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#include <bitcoin/privkey.h>
#include <ccan/crypto/hkdf_sha256/hkdf_sha256.h>
#include <ccan/err/err.h>
#include <ccan/noerr/noerr.h>
#include <ccan/read_write_all/read_write_all.h>
#include <ccan/str/str.h>
#include <ccan/tal/path/path.h>
#include <common/bech32.h>
#include <common/derive_basepoints.h>
#include <common/node_id.h>
#include <common/type_to_string.h>
#include <common/utils.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <sodium.h>
#include <sys/stat.h>
#include <unistd.h>
#define ERROR_HSM_FILE errno
#define ERROR_USAGE 2
#define ERROR_LIBSODIUM 3
#define ERROR_LIBWALLY 4
#define ERROR_KEYDERIV 5
static void show_usage(const char *progname)
{
printf("%s <method> [arguments]\n", progname);
printf("methods:\n");
printf(" - decrypt <path/to/hsm_secret> <password>\n");
printf(" - encrypt <path/to/hsm_secret> <password>\n");
printf(" - dumpcommitments <node id> <channel dbid> <depth> "
"<path/to/hsm_secret> [hsm_secret password]\n");
printf(" - guesstoremote <P2WPKH address> <node id> <tries> "
"<path/to/hsm_secret> [hsm_secret password]\n");
exit(0);
}
static bool ensure_hsm_secret_exists(int fd, const char *path)
{
const char *config_dir = path_dirname(NULL, path);
if (fsync(fd) != 0) {
close(fd);
return false;
}
if (close(fd) != 0)
return false;
fd = open(config_dir, O_RDONLY);
if (fd < 0)
return false;
if (fsync(fd) != 0) {
close(fd);
return false;
}
close(fd);
tal_free(config_dir);
return true;
}
static void get_hsm_secret(struct secret *hsm_secret,
const char *hsm_secret_path)
{
int fd;
fd = open(hsm_secret_path, O_RDONLY);
if (fd < 0)
err(ERROR_HSM_FILE, "Could not open hsm_secret");
if (!read_all(fd, hsm_secret, sizeof(*hsm_secret)))
err(ERROR_HSM_FILE, "Could not read hsm_secret");
close(fd);
}
/* Derive the encryption key from the password provided, and try to decrypt
* the cipher. */
static void get_encrypted_hsm_secret(struct secret *hsm_secret,
const char *hsm_secret_path,
const char *passwd)
{
int fd;
struct secret key;
u8 salt[16] = "c-lightning\0\0\0\0\0";
crypto_secretstream_xchacha20poly1305_state crypto_state;
u8 header[crypto_secretstream_xchacha20poly1305_HEADERBYTES];
/* The cipher size is static with xchacha20poly1305. */
u8 cipher[sizeof(struct secret) + crypto_secretstream_xchacha20poly1305_ABYTES];
fd = open(hsm_secret_path, O_RDONLY);
if (fd < 0)
err(ERROR_HSM_FILE, "Could not open hsm_secret");
if (!read_all(fd, header, crypto_secretstream_xchacha20poly1305_HEADERBYTES))
err(ERROR_HSM_FILE, "Could not read cipher header");
if (!read_all(fd, cipher, sizeof(cipher)))
err(ERROR_HSM_FILE, "Could not read cipher body");
if (crypto_pwhash(key.data, sizeof(key.data), passwd, strlen(passwd), salt,
crypto_pwhash_argon2id_OPSLIMIT_MODERATE,
crypto_pwhash_argon2id_MEMLIMIT_MODERATE,
crypto_pwhash_ALG_ARGON2ID13) != 0)
err(ERROR_LIBSODIUM, "Could not derive a key from the password.");
if (crypto_secretstream_xchacha20poly1305_init_pull(&crypto_state, header,
key.data) != 0)
err(ERROR_LIBSODIUM, "Could not initialize the crypto state");
if (crypto_secretstream_xchacha20poly1305_pull(&crypto_state, hsm_secret->data,
NULL, 0, cipher, sizeof(cipher),
NULL, 0) != 0)
err(ERROR_LIBSODIUM, "Could not retrieve the seed. Wrong password ?");
close(fd);
}
/* Taken from hsmd. */
static void get_channel_seed(struct secret *channel_seed, struct node_id *peer_id,
u64 dbid, struct secret *hsm_secret)
{
struct secret channel_base;
u8 input[sizeof(peer_id->k) + sizeof(dbid)];
/*~ Again, "per-peer" should be "per-channel", but Hysterical Raisins */
const char *info = "per-peer seed";
/*~ We use the DER encoding of the pubkey, because it's platform
* independent. Since the dbid is unique, however, it's completely
* unnecessary, but again, existing users can't be broken. */
/* FIXME: lnd has a nicer BIP32 method for deriving secrets which we
* should migrate to. */
hkdf_sha256(&channel_base, sizeof(struct secret), NULL, 0,
hsm_secret, sizeof(*hsm_secret),
/*~ Initially, we didn't support multiple channels per
* peer at all: a channel had to be completely forgotten
* before another could exist. That was slightly relaxed,
* but the phrase "peer seed" is wired into the seed
* generation here, so we need to keep it that way for
* existing clients, rather than using "channel seed". */
"peer seed", strlen("peer seed"));
memcpy(input, peer_id->k, sizeof(peer_id->k));
BUILD_ASSERT(sizeof(peer_id->k) == PUBKEY_CMPR_LEN);
/*~ For all that talk about platform-independence, note that this
* field is endian-dependent! But let's face it, little-endian won.
* In related news, we don't support EBCDIC or middle-endian. */
memcpy(input + PUBKEY_CMPR_LEN, &dbid, sizeof(dbid));
hkdf_sha256(channel_seed, sizeof(*channel_seed),
input, sizeof(input),
&channel_base, sizeof(channel_base),
info, strlen(info));
}
static int decrypt_hsm(const char *hsm_secret_path, const char *passwd)
{
int fd;
struct stat st;
struct secret hsm_secret;
const char *dir, *backup;
if (sodium_init() == -1)
err(ERROR_LIBSODIUM,
"Could not initialize libsodium. Not enough entropy ?");
dir = path_dirname(NULL, hsm_secret_path);
backup = path_join(dir, dir, "hsm_secret.backup");
if (stat(hsm_secret_path, &st) != 0)
err(ERROR_HSM_FILE, "Could not stat hsm_secret");
if (st.st_size <= 32)
err(ERROR_HSM_FILE, "hsm_secret is not encrypted");
get_encrypted_hsm_secret(&hsm_secret, hsm_secret_path, passwd);
/* Create a backup file, "just in case". */
rename(hsm_secret_path, backup);
fd = open(hsm_secret_path, O_CREAT|O_EXCL|O_WRONLY, 0400);
if (fd < 0)
err(ERROR_HSM_FILE, "Could not open new hsm_secret");
if (!write_all(fd, &hsm_secret, sizeof(hsm_secret))) {
unlink_noerr(hsm_secret_path);
close(fd);
rename("hsm_secret.backup", hsm_secret_path);
err(ERROR_HSM_FILE,
"Failure writing plaintext seed to hsm_secret.");
}
/* Be as paranoïd as in hsmd with the file state on disk. */
if (!ensure_hsm_secret_exists(fd, hsm_secret_path)) {
unlink_noerr(hsm_secret_path);
rename(backup, hsm_secret_path);
err(ERROR_HSM_FILE,
"Could not ensure hsm_secret existence.");
}
unlink_noerr(backup);
tal_free(dir);
printf("Succesfully decrypted hsm_secret, be careful now :-).\n");
return 0;
}
static int encrypt_hsm(const char *hsm_secret_path, const char *passwd)
{
int fd;
struct stat st;
struct secret key, hsm_secret;
u8 salt[16] = "c-lightning\0\0\0\0\0";
crypto_secretstream_xchacha20poly1305_state crypto_state;
u8 header[crypto_secretstream_xchacha20poly1305_HEADERBYTES];
/* The cipher size is static with xchacha20poly1305. */
u8 cipher[sizeof(struct secret) + crypto_secretstream_xchacha20poly1305_ABYTES];
const char *dir, *backup;
dir = path_dirname(NULL, hsm_secret_path);
backup = path_join(dir, dir, "hsm_secret.backup");
if (sodium_init() == -1)
err(ERROR_LIBSODIUM,
"Could not initialize libsodium. Not enough entropy ?");
if (stat(hsm_secret_path, &st) != 0)
err(ERROR_HSM_FILE, "Could not stat hsm_secret");
if (st.st_size > 32)
err(ERROR_USAGE, "hsm_secret is already encrypted");
get_hsm_secret(&hsm_secret, hsm_secret_path);
/* Derive the encryption key from the password provided, and try to encrypt
* the seed. */
if (crypto_pwhash(key.data, sizeof(key.data), passwd, strlen(passwd), salt,
crypto_pwhash_argon2id_OPSLIMIT_MODERATE,
crypto_pwhash_argon2id_MEMLIMIT_MODERATE,
crypto_pwhash_ALG_ARGON2ID13) != 0)
err(ERROR_LIBSODIUM, "Could not derive a key from the password.");
if (crypto_secretstream_xchacha20poly1305_init_push(&crypto_state, header,
key.data) != 0)
err(ERROR_LIBSODIUM, "Could not initialize the crypto state");
if (crypto_secretstream_xchacha20poly1305_push(&crypto_state, cipher,
NULL, hsm_secret.data,
sizeof(hsm_secret.data),
NULL, 0, 0) != 0)
err(ERROR_LIBSODIUM, "Could not encrypt the seed.");
/* Create a backup file, "just in case". */
rename(hsm_secret_path, backup);
fd = open(hsm_secret_path, O_CREAT|O_EXCL|O_WRONLY, 0400);
if (fd < 0)
err(ERROR_HSM_FILE, "Could not open new hsm_secret");
/* Write the encrypted hsm_secret. */
if (!write_all(fd, header, sizeof(header))
|| !write_all(fd, cipher, sizeof(cipher))) {
unlink_noerr(hsm_secret_path);
close(fd);
rename(backup, hsm_secret_path);
err(ERROR_HSM_FILE, "Failure writing cipher to hsm_secret.");
}
/* Be as paranoïd as in hsmd with the file state on disk. */
if (!ensure_hsm_secret_exists(fd, hsm_secret_path)) {
unlink_noerr(hsm_secret_path);
rename(backup, hsm_secret_path);
err(ERROR_HSM_FILE, "Could not ensure hsm_secret existence.");
}
unlink_noerr(backup);
tal_free(dir);
printf("Succesfully encrypted hsm_secret. You'll now have to pass the "
"--encrypted-hsm startup option.\n");
return 0;
}
static int dump_commitments_infos(struct node_id *node_id, u64 channel_id,
u64 depth, char *hsm_secret_path, char *passwd)
{
struct sha256 shaseed;
struct secret hsm_secret, channel_seed, per_commitment_secret;
struct pubkey per_commitment_point;
secp256k1_ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY
| SECP256K1_CONTEXT_SIGN);
if (passwd)
get_encrypted_hsm_secret(&hsm_secret, hsm_secret_path, passwd);
else
get_hsm_secret(&hsm_secret, hsm_secret_path);
get_channel_seed(&channel_seed, node_id, channel_id, &hsm_secret);
derive_shaseed(&channel_seed, &shaseed);
printf("shaseed: %s\n", type_to_string(tmpctx, struct sha256, &shaseed));
for (u64 i = 0; i < depth; i++) {
if (!per_commit_secret(&shaseed, &per_commitment_secret, i))
err(ERROR_KEYDERIV, "Could not derive secret #%"PRIu64, i);
printf("commit secret #%"PRIu64": %s\n",
i, tal_hexstr(tmpctx, per_commitment_secret.data,
sizeof(per_commitment_secret.data)));
if (!per_commit_point(&shaseed, &per_commitment_point, i))
err(ERROR_KEYDERIV, "Could not derive point #%"PRIu64, i);
printf("commit point #%"PRIu64": %s\n",
i, type_to_string(tmpctx, struct pubkey, &per_commitment_point));
}
return 0;
}
/* In case of an unilateral close from the remote side while we suffered a
* loss of data, this tries to recover the private key from the `to_remote`
* output.
* This basically iterates over every `dbid` to derive the channel_seed and
* then derives the payment basepoint to compare to the pubkey hash specified
* in the witness programm.
* Note that since a node generates the key for the to_remote output from its
* *local* per_commitment_point, there is nothing we can do if
* `option_static_remotekey` was not negotiated.
*
* :param address: The bech32 address of the v0 P2WPKH witness programm
* :param node_id: The id of the node with which the channel was established
* :param tries: How many dbids to try.
* :param hsm_secret_path: The path to the hsm_secret
* :param passwd: The *optional* hsm_secret password
*/
static int guess_to_remote(const char *address, struct node_id *node_id,
u64 tries, char *hsm_secret_path, char *passwd)
{
struct secret hsm_secret, channel_seed, basepoint_secret;
struct pubkey basepoint;
struct ripemd160 pubkeyhash;
/* We only support P2WPKH, hence 20. */
u8 goal_pubkeyhash[20];
/* See common/bech32.h for buffer size. */
char hrp[strlen(address) - 6];
int witver;
size_t witlen;
/* Get the hrp to accept addresses from any network. */
if (bech32_decode(hrp, goal_pubkeyhash, &witlen, address, 90) != 1)
errx(ERROR_USAGE, "Could not get address' network");
if (segwit_addr_decode(&witver, goal_pubkeyhash, &witlen, hrp, address) != 1)
errx(ERROR_USAGE, "Wrong bech32 address");
secp256k1_ctx = secp256k1_context_create(SECP256K1_CONTEXT_VERIFY
| SECP256K1_CONTEXT_SIGN);
if (passwd)
get_encrypted_hsm_secret(&hsm_secret, hsm_secret_path, passwd);
else
get_hsm_secret(&hsm_secret, hsm_secret_path);
for (u64 dbid = 1; dbid < tries ; dbid++) {
get_channel_seed(&channel_seed, node_id, dbid, &hsm_secret);
if (!derive_payment_basepoint(&channel_seed,
&basepoint, &basepoint_secret))
errx(ERROR_KEYDERIV, "Could not derive basepoints for dbid %"PRIu64
" and channel seed %s.", dbid,
type_to_string(tmpctx,
struct secret, &channel_seed));
pubkey_to_hash160(&basepoint, &pubkeyhash);
if (memcmp(pubkeyhash.u.u8, goal_pubkeyhash, 20) == 0) {
printf("bech32 : %s\n", address);
printf("pubkey hash : %s\n",
tal_hexstr(tmpctx, pubkeyhash.u.u8, 20));
printf("pubkey : %s \n",
type_to_string(tmpctx, struct pubkey, &basepoint));
printf("privkey : %s \n",
type_to_string(tmpctx, struct secret, &basepoint_secret));
return 0;
}
}
printf("Could not find any basepoint matching the provided witness programm.\n"
"Are you sure that the channel used `option_static_remotekey` ?\n");
return 1;
}
int main(int argc, char *argv[])
{
const char *method;
setup_locale();
err_set_progname(argv[0]);
method = argc > 1 ? argv[1] : NULL;
if (!method)
show_usage(argv[0]);
if (streq(method, "decrypt")) {
if (argc < 4)
show_usage(argv[0]);
return decrypt_hsm(argv[2], argv[3]);
}
if (streq(method, "encrypt")) {
if (argc < 4)
show_usage(argv[0]);
return encrypt_hsm(argv[2], argv[3]);
}
if (streq(method, "dumpcommitments")) {
/* node_id channel_id depth hsm_secret ?password? */
if (argc < 6)
show_usage(argv[0]);
struct node_id node_id;
if (!node_id_from_hexstr(argv[2], strlen(argv[2]), &node_id))
err(ERROR_USAGE, "Bad node id");
return dump_commitments_infos(&node_id, atol(argv[3]), atol(argv[4]),
argv[5], argc >= 7 ? argv[6] : NULL);
}
if (streq(method, "guesstoremote")) {
/* address node_id depth hsm_secret ?password? */
if (argc < 6)
show_usage(argv[0]);
struct node_id node_id;
if (!node_id_from_hexstr(argv[3], strlen(argv[3]), &node_id))
errx(ERROR_USAGE, "Bad node id");
return guess_to_remote(argv[2], &node_id, atol(argv[4]),
argv[5], argc >= 7 ? argv[6] : NULL);
}
show_usage(argv[0]);
}