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feat: seal peer sync with X25519 + XChaCha20-Poly1305 (0.9.17)

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Encrypt parliament context sync after Realm mutual auth without pulling in OpenSSL.

Co-authored-by: Cursor <cursoragent@cursor.com>
This commit is contained in:
WHC
2026-10-29 11:16:26 +08:00
co-authored by Cursor
parent a3e115539e
commit 5900b53642
5 changed files with 241 additions and 56 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/peer_auth.c
+195 -49
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@@ -223,6 +223,160 @@ static int read_ok(os_socket_t s, int timeout_ms) {
return ok ? 0 : -1;
}
static int send_kx_pk(os_socket_t s, const uint8_t pk[32], int timeout_ms) {
char hex[65];
hex_encode(pk, 32, hex);
cJSON *o = cJSON_CreateObject();
if (!o)
return -1;
cJSON_AddNumberToObject(o, "v", 1);
cJSON_AddStringToObject(o, "op", "kx");
cJSON_AddStringToObject(o, "pk", hex);
char *line = cJSON_PrintUnformatted(o);
cJSON_Delete(o);
if (!line)
return -1;
int rc = send_line(s, line, timeout_ms);
free(line);
return rc;
}
static int read_kx_pk(os_socket_t s, uint8_t pk[32], int timeout_ms) {
char *line = recv_line(s, timeout_ms);
if (!line)
return -1;
cJSON *o = cJSON_Parse(line);
free(line);
if (!o)
return -1;
const cJSON *op = cJSON_GetObjectItemCaseSensitive(o, "op");
const cJSON *p = cJSON_GetObjectItemCaseSensitive(o, "pk");
int ok = cJSON_IsString(op) && !strcmp(op->valuestring, "kx") &&
cJSON_IsString(p) && hex_decode(p->valuestring, pk, 32) == 0;
cJSON_Delete(o);
return ok ? 0 : -1;
}
static int peer_kx(os_socket_t s, int as_client, uint8_t out_key[32],
int timeout_ms) {
uint8_t eph_sk[32], eph_pk[32], their_pk[32], shared[32];
if (fill_random(eph_sk, 32) != 0)
return -1;
crypto_x25519_public_key(eph_pk, eph_sk);
if (as_client) {
if (send_kx_pk(s, eph_pk, timeout_ms) != 0 ||
read_kx_pk(s, their_pk, timeout_ms) != 0) {
crypto_wipe(eph_sk, sizeof(eph_sk));
return -1;
}
} else {
if (read_kx_pk(s, their_pk, timeout_ms) != 0 ||
send_kx_pk(s, eph_pk, timeout_ms) != 0) {
crypto_wipe(eph_sk, sizeof(eph_sk));
return -1;
}
}
crypto_x25519(shared, eph_sk, their_pk);
crypto_wipe(eph_sk, sizeof(eph_sk));
crypto_blake2b_ctx ctx;
crypto_blake2b_init(&ctx, 32);
crypto_blake2b_update(&ctx, shared, 32);
crypto_blake2b_update(&ctx, (const uint8_t *)"cst-peer-aead-v1", 16);
crypto_blake2b_final(&ctx, out_key);
crypto_wipe(shared, sizeof(shared));
return 0;
}
static void ctr_nonce(uint8_t nonce[24], uint64_t ctr) {
memset(nonce, 0, 24);
for (int i = 0; i < 8; i++)
nonce[16 + i] = (uint8_t)((ctr >> (56 - 8 * i)) & 0xff);
}
static int send_sealed(cst_peer_session_t *sess, const void *plain, size_t n,
int timeout_ms) {
if (!sess || !sess->sealed || n > 2 * 1024 * 1024)
return -1;
os_socket_t s = (os_socket_t)sess->sock;
uint8_t nonce[24];
ctr_nonce(nonce, sess->send_ctr++);
uint8_t *cipher = malloc(n ? n : 1);
uint8_t mac[16];
if (!cipher)
return -1;
crypto_aead_lock(cipher, mac, sess->aead_key, nonce, NULL, 0,
(const uint8_t *)plain, n);
uint32_t body = 24u + (uint32_t)n + 16u;
uint8_t hdr[4] = {(uint8_t)(body >> 24), (uint8_t)(body >> 16),
(uint8_t)(body >> 8), (uint8_t)body};
int rc = -1;
if (os_net_send_all(s, hdr, 4, timeout_ms) == 0 &&
os_net_send_all(s, nonce, 24, timeout_ms) == 0 &&
(n == 0 || os_net_send_all(s, cipher, n, timeout_ms) == 0) &&
os_net_send_all(s, mac, 16, timeout_ms) == 0)
rc = 0;
free(cipher);
return rc;
}
static int recv_exact(os_socket_t s, void *buf, size_t n, int timeout_ms) {
size_t got = 0;
while (got < n) {
long r = os_net_recv(s, (char *)buf + got, n - got, timeout_ms);
if (r <= 0)
return -1;
got += (size_t)r;
}
return 0;
}
static int recv_sealed(cst_peer_session_t *sess, uint8_t **out, size_t *out_n,
int timeout_ms) {
*out = NULL;
*out_n = 0;
if (!sess || !sess->sealed)
return -1;
os_socket_t s = (os_socket_t)sess->sock;
uint8_t hdr[4];
if (recv_exact(s, hdr, 4, timeout_ms) != 0)
return -1;
uint32_t body = ((uint32_t)hdr[0] << 24) | ((uint32_t)hdr[1] << 16) |
((uint32_t)hdr[2] << 8) | (uint32_t)hdr[3];
if (body < 24 + 16 || body > 24 + 16 + 2 * 1024 * 1024)
return -1;
size_t n = body - 24 - 16;
uint8_t nonce[24], mac[16];
uint8_t *cipher = malloc(n ? n : 1);
uint8_t *plain = malloc(n + 1);
if (!cipher || !plain) {
free(cipher);
free(plain);
return -1;
}
if (recv_exact(s, nonce, 24, timeout_ms) != 0 ||
(n && recv_exact(s, cipher, n, timeout_ms) != 0) ||
recv_exact(s, mac, 16, timeout_ms) != 0) {
free(cipher);
free(plain);
return -1;
}
uint8_t expect[24];
ctr_nonce(expect, sess->recv_ctr);
if (memcmp(nonce, expect, 24) != 0 ||
crypto_aead_unlock(plain, mac, sess->aead_key, nonce, NULL, 0, cipher,
n) != 0) {
free(cipher);
free(plain);
return -1;
}
sess->recv_ctr++;
free(cipher);
plain[n] = 0;
*out = plain;
*out_n = n;
return 0;
}
static int handshake_as_client(os_socket_t s, const cst_realm_cert_t *self,
const uint8_t self_sk[64],
const uint8_t realm_pk[32], int timeout_ms,
@@ -299,6 +453,13 @@ int cst_peer_dial(const char *host, int port, const cst_realm_cert_t *self,
snprintf(out->host, sizeof(out->host), "%s", host);
out->port = port;
out->sock = (intptr_t)s;
if (peer_kx(s, 1, out->aead_key, timeout_ms) != 0) {
if (err && err_sz)
snprintf(err, err_sz, "peer key exchange failed");
cst_peer_close(out);
return -1;
}
out->sealed = 1;
return 0;
}
@@ -330,6 +491,13 @@ int cst_peer_accept(intptr_t listen_sock, const cst_realm_cert_t *self,
os_net_peer(s, out->host, sizeof(out->host));
out->port = 0;
out->sock = (intptr_t)s;
if (peer_kx(s, 0, out->aead_key, timeout_ms) != 0) {
if (err && err_sz)
snprintf(err, err_sz, "peer key exchange failed");
cst_peer_close(out);
return -1;
}
out->sealed = 1;
return 0;
}
@@ -339,10 +507,13 @@ void cst_peer_close(cst_peer_session_t *s) {
if (s->sock != 0 && s->sock != (intptr_t)OS_SOCKET_BAD)
os_net_close((os_socket_t)s->sock);
s->sock = (intptr_t)OS_SOCKET_BAD;
crypto_wipe(s->aead_key, sizeof(s->aead_key));
s->sealed = 0;
s->send_ctr = s->recv_ctr = 0;
}
static int send_sync_hdr(os_socket_t s, const cst_peer_sync_bundle_t *b,
int timeout_ms) {
static int send_sync_bundle(cst_peer_session_t *sess,
const cst_peer_sync_bundle_t *b, int timeout_ms) {
cJSON *o = cJSON_CreateObject();
if (!o)
return -1;
@@ -352,30 +523,25 @@ static int send_sync_hdr(os_socket_t s, const cst_peer_sync_bundle_t *b,
cJSON_AddStringToObject(o, "parliament_id", b->parliament_id);
cJSON_AddStringToObject(o, "project_id", b->project_id);
cJSON_AddStringToObject(o, "chair", b->chair_instance);
size_t clen = b->context ? strlen(b->context) : 0;
cJSON_AddNumberToObject(o, "context_len", (double)clen);
char *line = cJSON_PrintUnformatted(o);
cJSON_AddStringToObject(o, "context", b->context ? b->context : "");
char *txt = cJSON_PrintUnformatted(o);
cJSON_Delete(o);
if (!line)
if (!txt)
return -1;
int rc = send_line(s, line, timeout_ms);
free(line);
if (rc != 0)
return -1;
if (clen > 0 &&
os_net_send_all(s, b->context, clen, timeout_ms) != 0)
return -1;
return 0;
int rc = send_sealed(sess, txt, strlen(txt), timeout_ms);
free(txt);
return rc;
}
static int read_sync_hdr(os_socket_t s, cst_peer_sync_bundle_t *b,
int timeout_ms) {
static int read_sync_bundle(cst_peer_session_t *sess, cst_peer_sync_bundle_t *b,
int timeout_ms) {
memset(b, 0, sizeof(*b));
char *line = recv_line(s, timeout_ms);
if (!line)
uint8_t *plain = NULL;
size_t n = 0;
if (recv_sealed(sess, &plain, &n, timeout_ms) != 0)
return -1;
cJSON *o = cJSON_Parse(line);
free(line);
cJSON *o = cJSON_ParseWithLength((char *)plain, n);
free(plain);
if (!o)
return -1;
const cJSON *op = cJSON_GetObjectItemCaseSensitive(o, "op");
@@ -397,51 +563,31 @@ static int read_sync_hdr(os_socket_t s, cst_peer_sync_bundle_t *b,
if (cJSON_IsString(v))
snprintf(b->chair_instance, sizeof(b->chair_instance), "%s",
v->valuestring);
size_t clen = 0;
v = cJSON_GetObjectItemCaseSensitive(o, "context_len");
if (cJSON_IsNumber(v) && v->valuedouble >= 0)
clen = (size_t)v->valuedouble;
cJSON_Delete(o);
if (clen > 2 * 1024 * 1024)
return -1;
if (clen == 0) {
v = cJSON_GetObjectItemCaseSensitive(o, "context");
if (cJSON_IsString(v))
b->context = strdup(v->valuestring);
else
b->context = strdup("");
return b->context ? 0 : -1;
}
char *ctx = malloc(clen + 1);
if (!ctx)
return -1;
size_t got = 0;
while (got < clen) {
long r = os_net_recv(s, ctx + got, clen - got, timeout_ms);
if (r <= 0) {
free(ctx);
return -1;
}
got += (size_t)r;
}
ctx[clen] = 0;
b->context = ctx;
return 0;
cJSON_Delete(o);
return b->context ? 0 : -1;
}
int cst_peer_sync(cst_peer_session_t *s, cst_peer_sync_bundle_t *local,
int timeout_ms, char *err, size_t err_sz) {
if (err && err_sz)
err[0] = 0;
if (!s || !local || s->sock == (intptr_t)OS_SOCKET_BAD) {
if (!s || !local || s->sock == (intptr_t)OS_SOCKET_BAD || !s->sealed) {
if (err && err_sz)
snprintf(err, err_sz, "bad peer session");
return -1;
}
os_socket_t sock = (os_socket_t)s->sock;
if (send_sync_hdr(sock, local, timeout_ms) != 0) {
if (send_sync_bundle(s, local, timeout_ms) != 0) {
if (err && err_sz)
snprintf(err, err_sz, "sync send failed");
return -1;
}
cst_peer_sync_bundle_t remote;
if (read_sync_hdr(sock, &remote, timeout_ms) != 0) {
if (read_sync_bundle(s, &remote, timeout_ms) != 0) {
if (err && err_sz)
snprintf(err, err_sz, "sync recv failed");
return -1;