diff --git a/scrapy/core/downloader/tls.py b/scrapy/core/downloader/tls.py
index df805118249..56e63563479 100644
--- a/scrapy/core/downloader/tls.py
+++ b/scrapy/core/downloader/tls.py
@@ -1,7 +1,9 @@
 import logging
 from OpenSSL import SSL
+import OpenSSL._util as pyOpenSSLutil
 
 from scrapy import twisted_version
+from scrapy.utils.python import to_native_str
 
 
 logger = logging.getLogger(__name__)
@@ -20,6 +22,20 @@
     METHOD_TLSv12: getattr(SSL, 'TLSv1_2_METHOD', 6),   # TLS 1.2 only
 }
 
+
+def ffi_buf_to_string(buf):
+    return to_native_str(pyOpenSSLutil.ffi.string(buf))
+
+
+def x509name_to_string(x509name):
+    # from OpenSSL.crypto.X509Name.__repr__
+    result_buffer = pyOpenSSLutil.ffi.new("char[]", 512)
+    format_result = pyOpenSSLutil.lib.X509_NAME_oneline(
+        x509name._name, result_buffer, len(result_buffer))
+
+    return ffi_buf_to_string(result_buffer)
+
+
 if twisted_version >= (14, 0, 0):
     # ClientTLSOptions requires a recent-enough version of Twisted.
     # Not having ScrapyClientTLSOptions should not matter for older
@@ -65,13 +81,51 @@ class ScrapyClientTLSOptions(ClientTLSOptions):
         Same as Twisted's private _sslverify.ClientTLSOptions,
         except that VerificationError, CertificateError and ValueError
         exceptions are caught, so that the connection is not closed, only
-        logging warnings.
+        logging warnings. Also, HTTPS connection parameters logging is added.
         """
 
         def _identityVerifyingInfoCallback(self, connection, where, ret):
             if where & SSL_CB_HANDSHAKE_START:
                 set_tlsext_host_name(connection, self._hostnameBytes)
             elif where & SSL_CB_HANDSHAKE_DONE:
+                logger.debug('SSL connection to %s using protocol %s, cipher %s',
+                             self._hostnameASCII,
+                             connection.get_protocol_version_name(),
+                             connection.get_cipher_name(),
+                             )
+                server_cert = connection.get_peer_certificate()
+                logger.debug('SSL connection certificate: issuer "%s", subject "%s"',
+                             x509name_to_string(server_cert.get_issuer()),
+                             x509name_to_string(server_cert.get_subject()),
+                             )
+
+                if hasattr(pyOpenSSLutil.lib, 'SSL_get_server_tmp_key'):  # requires OpenSSL 1.0.2
+                    # adapted from OpenSSL apps/s_cb.c::ssl_print_tmp_key()
+                    temp_key_p = pyOpenSSLutil.ffi.new("EVP_PKEY **")
+                    pyOpenSSLutil.lib.SSL_get_server_tmp_key(connection._ssl, temp_key_p)
+                    if temp_key_p != pyOpenSSLutil.ffi.NULL:
+                        temp_key = temp_key_p[0]
+                        pyOpenSSLutil.ffi.gc(temp_key, pyOpenSSLutil.lib.EVP_PKEY_free)
+                        key_info = []
+                        key_type = pyOpenSSLutil.lib.EVP_PKEY_id(temp_key)
+                        if key_type == pyOpenSSLutil.lib.EVP_PKEY_RSA:
+                            key_info.append('RSA')
+                        elif key_type == pyOpenSSLutil.lib.EVP_PKEY_DH:
+                            key_info.append('DH')
+                        elif key_type == pyOpenSSLutil.lib.EVP_PKEY_EC:
+                            key_info.append('ECDH')
+                            ec_key = pyOpenSSLutil.lib.EVP_PKEY_get1_EC_KEY(temp_key)
+                            pyOpenSSLutil.ffi.gc(ec_key, pyOpenSSLutil.lib.EC_KEY_free)
+                            nid = pyOpenSSLutil.lib.EC_GROUP_get_curve_name(pyOpenSSLutil.lib.EC_KEY_get0_group(ec_key))
+                            cname = pyOpenSSLutil.lib.EC_curve_nid2nist(nid)
+                            if cname == pyOpenSSLutil.ffi.NULL:
+                                cname = pyOpenSSLutil.lib.OBJ_nid2sn(nid)
+                            key_info.append(ffi_buf_to_string(cname))
+                        else:
+                            key_info.append(ffi_buf_to_string(pyOpenSSLutil.lib.OBJ_nid2sn(key_type)))
+                        key_info.append('%s bits' % pyOpenSSLutil.lib.EVP_PKEY_bits(temp_key))
+                        logger.debug('SSL temp key: %s', ', '.join(key_info))
+
                 try:
                     verifyHostname(connection, self._hostnameASCII)
                 except verification_errors as e: