Support alternate hash algorithms

etc/couchdb/default.d/browserid.ini

@@ -5,6 +5,7 @@
   enabled = false
   verify_url = https://verifier.login.persona.org/verify
   audience = http://example.com
+; hash_algorithm = <choose one of: none, hmac, gravatar. If hmac, set hash_secret below >
 ; hash_secret = <long crypto-random string, e.g. from https://api.wordpress.org/secret-key/1.1/>
 
 [httpd_global_handlers]

priv/main.js

@@ -172,6 +172,10 @@ $.couch.browserid.login(function(ev, er, userCtx) {
   widget.unbind('click');
 
   var iurl = 'https://www.gravatar.com/avatar/' + Crypto.MD5($.trim(email).toLowerCase()) + "?s=32";
+  if (email.indexOf('@') === -1) {
+    // it is probably already a gravatar hash
+    iurl = 'https://www.gravatar.com/avatar/' + email + "?s=32";
+  }
   var gravatar_img = $("<img>").attr('src', iurl);
   gravatar_img.appendTo($("#browserid .picture"));
 

src/couch_httpd_browserid.erl

@@ -23,15 +23,22 @@
 %% * Possibly auto-create user doc in browserid_authentication_handler/1
 %% * Do something sane with providers other than browserid.org
 
-% hash_if_required looks for hash_secret in browserid section of config
+% hash_if_required looks for hash_algorithm in browserid section of config
+% if not found, default to hmac to keep backward compat.
+hash_if_required(Email) -> ok
+    , Algorithm = couch_config:get("browserid", "hash_algorithm", "hmac")
+    , ?LOG_DEBUG("Algorithm chosen: ~s", [Algorithm])
+    , hash_if_required(Algorithm, Email).
+
+% hash_if_required (hmac) looks for hash_secret in browserid section of config
 % If it exist and isn't an empty string, uses it as hmac key according to code from
 % http://stackoverflow.com/questions/4193543/erlang-calculating-hmac-sha1-example/4202361#4202361
 % If missing or empty (i.e. admin doesn't want to hash usernames), simply returns the argument
 % (this is the default)
 % If you use hash_secret, make sure the string is long enough and cryptographically random
 % Tip: use one of the strings from https://api.wordpress.org/secret-key/1.1/ :)
 
-hash_if_required(Email) -> ok
+hash_if_required("hmac", Email) -> ok
     , Hashkey = couch_config:get("browserid", "hash_secret", undefined)
     , case Hashkey
         of undefined -> ok
@@ -40,8 +47,27 @@ hash_if_required(Email) -> ok
             , <<Mac:160/integer>> = crypto:sha_mac(?l2b(Key),Email)
             , ?l2b(lists:flatten(io_lib:format("~40.16.0b", [Mac])))
         end
+    ;
+
+% hash_if_required (gravatar) looks provides the same hasing as gravatar, 
+% and is based on the code from https://github.com/kanso/gravatar/blob/master/gravatar.js#L17
+hash_if_required("gravatar", Email) -> ok
+    , Trim = re:replace(Email, "(^\\s+)|(\\s+$)", "", [global,{return,list}])
+    , Lower = string:to_lower(Trim)
+    , <<Md5:128/integer>> = crypto:md5(Lower)
+    , ?l2b(lists:flatten(io_lib:format("~32.16.0b", [Md5])))
+    ;
+
+hash_if_required("none", Email) -> Email;
+
+% hash_if_required (_) returns the Email, and warns user.
+hash_if_required(_, Email) -> ok
+    , Message = <<"No hash_algorithm specified. Not hashing email address.">>
+    , ?LOG_ERROR("~s", [Message])
+    , hash_if_required(none, Email)
     .
 
+
 handle_id_req(#httpd{method='GET'}=Req) -> ok
     , case code:priv_dir(browserid_couchdb)
         of {error, bad_name} -> ok