Add ChaCha20 bench

src/Makefile.bench.include

@@ -21,6 +21,7 @@ bench_bench_bitcoin_SOURCES = \
   bench/duplicate_inputs.cpp \
   bench/examples.cpp \
   bench/rollingbloom.cpp \
+  bench/chacha20.cpp \
   bench/crypto_hash.cpp \
   bench/ccoins_caching.cpp \
   bench/gcs_filter.cpp \

src/bench/chacha20.cpp

@@ -0,0 +1,46 @@
+// 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 <hash.h>
+#include <crypto/chacha20.h>
+
+/* Number of bytes to process per iteration */
+static const uint64_t BUFFER_SIZE_TINY  = 64;
+static const uint64_t BUFFER_SIZE_SMALL = 256;
+static const uint64_t BUFFER_SIZE_LARGE = 1024*1024;
+
+static void CHACHA20(benchmark::State& state, size_t buffersize)
+{
+    std::vector<uint8_t> key(32,0);
+    ChaCha20 ctx(key.data(), key.size());
+    ctx.SetIV(0);
+    ctx.Seek(0);
+    std::vector<uint8_t> in(buffersize,0);
+    std::vector<uint8_t> out(buffersize,0);
+    while (state.KeepRunning()) {
+        ctx.Crypt(in.data(), out.data(), in.size());
+    }
+}
+
+static void CHACHA20_64BYTES(benchmark::State& state)
+{
+    CHACHA20(state, BUFFER_SIZE_TINY);
+}
+
+static void CHACHA20_256BYTES(benchmark::State& state)
+{
+    CHACHA20(state, BUFFER_SIZE_SMALL);
+}
+
+static void CHACHA20_1MB(benchmark::State& state)
+{
+    CHACHA20(state, BUFFER_SIZE_LARGE);
+}
+
+BENCHMARK(CHACHA20_64BYTES, 500000);
+BENCHMARK(CHACHA20_256BYTES, 250000);
+BENCHMARK(CHACHA20_1MB, 340);