Merge bitcoin/bitcoin#28008: BIP324 ciphersuite

1c7582e tests: add decryption test to bip324_tests (Pieter Wuille)
990f0f8 Add BIP324Cipher, encapsulating key agreement, derivation, and stream/AEAD ciphers (Pieter Wuille)
c91cedf crypto: support split plaintext in ChaCha20Poly1305 Encrypt/Decrypt (Pieter Wuille)
af2b44c bench: add benchmark for FSChaCha20Poly1305 (Pieter Wuille)
aa8cee9 crypto: add FSChaCha20Poly1305, rekeying wrapper around ChaCha20Poly1305 (Pieter Wuille)
0fee267 crypto: add FSChaCha20, a rekeying wrapper around ChaCha20 (Pieter Wuille)
9ff0768 crypto: add the ChaCha20Poly1305 AEAD as specified in RFC8439 (Pieter Wuille)
9fd085a crypto: remove outdated variant of ChaCha20Poly1305 AEAD (Pieter Wuille)

Pull request description:

  Depends on #27985 and #27993, based on and partially replaces #25361, part of #27634. Draft while dependencies are not merged.

  This adds implementations of:
  * The ChaCha20Poly1305 AEAD from [RFC8439 section 2.8](https://datatracker.ietf.org/doc/html/rfc8439#section-2.8), including test vectors.
  * The FSChaCha20 stream cipher as specified in [BIP324](https://github.com/bitcoin/bips/blob/master/bip-0324.mediawiki#rekeying-wrappers-fschacha20poly1305-and-fschacha20), a rekeying wrapper around ChaCha20.
  * The FSChaCha20Poly1305 AEAD as specified in [BIP324](https://github.com/bitcoin/bips/blob/master/bip-0324.mediawiki#rekeying-wrappers-fschacha20poly1305-and-fschacha20), a rekeying wrapper around ChaCha20Poly1305.
  * A BIP324Cipher class that encapsulates key agreement, key derivation, and stream ciphers and AEADs for [BIP324 packet encoding](https://github.com/bitcoin/bips/blob/master/bip-0324.mediawiki#overall-packet-encryption-and-decryption-pseudocode).

  The ChaCha20Poly1305 and FSChaCha20Poly1305 implementations are new, taking advance of the improvements in #27993.

ACKs for top commit:
  jamesob:
    reACK 1c7582e
  theStack:
    ACK 1c7582e
  stratospher:
    tested ACK 1c7582e.

Tree-SHA512: 06728b4b95b21c5b732ed08faf40e94d0583f9d86ff4db3b92dd519dcd9fbfa0f310bc66ef1e59c9e49dd844ba8c5ac06e2001762a804fb5aa97027816045a46

Author: fanquake

src/Makefile.am

@@ -124,6 +124,7 @@ BITCOIN_CORE_H = \
   banman.h \
   base58.h \
   bech32.h \
+  bip324.h \
   blockencodings.h \
   blockfilter.h \
   chain.h \
@@ -376,6 +377,7 @@ libbitcoin_node_a_SOURCES = \
   addrdb.cpp \
   addrman.cpp \
   banman.cpp \
+  bip324.cpp \
   blockencodings.cpp \
   blockfilter.cpp \
   chain.cpp \
@@ -546,10 +548,10 @@ crypto_libbitcoin_crypto_base_la_LDFLAGS = $(AM_LDFLAGS) -static
 crypto_libbitcoin_crypto_base_la_SOURCES = \
   crypto/aes.cpp \
   crypto/aes.h \
-  crypto/chacha_poly_aead.h \
-  crypto/chacha_poly_aead.cpp \
   crypto/chacha20.h \
   crypto/chacha20.cpp \
+  crypto/chacha20poly1305.h \
+  crypto/chacha20poly1305.cpp \
   crypto/common.h \
   crypto/hkdf_sha256_32.cpp \
   crypto/hkdf_sha256_32.h \

src/Makefile.bench.include

@@ -22,7 +22,6 @@ bench_bench_bitcoin_SOURCES = \
   bench/block_assemble.cpp \
   bench/ccoins_caching.cpp \
   bench/chacha20.cpp \
-  bench/chacha_poly_aead.cpp \
   bench/checkblock.cpp \
   bench/checkqueue.cpp \
   bench/crypto_hash.cpp \

src/Makefile.test.include

@@ -74,6 +74,7 @@ BITCOIN_TESTS =\
   test/base64_tests.cpp \
   test/bech32_tests.cpp \
   test/bip32_tests.cpp \
+  test/bip324_tests.cpp \
   test/blockchain_tests.cpp \
   test/blockencodings_tests.cpp \
   test/blockfilter_index_tests.cpp \
@@ -246,6 +247,7 @@ test_fuzz_fuzz_SOURCES = \
  test/fuzz/banman.cpp \
  test/fuzz/base_encode_decode.cpp \
  test/fuzz/bech32.cpp \
+ test/fuzz/bip324.cpp \
  test/fuzz/bitdeque.cpp \
  test/fuzz/block.cpp \
  test/fuzz/block_header.cpp \
@@ -261,7 +263,6 @@ test_fuzz_fuzz_SOURCES = \
  test/fuzz/crypto_aes256.cpp \
  test/fuzz/crypto_aes256cbc.cpp \
  test/fuzz/crypto_chacha20.cpp \
- test/fuzz/crypto_chacha20_poly1305_aead.cpp \
  test/fuzz/crypto_common.cpp \
  test/fuzz/crypto_diff_fuzz_chacha20.cpp \
  test/fuzz/crypto_hkdf_hmac_sha256_l32.cpp \

src/bench/chacha20.cpp

@@ -5,6 +5,7 @@
 
 #include <bench/bench.h>
 #include <crypto/chacha20.h>
+#include <crypto/chacha20poly1305.h>
 
 /* Number of bytes to process per iteration */
 static const uint64_t BUFFER_SIZE_TINY  = 64;
@@ -23,6 +24,18 @@ static void CHACHA20(benchmark::Bench& bench, size_t buffersize)
     });
 }
 
+static void FSCHACHA20POLY1305(benchmark::Bench& bench, size_t buffersize)
+{
+    std::vector<std::byte> key(32);
+    FSChaCha20Poly1305 ctx(key, 224);
+    std::vector<std::byte> in(buffersize);
+    std::vector<std::byte> aad;
+    std::vector<std::byte> out(buffersize + FSChaCha20Poly1305::EXPANSION);
+    bench.batch(in.size()).unit("byte").run([&] {
+        ctx.Encrypt(in, aad, out);
+    });
+}
+
 static void CHACHA20_64BYTES(benchmark::Bench& bench)
 {
     CHACHA20(bench, BUFFER_SIZE_TINY);
@@ -38,6 +51,24 @@ static void CHACHA20_1MB(benchmark::Bench& bench)
     CHACHA20(bench, BUFFER_SIZE_LARGE);
 }
 
+static void FSCHACHA20POLY1305_64BYTES(benchmark::Bench& bench)
+{
+    FSCHACHA20POLY1305(bench, BUFFER_SIZE_TINY);
+}
+
+static void FSCHACHA20POLY1305_256BYTES(benchmark::Bench& bench)
+{
+    FSCHACHA20POLY1305(bench, BUFFER_SIZE_SMALL);
+}
+
+static void FSCHACHA20POLY1305_1MB(benchmark::Bench& bench)
+{
+    FSCHACHA20POLY1305(bench, BUFFER_SIZE_LARGE);
+}
+
 BENCHMARK(CHACHA20_64BYTES, benchmark::PriorityLevel::HIGH);
 BENCHMARK(CHACHA20_256BYTES, benchmark::PriorityLevel::HIGH);
 BENCHMARK(CHACHA20_1MB, benchmark::PriorityLevel::HIGH);
+BENCHMARK(FSCHACHA20POLY1305_64BYTES, benchmark::PriorityLevel::HIGH);
+BENCHMARK(FSCHACHA20POLY1305_256BYTES, benchmark::PriorityLevel::HIGH);
+BENCHMARK(FSCHACHA20POLY1305_1MB, benchmark::PriorityLevel::HIGH);

src/bench/chacha_poly_aead.cpp

@@ -0,0 +1,111 @@
+// Copyright (c) 2023 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <bip324.h>
+
+#include <chainparams.h>
+#include <crypto/chacha20.h>
+#include <crypto/chacha20poly1305.h>
+#include <crypto/hkdf_sha256_32.h>
+#include <random.h>
+#include <span.h>
+#include <support/cleanse.h>
+
+#include <algorithm>
+#include <assert.h>
+#include <cstdint>
+#include <cstddef>
+
+BIP324Cipher::BIP324Cipher() noexcept
+{
+    m_key.MakeNewKey(true);
+    uint256 entropy = GetRandHash();
+    m_our_pubkey = m_key.EllSwiftCreate(MakeByteSpan(entropy));
+}
+
+BIP324Cipher::BIP324Cipher(const CKey& key, Span<const std::byte> ent32) noexcept :
+    m_key(key)
+{
+    m_our_pubkey = m_key.EllSwiftCreate(ent32);
+}
+
+BIP324Cipher::BIP324Cipher(const CKey& key, const EllSwiftPubKey& pubkey) noexcept :
+    m_key(key), m_our_pubkey(pubkey) {}
+
+void BIP324Cipher::Initialize(const EllSwiftPubKey& their_pubkey, bool initiator, bool self_decrypt) noexcept
+{
+    // Determine salt (fixed string + network magic bytes)
+    const auto& message_header = Params().MessageStart();
+    std::string salt = std::string{"bitcoin_v2_shared_secret"} + std::string(std::begin(message_header), std::end(message_header));
+
+    // Perform ECDH to derive shared secret.
+    ECDHSecret ecdh_secret = m_key.ComputeBIP324ECDHSecret(their_pubkey, m_our_pubkey, initiator);
+
+    // Derive encryption keys from shared secret, and initialize stream ciphers and AEADs.
+    bool side = (initiator != self_decrypt);
+    CHKDF_HMAC_SHA256_L32 hkdf(UCharCast(ecdh_secret.data()), ecdh_secret.size(), salt);
+    std::array<std::byte, 32> hkdf_32_okm;
+    hkdf.Expand32("initiator_L", UCharCast(hkdf_32_okm.data()));
+    (side ? m_send_l_cipher : m_recv_l_cipher).emplace(hkdf_32_okm, REKEY_INTERVAL);
+    hkdf.Expand32("initiator_P", UCharCast(hkdf_32_okm.data()));
+    (side ? m_send_p_cipher : m_recv_p_cipher).emplace(hkdf_32_okm, REKEY_INTERVAL);
+    hkdf.Expand32("responder_L", UCharCast(hkdf_32_okm.data()));
+    (side ? m_recv_l_cipher : m_send_l_cipher).emplace(hkdf_32_okm, REKEY_INTERVAL);
+    hkdf.Expand32("responder_P", UCharCast(hkdf_32_okm.data()));
+    (side ? m_recv_p_cipher : m_send_p_cipher).emplace(hkdf_32_okm, REKEY_INTERVAL);
+
+    // Derive garbage terminators from shared secret.
+    hkdf.Expand32("garbage_terminators", UCharCast(hkdf_32_okm.data()));
+    std::copy(std::begin(hkdf_32_okm), std::begin(hkdf_32_okm) + GARBAGE_TERMINATOR_LEN,
+        (initiator ? m_send_garbage_terminator : m_recv_garbage_terminator).begin());
+    std::copy(std::end(hkdf_32_okm) - GARBAGE_TERMINATOR_LEN, std::end(hkdf_32_okm),
+        (initiator ? m_recv_garbage_terminator : m_send_garbage_terminator).begin());
+
+    // Derive session id from shared secret.
+    hkdf.Expand32("session_id", UCharCast(m_session_id.data()));
+
+    // Wipe all variables that contain information which could be used to re-derive encryption keys.
+    memory_cleanse(ecdh_secret.data(), ecdh_secret.size());
+    memory_cleanse(hkdf_32_okm.data(), sizeof(hkdf_32_okm));
+    memory_cleanse(&hkdf, sizeof(hkdf));
+    m_key = CKey();
+}
+
+void BIP324Cipher::Encrypt(Span<const std::byte> contents, Span<const std::byte> aad, bool ignore, Span<std::byte> output) noexcept
+{
+    assert(output.size() == contents.size() + EXPANSION);
+
+    // Encrypt length.
+    std::byte len[LENGTH_LEN];
+    len[0] = std::byte{(uint8_t)(contents.size() & 0xFF)};
+    len[1] = std::byte{(uint8_t)((contents.size() >> 8) & 0xFF)};
+    len[2] = std::byte{(uint8_t)((contents.size() >> 16) & 0xFF)};
+    m_send_l_cipher->Crypt(len, output.first(LENGTH_LEN));
+
+    // Encrypt plaintext.
+    std::byte header[HEADER_LEN] = {ignore ? IGNORE_BIT : std::byte{0}};
+    m_send_p_cipher->Encrypt(header, contents, aad, output.subspan(LENGTH_LEN));
+}
+
+uint32_t BIP324Cipher::DecryptLength(Span<const std::byte> input) noexcept
+{
+    assert(input.size() == LENGTH_LEN);
+
+    std::byte buf[LENGTH_LEN];
+    // Decrypt length
+    m_recv_l_cipher->Crypt(input, buf);
+    // Convert to number.
+    return uint32_t(buf[0]) + (uint32_t(buf[1]) << 8) + (uint32_t(buf[2]) << 16);
+}
+
+bool BIP324Cipher::Decrypt(Span<const std::byte> input, Span<const std::byte> aad, bool& ignore, Span<std::byte> contents) noexcept
+{
+    assert(input.size() + LENGTH_LEN == contents.size() + EXPANSION);
+
+    std::byte header[HEADER_LEN];
+    if (!m_recv_p_cipher->Decrypt(input, aad, header, contents)) return false;
+
+    ignore = (header[0] & IGNORE_BIT) == IGNORE_BIT;
+    return true;
+}