sami7777
55c202516d
Add libsecp256k1 v0.7.1 as src/secp256k1 submodule and introduce crypto_ecdsa / crypto_ecdh wrappers as drop-in replacements for the OpenSSL ECDSA_verify / ECDSA_sign / ECDH_compute_key call sites used by key.cpp and smessage.cpp. Wrappers preserve on-chain compatibility (lax DER parsing, 65-byte recoverable compact sigs, SEC1 priv-key DER round-trip, raw-X ECDH output for smsg KDF). CMake wires the submodule and new sources into the build. Mid-refactor; landing as a checkpoint before stacking sync-pipeline work on top. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
32 lines
1.4 KiB
C++
32 lines
1.4 KiB
C++
// Copyright (c) 2026 The Triangles developers
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef TRIANGLES_CRYPTO_ECDH_H
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#define TRIANGLES_CRYPTO_ECDH_H
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#include <cstddef>
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/**
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* Compute the shared secret X coordinate via secp256k1 ECDH.
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*
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* Output matches OpenSSL's ECDH_compute_key(buf, 32, peer_pub, our_priv, NULL)
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* — i.e. the raw X coordinate of the shared point, with no KDF applied. This
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* preserves bit-for-bit compatibility with smessage's existing key derivation
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* (which feeds the X coordinate into SHA-512 itself), so historical encrypted
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* messages remain decryptable after the migration off OpenSSL EC.
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*
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* @param out32 32-byte buffer for the shared X coordinate.
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* @param privkey32 32-byte secret scalar (big-endian).
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* @param pubkey Peer public key, serialized as either 33 bytes (compressed)
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* or 65 bytes (uncompressed).
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* @param pubkey_len 33 or 65; any other length fails immediately.
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* @return true on success, false if the public key is malformed or the
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* private key is invalid (zero / >= curve order).
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*/
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bool ECDH_xonly_secp256k1(unsigned char out32[32],
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const unsigned char privkey32[32],
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const unsigned char* pubkey,
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std::size_t pubkey_len);
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#endif // TRIANGLES_CRYPTO_ECDH_H
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