diff --git a/src/crypto/siphash/siphash.c b/src/crypto/siphash/siphash.c
new file mode 100644
index 0000000..7e4e9c5
--- /dev/null
+++ b/src/crypto/siphash/siphash.c
@@ -0,0 +1,80 @@
+/* Copyright (c) 2019, Google Inc.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
+
+#include <stdint.h>
+#include <string.h>
+
+#include <openssl/siphash.h>
+
+
+static void siphash_round(uint64_t v[4]) {
+  v[0] += v[1];
+  v[2] += v[3];
+  v[1] = (v[1] << 13) | (v[1] >> (64 - 13));
+  v[3] = (v[3] << 16) | (v[3] >> (64 - 16));
+  v[1] ^= v[0];
+  v[3] ^= v[2];
+  v[0] = (v[0] << 32) | (v[0] >> 32);
+  v[2] += v[1];
+  v[0] += v[3];
+  v[1] = (v[1] << 17) | (v[1] >> (64 - 17));
+  v[3] = (v[3] << 21) | (v[3] >> (64 - 21));
+  v[1] ^= v[2];
+  v[3] ^= v[0];
+  v[2] = (v[2] << 32) | (v[2] >> 32);
+}
+
+uint64_t SIPHASH_24(const uint64_t key[2], const uint8_t *input,
+                    size_t input_len) {
+  const size_t orig_input_len = input_len;
+
+  uint64_t v[4];
+  v[0] = key[0] ^ UINT64_C(0x736f6d6570736575);
+  v[1] = key[1] ^ UINT64_C(0x646f72616e646f6d);
+  v[2] = key[0] ^ UINT64_C(0x6c7967656e657261);
+  v[3] = key[1] ^ UINT64_C(0x7465646279746573);
+
+  while (input_len >= sizeof(uint64_t)) {
+    uint64_t m;
+    memcpy(&m, input, sizeof(m));
+    v[3] ^= m;
+    siphash_round(v);
+    siphash_round(v);
+    v[0] ^= m;
+
+    input += sizeof(uint64_t);
+    input_len -= sizeof(uint64_t);
+  }
+
+  union {
+    uint8_t bytes[8];
+    uint64_t word;
+  } last_block;
+  last_block.word = 0;
+  memcpy(last_block.bytes, input, input_len);
+  last_block.bytes[7] = orig_input_len & 0xff;
+
+  v[3] ^= last_block.word;
+  siphash_round(v);
+  siphash_round(v);
+  v[0] ^= last_block.word;
+
+  v[2] ^= 0xff;
+  siphash_round(v);
+  siphash_round(v);
+  siphash_round(v);
+  siphash_round(v);
+
+  return v[0] ^ v[1] ^ v[2] ^ v[3];
+}