h->act3.ciphertext, sizeof(h->act3.ciphertext));
SUPERVERBOSE("# c=0x%s",
tal_hexstr(tmpctx,
h->act3.ciphertext, sizeof(h->act3.ciphertext)));
/* BOLT #8:
* 2. `h = SHA-256(h || c)`
*/
sha_mix_in(&h->h, h->act3.ciphertext, sizeof(h->act3.ciphertext));
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
/* BOLT #8:
*
* 3. `ss = ECDH(re, s.priv)`
* * where `re` is the ephemeral public key of the responder.
*
*/
if (!hsm_do_ecdh(&h->ss, &h->re))
return handshake_failed(conn, h);
SUPERVERBOSE("# ss=0x%s", tal_hexstr(tmpctx, &h->ss, sizeof(h->ss)));
/* BOLT #8:
*
* 4. `ck, temp_k3 = HKDF(ck, ss)`
* * The final intermediate shared secret is mixed into the running
* chaining key.
*/
hkdf_two_keys(&h->ck, &h->temp_k, &h->ck, &h->ss, sizeof(h->ss));
SUPERVERBOSE("# ck,temp_k3=0x%s,0x%s",
tal_hexstr(tmpctx, &h->ck, sizeof(h->ck)),
tal_hexstr(tmpctx, &h->temp_k, sizeof(h->temp_k)));
/* BOLT #8:
*
* 5. `t = encryptWithAD(temp_k3, 0, h, zero)`
* * where `zero` is a zero-length plaintext
*
*/
encrypt_ad(&h->temp_k, 0, &h->h, sizeof(h->h), NULL, 0,
h->act3.tag, sizeof(h->act3.tag));
SUPERVERBOSE("# t=0x%s",
tal_hexstr(tmpctx, h->act3.tag, sizeof(h->act3.tag)));
/* BOLT #8:
*
* 8. Send `m = 0 || c || t` over the network buffer.
*
*/
h->act3.v = 0;
SUPERVERBOSE("output: 0x%s", tal_hexstr(tmpctx, &h->act3, ACT_THREE_SIZE));
return io_write(conn, &h->act3, ACT_THREE_SIZE, handshake_succeeded, h);
}
static struct io_plan *act_two_initiator2(struct io_conn *conn,
struct handshake *h)
{
SUPERVERBOSE("input: 0x%s", tal_hexstr(tmpctx, &h->act2, ACT_TWO_SIZE));
/* BOLT #8:
*
* 3. If `v` is an unrecognized handshake version, then the responder
* MUST abort the connection attempt.
*/
if (h->act2.v != 0)
return handshake_failed(conn, h);
/* BOLT #8:
*
* * The raw bytes of the remote party's ephemeral public key
* (`re`) are to be deserialized into a point on the curve using
* affine coordinates as encoded by the key's serialized
* composed format.
*/
if (secp256k1_ec_pubkey_parse(secp256k1_ctx, &h->re.pubkey,
h->act2.pubkey, sizeof(h->act2.pubkey)) != 1)
return handshake_failed(conn, h);
SUPERVERBOSE("# re=0x%s", type_to_string(tmpctx, struct pubkey, &h->re));
/* BOLT #8:
*
* 4. `h = SHA-256(h || re.serializeCompressed())`
*/
sha_mix_in_key(&h->h, &h->re);
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
/* BOLT #8:
*
* 5. `ss = ECDH(re, e.priv)`
* * where `re` is the responder's ephemeral public key
*/
if (!secp256k1_ecdh(secp256k1_ctx, h->ss.data, &h->re.pubkey,
h->e.priv.secret.data))
return handshake_failed(conn, h);
SUPERVERBOSE("# ss=0x%s", tal_hexstr(tmpctx, &h->ss, sizeof(h->ss)));
/* BOLT #8:
*
* 6. `ck, temp_k2 = HKDF(ck, ss)`
* * A new temporary encryption key is generated, which is
* used to generate the authenticating MAC.
*/
hkdf_two_keys(&h->ck, &h->temp_k, &h->ck, &h->ss, sizeof(h->ss));
SUPERVERBOSE("# ck,temp_k2=0x%s,0x%s",
tal_hexstr(tmpctx, &h->ck, sizeof(h->ck)),
tal_hexstr(tmpctx, &h->temp_k, sizeof(h->temp_k)));
/* BOLT #8:
*
* 7. `p = decryptWithAD(temp_k2, 0, h, c)`
* * If the MAC check in this operation fails, then the initiator
* MUST terminate the connection without any further messages.
*/
if (!decrypt(&h->temp_k, 0, &h->h, sizeof(h->h),
h->act2.tag, sizeof(h->act2.tag), NULL, 0))
return handshake_failed(conn, h);
/* BOLT #8:
*
* 8. `h = SHA-256(h || c)`
* * The received ciphertext is mixed into the handshake digest.
* This step serves to ensure the payload wasn't modified by a
* MITM.
*/
sha_mix_in(&h->h, h->act2.tag, sizeof(h->act2.tag));
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
return act_three_initiator(conn, h);
}
static struct io_plan *act_two_initiator(struct io_conn *conn,
struct handshake *h)
{
SUPERVERBOSE("Initiator: Act 2");
/* BOLT #8:
*
* 1. Read _exactly_ 50 bytes from the network buffer.
*
* 2. Parse the read message (`m`) into `v`, `re` and `c`:
* * where `v` is the _first_ byte of `m`, `re` is the next 33
* bytes of `m`, and `c` is the last 16 bytes of `m`.
*/
return io_read(conn, &h->act2, ACT_TWO_SIZE, act_two_initiator2, h);
}
static struct io_plan *act_one_initiator(struct io_conn *conn,
struct handshake *h)
{
size_t len;
SUPERVERBOSE("Initiator: Act 1");
/* BOLT #8:
*
* **Sender Actions:**
*
* 1. `e = generateKey()`
*/
h->e = generate_key();
SUPERVERBOSE("e.priv: 0x%s",
tal_hexstr(tmpctx, &h->e.priv, sizeof(h->e.priv)));
SUPERVERBOSE("e.pub: 0x%s",
type_to_string(tmpctx, struct pubkey, &h->e.pub));
/* BOLT #8:
*
* 2. `h = SHA-256(h || e.pub.serializeCompressed())`
* * The newly generated ephemeral key is accumulated into the
* running handshake digest.
*/
sha_mix_in_key(&h->h, &h->e.pub);
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
/* BOLT #8:
*
* 3. `ss = ECDH(rs, e.priv)`
* * The initiator performs an ECDH between its newly generated
* ephemeral key and the remote node's static public key.
*/
if (!secp256k1_ecdh(secp256k1_ctx, h->ss.data,
&h->their_id.pubkey, h->e.priv.secret.data))
return handshake_failed(conn, h);
SUPERVERBOSE("# ss=0x%s", tal_hexstr(tmpctx, h->ss.data, sizeof(h->ss.data)));
/* BOLT #8:
*
* 4. `ck, temp_k1 = HKDF(ck, ss)`
* * A new temporary encryption key is generated, which is
* used to generate the authenticating MAC.
*/
hkdf_two_keys(&h->ck, &h->temp_k, &h->ck, &h->ss, sizeof(h->ss));
SUPERVERBOSE("# ck,temp_k1=0x%s,0x%s",
tal_hexstr(tmpctx, &h->ck, sizeof(h->ck)),
tal_hexstr(tmpctx, &h->temp_k, sizeof(h->temp_k)));
/* BOLT #8:
* 5. `c = encryptWithAD(temp_k1, 0, h, zero)`
* * where `zero` is a zero-length plaintext
*/
encrypt_ad(&h->temp_k, 0, &h->h, sizeof(h->h), NULL, 0,
h->act1.tag, sizeof(h->act1.tag));
SUPERVERBOSE("# c=%s",
tal_hexstr(tmpctx, h->act1.tag, sizeof(h->act1.tag)));
/* BOLT #8:
* 6. `h = SHA-256(h || c)`
* * Finally, the generated ciphertext is accumulated into the
* authenticating handshake digest.
*/
sha_mix_in(&h->h, h->act1.tag, sizeof(h->act1.tag));
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
/* BOLT #8:
*
* 7. Send `m = 0 || e.pub.serializeCompressed() || c` to the responder over the network buffer.
*/
h->act1.v = 0;
len = sizeof(h->act1.pubkey);
secp256k1_ec_pubkey_serialize(secp256k1_ctx, h->act1.pubkey, &len,
&h->e.pub.pubkey,
SECP256K1_EC_COMPRESSED);
SUPERVERBOSE("output: 0x%s", tal_hexstr(tmpctx, &h->act1, ACT_ONE_SIZE));
check_act_one(&h->act1);
return io_write(conn, &h->act1, ACT_ONE_SIZE, act_two_initiator, h);
}
static struct io_plan *act_three_responder2(struct io_conn *conn,
struct handshake *h)
{
u8 der[PUBKEY_DER_LEN];
SUPERVERBOSE("input: 0x%s", tal_hexstr(tmpctx, &h->act3, ACT_THREE_SIZE));
/* BOLT #8:
*
* 2. Parse the read message (`m`) into `v`, `c` and `t`:
* * where `v` is the _first_ byte of `m`, `c` is the next 49
* bytes of `m`, and `t` is the last 16 bytes of `m`.
*/
/* BOLT #8:
*
* 3. If `v` is an unrecognized handshake version, then the responder
* MUST abort the connection attempt.
*/
if (h->act3.v != 0)
return handshake_failed(conn, h);
/* BOLT #8:
*
* 4. `rs = decryptWithAD(temp_k2, 1, h, c)`
* * At this point, the responder has recovered the static public
* key of the initiator.
*/
if (!decrypt(&h->temp_k, 1, &h->h, sizeof(h->h),
h->act3.ciphertext, sizeof(h->act3.ciphertext),
der, sizeof(der)))
return handshake_failed(conn, h);
SUPERVERBOSE("# rs=0x%s", tal_hexstr(tmpctx, der, sizeof(der)));
if (secp256k1_ec_pubkey_parse(secp256k1_ctx, &h->their_id.pubkey,
der, sizeof(der)) != 1)
return handshake_failed(conn, h);
/* BOLT #8:
*
* 5. `h = SHA-256(h || c)`
*
*/
sha_mix_in(&h->h, h->act3.ciphertext, sizeof(h->act3.ciphertext));
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
/* BOLT #8:
*
* 6. `ss = ECDH(rs, e.priv)`
* * where `e` is the responder's original ephemeral key
*/
if (!secp256k1_ecdh(secp256k1_ctx, h->ss.data, &h->their_id.pubkey,
h->e.priv.secret.data))
return handshake_failed(conn, h);
SUPERVERBOSE("# ss=0x%s", tal_hexstr(tmpctx, &h->ss, sizeof(h->ss)));
/* BOLT #8:
* 7. `ck, temp_k3 = HKDF(ck, ss)`
*/
hkdf_two_keys(&h->ck, &h->temp_k, &h->ck, &h->ss, sizeof(h->ss));
SUPERVERBOSE("# ck,temp_k3=0x%s,0x%s",
tal_hexstr(tmpctx, &h->ck, sizeof(h->ck)),
tal_hexstr(tmpctx, &h->temp_k, sizeof(h->temp_k)));
/* BOLT #8:
* 8. `p = decryptWithAD(temp_k3, 0, h, t)`
* * If the MAC check in this operation fails, then the responder
* MUST terminate the connection without any further messages.
*
*/
if (!decrypt(&h->temp_k, 0, &h->h, sizeof(h->h),
h->act3.tag, sizeof(h->act3.tag), NULL, 0))
return handshake_failed(conn, h);
check_act_three(&h->act3);
return handshake_succeeded(conn, h);
}
static struct io_plan *act_three_responder(struct io_conn *conn,
struct handshake *h)
{
SUPERVERBOSE("Responder: Act 3");
/* BOLT #8:
*
* **Receiver Actions:**
*
* 1. Read _exactly_ 66 bytes from the network buffer.
*/
return io_read(conn, &h->act3, ACT_THREE_SIZE, act_three_responder2, h);
}
static struct io_plan *act_two_responder(struct io_conn *conn,
struct handshake *h)
{
size_t len;
SUPERVERBOSE("Responder: Act 2");
/* BOLT #8:
*
* **Sender Actions:**
*
* 1. `e = generateKey()`
*/
h->e = generate_key();
SUPERVERBOSE("# e.pub=0x%s e.priv=0x%s",
type_to_string(tmpctx, struct pubkey, &h->e.pub),
tal_hexstr(tmpctx, &h->e.priv, sizeof(h->e.priv)));
/* BOLT #8:
*
* 2. `h = SHA-256(h || e.pub.serializeCompressed())`
* * The newly generated ephemeral key is accumulated into the
* running handshake digest.
*/
sha_mix_in_key(&h->h, &h->e.pub);
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
/* BOLT #8:
*
* 3. `ss = ECDH(re, e.priv)`
* * where `re` is the ephemeral key of the initiator, which was
* received during Act One
*/
if (!secp256k1_ecdh(secp256k1_ctx, h->ss.data, &h->re.pubkey,
h->e.priv.secret.data))
return handshake_failed(conn, h);
SUPERVERBOSE("# ss=0x%s", tal_hexstr(tmpctx, &h->ss, sizeof(h->ss)));
/* BOLT #8:
*
* 4. `ck, temp_k2 = HKDF(ck, ss)`
* * A new temporary encryption key is generated, which is
* used to generate the authenticating MAC.
*/
hkdf_two_keys(&h->ck, &h->temp_k, &h->ck, &h->ss, sizeof(h->ss));
SUPERVERBOSE("# ck,temp_k2=0x%s,0x%s",
tal_hexstr(tmpctx, &h->ck, sizeof(h->ck)),
tal_hexstr(tmpctx, &h->temp_k, sizeof(h->temp_k)));
/* BOLT #8:
*
* 5. `c = encryptWithAD(temp_k2, 0, h, zero)`
* * where `zero` is a zero-length plaintext
*/
encrypt_ad(&h->temp_k, 0, &h->h, sizeof(h->h), NULL, 0,
h->act2.tag, sizeof(h->act2.tag));
SUPERVERBOSE("# c=0x%s", tal_hexstr(tmpctx, h->act2.tag, sizeof(h->act2.tag)));
/* BOLT #8:
*
* 6. `h = SHA-256(h || c)`
* * Finally, the generated ciphertext is accumulated into the
* authenticating handshake digest.
*/
sha_mix_in(&h->h, h->act2.tag, sizeof(h->act2.tag));
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
/* BOLT #8:
*
* 7. Send `m = 0 || e.pub.serializeCompressed() || c` to the initiator over the network buffer.
*/
h->act2.v = 0;
len = sizeof(h->act2.pubkey);
secp256k1_ec_pubkey_serialize(secp256k1_ctx, h->act2.pubkey, &len,
&h->e.pub.pubkey,
SECP256K1_EC_COMPRESSED);
SUPERVERBOSE("output: 0x%s", tal_hexstr(tmpctx, &h->act2, ACT_TWO_SIZE));
check_act_two(&h->act2);
return io_write(conn, &h->act2, ACT_TWO_SIZE, act_three_responder, h);
}
static struct io_plan *act_one_responder2(struct io_conn *conn,
struct handshake *h)
{
/* BOLT #8:
*
* 3. If `v` is an unrecognized handshake version, then the responder
* MUST abort the connection attempt.
*/
if (h->act1.v != 0)
return handshake_failed(conn, h);
/* BOLT #8:
* * The raw bytes of the remote party's ephemeral public key
* (`e`) are to be deserialized into a point on the curve using
* affine coordinates as encoded by the key's serialized
* composed format.
*/
if (secp256k1_ec_pubkey_parse(secp256k1_ctx, &h->re.pubkey,
h->act1.pubkey, sizeof(h->act1.pubkey)) != 1)
return handshake_failed(conn, h);
SUPERVERBOSE("# re=0x%s", type_to_string(tmpctx, struct pubkey, &h->re));
/* BOLT #8:
*
* 4. `h = SHA-256(h || re.serializeCompressed())`
* * The responder accumulates the initiator's ephemeral key into the
* authenticating handshake digest.
*/
sha_mix_in_key(&h->h, &h->re);
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
/* BOLT #8:
* 5. `ss = ECDH(re, s.priv)`
* * The responder performs an ECDH between its static private key and
* the initiator's ephemeral public key.
*/
if (!hsm_do_ecdh(&h->ss, &h->re))
return handshake_failed(conn, h);
SUPERVERBOSE("# ss=0x%s", tal_hexstr(tmpctx, &h->ss, sizeof(h->ss)));
/* BOLT #8:
*
* 6. `ck, temp_k1 = HKDF(ck, ss)`
* * A new temporary encryption key is generated, which will
* shortly be used to check the authenticating MAC.
*/
hkdf_two_keys(&h->ck, &h->temp_k, &h->ck, &h->ss, sizeof(h->ss));
SUPERVERBOSE("# ck,temp_k1=0x%s,0x%s",
tal_hexstr(tmpctx, &h->ck, sizeof(h->ck)),
tal_hexstr(tmpctx, &h->temp_k, sizeof(h->temp_k)));
/* BOLT #8:
*
* 7. `p = decryptWithAD(temp_k1, 0, h, c)`
* * If the MAC check in this operation fails, then the initiator
* does _not_ know the responder's static public key. If so, then
* the responder MUST terminate the connection without any further
* messages.
*/
if (!decrypt(&h->temp_k, 0, &h->h, sizeof(h->h),
h->act1.tag, sizeof(h->act1.tag), NULL, 0))
return handshake_failed(conn, h);
/* BOLT #8:
*
* 8. `h = SHA-256(h || c)`
* * The received ciphertext is mixed into the handshake digest.
* This step serves to ensure the payload wasn't modified by a
* MITM.
*/
sha_mix_in(&h->h, h->act1.tag, sizeof(h->act1.tag));
SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));
return act_two_responder(conn, h);
}
static struct io_plan *act_one_responder(struct io_conn *conn,
struct handshake *h)
{
SUPERVERBOSE("Responder: Act 1");
/* BOLT #8:
*
* 1. Read _exactly_ 50 bytes from the network buffer.
*
* 2. Parse the read message (`m`) into `v`, `re` and `c`:
* * where `v` is the _first_ byte of `m`, `re` is the next 33
* bytes of `m`, and `c` is the last 16 bytes of `m`.
*/
return io_read(conn, &h->act1, ACT_ONE_SIZE, act_one_responder2, h);
}
struct io_plan *responder_handshake_(struct io_conn *conn,
const struct pubkey *my_id,
const struct wireaddr_internal *addr,
struct io_plan *(*cb)(struct io_conn *,
const struct pubkey *,
const struct wireaddr_internal *,
const struct crypto_state *,
void *cbarg),
void *cbarg)
{
struct handshake *h = new_handshake(conn, my_id);
h->side = RESPONDER;
h->my_id = *my_id;
h->addr = *addr;
h->cbarg = cbarg;
h->cb = cb;
return act_one_responder(conn, h);
}
struct io_plan *initiator_handshake_(struct io_conn *conn,
const struct pubkey *my_id,
const struct pubkey *their_id,
const struct wireaddr_internal *addr,
struct io_plan *(*cb)(struct io_conn *,
const struct pubkey *,
const struct wireaddr_internal *,
const struct crypto_state *,
void *cbarg),
void *cbarg)
{
struct handshake *h = new_handshake(conn, their_id);
h->side = INITIATOR;
h->my_id = *my_id;
h->their_id = *their_id;
h->addr = *addr;
h->cbarg = cbarg;
h->cb = cb;
return act_one_initiator(conn, h);
}