Seal delivered sends to the receiver's key (086)

--seal OUTPUT=KEY seals each request's body whole to the receiving node's
public key with HPKE (RFC 9180, base mode: X25519, HKDF-SHA256, AES-128-GCM
where the CPU has AES, else ChaCha20-Poly1305), bound to the request's
source, first number and count; X-Pure-Seal names the suite. A receiver's
--key is a raw 32-byte file, made 0600 when missing, held in OpenSSL's
secure heap; it opens the body where it lies (400 seal when it does not
open) and zeroes the plain text when the request's ticket goes.
--sealed-only refuses unsealed deliveries (403 unsealed).

The check puts a recording relay between two apps: every order applies
once, no body shows an item or a field name, a flipped bit is refused, a
replayed request applies nothing twice, and a seal to another key does not
open. Its hosts choose their own ports (--port 0). Sealed sends drain at
233-235k a second against 469-470k plain (Raspberry Pi 5): three X25519
operations a request, 164 us each. The plain request path measured the
same as before.

1 files changed, 4 insertions, 0 deletions

diff --git a/serve/deliver.h b/serve/deliver.h
index 2d1da29..70b03b9 100644
--- a/serve/deliver.h
+++ b/serve/deliver.h
@@ -23,6 +23,10 @@ void pure_wire_trust(const char *ca_file);
 PureWire *pure_wire_open(const PureModule *m, const char *output, const char *url, const char *source,
                          char *error, size_t size);
 uint32_t pure_wire_output(const PureWire *);
+/* Seal the wire's sends to the receiver's public key (serve/seal.h): each
+ * request's body, bound to its source, first number and count, goes with
+ * X-Pure-Seal naming the suite. Before pure_wire_start. */
+void pure_wire_seal(PureWire *, const unsigned char peer[32]);
 /* The owner's side: queue a saved send numbered after the last queued one
  * (it is encoded now); false when it cannot be (a bytes field that is not
  * UTF-8 has no JSON form), and the wire then stops at it. */