Implement keccak-f[1600] and SHA3-256

1 files changed, 128 insertions, 0 deletions

diff --git a/src/crypto/sha3.cpp b/src/crypto/sha3.cpp
new file mode 100644
index 0000000000..5f9ce45146
--- /dev/null
+++ b/src/crypto/sha3.cpp
@@ -0,0 +1,128 @@
+// Copyright (c) 2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+// Based on https://github.com/mjosaarinen/tiny_sha3/blob/master/sha3.c
+// by Markku-Juhani O. Saarinen <mjos@iki.fi>
+
+#include <crypto/sha3.h>
+#include <crypto/common.h>
+#include <span.h>
+
+#include <algorithm>
+#include <array> // For std::begin and std::end.
+
+#include <stdint.h>
+
+// Internal implementation code.
+namespace
+{
+uint64_t Rotl(uint64_t x, int n) { return (x << n) | (x >> (64 - n)); }
+} // namespace
+
+void KeccakF(uint64_t (&st)[25])
+{
+    static constexpr uint64_t RNDC[24] = {
+        0x0000000000000001, 0x0000000000008082, 0x800000000000808a, 0x8000000080008000,
+        0x000000000000808b, 0x0000000080000001, 0x8000000080008081, 0x8000000000008009,
+        0x000000000000008a, 0x0000000000000088, 0x0000000080008009, 0x000000008000000a,
+        0x000000008000808b, 0x800000000000008b, 0x8000000000008089, 0x8000000000008003,
+        0x8000000000008002, 0x8000000000000080, 0x000000000000800a, 0x800000008000000a,
+        0x8000000080008081, 0x8000000000008080, 0x0000000080000001, 0x8000000080008008
+    };
+    static constexpr int ROTC[24] = {
+        1,  3,  6,  10, 15, 21, 28, 36, 45, 55, 2,  14,
+        27, 41, 56, 8,  25, 43, 62, 18, 39, 61, 20, 44
+    };
+    static constexpr int PILN[24] = {
+        10, 7,  11, 17, 18, 3, 5,  16, 8,  21, 24, 4,
+        15, 23, 19, 13, 12, 2, 20, 14, 22, 9,  6,  1
+    };
+    static constexpr int ROUNDS = 24;
+
+    for (int round = 0; round < ROUNDS; ++round) {
+        uint64_t bc[5], t;
+
+        // Theta
+        for (int i = 0; i < 5; i++) {
+            bc[i] = st[i] ^ st[i + 5] ^ st[i + 10] ^ st[i + 15] ^ st[i + 20];
+        }
+
+        for (int i = 0; i < 5; i++) {
+            t = bc[(i + 4) % 5] ^ Rotl(bc[(i + 1) % 5], 1);
+            for (int j = 0; j < 25; j += 5) st[j + i] ^= t;
+        }
+
+        // Rho Pi
+        t = st[1];
+        for (int i = 0; i < 24; i++) {
+            int j = PILN[i];
+            bc[0] = st[j];
+            st[j] = Rotl(t, ROTC[i]);
+            t = bc[0];
+        }
+
+        // Chi
+        for (int j = 0; j < 25; j += 5) {
+            for (int i = 0; i < 5; i++) bc[i] = st[j + i];
+            for (int i = 0; i < 5; i++) {
+                st[j + i] ^= (~bc[(i + 1) % 5]) & bc[(i + 2) % 5];
+            }
+        }
+
+        //  Iota
+        st[0] ^= RNDC[round];
+    }
+}
+
+SHA3_256& SHA3_256::Write(Span<const unsigned char> data)
+{
+    if (m_bufsize && m_bufsize + data.size() >= sizeof(m_buffer)) {
+        // Fill the buffer and process it.
+        std::copy(data.begin(), data.begin() + sizeof(m_buffer) - m_bufsize, m_buffer + m_bufsize);
+        data = data.subspan(sizeof(m_buffer) - m_bufsize);
+        m_state[m_pos++] ^= ReadLE64(m_buffer);
+        m_bufsize = 0;
+        if (m_pos == RATE_BUFFERS) {
+            KeccakF(m_state);
+            m_pos = 0;
+        }
+    }
+    while (data.size() >= sizeof(m_buffer)) {
+        // Process chunks directly from the buffer.
+        m_state[m_pos++] ^= ReadLE64(data.data());
+        data = data.subspan(8);
+        if (m_pos == RATE_BUFFERS) {
+            KeccakF(m_state);
+            m_pos = 0;
+        }
+    }
+    if (data.size()) {
+        // Keep the remainder in the buffer.
+        std::copy(data.begin(), data.end(), m_buffer + m_bufsize);
+        m_bufsize += data.size();
+    }
+    return *this;
+}
+
+SHA3_256& SHA3_256::Finalize(Span<unsigned char> output)
+{
+    assert(output.size() == OUTPUT_SIZE);
+    std::fill(m_buffer + m_bufsize, m_buffer + sizeof(m_buffer), 0);
+    m_buffer[m_bufsize] ^= 0x06;
+    m_state[m_pos] ^= ReadLE64(m_buffer);
+    m_state[RATE_BUFFERS - 1] ^= 0x8000000000000000;
+    KeccakF(m_state);
+    for (unsigned i = 0; i < 4; ++i) {
+        WriteLE64(output.data() + 8 * i, m_state[i]);
+    }
+    return *this;
+}
+
+SHA3_256& SHA3_256::Reset()
+{
+    m_bufsize = 0;
+    m_pos = 0;
+    std::fill(std::begin(m_state), std::end(m_state), 0);
+    return *this;
+}