T04: promote security events to warnings — SASL auth failure, TLS
handshake failure, cert-failure details, see-other-host redirect;
DISABLE_TLS, TRUST_TLS and LEGACY_AUTH get a log warning plus a
console notice (REQ-LOG-01, REQ-LOG-02, REQ-AUTH-03)

T05: warn when a session ends up unencrypted without the user having
asked for it; refuse in-band registration on an unencrypted stream;
warn on each HTTP transfer with certificate verification disabled
(REQ-CRY-03, REQ-CFG-01)

T06: pin the update check to https with peer/host verification and no
redirects; strict N.N.N parser for the fetched version, which is
untrusted network input (REQ-VUL-02)

T09: no plaintext logging on failed MUC OMEMO sends; OTR opportunistic
first message passes allow_unencrypted_message(); get_random_string()
draws from a CSPRNG without modulo bias; guard the identity-key length
decrement against unsigned underflow (REQ-CRY-01, REQ-CRY-02,
REQ-CRY-07, REQ-MEM-05)

REQ-VUL-03 and REQ-CRY-09 are already satisfied on master and are
left unchanged.

@@ -473,1 +476,3 @@
-    curl_easy_perform(handle);
+    curl_easy_setopt(handle, CURLOPT_SSL_VERIFYPEER, 1L);
+    curl_easy_setopt(handle, CURLOPT_SSL_VERIFYHOST, 2L);
+    curl_easy_setopt(handle, CURLOPT_FOLLOWLOCATION, 0L);

@@ -474,0 +482,4 @@
+#else
+    curl_easy_setopt(handle, CURLOPT_PROTOCOLS, CURLPROTO_HTTPS);
+    curl_easy_setopt(handle, CURLOPT_REDIR_PROTOCOLS, CURLPROTO_HTTPS);
+#endif

@@ -484,0 +527,4 @@
+        gint64 value = 0;
+        while (g_ascii_isdigit(*curr)) {
+            value = value * 10 + (*curr - '0');
+            if (value > G_MAXINT) {

@@ -702,0 +765,4 @@
+    }
+#endif
+
+    FILE* urandom = fopen("/dev/urandom", "rb");

@@ -201,3 +201,1 @@
-        groupchat_log_omemo_msg_out(mucwin->roomjid, message);
-        log_database_add_outgoing_muc(id, mucwin->roomjid, message, replace_id, PROF_MSG_ENC_OMEMO);
-        mucwin_outgoing_msg(mucwin, message, id, PROF_MSG_ENC_OMEMO, replace_id);
+        if (id != NULL) { // nothing was sent, so don't persist or echo the plaintext

@@ -206,3 +206,3 @@
 {
     cons_show_error("Login failed.");
-    log_info("Login failed");
+    log_warning("[SECURITY] Authentication failed for %s", STR_MAYBE_NULL(session_get_account_name()));

@@ -1434,2 +1434,4 @@
     unsigned char* identity_public_key_data = signal_buffer_data(identity_public_key);
 
+    if (identity_public_key_len == 0) {
+        log_error("[OMEMO] cannot fingerprint an empty identity key"); // the decrement below would wrap

@@ -331,6 +332,10 @@ otr_on_message_send(ProfChatWin* chatwin, const char* const message, gboolean re
 
     // tag and send for policy opportunistic
     if (policy == PROF_OTRPOLICY_OPPORTUNISTIC) {
+        // the tagged first message is still plaintext on the wire

@@ -54,0 +57,4 @@
+http_warn_insecure_transfer(ProfWin* window, char* id, const char* const url)
+{
+    log_warning("[SECURITY] TLS certificate verification disabled for transfer: %s", url);
+    http_print_transfer_update(window, id, THEME_ERROR, 0,

@@ -215,0 +217,4 @@
+
+    if (flags & XMPP_CONN_FLAG_DISABLE_TLS) {
+        log_warning("[SECURITY] TLS is disabled for this connection: traffic and credentials are sent in the clear");
+        cons_show_error("Security warning: TLS is disabled, this connection is unencrypted.");

@@ -960,0 +985,4 @@
+        // tls.policy=allow negotiates opportunistically, so an unrequested downgrade must not pass silently
+        if (!connection_is_secured() && !conn.tls_disabled_by_user) {
+            log_warning("[SECURITY] Logged in over an unencrypted connection to %s: the server offered no usable TLS", conn.domain);
+            cons_show_error("Security warning: this session is NOT encrypted, the server did not provide TLS. Use '/account set <account> tls force' to require it.");

@@ -1126,0 +1157,4 @@
+            g_key_file_set_string(keyfile.keyfile, "identifier", "random_bytes", profanity_instance_id);
+            save_keyfile(&keyfile);
+        } else {
+            log_error("Could not generate an instance identifier: no random source available");

@@ -1091,1 +1091,4 @@
     assert_false(release_is_new("1.0.0", NULL));
+
+    // the found version is untrusted network input: nothing but strictly N.N.N may parse
+    assert_false(release_is_new("0.16.0", "  1.0.0"));       // leading whitespace