Implement ED448 and ED25519 support in xkey_provider

OpenSSL's implementation of ED448 and ED25519 has a few idiosyncrasies.
Instead of belonging to the elliptic curve type or to a common Edwards
curve type, ED448 and ED25519 have each their own type.

Also, OpenSSL expects signatures using these curves to be done with the
EVP_DigestSign API instead of the EVP_Sign API but using md=NULL.

This has been tested using a "fake" external key that used a normal
software key instead of a hardware implementation but that makes no
difference from the perspective of xkey_provider/management interface.

Patch v2: remove name functions from ed448/ed25519, ensure md is NULL
          for ed448/ed25519 and handle NULL/none better in general.
Patch v3: do not pass NULL as string for the OSSL params.

Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Selva Nair <selva.nair@gmail.com>
Message-Id: <20220516104807.2568937-1-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg24363.html

Signed-off-by: Gert Doering <gert@greenie.muc.de>

diff --git a/src/openvpn/xkey_common.h b/src/openvpn/xkey_common.h
index 35cbcf57608207a12d3d95cbef7a0f0dbdab36d8..e0e5ed5b2962810cdc657c0a2f8a3ba65ec7ad75 100644 (file)
--- a/src/openvpn/xkey_common.h
+++ b/src/openvpn/xkey_common.h
@@ -43,7 +43,7 @@ OSSL_provider_init_fn xkey_provider_init;
 #define XKEY_PROV_PROPS "provider=ovpn.xkey"
 
 /**
- * Stuct to encapsulate signature algorithm parameters to pass
+ * Struct to encapsulate signature algorithm parameters to pass
  * to sign operation.
  */
 typedef struct {

diff --git a/src/openvpn/xkey_helper.c b/src/openvpn/xkey_helper.c
index 898ea8a6370a90362a737b363d76985cad24636d..287f9df8b7b66cbe5155aa1df9c9d65b3618ccbf 100644 (file)
--- a/src/openvpn/xkey_helper.c
+++ b/src/openvpn/xkey_helper.c
@@ -179,7 +179,8 @@ xkey_management_sign(void *unused, unsigned char *sig, size_t *siglen,
     bool is_message = !strcmp(alg.op, "DigestSign"); /* tbs is message, not digest */
 
     /* if management client cannot do digest -- we do it here */
-    if (!strcmp(alg.op, "DigestSign") && !(flags & MF_EXTERNAL_KEY_DIGEST))
+    if (!strcmp(alg.op, "DigestSign") && !(flags & MF_EXTERNAL_KEY_DIGEST)
+        && strcmp(alg.mdname, "none"))
     {
         dmsg(D_XKEY, "xkey_management_sign: computing digest");
         if (xkey_digest(tbs, tbslen, buf, &buflen, alg.mdname))
@@ -206,6 +207,10 @@ xkey_management_sign(void *unused, unsigned char *sig, size_t *siglen,
             openvpn_snprintf(alg_str, sizeof(alg_str), "ECDSA,hashalg=%s", alg.mdname);
         }
     }
+    else if (!strcmp(alg.keytype, "ED448") || !strcmp(alg.keytype, "ED25519"))
+    {
+        strncpynt(alg_str, alg.keytype, sizeof(alg_str));
+    }
     /* else assume RSA key */
     else if (!strcmp(alg.padmode, "pkcs1") && (flags & MF_EXTERNAL_KEY_PKCS1PAD))
     {

diff --git a/src/openvpn/xkey_provider.c b/src/openvpn/xkey_provider.c
index a9f16d7cbef8d57bcdb1c190508afebde8f04f7c..c6965718a14901b665dc44ec63f7f57319b9d5e8 100644 (file)
--- a/src/openvpn/xkey_provider.c
+++ b/src/openvpn/xkey_provider.c
@@ -99,12 +99,28 @@ typedef struct
     int refcount;                /**< reference count */
 } XKEY_KEYDATA;
 
-static int
-KEYTYPE(const XKEY_KEYDATA *key)
+static inline const char *
+get_keytype(const XKEY_KEYDATA *key)
 {
-    return key->pubkey ? EVP_PKEY_get_id(key->pubkey) : 0;
+    int keytype = key->pubkey ? EVP_PKEY_get_id(key->pubkey) : 0;
+
+    switch (keytype)
+    {
+        case EVP_PKEY_RSA:
+            return "RSA";
+
+        case EVP_PKEY_ED448:
+            return "ED448";
+
+        case EVP_PKEY_ED25519:
+            return "ED25519";
+
+        default:
+            return "EC";
+    }
 }
 
+
 static int
 KEYSIZE(const XKEY_KEYDATA *key)
 {
@@ -310,6 +326,22 @@ ec_keymgmt_import(void *keydata, int selection, const OSSL_PARAM params[])
     return keymgmt_import(keydata, selection, params, "EC");
 }
 
+static int
+ed448_keymgmt_import(void *keydata, int selection, const OSSL_PARAM params[])
+{
+    xkey_dmsg(D_XKEY, "entry");
+
+    return keymgmt_import(keydata, selection, params, "ED448");
+}
+
+static int
+ed25519_keymgmt_import(void *keydata, int selection, const OSSL_PARAM params[])
+{
+    xkey_dmsg(D_XKEY, "entry");
+
+    return keymgmt_import(keydata, selection, params, "ED25519");
+}
+
 /* This function has to exist for key import to work
  * though we do not support import of individual params
  * like n or e. We simply return an empty list here for
@@ -449,7 +481,7 @@ keymgmt_import_helper(XKEY_KEYDATA *key, const OSSL_PARAM *params)
         ASSERT(pkey);
 
         int id = EVP_PKEY_get_id(pkey);
-        if (id != EVP_PKEY_RSA && id != EVP_PKEY_EC)
+        if (id != EVP_PKEY_RSA && id != EVP_PKEY_EC && id != EVP_PKEY_ED25519 && id != EVP_PKEY_ED448)
         {
             msg(M_WARN, "Error: xkey keymgmt_import: unknown key type (%d)", id);
             return 0;
@@ -588,10 +620,43 @@ static const OSSL_DISPATCH ec_keymgmt_functions[] = {
     {0, NULL }
 };
 
+static const OSSL_DISPATCH ed448_keymgmt_functions[] = {
+    {OSSL_FUNC_KEYMGMT_NEW, (void (*)(void))keymgmt_new},
+    {OSSL_FUNC_KEYMGMT_FREE, (void (*)(void))keymgmt_free},
+    {OSSL_FUNC_KEYMGMT_LOAD, (void (*)(void))keymgmt_load},
+    {OSSL_FUNC_KEYMGMT_HAS, (void (*)(void))keymgmt_has},
+    {OSSL_FUNC_KEYMGMT_MATCH, (void (*)(void))keymgmt_match},
+    {OSSL_FUNC_KEYMGMT_IMPORT, (void (*)(void))ed448_keymgmt_import},
+    {OSSL_FUNC_KEYMGMT_IMPORT_TYPES, (void (*)(void))keymgmt_import_types},
+    {OSSL_FUNC_KEYMGMT_GETTABLE_PARAMS, (void (*)(void))keymgmt_gettable_params},
+    {OSSL_FUNC_KEYMGMT_GET_PARAMS, (void (*)(void))keymgmt_get_params},
+    {OSSL_FUNC_KEYMGMT_SET_PARAMS, (void (*)(void))keymgmt_set_params},
+    {OSSL_FUNC_KEYMGMT_SETTABLE_PARAMS, (void (*)(void))keymgmt_gettable_params},       /* same as gettable */
+    {0, NULL }
+};
+
+static const OSSL_DISPATCH ed25519_keymgmt_functions[] = {
+    {OSSL_FUNC_KEYMGMT_NEW, (void (*)(void))keymgmt_new},
+    {OSSL_FUNC_KEYMGMT_FREE, (void (*)(void))keymgmt_free},
+    {OSSL_FUNC_KEYMGMT_LOAD, (void (*)(void))keymgmt_load},
+    {OSSL_FUNC_KEYMGMT_HAS, (void (*)(void))keymgmt_has},
+    {OSSL_FUNC_KEYMGMT_MATCH, (void (*)(void))keymgmt_match},
+    {OSSL_FUNC_KEYMGMT_IMPORT, (void (*)(void))ed25519_keymgmt_import},
+    {OSSL_FUNC_KEYMGMT_IMPORT_TYPES, (void (*)(void))keymgmt_import_types},
+    {OSSL_FUNC_KEYMGMT_GETTABLE_PARAMS, (void (*)(void))keymgmt_gettable_params},
+    {OSSL_FUNC_KEYMGMT_GET_PARAMS, (void (*)(void))keymgmt_get_params},
+    {OSSL_FUNC_KEYMGMT_SET_PARAMS, (void (*)(void))keymgmt_set_params},
+    {OSSL_FUNC_KEYMGMT_SETTABLE_PARAMS, (void (*)(void))keymgmt_gettable_params},       /* same as gettable */
+    {0, NULL }
+};
+
+
 const OSSL_ALGORITHM keymgmts[] = {
     {"RSA:rsaEncryption", XKEY_PROV_PROPS, rsa_keymgmt_functions, "OpenVPN xkey RSA Key Manager"},
     {"RSA-PSS:RSASSA-PSS", XKEY_PROV_PROPS, rsa_keymgmt_functions, "OpenVPN xkey RSA-PSS Key Manager"},
     {"EC:id-ecPublicKey", XKEY_PROV_PROPS, ec_keymgmt_functions, "OpenVPN xkey EC Key Manager"},
+    {"ED448", XKEY_PROV_PROPS, ed448_keymgmt_functions, "OpenVPN xkey ED448 Key Manager"},
+    {"ED25519", XKEY_PROV_PROPS, ed25519_keymgmt_functions, "OpenVPN xkey ED25519 Key Manager"},
     {NULL, NULL, NULL, NULL}
 };
 
@@ -649,6 +714,11 @@ static const char *saltlen_names[] = {"digest", "max", "auto", NULL};
 static const char *
 xkey_mdname(const char *name)
 {
+    if (name == NULL)
+    {
+        return "none";
+    }
+
     int i = 0;
 
     int nid = EVP_MD_get_type(EVP_get_digestbyname(name));
@@ -835,7 +905,7 @@ signature_sign_init(void *ctx, void *provkey, const OSSL_PARAM params[])
     }
     sctx->keydata = provkey;
     sctx->keydata->refcount++; /* we are keeping a copy */
-    sctx->sigalg.keytype = KEYTYPE(sctx->keydata) == EVP_PKEY_RSA ? "RSA" : "EC";
+    sctx->sigalg.keytype = get_keytype(sctx->keydata);
 
     signature_set_ctx_params(sctx, params);
 
@@ -929,10 +999,21 @@ signature_digest_sign_init(void *ctx, const char *mdname,
     }
     sctx->keydata = provkey; /* used by digest_sign */
     sctx->keydata->refcount++;
-    sctx->sigalg.keytype = KEYTYPE(sctx->keydata) == EVP_PKEY_RSA ? "RSA" : "EC";
+    sctx->sigalg.keytype = get_keytype(sctx->keydata);
 
     signature_set_ctx_params(ctx, params);
-    if (mdname)
+    if (!strcmp(sctx->sigalg.keytype, "ED448") || !strcmp(sctx->sigalg.keytype, "ED25519"))
+    {
+        /* EdDSA requires NULL as digest for the DigestSign API instead
+         * of using the normal Sign API. Ensure it is actually NULL too */
+        if (mdname != NULL)
+        {
+            msg(M_WARN, "xkey digest_sign_init: mdname must be NULL for ED448/ED25519.");
+            return 0;
+        }
+        sctx->sigalg.mdname = "none";
+    }
+    else if (mdname)
     {
         sctx->sigalg.mdname = xkey_mdname(mdname); /* get a string literal pointer */
     }
@@ -1073,6 +1154,8 @@ static const OSSL_DISPATCH signature_functions[] = {
 const OSSL_ALGORITHM signatures[] = {
     {"RSA:rsaEncryption", XKEY_PROV_PROPS, signature_functions, "OpenVPN xkey RSA Signature"},
     {"ECDSA", XKEY_PROV_PROPS, signature_functions, "OpenVPN xkey ECDSA Signature"},
+    {"ED448", XKEY_PROV_PROPS, signature_functions, "OpenVPN xkey Ed448 Signature"},
+    {"ED25519", XKEY_PROV_PROPS, signature_functions, "OpenVPN xkey Ed25519 Signature"},
     {NULL, NULL, NULL, NULL}
 };
 

diff --git a/tests/unit_tests/openvpn/test_provider.c b/tests/unit_tests/openvpn/test_provider.c
index dc39534ecf242efd659b9d0733fdc51d5cdf78fb..47e7e395f6d943838a5e6578b14fc33ee2e7da8d 100644 (file)
--- a/tests/unit_tests/openvpn/test_provider.c
+++ b/tests/unit_tests/openvpn/test_provider.c
@@ -66,7 +66,11 @@ static const char *const pubkey2 = "-----BEGIN PUBLIC KEY-----\n"
                                    "u95ff1JiUaJIkYNIkZA+hwIPFVH5aJcSCv3SPIeDS2VUAESNKHZJBQ==\n"
                                    "-----END PUBLIC KEY-----\n";
 
-static const char *pubkeys[] = {pubkey1, pubkey2};
+static const char *const pubkey3 = "-----BEGIN PUBLIC KEY-----\n"
+                                   "MCowBQYDK2VwAyEA+q5xjF5hGyyqYZidJdz/0saEQabL3N4wIZJBxNGbgJE=\n"
+                                   "-----END PUBLIC KEY-----";
+
+static const char *pubkeys[] = {pubkey1, pubkey2, pubkey3};
 
 static const char *prov_name = "ovpn.xkey";
 
@@ -158,12 +162,17 @@ management_query_pk_sig(struct management *man, const char *b64_data,
     if (strstr(algorithm, "data=message"))
     {
         expected_tbs = test_msg_b64;
-        assert_non_null(strstr(algorithm, "hashalg=SHA256"));
+        /* ED25519 does not have a hash algorithm even though it goes via
+         * the DigestSign path (data=message) */
+        if (!strstr(algorithm, "ED25519"))
+        {
+            assert_non_null(strstr(algorithm, "hashalg=SHA256"));
+        }
     }
     assert_string_equal(b64_data, expected_tbs);
 
-    /* We test using ECDSA or PSS with saltlen = digest */
-    if (!strstr(algorithm, "ECDSA"))
+    /* We test using ED25519, ECDSA or PSS with saltlen = digest */
+    if (!strstr(algorithm, "ECDSA") && !strstr(algorithm, "ED25519"))
     {
         assert_non_null(strstr(algorithm, "RSA_PKCS1_PSS_PADDING,hashalg=SHA256,saltlen=digest"));
     }
@@ -228,6 +237,12 @@ digest_sign(EVP_PKEY *pkey)
         params[3] = OSSL_PARAM_construct_utf8_string(OSSL_SIGNATURE_PARAM_MGF1_DIGEST, (char *)saltlen, 0);
         params[4] = OSSL_PARAM_construct_end();
     }
+    else if (EVP_PKEY_get_id(pkey) == EVP_PKEY_ED25519)
+    {
+        mdname = NULL;
+        params[0] = OSSL_PARAM_construct_end();
+    }
+
 
     EVP_PKEY_CTX *pctx = NULL;
     EVP_MD_CTX *mctx = EVP_MD_CTX_new();
@@ -328,13 +343,20 @@ xkey_sign(void *handle, unsigned char *sig, size_t *siglen,
         assert_memory_equal(tbs, test_digest, sizeof(test_digest));
     }
 
-    /* For the test use sha256 and PSS padding for RSA */
-    assert_int_equal(OBJ_sn2nid(s.mdname), NID_sha256);
+    /* For the test use sha256 and PSS padding for RSA and none for EDDSA */
+    if (!strcmp(s.keytype, "ED25519"))
+    {
+        assert_string_equal(s.mdname, "none");
+    }
+    else
+    {
+        assert_int_equal(OBJ_sn2nid(s.mdname), NID_sha256);
+    }
     if (!strcmp(s.keytype, "RSA"))
     {
         assert_string_equal(s.padmode, "pss"); /* we use PSS for the test */
     }
-    else if (strcmp(s.keytype, "EC"))
+    else if (strcmp(s.keytype, "EC") && strcmp(s.keytype, "ED25519"))
     {
         fail_msg("Unknown keytype: %s", s.keytype);
     }