Checkpoint the party/runtime stack before share-program and malicious-mode work.

Ship the TLS mesh, composer, Beaver/Yao/leaf MPC, prep/online paths, apps, and docs so the tree is pushable before elevating share_expr, security_mode, and prep resume.

Co-authored-by: Cursor <cursoragent@cursor.com>

party/key_io.hpp

@@ -0,0 +1,70 @@
+/// @file party/key_io.hpp
+/// @brief Ship a copyable DPF key as a framed byte blob.
+#ifndef LIBDPF_PARTY_KEY_IO_HPP__
+#define LIBDPF_PARTY_KEY_IO_HPP__
+
+#include <cstdint>
+#include <cstring>
+#include <new>
+#include <stdexcept>
+#include <utility>
+#include <vector>
+
+#include "dpf/net/channel.hpp"
+#include "dpf/net/trio.hpp"
+
+namespace dpf
+{
+namespace party
+{
+
+template <typename Key>
+void send_key(net::channel & c, const Key & key)
+{
+    Key copy(key);
+    c.send_bytes(net::msg::dpf_key,
+        reinterpret_cast<const std::uint8_t *>(&copy), sizeof(Key));
+}
+
+template <typename Key>
+Key recv_key(net::channel & c)
+{
+    auto body = c.recv_bytes(net::msg::dpf_key);
+    if (body.size() != sizeof(Key))
+        throw std::runtime_error("recv_key size mismatch");
+    alignas(Key) unsigned char raw[sizeof(Key)];
+    std::memcpy(raw, body.data(), sizeof(Key));
+    Key * p = std::launder(reinterpret_cast<Key *>(raw));
+    Key out(std::move(*p));
+    p->~Key();
+    return out;
+}
+
+/// @brief Send a key blob through the trio hook (or mesh when unset).
+template <typename Key>
+void send_key(net::trio & net, net::role peer, const Key & key)
+{
+    Key copy(key);
+    net.send_bytes_to(peer, net::msg::dpf_key,
+        reinterpret_cast<const std::uint8_t *>(&copy), sizeof(Key));
+}
+
+/// @brief Receive a key blob through the trio hook (or mesh when unset).
+template <typename Key>
+Key recv_key(net::trio & net, net::role peer)
+{
+    auto body = net.recv_bytes_from(peer, net::msg::dpf_key);
+    if (body.size() != sizeof(Key))
+        throw std::runtime_error("recv_key size mismatch");
+    alignas(Key) unsigned char raw[sizeof(Key)];
+    std::memcpy(raw, body.data(), sizeof(Key));
+    Key * p = std::launder(reinterpret_cast<Key *>(raw));
+    Key out(std::move(*p));
+    p->~Key();
+    return out;
+}
+
+}  // namespace party
+}  // namespace dpf
+
+#endif  // LIBDPF_PARTY_KEY_IO_HPP__