Merge #15649: Add ChaCha20Poly1305@Bitcoin AEAD

bb326add9f38f2a8e5ce5ee29d98ce08038200d8 Add ChaCha20Poly1305@Bitcoin AEAD benchmark (Jonas Schnelli)
99aea045d688059caf89c0e485fa427bd28eddd8 Add ChaCha20Poly1305@Bitcoin tests (Jonas Schnelli)
af5d1b5f4a7b56628a76af21284c258d845894f0 Add ChaCha20Poly1305@Bitcoin AEAD implementation (Jonas Schnelli)

Pull request description:

  This adds a new AEAD (authenticated encryption with additional data) construct optimised for small messages (like used in Bitcoins p2p network).

  Includes: #15519, #15512 (please review those first).

  The construct is specified here.
  https://gist.github.com/jonasschnelli/c530ea8421b8d0e80c51486325587c52#ChaCha20Poly1305Bitcoin_Cipher_Suite

  This aims for being used in v2 peer-to-peer messages.

ACKs for top commit:
  laanwj:
    code review ACK bb326add9f38f2a8e5ce5ee29d98ce08038200d8

Tree-SHA512: 15bcb86c510fce7abb7a73536ff2ae89893b24646bf108c6cf18f064d672dbbbea8b1dd0868849fdac0c6854e498f1345d01dab56d1c92031afd728302234686

6 files changed, 525 insertions, 1 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index e4c542fa25..e86c580934 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -352,6 +352,8 @@ crypto_libbitcoin_crypto_base_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 crypto_libbitcoin_crypto_base_a_SOURCES = \
   crypto/aes.cpp \
   crypto/aes.h \
+  crypto/chacha_poly_aead.h \
+  crypto/chacha_poly_aead.cpp \
   crypto/chacha20.h \
   crypto/chacha20.cpp \
   crypto/common.h \
@@ -614,7 +616,7 @@ bitcoin_wallet_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(CRYPTO_LIBS) $(EVENT_PTHREAD
 # bitcoinconsensus library #
 if BUILD_BITCOIN_LIBS
 include_HEADERS = script/bitcoinconsensus.h
-libbitcoinconsensus_la_SOURCES = $(crypto_libbitcoin_crypto_base_a_SOURCES) $(libbitcoin_consensus_a_SOURCES)
+libbitcoinconsensus_la_SOURCES = support/cleanse.cpp $(crypto_libbitcoin_crypto_base_a_SOURCES) $(libbitcoin_consensus_a_SOURCES)
 
 if GLIBC_BACK_COMPAT
   libbitcoinconsensus_la_SOURCES += compat/glibc_compat.cpp
diff --git a/src/Makefile.bench.include b/src/Makefile.bench.include
index c1d9bf281c..e421b377a0 100644
--- a/src/Makefile.bench.include
+++ b/src/Makefile.bench.include
@@ -24,6 +24,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/examples.cpp \
   bench/rollingbloom.cpp \
   bench/chacha20.cpp \
+  bench/chacha_poly_aead.cpp \
   bench/crypto_hash.cpp \
   bench/ccoins_caching.cpp \
   bench/gcs_filter.cpp \
diff --git a/src/bench/chacha_poly_aead.cpp b/src/bench/chacha_poly_aead.cpp
new file mode 100644
index 0000000000..f5f7297490
--- /dev/null
+++ b/src/bench/chacha_poly_aead.cpp
@@ -0,0 +1,123 @@
+// Copyright (c) 2019 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 <iostream>
+
+#include <bench/bench.h>
+#include <crypto/chacha_poly_aead.h>
+#include <crypto/poly1305.h> // for the POLY1305_TAGLEN constant
+#include <hash.h>
+
+#include <limits>
+#include <assert.h>
+
+/* Number of bytes to process per iteration */
+static constexpr uint64_t BUFFER_SIZE_TINY = 64;
+static constexpr uint64_t BUFFER_SIZE_SMALL = 256;
+static constexpr uint64_t BUFFER_SIZE_LARGE = 1024 * 1024;
+
+static const unsigned char k1[32] = {0};
+static const unsigned char k2[32] = {0};
+
+static ChaCha20Poly1305AEAD aead(k1, 32, k2, 32);
+
+static void CHACHA20_POLY1305_AEAD(benchmark::State& state, size_t buffersize, bool include_decryption)
+{
+    std::vector<unsigned char> in(buffersize + CHACHA20_POLY1305_AEAD_AAD_LEN + POLY1305_TAGLEN, 0);
+    std::vector<unsigned char> out(buffersize + CHACHA20_POLY1305_AEAD_AAD_LEN + POLY1305_TAGLEN, 0);
+    uint64_t seqnr_payload = 0;
+    uint64_t seqnr_aad = 0;
+    int aad_pos = 0;
+    uint32_t len = 0;
+    while (state.KeepRunning()) {
+        // encrypt or decrypt the buffer with a static key
+        assert(aead.Crypt(seqnr_payload, seqnr_aad, aad_pos, out.data(), out.size(), in.data(), buffersize, true));
+
+        if (include_decryption) {
+            // if we decrypt, include the GetLength
+            assert(aead.GetLength(&len, seqnr_aad, aad_pos, in.data()));
+            assert(aead.Crypt(seqnr_payload, seqnr_aad, aad_pos, out.data(), out.size(), in.data(), buffersize, true));
+        }
+
+        // increase main sequence number
+        seqnr_payload++;
+        // increase aad position (position in AAD keystream)
+        aad_pos += CHACHA20_POLY1305_AEAD_AAD_LEN;
+        if (aad_pos + CHACHA20_POLY1305_AEAD_AAD_LEN > CHACHA20_ROUND_OUTPUT) {
+            aad_pos = 0;
+            seqnr_aad++;
+        }
+        if (seqnr_payload + 1 == std::numeric_limits<uint64_t>::max()) {
+            // reuse of nonce+key is okay while benchmarking.
+            seqnr_payload = 0;
+            seqnr_aad = 0;
+            aad_pos = 0;
+        }
+    }
+}
+
+static void CHACHA20_POLY1305_AEAD_64BYTES_ONLY_ENCRYPT(benchmark::State& state)
+{
+    CHACHA20_POLY1305_AEAD(state, BUFFER_SIZE_TINY, false);
+}
+
+static void CHACHA20_POLY1305_AEAD_256BYTES_ONLY_ENCRYPT(benchmark::State& state)
+{
+    CHACHA20_POLY1305_AEAD(state, BUFFER_SIZE_SMALL, false);
+}
+
+static void CHACHA20_POLY1305_AEAD_1MB_ONLY_ENCRYPT(benchmark::State& state)
+{
+    CHACHA20_POLY1305_AEAD(state, BUFFER_SIZE_LARGE, false);
+}
+
+static void CHACHA20_POLY1305_AEAD_64BYTES_ENCRYPT_DECRYPT(benchmark::State& state)
+{
+    CHACHA20_POLY1305_AEAD(state, BUFFER_SIZE_TINY, true);
+}
+
+static void CHACHA20_POLY1305_AEAD_256BYTES_ENCRYPT_DECRYPT(benchmark::State& state)
+{
+    CHACHA20_POLY1305_AEAD(state, BUFFER_SIZE_SMALL, true);
+}
+
+static void CHACHA20_POLY1305_AEAD_1MB_ENCRYPT_DECRYPT(benchmark::State& state)
+{
+    CHACHA20_POLY1305_AEAD(state, BUFFER_SIZE_LARGE, true);
+}
+
+// Add Hash() (dbl-sha256) bench for comparison
+
+static void HASH(benchmark::State& state, size_t buffersize)
+{
+    uint8_t hash[CHash256::OUTPUT_SIZE];
+    std::vector<uint8_t> in(buffersize,0);
+    while (state.KeepRunning())
+        CHash256().Write(in.data(), in.size()).Finalize(hash);
+}
+
+static void HASH_64BYTES(benchmark::State& state)
+{
+    HASH(state, BUFFER_SIZE_TINY);
+}
+
+static void HASH_256BYTES(benchmark::State& state)
+{
+    HASH(state, BUFFER_SIZE_SMALL);
+}
+
+static void HASH_1MB(benchmark::State& state)
+{
+    HASH(state, BUFFER_SIZE_LARGE);
+}
+
+BENCHMARK(CHACHA20_POLY1305_AEAD_64BYTES_ONLY_ENCRYPT, 500000);
+BENCHMARK(CHACHA20_POLY1305_AEAD_256BYTES_ONLY_ENCRYPT, 250000);
+BENCHMARK(CHACHA20_POLY1305_AEAD_1MB_ONLY_ENCRYPT, 340);
+BENCHMARK(CHACHA20_POLY1305_AEAD_64BYTES_ENCRYPT_DECRYPT, 500000);
+BENCHMARK(CHACHA20_POLY1305_AEAD_256BYTES_ENCRYPT_DECRYPT, 250000);
+BENCHMARK(CHACHA20_POLY1305_AEAD_1MB_ENCRYPT_DECRYPT, 340);
+BENCHMARK(HASH_64BYTES, 500000);
+BENCHMARK(HASH_256BYTES, 250000);
+BENCHMARK(HASH_1MB, 340);
diff --git a/src/crypto/chacha_poly_aead.cpp b/src/crypto/chacha_poly_aead.cpp
new file mode 100644
index 0000000000..6a3d43deb1
--- /dev/null
+++ b/src/crypto/chacha_poly_aead.cpp
@@ -0,0 +1,126 @@
+// Copyright (c) 2019 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 <crypto/chacha_poly_aead.h>
+
+#include <crypto/common.h>
+#include <crypto/poly1305.h>
+#include <support/cleanse.h>
+
+#include <assert.h>
+#include <string.h>
+
+#include <cstdio>
+#include <limits>
+
+#ifndef HAVE_TIMINGSAFE_BCMP
+
+int timingsafe_bcmp(const unsigned char* b1, const unsigned char* b2, size_t n)
+{
+    const unsigned char *p1 = b1, *p2 = b2;
+    int ret = 0;
+
+    for (; n > 0; n--)
+        ret |= *p1++ ^ *p2++;
+    return (ret != 0);
+}
+
+#endif // TIMINGSAFE_BCMP
+
+ChaCha20Poly1305AEAD::ChaCha20Poly1305AEAD(const unsigned char* K_1, size_t K_1_len, const unsigned char* K_2, size_t K_2_len)
+{
+    assert(K_1_len == CHACHA20_POLY1305_AEAD_KEY_LEN);
+    assert(K_2_len == CHACHA20_POLY1305_AEAD_KEY_LEN);
+    m_chacha_main.SetKey(K_1, CHACHA20_POLY1305_AEAD_KEY_LEN);
+    m_chacha_header.SetKey(K_2, CHACHA20_POLY1305_AEAD_KEY_LEN);
+
+    // set the cached sequence number to uint64 max which hints for an unset cache.
+    // we can't hit uint64 max since the rekey rule (which resets the sequence number) is 1GB
+    m_cached_aad_seqnr = std::numeric_limits<uint64_t>::max();
+}
+
+bool ChaCha20Poly1305AEAD::Crypt(uint64_t seqnr_payload, uint64_t seqnr_aad, int aad_pos, unsigned char* dest, size_t dest_len /* length of the output buffer for sanity checks */, const unsigned char* src, size_t src_len, bool is_encrypt)
+{
+    // check buffer boundaries
+    if (
+        // if we encrypt, make sure the source contains at least the expected AAD and the destination has at least space for the source + MAC
+        (is_encrypt && (src_len < CHACHA20_POLY1305_AEAD_AAD_LEN || dest_len < src_len + POLY1305_TAGLEN)) ||
+        // if we decrypt, make sure the source contains at least the expected AAD+MAC and the destination has at least space for the source - MAC
+        (!is_encrypt && (src_len < CHACHA20_POLY1305_AEAD_AAD_LEN + POLY1305_TAGLEN || dest_len < src_len - POLY1305_TAGLEN))) {
+        return false;
+    }
+
+    unsigned char expected_tag[POLY1305_TAGLEN], poly_key[POLY1305_KEYLEN];
+    memset(poly_key, 0, sizeof(poly_key));
+    m_chacha_main.SetIV(seqnr_payload);
+
+    // block counter 0 for the poly1305 key
+    // use lower 32bytes for the poly1305 key
+    // (throws away 32 unused bytes (upper 32) from this ChaCha20 round)
+    m_chacha_main.Seek(0);
+    m_chacha_main.Crypt(poly_key, poly_key, sizeof(poly_key));
+
+    // if decrypting, verify the tag prior to decryption
+    if (!is_encrypt) {
+        const unsigned char* tag = src + src_len - POLY1305_TAGLEN;
+        poly1305_auth(expected_tag, src, src_len - POLY1305_TAGLEN, poly_key);
+
+        // constant time compare the calculated MAC with the provided MAC
+        if (timingsafe_bcmp(expected_tag, tag, POLY1305_TAGLEN) != 0) {
+            memory_cleanse(expected_tag, sizeof(expected_tag));
+            memory_cleanse(poly_key, sizeof(poly_key));
+            return false;
+        }
+        memory_cleanse(expected_tag, sizeof(expected_tag));
+        // MAC has been successfully verified, make sure we don't covert it in decryption
+        src_len -= POLY1305_TAGLEN;
+    }
+
+    // calculate and cache the next 64byte keystream block if requested sequence number is not yet the cache
+    if (m_cached_aad_seqnr != seqnr_aad) {
+        m_cached_aad_seqnr = seqnr_aad;
+        m_chacha_header.SetIV(seqnr_aad);
+        m_chacha_header.Seek(0);
+        m_chacha_header.Keystream(m_aad_keystream_buffer, CHACHA20_ROUND_OUTPUT);
+    }
+    // crypt the AAD (3 bytes message length) with given position in AAD cipher instance keystream
+    dest[0] = src[0] ^ m_aad_keystream_buffer[aad_pos];
+    dest[1] = src[1] ^ m_aad_keystream_buffer[aad_pos + 1];
+    dest[2] = src[2] ^ m_aad_keystream_buffer[aad_pos + 2];
+
+    // Set the playload ChaCha instance block counter to 1 and crypt the payload
+    m_chacha_main.Seek(1);
+    m_chacha_main.Crypt(src + CHACHA20_POLY1305_AEAD_AAD_LEN, dest + CHACHA20_POLY1305_AEAD_AAD_LEN, src_len - CHACHA20_POLY1305_AEAD_AAD_LEN);
+
+    // If encrypting, calculate and append tag
+    if (is_encrypt) {
+        // the poly1305 tag expands over the AAD (3 bytes length) & encrypted payload
+        poly1305_auth(dest + src_len, dest, src_len, poly_key);
+    }
+
+    // cleanse no longer required MAC and polykey
+    memory_cleanse(poly_key, sizeof(poly_key));
+    return true;
+}
+
+bool ChaCha20Poly1305AEAD::GetLength(uint32_t* len24_out, uint64_t seqnr_aad, int aad_pos, const uint8_t* ciphertext)
+{
+    // enforce valid aad position to avoid accessing outside of the 64byte keystream cache
+    // (there is space for 21 times 3 bytes)
+    assert(aad_pos >= 0 && aad_pos < CHACHA20_ROUND_OUTPUT - CHACHA20_POLY1305_AEAD_AAD_LEN);
+    if (m_cached_aad_seqnr != seqnr_aad) {
+        // we need to calculate the 64 keystream bytes since we reached a new aad sequence number
+        m_cached_aad_seqnr = seqnr_aad;
+        m_chacha_header.SetIV(seqnr_aad);                                         // use LE for the nonce
+        m_chacha_header.Seek(0);                                                  // block counter 0
+        m_chacha_header.Keystream(m_aad_keystream_buffer, CHACHA20_ROUND_OUTPUT); // write keystream to the cache
+    }
+
+    // decrypt the ciphertext length by XORing the right position of the 64byte keystream cache with the ciphertext
+    *len24_out = (ciphertext[0] ^ m_aad_keystream_buffer[aad_pos + 0]) |
+                 (ciphertext[1] ^ m_aad_keystream_buffer[aad_pos + 1]) << 8 |
+                 (ciphertext[2] ^ m_aad_keystream_buffer[aad_pos + 2]) << 16;
+
+    return true;
+}
diff --git a/src/crypto/chacha_poly_aead.h b/src/crypto/chacha_poly_aead.h
new file mode 100644
index 0000000000..b3ba781cdd
--- /dev/null
+++ b/src/crypto/chacha_poly_aead.h
@@ -0,0 +1,146 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_CRYPTO_CHACHA_POLY_AEAD_H
+#define BITCOIN_CRYPTO_CHACHA_POLY_AEAD_H
+
+#include <crypto/chacha20.h>
+
+#include <cmath>
+
+static constexpr int CHACHA20_POLY1305_AEAD_KEY_LEN = 32;
+static constexpr int CHACHA20_POLY1305_AEAD_AAD_LEN = 3; /* 3 bytes length */
+static constexpr int CHACHA20_ROUND_OUTPUT = 64;         /* 64 bytes per round */
+static constexpr int AAD_PACKAGES_PER_ROUND = 21;        /* 64 / 3 round down*/
+
+/* A AEAD class for ChaCha20-Poly1305@bitcoin.
+ *
+ * ChaCha20 is a stream cipher designed by Daniel Bernstein and described in
+ * <ref>[http://cr.yp.to/chacha/chacha-20080128.pdf ChaCha20]</ref>. It operates
+ * by permuting 128 fixed bits, 128 or 256 bits of key, a 64 bit nonce and a 64
+ * bit counter into 64 bytes of output. This output is used as a keystream, with
+ * any unused bytes simply discarded.
+ *
+ * Poly1305 <ref>[http://cr.yp.to/mac/poly1305-20050329.pdf Poly1305]</ref>, also
+ * by Daniel Bernstein, is a one-time Carter-Wegman MAC that computes a 128 bit
+ * integrity tag given a message and a single-use 256 bit secret key.
+ *
+ * The chacha20-poly1305@bitcoin combines these two primitives into an
+ * authenticated encryption mode. The construction used is based on that proposed
+ * for TLS by Adam Langley in
+ * <ref>[http://tools.ietf.org/html/draft-agl-tls-chacha20poly1305-03 "ChaCha20
+ * and Poly1305 based Cipher Suites for TLS", Adam Langley]</ref>, but differs in
+ * the layout of data passed to the MAC and in the addition of encryption of the
+ * packet lengths.
+ *
+ * ==== Detailed Construction ====
+ *
+ * The chacha20-poly1305@bitcoin cipher requires two 256 bits of key material as
+ * output from the key exchange. Each key (K_1 and K_2) are used by two separate
+ * instances of chacha20.
+ *
+ * The instance keyed by K_1 is a stream cipher that is used only to encrypt the 3
+ * byte packet length field and has its own sequence number. The second instance,
+ * keyed by K_2, is used in conjunction with poly1305 to build an AEAD
+ * (Authenticated Encryption with Associated Data) that is used to encrypt and
+ * authenticate the entire packet.
+ *
+ * Two separate cipher instances are used here so as to keep the packet lengths
+ * confidential but not create an oracle for the packet payload cipher by
+ * decrypting and using the packet length prior to checking the MAC. By using an
+ * independently-keyed cipher instance to encrypt the length, an active attacker
+ * seeking to exploit the packet input handling as a decryption oracle can learn
+ * nothing about the payload contents or its MAC (assuming key derivation,
+ * ChaCha20 and Poly1305 are secure).
+ *
+ * The AEAD is constructed as follows: for each packet, generate a Poly1305 key by
+ * taking the first 256 bits of ChaCha20 stream output generated using K_2, an IV
+ * consisting of the packet sequence number encoded as an LE uint64 and a ChaCha20
+ * block counter of zero. The K_2 ChaCha20 block counter is then set to the
+ * little-endian encoding of 1 (i.e. {1, 0, 0, 0, 0, 0, 0, 0}) and this instance
+ * is used for encryption of the packet payload.
+ *
+ * ==== Packet Handling ====
+ *
+ * When receiving a packet, the length must be decrypted first. When 3 bytes of
+ * ciphertext length have been received, they may be decrypted.
+ *
+ * A ChaCha20 round always calculates 64bytes which is sufficient to crypt 21
+ * times a 3 bytes length field (21*3 = 63). The length field sequence number can
+ * thus be used 21 times (keystream caching).
+ *
+ * The length field must be enc-/decrypted with the ChaCha20 keystream keyed with
+ * K_1 defined by block counter 0, the length field sequence number in little
+ * endian and a keystream position from 0 to 60.
+ *
+ * Once the entire packet has been received, the MAC MUST be checked before
+ * decryption. A per-packet Poly1305 key is generated as described above and the
+ * MAC tag calculated using Poly1305 with this key over the ciphertext of the
+ * packet length and the payload together. The calculated MAC is then compared in
+ * constant time with the one appended to the packet and the packet decrypted
+ * using ChaCha20 as described above (with K_2, the packet sequence number as
+ * nonce and a starting block counter of 1).
+ *
+ * Detection of an invalid MAC MUST lead to immediate connection termination.
+ *
+ * To send a packet, first encode the 3 byte length and encrypt it using K_1 as
+ * described above. Encrypt the packet payload (using K_2) and append it to the
+ * encrypted length. Finally, calculate a MAC tag and append it.
+ *
+ * The initiating peer MUST use <code>K_1_A, K_2_A</code> to encrypt messages on
+ * the send channel, <code>K_1_B, K_2_B</code> MUST be used to decrypt messages on
+ * the receive channel.
+ *
+ * The responding peer MUST use <code>K_1_A, K_2_A</code> to decrypt messages on
+ * the receive channel, <code>K_1_B, K_2_B</code> MUST be used to encrypt messages
+ * on the send channel.
+ *
+ * Optimized implementations of ChaCha20-Poly1305@bitcoin are relatively fast in
+ * general, therefore it is very likely that encrypted messages require not more
+ * CPU cycles per bytes then the current unencrypted p2p message format
+ * (ChaCha20/Poly1305 versus double SHA256).
+ *
+ * The initial packet sequence numbers are 0.
+ *
+ * K_2 ChaCha20 cipher instance (payload) must never reuse a {key, nonce} for
+ * encryption nor may it be used to encrypt more than 2^70 bytes under the same
+ * {key, nonce}.
+ *
+ * K_1 ChaCha20 cipher instance (length field/AAD) must never reuse a {key, nonce,
+ * position-in-keystream} for encryption nor may it be used to encrypt more than
+ * 2^70 bytes under the same {key, nonce}.
+ *
+ * We use message sequence numbers for both communication directions.
+ */
+
+class ChaCha20Poly1305AEAD
+{
+private:
+    ChaCha20 m_chacha_main;                                      // payload and poly1305 key-derivation cipher instance
+    ChaCha20 m_chacha_header;                                    // AAD cipher instance (encrypted length)
+    unsigned char m_aad_keystream_buffer[CHACHA20_ROUND_OUTPUT]; // aad keystream cache
+    uint64_t m_cached_aad_seqnr;                                 // aad keystream cache hint
+
+public:
+    ChaCha20Poly1305AEAD(const unsigned char* K_1, size_t K_1_len, const unsigned char* K_2, size_t K_2_len);
+
+    explicit ChaCha20Poly1305AEAD(const ChaCha20Poly1305AEAD&) = delete;
+
+    /** Encrypts/decrypts a packet
+        seqnr_payload, the message sequence number
+        seqnr_aad, the messages AAD sequence number which allows reuse of the AAD keystream
+        aad_pos, position to use in the AAD keystream to encrypt the AAD
+        dest, output buffer, must be of a size equal or larger then CHACHA20_POLY1305_AEAD_AAD_LEN + payload (+ POLY1305_TAG_LEN in encryption) bytes
+        destlen, length of the destination buffer
+        src, the AAD+payload to encrypt or the AAD+payload+MAC to decrypt
+        src_len, the length of the source buffer
+        is_encrypt, set to true if we encrypt (creates and appends the MAC instead of verifying it)
+        */
+    bool Crypt(uint64_t seqnr_payload, uint64_t seqnr_aad, int aad_pos, unsigned char* dest, size_t dest_len, const unsigned char* src, size_t src_len, bool is_encrypt);
+
+    /** decrypts the 3 bytes AAD data and decodes it into a uint32_t field */
+    bool GetLength(uint32_t* len24_out, uint64_t seqnr_aad, int aad_pos, const uint8_t* ciphertext);
+};
+
+#endif // BITCOIN_CRYPTO_CHACHA_POLY_AEAD_H
diff --git a/src/test/crypto_tests.cpp b/src/test/crypto_tests.cpp
index 4e2acca4c3..4ac12bf969 100644
--- a/src/test/crypto_tests.cpp
+++ b/src/test/crypto_tests.cpp
@@ -4,6 +4,7 @@
 
 #include <crypto/aes.h>
 #include <crypto/chacha20.h>
+#include <crypto/chacha_poly_aead.h>
 #include <crypto/poly1305.h>
 #include <crypto/hkdf_sha256_32.h>
 #include <crypto/hmac_sha256.h>
@@ -585,6 +586,131 @@ BOOST_AUTO_TEST_CASE(hkdf_hmac_sha256_l32_tests)
                 "8da4e775a563c18f715f802a063c5a31b8a11f5c5ee1879ec3454e5f3c738d2d");
 }
 
+static void TestChaCha20Poly1305AEAD(bool must_succeed, unsigned int expected_aad_length, const std::string& hex_m, const std::string& hex_k1, const std::string& hex_k2, const std::string& hex_aad_keystream, const std::string& hex_encrypted_message, const std::string& hex_encrypted_message_seq_999)
+{
+    // we need two sequence numbers, one for the payload cipher instance...
+    uint32_t seqnr_payload = 0;
+    // ... and one for the AAD (length) cipher instance
+    uint32_t seqnr_aad = 0;
+    // we need to keep track of the position in the AAD cipher instance
+    // keystream since we use the same 64byte output 21 times
+    // (21 times 3 bytes length < 64)
+    int aad_pos = 0;
+
+    std::vector<unsigned char> aead_K_1 = ParseHex(hex_k1);
+    std::vector<unsigned char> aead_K_2 = ParseHex(hex_k2);
+    std::vector<unsigned char> plaintext_buf = ParseHex(hex_m);
+    std::vector<unsigned char> expected_aad_keystream = ParseHex(hex_aad_keystream);
+    std::vector<unsigned char> expected_ciphertext_and_mac = ParseHex(hex_encrypted_message);
+    std::vector<unsigned char> expected_ciphertext_and_mac_sequence999 = ParseHex(hex_encrypted_message_seq_999);
+
+    std::vector<unsigned char> ciphertext_buf(plaintext_buf.size() + POLY1305_TAGLEN, 0);
+    std::vector<unsigned char> plaintext_buf_new(plaintext_buf.size(), 0);
+    std::vector<unsigned char> cmp_ctx_buffer(64);
+    uint32_t out_len = 0;
+
+    // create the AEAD instance
+    ChaCha20Poly1305AEAD aead(aead_K_1.data(), aead_K_1.size(), aead_K_2.data(), aead_K_2.size());
+
+    // create a chacha20 instance to compare against
+    ChaCha20 cmp_ctx(aead_K_2.data(), 32);
+
+    // encipher
+    bool res = aead.Crypt(seqnr_payload, seqnr_aad, aad_pos, ciphertext_buf.data(), ciphertext_buf.size(), plaintext_buf.data(), plaintext_buf.size(), true);
+    // make sure the operation succeeded if expected to succeed
+    BOOST_CHECK_EQUAL(res, must_succeed);
+    if (!res) return;
+
+    // verify ciphertext & mac against the test vector
+    BOOST_CHECK_EQUAL(expected_ciphertext_and_mac.size(), ciphertext_buf.size());
+    BOOST_CHECK(memcmp(ciphertext_buf.data(), expected_ciphertext_and_mac.data(), ciphertext_buf.size()) == 0);
+
+    // manually construct the AAD keystream
+    cmp_ctx.SetIV(seqnr_aad);
+    cmp_ctx.Seek(0);
+    cmp_ctx.Keystream(cmp_ctx_buffer.data(), 64);
+    BOOST_CHECK(memcmp(expected_aad_keystream.data(), cmp_ctx_buffer.data(), expected_aad_keystream.size()) == 0);
+    // crypt the 3 length bytes and compare the length
+    uint32_t len_cmp = 0;
+    len_cmp = (ciphertext_buf[0] ^ cmp_ctx_buffer[aad_pos + 0]) |
+              (ciphertext_buf[1] ^ cmp_ctx_buffer[aad_pos + 1]) << 8 |
+              (ciphertext_buf[2] ^ cmp_ctx_buffer[aad_pos + 2]) << 16;
+    BOOST_CHECK_EQUAL(len_cmp, expected_aad_length);
+
+    // encrypt / decrypt 1000 packets
+    for (size_t i = 0; i < 1000; ++i) {
+        res = aead.Crypt(seqnr_payload, seqnr_aad, aad_pos, ciphertext_buf.data(), ciphertext_buf.size(), plaintext_buf.data(), plaintext_buf.size(), true);
+        BOOST_CHECK(res);
+        BOOST_CHECK(aead.GetLength(&out_len, seqnr_aad, aad_pos, ciphertext_buf.data()));
+        BOOST_CHECK_EQUAL(out_len, expected_aad_length);
+        res = aead.Crypt(seqnr_payload, seqnr_aad, aad_pos, plaintext_buf_new.data(), plaintext_buf_new.size(), ciphertext_buf.data(), ciphertext_buf.size(), false);
+        BOOST_CHECK(res);
+
+        // make sure we repetitive get the same plaintext
+        BOOST_CHECK(memcmp(plaintext_buf.data(), plaintext_buf_new.data(), plaintext_buf.size()) == 0);
+
+        // compare sequence number 999 against the test vector
+        if (seqnr_payload == 999) {
+            BOOST_CHECK(memcmp(ciphertext_buf.data(), expected_ciphertext_and_mac_sequence999.data(), expected_ciphertext_and_mac_sequence999.size()) == 0);
+        }
+        // set nonce and block counter, output the keystream
+        cmp_ctx.SetIV(seqnr_aad);
+        cmp_ctx.Seek(0);
+        cmp_ctx.Keystream(cmp_ctx_buffer.data(), 64);
+
+        // crypt the 3 length bytes and compare the length
+        len_cmp = 0;
+        len_cmp = (ciphertext_buf[0] ^ cmp_ctx_buffer[aad_pos + 0]) |
+                  (ciphertext_buf[1] ^ cmp_ctx_buffer[aad_pos + 1]) << 8 |
+                  (ciphertext_buf[2] ^ cmp_ctx_buffer[aad_pos + 2]) << 16;
+        BOOST_CHECK_EQUAL(len_cmp, expected_aad_length);
+
+        // increment the sequence number(s)
+        // always increment the payload sequence number
+        // increment the AAD keystream position by its size (3)
+        // increment the AAD sequence number if we would hit the 64 byte limit
+        seqnr_payload++;
+        aad_pos += CHACHA20_POLY1305_AEAD_AAD_LEN;
+        if (aad_pos + CHACHA20_POLY1305_AEAD_AAD_LEN > CHACHA20_ROUND_OUTPUT) {
+            aad_pos = 0;
+            seqnr_aad++;
+        }
+    }
+}
+
+BOOST_AUTO_TEST_CASE(chacha20_poly1305_aead_testvector)
+{
+    /* test chacha20poly1305@bitcoin AEAD */
+
+    // must fail with no message
+    TestChaCha20Poly1305AEAD(false, 0,
+        "",
+        "0000000000000000000000000000000000000000000000000000000000000000",
+        "0000000000000000000000000000000000000000000000000000000000000000", "", "", "");
+
+    TestChaCha20Poly1305AEAD(true, 0,
+        /* m  */ "0000000000000000000000000000000000000000000000000000000000000000",
+        /* k1 (payload) */ "0000000000000000000000000000000000000000000000000000000000000000",
+        /* k2 (AAD) */ "0000000000000000000000000000000000000000000000000000000000000000",
+        /* AAD keystream */ "76b8e0ada0f13d90405d6ae55386bd28bdd219b8a08ded1aa836efcc8b770dc7da41597c5157488d7724e03fb8d84a376a43b8f41518a11cc387b669b2ee6586",
+        /* encrypted message & MAC */ "76b8e09f07e7be5551387a98ba977c732d080dcb0f29a048e3656912c6533e32d2fc11829c1b6c1df1f551cd6131ff08",
+        /* encrypted message & MAC at sequence 999 */ "b0a03d5bd2855d60699e7d3a3133fa47be740fe4e4c1f967555e2d9271f31c3aaa7aa16ec62c5e24f040c08bb20c3598");
+    TestChaCha20Poly1305AEAD(true, 1,
+        "0100000000000000000000000000000000000000000000000000000000000000",
+        "0000000000000000000000000000000000000000000000000000000000000000",
+        "0000000000000000000000000000000000000000000000000000000000000000",
+        "76b8e0ada0f13d90405d6ae55386bd28bdd219b8a08ded1aa836efcc8b770dc7da41597c5157488d7724e03fb8d84a376a43b8f41518a11cc387b669b2ee6586",
+        "77b8e09f07e7be5551387a98ba977c732d080dcb0f29a048e3656912c6533e32baf0c85b6dff8602b06cf52a6aefc62e",
+        "b1a03d5bd2855d60699e7d3a3133fa47be740fe4e4c1f967555e2d9271f31c3a8bd94d54b5ecabbc41ffbb0c90924080");
+    TestChaCha20Poly1305AEAD(true, 255,
+        "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",
+        "000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f",
+        "ff0102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f",
+        "c640c1711e3ee904ac35c57ab9791c8a1c408603a90b77a83b54f6c844cb4b06d94e7fc6c800e165acd66147e80ec45a567f6ce66d05ec0cae679dceeb890017",
+        "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",
+        "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");
+}
+
 BOOST_AUTO_TEST_CASE(countbits_tests)
 {
     FastRandomContext ctx;