[Openvpn-devel,v9] Add siphash reference implementation

Message ID 20260312153329.4700-1-gert@greenie.muc.de
State New
Headers show
Series [Openvpn-devel,v9] Add siphash reference implementation | expand

Commit Message

Gert Doering March 12, 2026, 3:33 p.m. UTC
From: Arne Schwabe <arne@rfc2549.org>

OpenSSL only supports SIPHASH with OpenSSL 3.1 and newer. The source code of
siphash is quite small and has very liberal CC0 license, so include it instead
of pulling an extra library for it.

Change-Id: I1292894fe7f537049a97bee97af4419e5e854a00
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: MaxF <max@max-fillinger.net>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/29
---

This change was reviewed on Gerrit and approved by at least one
developer. I request to merge it to master.

Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/29
This mail reflects revision 9 of this Change.

Acked-by according to Gerrit (reflected above):
MaxF <max@max-fillinger.net>

Comments

Gert Doering March 12, 2026, 4:20 p.m. UTC | #1
In itself, this does not actually *do* anything, just adds two files
(and Max has ACKed that "this is right implementation").  A future
commit can then add Makefile handling, compat handling, etc.

Your patch has been applied to the master branch.

commit ea3b48f6758acdd5b9d001139b6237c7f913bb8b
Author: Arne Schwabe
Date:   Thu Mar 12 16:33:23 2026 +0100

     Add siphash reference implementation

     Signed-off-by: Arne Schwabe <arne@rfc2549.org>
     Acked-by: MaxF <max@max-fillinger.net>
     Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/29
     Message-Id: <20260312153329.4700-1-gert@greenie.muc.de>
     URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg36072.html
     Signed-off-by: Gert Doering <gert@greenie.muc.de>


--
kind regards,

Gert Doering

Patch

diff --git a/src/openvpn/siphash.h b/src/openvpn/siphash.h
new file mode 100644
index 0000000..ef61110
--- /dev/null
+++ b/src/openvpn/siphash.h
@@ -0,0 +1,29 @@ 
+/*
+ * SipHash reference C implementation
+ *
+ * Copyright (c) 2012-2021 Jean-Philippe Aumasson
+ * <jeanphilippe.aumasson@gmail.com>
+ * Copyright (c) 2012-2014 Daniel J. Bernstein <djb@cr.yp.to>
+ *
+ * To the extent possible under law, the author(s) have dedicated all copyright
+ * and related and neighboring rights to this software to the public domain
+ * worldwide. This software is distributed without any warranty.
+ *
+ * You should have received a copy of the CC0 Public Domain Dedication along
+ * with
+ * this software. If not, see
+ * <http://creativecommons.org/publicdomain/zero/1.0/>.
+ */
+
+#ifndef SIPHASH_H
+#define SIPHASH_H
+
+#include <inttypes.h>
+
+/* siphash always uses 128-bit keys */
+#define SIPHASH_KEY_SIZE 16
+
+int siphash(const void *in, size_t inlen, const void *k, uint8_t *out,
+            size_t outlen);
+
+#endif
diff --git a/src/openvpn/siphash_reference.c b/src/openvpn/siphash_reference.c
new file mode 100644
index 0000000..b21a86e
--- /dev/null
+++ b/src/openvpn/siphash_reference.c
@@ -0,0 +1,224 @@ 
+/*
+ * SipHash reference C implementation
+ *
+ * Copyright 2012-2024 JP Aumasson
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+/* Note:  the reference implementation is also available under CC0 license
+ * (dual licensed) we included the MIT license here since it is shorter */
+
+#include "siphash.h"
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+
+/* default: SipHash-2-4 */
+#ifndef cROUNDS
+#define cROUNDS 2
+#endif
+#ifndef dROUNDS
+#define dROUNDS 4
+#endif
+
+#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
+
+#define U32TO8_LE(p, v)            \
+    (p)[0] = (uint8_t)((v));       \
+    (p)[1] = (uint8_t)((v) >> 8);  \
+    (p)[2] = (uint8_t)((v) >> 16); \
+    (p)[3] = (uint8_t)((v) >> 24);
+
+#define U64TO8_LE(p, v)              \
+    U32TO8_LE((p), (uint32_t)((v))); \
+    U32TO8_LE((p) + 4, (uint32_t)((v) >> 32));
+
+#define U8TO64_LE(p)                                           \
+    (((uint64_t)((p)[0])) | ((uint64_t)((p)[1]) << 8)          \
+     | ((uint64_t)((p)[2]) << 16) | ((uint64_t)((p)[3]) << 24) \
+     | ((uint64_t)((p)[4]) << 32) | ((uint64_t)((p)[5]) << 40) \
+     | ((uint64_t)((p)[6]) << 48) | ((uint64_t)((p)[7]) << 56))
+
+#define SIPROUND           \
+    do                     \
+    {                      \
+        v0 += v1;          \
+        v1 = ROTL(v1, 13); \
+        v1 ^= v0;          \
+        v0 = ROTL(v0, 32); \
+        v2 += v3;          \
+        v3 = ROTL(v3, 16); \
+        v3 ^= v2;          \
+        v0 += v3;          \
+        v3 = ROTL(v3, 21); \
+        v3 ^= v0;          \
+        v2 += v1;          \
+        v1 = ROTL(v1, 17); \
+        v1 ^= v2;          \
+        v2 = ROTL(v2, 32); \
+    } while (0)
+
+#ifdef DEBUG_SIPHASH
+#include <stdio.h>
+
+#define TRACE                                            \
+    do                                                   \
+    {                                                    \
+        printf("(%3zu) v0 %016" PRIx64 "\n", inlen, v0); \
+        printf("(%3zu) v1 %016" PRIx64 "\n", inlen, v1); \
+        printf("(%3zu) v2 %016" PRIx64 "\n", inlen, v2); \
+        printf("(%3zu) v3 %016" PRIx64 "\n", inlen, v3); \
+    } while (0)
+#else /* ifdef DEBUG_SIPHASH */
+#define TRACE
+#endif
+
+/*
+ *  Computes a SipHash value
+ * in: pointer to input data (read-only)
+ *  inlen: input data length in bytes (any size_t value)
+ * k: pointer to the key data (read-only), must be 16 bytes
+ * out: pointer to output data (write-only), outlen bytes must be allocated
+ *  outlen: length of the output in bytes, must be 8 or 16
+ */
+int
+siphash(const void *in, const size_t inlen, const void *k, uint8_t *out,
+        const size_t outlen)
+{
+    const unsigned char *ni = (const unsigned char *)in;
+    const unsigned char *kk = (const unsigned char *)k;
+
+    assert((outlen == 8) || (outlen == 16));
+    uint64_t v0 = UINT64_C(0x736f6d6570736575);
+    uint64_t v1 = UINT64_C(0x646f72616e646f6d);
+    uint64_t v2 = UINT64_C(0x6c7967656e657261);
+    uint64_t v3 = UINT64_C(0x7465646279746573);
+    uint64_t k0 = U8TO64_LE(kk);
+    uint64_t k1 = U8TO64_LE(kk + 8);
+    uint64_t m;
+    int i;
+    const unsigned char *end = ni + inlen - (inlen % sizeof(uint64_t));
+    const int left = inlen & 7;
+    uint64_t b = ((uint64_t)inlen) << 56;
+    v3 ^= k1;
+    v2 ^= k0;
+    v1 ^= k1;
+    v0 ^= k0;
+
+    if (outlen == 16)
+    {
+        v1 ^= 0xee;
+    }
+
+    for (; ni != end; ni += 8)
+    {
+        m = U8TO64_LE(ni);
+        v3 ^= m;
+
+        TRACE;
+        for (i = 0; i < cROUNDS; ++i)
+        {
+            SIPROUND;
+        }
+
+        v0 ^= m;
+    }
+
+    switch (left)
+    {
+        case 7:
+            b |= ((uint64_t)ni[6]) << 48;
+
+        /* FALLTHRU */
+        case 6:
+            b |= ((uint64_t)ni[5]) << 40;
+
+        /* FALLTHRU */
+        case 5:
+            b |= ((uint64_t)ni[4]) << 32;
+
+        /* FALLTHRU */
+        case 4:
+            b |= ((uint64_t)ni[3]) << 24;
+
+        /* FALLTHRU */
+        case 3:
+            b |= ((uint64_t)ni[2]) << 16;
+
+        /* FALLTHRU */
+        case 2:
+            b |= ((uint64_t)ni[1]) << 8;
+
+        /* FALLTHRU */
+        case 1:
+            b |= ((uint64_t)ni[0]);
+            break;
+
+        case 0:
+            break;
+    }
+
+    v3 ^= b;
+
+    TRACE;
+    for (i = 0; i < cROUNDS; ++i)
+    {
+        SIPROUND;
+    }
+
+    v0 ^= b;
+
+    if (outlen == 16)
+    {
+        v2 ^= 0xee;
+    }
+    else
+    {
+        v2 ^= 0xff;
+    }
+
+    TRACE;
+    for (i = 0; i < dROUNDS; ++i)
+    {
+        SIPROUND;
+    }
+
+    b = v0 ^ v1 ^ v2 ^ v3;
+    U64TO8_LE(out, b);
+
+    if (outlen == 8)
+    {
+        return 0;
+    }
+
+    v1 ^= 0xdd;
+
+    TRACE;
+    for (i = 0; i < dROUNDS; ++i)
+    {
+        SIPROUND;
+    }
+
+    b = v0 ^ v1 ^ v2 ^ v3;
+    U64TO8_LE(out + 8, b);
+
+    return 0;
+}