Add support for raw private/public keys (#646)

Add OpenSSL::PKey.new_raw_private_key, #raw_private_key and public
equivalents. These methods are useful for importing and exporting keys
that support "raw private/public key". Currently, OpenSSL implements
X25519/X448 and Ed25519/Ed448 keys.

[rhe: rewrote commit message]

Co-authored-by: Bart de Water <bartdewater@gmail.com>

Author: sylph01

ext/openssl/ossl_pkey.c

@@ -628,6 +628,72 @@ ossl_pkey_initialize_copy(VALUE self, VALUE other)
 }
 #endif
 
+#ifdef HAVE_EVP_PKEY_NEW_RAW_PRIVATE_KEY
+/*
+ *  call-seq:
+ *      OpenSSL::PKey.new_raw_private_key(algo, string) -> PKey
+ *
+ * See the OpenSSL documentation for EVP_PKEY_new_raw_private_key()
+ */
+
+static VALUE
+ossl_pkey_new_raw_private_key(VALUE self, VALUE type, VALUE key)
+{
+    EVP_PKEY *pkey;
+    const EVP_PKEY_ASN1_METHOD *ameth;
+    int pkey_id;
+    size_t keylen;
+
+    StringValue(type);
+    StringValue(key);
+    ameth = EVP_PKEY_asn1_find_str(NULL, RSTRING_PTR(type), RSTRING_LENINT(type));
+    if (!ameth)
+        ossl_raise(ePKeyError, "algorithm %"PRIsVALUE" not found", type);
+    EVP_PKEY_asn1_get0_info(&pkey_id, NULL, NULL, NULL, NULL, ameth);
+
+    keylen = RSTRING_LEN(key);
+
+    pkey = EVP_PKEY_new_raw_private_key(pkey_id, NULL, (unsigned char *)RSTRING_PTR(key), keylen);
+    if (!pkey)
+        ossl_raise(ePKeyError, "EVP_PKEY_new_raw_private_key");
+
+    return ossl_pkey_new(pkey);
+}
+#endif
+
+#ifdef HAVE_EVP_PKEY_NEW_RAW_PRIVATE_KEY
+/*
+ *  call-seq:
+ *      OpenSSL::PKey.new_raw_public_key(algo, string) -> PKey
+ *
+ * See the OpenSSL documentation for EVP_PKEY_new_raw_public_key()
+ */
+
+static VALUE
+ossl_pkey_new_raw_public_key(VALUE self, VALUE type, VALUE key)
+{
+    EVP_PKEY *pkey;
+    const EVP_PKEY_ASN1_METHOD *ameth;
+    int pkey_id;
+    size_t keylen;
+
+    StringValue(type);
+    StringValue(key);
+    ameth = EVP_PKEY_asn1_find_str(NULL, RSTRING_PTR(type), RSTRING_LENINT(type));
+    if (!ameth)
+        ossl_raise(ePKeyError, "algorithm %"PRIsVALUE" not found", type);
+    EVP_PKEY_asn1_get0_info(&pkey_id, NULL, NULL, NULL, NULL, ameth);
+
+    keylen = RSTRING_LEN(key);
+
+    pkey = EVP_PKEY_new_raw_public_key(pkey_id, NULL, (unsigned char *)RSTRING_PTR(key), keylen);
+    if (!pkey)
+        ossl_raise(ePKeyError, "EVP_PKEY_new_raw_public_key");
+
+    return ossl_pkey_new(pkey);
+}
+#endif
+
 /*
  * call-seq:
  *    pkey.oid -> string
@@ -816,6 +882,35 @@ ossl_pkey_private_to_pem(int argc, VALUE *argv, VALUE self)
     return do_pkcs8_export(argc, argv, self, 0);
 }
 
+#ifdef HAVE_EVP_PKEY_NEW_RAW_PRIVATE_KEY
+/*
+ *  call-seq:
+ *     pkey.raw_private_key   => string
+ *
+ *  See the OpenSSL documentation for EVP_PKEY_get_raw_private_key()
+ */
+
+static VALUE
+ossl_pkey_raw_private_key(VALUE self)
+{
+    EVP_PKEY *pkey;
+    VALUE str;
+    size_t len;
+
+    GetPKey(self, pkey);
+    if (EVP_PKEY_get_raw_private_key(pkey, NULL, &len) != 1)
+        ossl_raise(ePKeyError, "EVP_PKEY_get_raw_private_key");
+    str = rb_str_new(NULL, len);
+
+    if (EVP_PKEY_get_raw_private_key(pkey, (unsigned char *)RSTRING_PTR(str), &len) != 1)
+        ossl_raise(ePKeyError, "EVP_PKEY_get_raw_private_key");
+
+    rb_str_set_len(str, len);
+
+    return str;
+}
+#endif
+
 VALUE
 ossl_pkey_export_spki(VALUE self, int to_der)
 {
@@ -865,6 +960,35 @@ ossl_pkey_public_to_pem(VALUE self)
     return ossl_pkey_export_spki(self, 0);
 }
 
+#ifdef HAVE_EVP_PKEY_NEW_RAW_PRIVATE_KEY
+/*
+ *  call-seq:
+ *     pkey.raw_public_key   => string
+ *
+ *  See the OpenSSL documentation for EVP_PKEY_get_raw_public_key()
+ */
+
+static VALUE
+ossl_pkey_raw_public_key(VALUE self)
+{
+    EVP_PKEY *pkey;
+    VALUE str;
+    size_t len;
+
+    GetPKey(self, pkey);
+    if (EVP_PKEY_get_raw_public_key(pkey, NULL, &len) != 1)
+        ossl_raise(ePKeyError, "EVP_PKEY_get_raw_public_key");
+    str = rb_str_new(NULL, len);
+
+    if (EVP_PKEY_get_raw_public_key(pkey, (unsigned char *)RSTRING_PTR(str), &len) != 1)
+        ossl_raise(ePKeyError, "EVP_PKEY_get_raw_public_key");
+
+    rb_str_set_len(str, len);
+
+    return str;
+}
+#endif
+
 /*
  *  call-seq:
  *      pkey.compare?(another_pkey) -> true | false
@@ -1602,6 +1726,10 @@ Init_ossl_pkey(void)
     rb_define_module_function(mPKey, "read", ossl_pkey_new_from_data, -1);
     rb_define_module_function(mPKey, "generate_parameters", ossl_pkey_s_generate_parameters, -1);
     rb_define_module_function(mPKey, "generate_key", ossl_pkey_s_generate_key, -1);
+#ifdef HAVE_EVP_PKEY_NEW_RAW_PRIVATE_KEY
+    rb_define_module_function(mPKey, "new_raw_private_key", ossl_pkey_new_raw_private_key, 2);
+    rb_define_module_function(mPKey, "new_raw_public_key", ossl_pkey_new_raw_public_key, 2);
+#endif
 
     rb_define_alloc_func(cPKey, ossl_pkey_alloc);
     rb_define_method(cPKey, "initialize", ossl_pkey_initialize, 0);
@@ -1617,6 +1745,10 @@ Init_ossl_pkey(void)
     rb_define_method(cPKey, "private_to_pem", ossl_pkey_private_to_pem, -1);
     rb_define_method(cPKey, "public_to_der", ossl_pkey_public_to_der, 0);
     rb_define_method(cPKey, "public_to_pem", ossl_pkey_public_to_pem, 0);
+#ifdef HAVE_EVP_PKEY_NEW_RAW_PRIVATE_KEY
+    rb_define_method(cPKey, "raw_private_key", ossl_pkey_raw_private_key, 0);
+    rb_define_method(cPKey, "raw_public_key", ossl_pkey_raw_public_key, 0);
+#endif
     rb_define_method(cPKey, "compare?", ossl_pkey_compare, 1);
 
     rb_define_method(cPKey, "sign", ossl_pkey_sign, -1);

test/openssl/test_pkey.rb

@@ -109,6 +109,19 @@ def test_ed25519
     assert_equal pub_pem, priv.public_to_pem
     assert_equal pub_pem, pub.public_to_pem
 
+    begin
+      assert_equal "4ccd089b28ff96da9db6c346ec114e0f5b8a319f35aba624da8cf6ed4fb8a6fb",
+        priv.raw_private_key.unpack1("H*")
+      assert_equal OpenSSL::PKey.new_raw_private_key("ED25519", priv.raw_private_key).private_to_pem,
+        priv.private_to_pem
+      assert_equal "3d4017c3e843895a92b70aa74d1b7ebc9c982ccf2ec4968cc0cd55f12af4660c",
+        priv.raw_public_key.unpack1("H*")
+      assert_equal OpenSSL::PKey.new_raw_public_key("ED25519", priv.raw_public_key).public_to_pem,
+        pub.public_to_pem
+    rescue NoMethodError
+      pend "running OpenSSL version does not have raw public key support"
+    end
+
     sig = [<<~EOF.gsub(/[^0-9a-f]/, "")].pack("H*")
     92a009a9f0d4cab8720e820b5f642540
     a2b27b5416503f8fb3762223ebdb69da
@@ -155,6 +168,32 @@ def test_x25519
     assert_equal alice_pem, alice.private_to_pem
     assert_equal bob_pem, bob.public_to_pem
     assert_equal [shared_secret].pack("H*"), alice.derive(bob)
+    begin
+      alice_private = OpenSSL::PKey.new_raw_private_key("X25519", alice.raw_private_key)
+      bob_public = OpenSSL::PKey.new_raw_public_key("X25519", bob.raw_public_key)
+      alice_private_raw = alice.raw_private_key.unpack1("H*")
+      bob_public_raw = bob.raw_public_key.unpack1("H*")
+    rescue NoMethodError
+      # OpenSSL < 1.1.1
+      pend "running OpenSSL version does not have raw public key support"
+    end
+    assert_equal alice_private.private_to_pem,
+      alice.private_to_pem
+    assert_equal bob_public.public_to_pem,
+      bob.public_to_pem
+    assert_equal "77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a",
+      alice_private_raw
+    assert_equal "de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f",
+      bob_public_raw
+  end
+
+  def raw_initialize
+    pend "Ed25519 is not implemented" unless OpenSSL::OPENSSL_VERSION_NUMBER >= 0x10101000 && # >= v1.1.1
+
+    assert_raise(OpenSSL::PKey::PKeyError) { OpenSSL::PKey.new_raw_private_key("foo123", "xxx") }
+    assert_raise(OpenSSL::PKey::PKeyError) { OpenSSL::PKey.new_raw_private_key("ED25519", "xxx") }
+    assert_raise(OpenSSL::PKey::PKeyError) { OpenSSL::PKey.new_raw_public_key("foo123", "xxx") }
+    assert_raise(OpenSSL::PKey::PKeyError) { OpenSSL::PKey.new_raw_public_key("ED25519", "xxx") }
   end
 
   def test_compare?