Add support for parameterized SipHash

The core SipHash supports either 8 or 16-byte output and a configurable
number of rounds.
The default behavior, as added to EVP, is to use 16-byte output and
2,4 rounds, which matches the behavior of most implementations.
There is an EVP_PKEY_CTRL that can control the output size.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2216)

1 files changed, 68 insertions, 0 deletions

diff --git a/crypto/siphash/siphash_ameth.c b/crypto/siphash/siphash_ameth.c
new file mode 100644
index 0000000000..d819461f8d
--- /dev/null
+++ b/crypto/siphash/siphash_ameth.c
@@ -0,0 +1,68 @@
+/*
+ * Copyright 2007-2017 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <stdio.h>
+#include "internal/cryptlib.h"
+#include <openssl/evp.h>
+#include "internal/asn1_int.h"
+#include "internal/siphash.h"
+#include "siphash_local.h"
+
+/*
+ * SIPHASH "ASN1" method. This is just here to indicate the maximum
+ * SIPHASH output length and to free up a SIPHASH key.
+ */
+
+static int siphash_size(const EVP_PKEY *pkey)
+{
+    return SIPHASH_MAX_DIGEST_SIZE;
+}
+
+static void siphash_key_free(EVP_PKEY *pkey)
+{
+    ASN1_OCTET_STRING *os = EVP_PKEY_get0(pkey);
+
+    if (os != NULL) {
+        if (os->data != NULL)
+            OPENSSL_cleanse(os->data, os->length);
+        ASN1_OCTET_STRING_free(os);
+    }
+}
+
+static int siphash_pkey_ctrl(EVP_PKEY *pkey, int op, long arg1, void *arg2)
+{
+    /* nothing (including ASN1_PKEY_CTRL_DEFAULT_MD_NID), is supported */
+    return -2;
+}
+
+static int siphash_pkey_public_cmp(const EVP_PKEY *a, const EVP_PKEY *b)
+{
+    return ASN1_OCTET_STRING_cmp(EVP_PKEY_get0(a), EVP_PKEY_get0(b));
+}
+
+const EVP_PKEY_ASN1_METHOD siphash_asn1_meth = {
+    EVP_PKEY_SIPHASH,
+    EVP_PKEY_SIPHASH,
+    0,
+
+    "SIPHASH",
+    "OpenSSL SIPHASH method",
+
+    0, 0, siphash_pkey_public_cmp, 0,
+
+    0, 0, 0,
+
+    siphash_size,
+    0, 0,
+    0, 0, 0, 0, 0, 0, 0,
+
+    siphash_key_free,
+    siphash_pkey_ctrl,
+    0, 0
+};