From 5ce650382352c1503f40abf08129ada69402af55 Mon Sep 17 00:00:00 2001
From: bitflash-coin <bookofshamers@outlook.com>
Date: Tue, 4 Aug 2026 06:34:32 -0700
Subject: public commit

---
 src/btfaddr.h | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 src/btfaddr.h

(limited to 'src/btfaddr.h')

diff --git a/src/btfaddr.h b/src/btfaddr.h
new file mode 100644
index 0000000..1addf8f
--- /dev/null
+++ b/src/btfaddr.h
@@ -0,0 +1,72 @@
+// Copyright (c) 2026 Bitflash developers
+// Distributed under the MIT/X11 software license.
+//
+// Bitflash hidden services -- self-certifying `.btf` addresses (a Tor `.onion`
+// analogue, ported from the Itzal design). An address IS the service's public
+// key: base32(pubkey[32] || checksum[2]).btf, derived from the owner's
+// secp256k1 x-only key, so it cannot be forged (no CA, no DNS). Resolving it
+// means proving a descriptor is signed by exactly this key.
+//
+// This is the ADDRESS + DESCRIPTOR layer. Reachability (rendezvous over the
+// embedded Nostr relays so the origin IP is never exposed) builds on top.
+
+#ifndef BITFLASH_BTFADDR_H
+#define BITFLASH_BTFADDR_H
+
+#include <string>
+#include <vector>
+#include <stdint.h>
+
+namespace btf
+{
+
+// Pseudo-TLD, resolved inside the Bitflash client, never by real DNS.
+extern const char* TLD; // ".btf"
+
+// RFC 4648 base32, lowercase, no padding (case-insensitive hostname label).
+std::string Base32Encode(const unsigned char* data, size_t n);
+bool        Base32Decode(const std::string& s, std::vector<unsigned char>& out);
+
+// Derive the `.btf` address for a 32-byte x-only public key.
+std::string Address(const unsigned char pubkey[32]);
+
+// True if a hostname is a `.btf` address (case-insensitive, optional trailing dot).
+bool IsBtf(const std::string& host);
+
+// Parse a `.btf` address back to its 32-byte public key, verifying the checksum.
+// Returns false if the label isn't valid base32, is too short, or checksum fails.
+bool ParseAddress(const std::string& addr, unsigned char pubkeyOut[32]);
+
+
+// ---- Service descriptor (published later on Nostr) -------------------------
+//
+// A descriptor tells a client how to REACH a service after resolving its
+// address: "service <pubkey> is reachable via <meeting_node>, encrypt end-to-end
+// to my x25519 key <enc>". It is signed by the service key and self-certifying:
+// the client requires the signature to verify under the exact pubkey the
+// address decodes to, so nobody can publish a descriptor for an address they
+// don't own (no hijacking, even via a malicious relay).
+
+struct Descriptor
+{
+    unsigned char pubkey[32];
+    std::string   enc;          // service x25519 public key (hex) for the E2E channel
+    std::string   meeting_node; // rendezvous node the service is registered at
+    uint64_t      created;
+};
+
+// Sign a descriptor. `ctx` is a secp256k1_context* (passed as void* to keep this
+// header free of secp headers); `seckey` is the 32-byte service secret key.
+// Returns the descriptor JSON as a string, or "" on failure.
+std::string SignDescriptor(void* ctx, const unsigned char seckey[32],
+                           const std::string& enc, const std::string& meeting_node,
+                           uint64_t created);
+
+// Verify a descriptor is validly signed by `expect_pubkey` (the key the resolved
+// `.btf` address encodes). Returns true and fills `out` on success.
+bool VerifyDescriptor(void* ctx, const std::string& jsonStr,
+                      const unsigned char expect_pubkey[32], Descriptor& out);
+
+} // namespace btf
+
+#endif
-- 
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