Add support for HMAC-SHA512.

I saw a post on comp.security.ssh just now where someone had
encountered an SSH server that would _only_ speak that, which makes it
worth bothering to implement.

The totally obvious implementation works, and passes the test cases
from RFC 6234.

(cherry picked from commit b77e985513)

crypto/hmac.c

@@ -160,6 +160,22 @@ static const char *hmac_text_name(ssh2_mac *mac)
     return ctx->text_name->s;
 }
 
+static const struct hmac_extra ssh_hmac_sha512_extra = { &ssh_sha512, "" };
+const ssh2_macalg ssh_hmac_sha512 = {
+    .new = hmac_new,
+    .free = hmac_free,
+    .setkey = hmac_key,
+    .start = hmac_start,
+    .genresult = hmac_genresult,
+    .next_message = nullmac_next_message,
+    .text_name = hmac_text_name,
+    .name = "hmac-sha2-512",
+    .etm_name = "hmac-sha2-512-etm@openssh.com",
+    .len = 64,
+    .keylen = 64,
+    .extra = &ssh_hmac_sha512_extra,
+};
+
 static const struct hmac_extra ssh_hmac_sha256_extra = { &ssh_sha256, "" };
 const ssh2_macalg ssh_hmac_sha256 = {
     .new = hmac_new,

ssh.h

@@ -1205,6 +1205,7 @@ extern const ssh2_macalg ssh_hmac_sha1_buggy;
 extern const ssh2_macalg ssh_hmac_sha1_96;
 extern const ssh2_macalg ssh_hmac_sha1_96_buggy;
 extern const ssh2_macalg ssh_hmac_sha256;
+extern const ssh2_macalg ssh_hmac_sha512;
 extern const ssh2_macalg ssh2_poly1305;
 extern const ssh2_macalg ssh2_aesgcm_mac;
 extern const ssh2_macalg ssh2_aesgcm_mac_sw;

ssh/transport2.c

@@ -20,7 +20,8 @@ const struct ssh_signkey_with_user_pref_id ssh2_hostkey_algs[] = {
 };
 
 const static ssh2_macalg *const macs[] = {
-    &ssh_hmac_sha256, &ssh_hmac_sha1, &ssh_hmac_sha1_96, &ssh_hmac_md5
+    &ssh_hmac_sha512, &ssh_hmac_sha256,
+    &ssh_hmac_sha1, &ssh_hmac_sha1_96, &ssh_hmac_md5
 };
 const static ssh2_macalg *const buggymacs[] = {
     &ssh_hmac_sha1_buggy, &ssh_hmac_sha1_96_buggy, &ssh_hmac_md5

test/cryptsuite.py

@@ -3579,30 +3579,41 @@ class standard_test_vectors(MyTestBase):
 
     def testHmacSHA(self):
         # Test cases from RFC 6234 section 8.5.
-        def vector(key, message, s1=None, s256=None):
+        def vector(key, message, s1=None, s256=None, s512=None):
             if s1 is not None:
                 self.assertEqualBin(
                     mac_str('hmac_sha1', key, message), unhex(s1))
             if s256 is not None:
                 self.assertEqualBin(
                     mac_str('hmac_sha256', key, message), unhex(s256))
+            if s512 is not None:
+                self.assertEqualBin(
+                    mac_str('hmac_sha512', key, message), unhex(s512))
         vector(
             unhex("0b"*20), "Hi There",
             "b617318655057264e28bc0b6fb378c8ef146be00",
-            "b0344c61d8db38535ca8afceaf0bf12b881dc200c9833da726e9376c2e32cff7")
+            "b0344c61d8db38535ca8afceaf0bf12b881dc200c9833da726e9376c2e32cff7",
+            "87aa7cdea5ef619d4ff0b4241a1d6cb02379f4e2ce4ec2787ad0b30545e17cde"
+            "daa833b7d6b8a702038b274eaea3f4e4be9d914eeb61f1702e696c203a126854")
         vector(
             "Jefe", "what do ya want for nothing?",
             "effcdf6ae5eb2fa2d27416d5f184df9c259a7c79",
-            "5bdcc146bf60754e6a042426089575c75a003f089d2739839dec58b964ec3843")
+            "5bdcc146bf60754e6a042426089575c75a003f089d2739839dec58b964ec3843",
+            "164b7a7bfcf819e2e395fbe73b56e0a387bd64222e831fd610270cd7ea250554"
+            "9758bf75c05a994a6d034f65f8f0e6fdcaeab1a34d4a6b4b636e070a38bce737")
         vector(
             unhex("aa"*20), unhex('dd'*50),
             "125d7342b9ac11cd91a39af48aa17b4f63f175d3",
-            "773ea91e36800e46854db8ebd09181a72959098b3ef8c122d9635514ced565FE")
+            "773ea91e36800e46854db8ebd09181a72959098b3ef8c122d9635514ced565FE",
+            "fa73b0089d56a284efb0f0756c890be9b1b5dbdd8ee81a3655f83e33b2279d39"
+            "bf3e848279a722c806b485a47e67c807b946a337bee8942674278859e13292fb")
         vector(
             unhex("0102030405060708090a0b0c0d0e0f10111213141516171819"),
             unhex("cd"*50),
             "4c9007f4026250c6bc8414f9bf50c86c2d7235da",
-            "82558a389a443c0ea4cc819899f2083a85f0faa3e578f8077a2e3ff46729665b")
+            "82558a389a443c0ea4cc819899f2083a85f0faa3e578f8077a2e3ff46729665b",
+            "b0ba465637458c6990e5a8c5f61d4af7e576d97ff94b872de76f8050361ee3db"
+            "a91ca5c11aa25eb4d679275cc5788063a5f19741120c4f2de2adebeb10a298dd")
         vector(
             unhex("aa"*80),
             "Test Using Larger Than Block-Size Key - Hash Key First",
@@ -3611,7 +3622,9 @@ class standard_test_vectors(MyTestBase):
             unhex("aa"*131),
             "Test Using Larger Than Block-Size Key - Hash Key First",
             s256="60e431591ee0b67f0d8a26aacbf5b77f"
-            "8e0bc6213728c5140546040f0ee37f54")
+            "8e0bc6213728c5140546040f0ee37f54", s512=
+            "80b24263c7c1a3ebb71493c1dd7be8b49b46d1f41b4aeec1121b013783f8f352"
+            "6b56d037e05f2598bd0fd2215d6a1e5295e64f73f63f0aec8b915a985d786598")
         vector(
             unhex("aa"*80),
             "Test Using Larger Than Block-Size Key and "
@@ -3622,7 +3635,10 @@ class standard_test_vectors(MyTestBase):
             "This is a test using a larger than block-size key and a "
             "larger than block-size data. The key needs to be hashed "
             "before being used by the HMAC algorithm.",
-            s256="9B09FFA71B942FCB27635FBCD5B0E944BFDC63644F0713938A7F51535C3A35E2")
+            s256="9b09ffa71b942fcb27635fbcd5b0e944"
+            "bfdc63644f0713938a7f51535c3a35e2", s512=
+            "e37b6a775dc87dbaa4dfa9f96e5e3ffddebd71f8867289865df5a32d20cdc944"
+            "b6022cac3c4982b10d5eeb55c3e4de15134676fb6de0446065c97440fa8c6a58")
 
     def testEd25519(self):
         def vector(privkey, pubkey, message, signature):

test/testcrypt-enum.h

@@ -35,6 +35,7 @@ BEGIN_ENUM_TYPE(macalg)
     ENUM_VALUE("hmac_sha1_96", &ssh_hmac_sha1_96)
     ENUM_VALUE("hmac_sha1_96_buggy", &ssh_hmac_sha1_96_buggy)
     ENUM_VALUE("hmac_sha256", &ssh_hmac_sha256)
+    ENUM_VALUE("hmac_sha512", &ssh_hmac_sha512)
     ENUM_VALUE("poly1305", &ssh2_poly1305)
     ENUM_VALUE("aesgcm", &ssh2_aesgcm_mac)
     ENUM_VALUE("aesgcm", &ssh2_aesgcm_mac)

test/testsc.c

@@ -339,6 +339,7 @@ VOLATILE_WRAPPED_DEFN(static, size_t, looplimit, (size_t x))
     X(Y, ssh_hmac_sha1_96)                      \
     X(Y, ssh_hmac_sha1_96_buggy)                \
     X(Y, ssh_hmac_sha256)                       \
+    X(Y, ssh_hmac_sha512)                       \
     /* end of list */
 
 #define ALL_MACS(X, Y)                                      \