raw
smg_comms_skeys_s...    1  -- Message reader & writers for SMG Communication Protocol
smg_comms_skeys_s...    2  -- S.MG, 2018
smg_comms_skeys_s...    3 
smg_comms_skeys_s...    4 with Interfaces; use Interfaces;
smg_comms_skeys_s...    5 with Serpent;
smg_comms_skeys_s...    6 with System; use System;
smg_comms_skeys_s...    7 
smg_comms_skeys_s...    8 package body Messages is
smg_comms_skeys_s...    9 
smg_comms_keymgm       10   ----------------------
smg_comms_keymgm       11   -- Serpent Messages --
smg_comms_keymgm       12   ----------------------
smg_comms_keymgm       13 
smg_comms_skeys_s...   14   procedure Write_SKeys_SMsg( Keyset  : in Serpent_Keyset;
smg_comms_skeys_s...   15                               Counter : in Interfaces.Unsigned_16;
smg_comms_skeys_s...   16                               Msg     : out Raw_Types.Serpent_Msg) is
smg_comms_keymgm       17   begin
smg_comms_keymgm       18     -- call internal write on Octets with correct type id
smg_comms_keymgm       19     Write_SKeys( Keyset, Counter, SKeys_S_Type, Msg );
smg_comms_keymgm       20   end Write_SKeys_SMsg;
smg_comms_keymgm       21 
smg_comms_keymgm       22 
smg_comms_keymgm       23   -- Reads a Serpent keyset from given Serpent Message
smg_comms_keymgm       24   procedure Read_SKeys_SMsg( Msg     : in Raw_Types.Serpent_Msg;
smg_comms_keymgm       25                              Counter : out Interfaces.Unsigned_16;
smg_comms_keymgm       26                              Keyset  : out Serpent_Keyset) is
smg_comms_keymgm       27   begin
smg_comms_keymgm       28     -- check type id and call internal Read_SKeys if correct
smg_comms_keymgm       29     if Msg(Msg'First) /= SKeys_S_Type then
smg_comms_keymgm       30       raise Invalid_Msg;
smg_comms_keymgm       31     else
smg_comms_keymgm       32       Read_SKeys( Msg, Counter, Keyset );
smg_comms_keymgm       33     end if;
smg_comms_keymgm       34   end Read_SKeys_SMsg;
smg_comms_keymgm       35 
smg_comms_keymgm       36   -- writes given key mgm structure into a Serpent message
smg_comms_keymgm       37   procedure Write_KMgm_SMsg( KMgm    : in Keys_Mgm;
smg_comms_keymgm       38                              Counter : in Interfaces.Unsigned_16;
smg_comms_keymgm       39                              Msg     : out Raw_Types.Serpent_Msg) is
smg_comms_keymgm       40   begin
smg_comms_keymgm       41     -- call internal write of key mgm with correct type ID
smg_comms_keymgm       42     Write_KMgm( KMgm, Counter, Key_Mgm_S_Type, Msg );
smg_comms_keymgm       43   end Write_KMgm_SMsg;
smg_comms_keymgm       44 
smg_comms_keymgm       45   -- reads a key mgm structure from the given Serpent message
smg_comms_keymgm       46   procedure Read_KMgm_SMsg( Msg     : in Raw_Types.Serpent_Msg;
smg_comms_keymgm       47                             Counter : out Interfaces.Unsigned_16;
smg_comms_keymgm       48                             KMgm    : out Keys_Mgm) is
smg_comms_keymgm       49   begin
smg_comms_keymgm       50     -- check type id and call internal Read_KMgm if correct
smg_comms_keymgm       51     if Msg(Msg'First) /= Key_Mgm_S_Type then
smg_comms_keymgm       52       raise Invalid_Msg;
smg_comms_keymgm       53     else
smg_comms_keymgm       54       Read_KMgm( Msg, Counter, KMgm );
smg_comms_keymgm       55     end if;
smg_comms_keymgm       56   end Read_KMgm_SMsg;
smg_comms_keymgm       57 
smg_comms_keymgm       58 
smg_comms_keymgm       59   ------------------
smg_comms_keymgm       60   -- RSA Messages --
smg_comms_keymgm       61   ------------------
smg_comms_keymgm       62 
smg_comms_keymgm       63   procedure Write_SKeys_RMsg( Keyset  : in Serpent_Keyset;
smg_comms_keymgm       64                               Counter : in Interfaces.Unsigned_16;
smg_comms_keymgm       65                               Msg     : out Raw_Types.RSA_Msg) is
smg_comms_keymgm       66   begin
smg_comms_keymgm       67     -- call internal write of Serpent keys with correct type ID
smg_comms_keymgm       68     Write_SKeys( Keyset, Counter, SKeys_R_Type, Msg );
smg_comms_keymgm       69   end Write_SKeys_RMsg;
smg_comms_keymgm       70 
smg_comms_keymgm       71   procedure Read_SKeys_RMsg( Msg     : in Raw_Types.RSA_Msg;
smg_comms_keymgm       72                              Counter : out Interfaces.Unsigned_16;
smg_comms_keymgm       73                              Keyset  : out Serpent_Keyset) is
smg_comms_keymgm       74   begin
smg_comms_keymgm       75     -- check type id and call internal Read_SKeys if correct
smg_comms_keymgm       76     if Msg(Msg'First) /= SKeys_R_Type then
smg_comms_keymgm       77       raise Invalid_Msg;
smg_comms_keymgm       78     else
smg_comms_keymgm       79       Read_SKeys( Msg, Counter, Keyset );
smg_comms_keymgm       80     end if;
smg_comms_keymgm       81   end Read_SKeys_RMsg;
smg_comms_keymgm       82 
smg_comms_keymgm       83   procedure Write_KMgm_RMsg( KMgm    : in Keys_Mgm;
smg_comms_keymgm       84                              Counter : in Interfaces.Unsigned_16;
smg_comms_keymgm       85                              Msg     : out Raw_Types.RSA_Msg) is
smg_comms_keymgm       86   begin
smg_comms_keymgm       87     -- call internal write of key mgm with correct type ID
smg_comms_keymgm       88     Write_KMgm( KMgm, Counter, Key_Mgm_R_Type, Msg );
smg_comms_keymgm       89   end Write_KMgm_RMsg;
smg_comms_keymgm       90 
smg_comms_keymgm       91   procedure Read_KMgm_RMsg( Msg     : in Raw_Types.RSA_Msg;
smg_comms_keymgm       92                             Counter : out Interfaces.Unsigned_16;
smg_comms_keymgm       93                             KMgm    : out Keys_Mgm) is
smg_comms_keymgm       94   begin
smg_comms_keymgm       95     -- check type id and call internal Read_KMgm if correct
smg_comms_keymgm       96     if Msg(Msg'First) /= Key_Mgm_R_Type then
smg_comms_keymgm       97       raise Invalid_Msg;
smg_comms_keymgm       98     else
smg_comms_keymgm       99       Read_KMgm( Msg, Counter, KMgm );
smg_comms_keymgm      100     end if;
smg_comms_keymgm      101   end Read_KMgm_RMsg;
smg_comms_keymgm      102 
smg_comms_keymgm      103   ------------------
smg_comms_keymgm      104   -- private part --
smg_comms_keymgm      105   ------------------
smg_comms_keymgm      106   procedure Cast_LE( LE: in out Raw_Types.Octets ) is
smg_comms_keymgm      107   begin
smg_comms_keymgm      108     -- flip octets ONLY if native is big endian.
smg_comms_keymgm      109     if System.Default_Bit_Order = System.High_Order_First then
smg_comms_keymgm      110       declare
smg_comms_keymgm      111         BE: constant Raw_Types.Octets := LE;
smg_comms_keymgm      112       begin
smg_comms_keymgm      113         for I in 1..LE'Length loop
smg_comms_keymgm      114           LE(LE'First+I-1) := BE(BE'Last-I+1);
smg_comms_keymgm      115         end loop;
smg_comms_keymgm      116       end;
smg_comms_keymgm      117     end if;
smg_comms_keymgm      118     -- NOTHING to do for native little endian
smg_comms_keymgm      119   end Cast_LE;
smg_comms_keymgm      120 
smg_comms_keymgm      121   procedure Write_SKeys( Keyset  : in Serpent_Keyset;
smg_comms_keymgm      122                          Counter : in Interfaces.Unsigned_16;
smg_comms_keymgm      123                          Type_ID : in Interfaces.Unsigned_8;
smg_comms_keymgm      124                          Msg     : out Raw_Types.Octets) is
smg_comms_skeys_s...  125     Pos   : Integer := Msg'First;
smg_comms_skeys_s...  126     Check : CRC32.CRC32;
smg_comms_skeys_s...  127     PadLen: Integer;
smg_comms_skeys_s...  128     K     : Serpent.Key;
smg_comms_skeys_s...  129   begin
smg_comms_skeys_s...  130     -- write Type ID
smg_comms_keymgm      131     Msg(Pos) := Type_ID;
smg_comms_skeys_s...  132     Pos := Pos + 1;
smg_comms_skeys_s...  133 
smg_comms_skeys_s...  134     -- write count of keys (NB: this IS 8 bits by definition)
smg_comms_skeys_s...  135     Msg(Pos) := Keyset.Keys'Length;
smg_comms_skeys_s...  136     Pos := Pos + 1;
smg_comms_skeys_s...  137 
smg_comms_skeys_s...  138     -- write keys
smg_comms_skeys_s...  139     for I in Keyset.Keys'Range loop
smg_comms_skeys_s...  140       -- retrieve Key to write
smg_comms_skeys_s...  141       K := Keyset.Keys( I );
smg_comms_skeys_s...  142 
smg_comms_skeys_s...  143       -- write key itself
smg_comms_skeys_s...  144       Msg(Pos..Pos+K'Length-1) := K;
smg_comms_skeys_s...  145       -- ensure little endian order in message
smg_comms_skeys_s...  146       Cast_LE(Msg(Pos..Pos+K'Length-1));
smg_comms_skeys_s...  147       Pos := Pos + K'Length;
smg_comms_skeys_s...  148 
smg_comms_skeys_s...  149       -- write CRC of key
smg_comms_skeys_s...  150       Check := CRC32.CRC( K );
smg_comms_skeys_s...  151       Msg(Pos..Pos+3) := Raw_Types.Cast(Check);
smg_comms_skeys_s...  152       Cast_LE(Msg(Pos..Pos+3));
smg_comms_skeys_s...  153       Pos := Pos + 4;
smg_comms_skeys_s...  154     end loop;
smg_comms_skeys_s...  155 
smg_comms_skeys_s...  156     -- write flag
smg_comms_skeys_s...  157     Msg(Pos) := Keyset.Flag;
smg_comms_skeys_s...  158     Pos := Pos + 1;
smg_comms_skeys_s...  159 
smg_comms_skeys_s...  160     -- write message counter
smg_comms_skeys_s...  161     Msg(Pos..Pos+1) := Raw_Types.Cast(Counter);
smg_comms_skeys_s...  162     Cast_LE(Msg(Pos..Pos+1));
smg_comms_skeys_s...  163     Pos := Pos + 2;
smg_comms_skeys_s...  164 
smg_comms_skeys_s...  165     -- write padding as needed; endianness is irrelevant here
smg_comms_skeys_s...  166     PadLen := Msg'Last - Pos + 1;
smg_comms_skeys_s...  167     if PadLen > 0 then
smg_comms_skeys_s...  168       declare
smg_comms_skeys_s...  169         Pad : Raw_Types.Octets(1..PadLen);
smg_comms_skeys_s...  170       begin
smg_comms_skeys_s...  171         RNG.Get_Octets( Pad );
smg_comms_skeys_s...  172         Msg(Pos..Pos+PadLen-1) := Pad;
smg_comms_skeys_s...  173       end;
smg_comms_skeys_s...  174     end if;
smg_comms_skeys_s...  175 
smg_comms_keymgm      176   end Write_SKeys;
smg_comms_skeys_s...  177 
smg_comms_keymgm      178   procedure Read_SKeys( Msg     : in Raw_Types.Octets;
smg_comms_keymgm      179                         Counter : out Interfaces.Unsigned_16;
smg_comms_keymgm      180                         Keyset  : out Serpent_Keyset) is
smg_comms_skeys_s...  181     Pos: Integer := Msg'First;
smg_comms_skeys_s...  182   begin
smg_comms_skeys_s...  183     -- read type and check
smg_comms_keymgm      184     if Msg(Pos) = SKeys_S_Type or 
smg_comms_keymgm      185        Msg(Pos) = SKeys_R_Type then
smg_comms_skeys_s...  186       Pos := Pos + 1;
smg_comms_skeys_s...  187     else
smg_comms_skeys_s...  188       raise Invalid_Msg;
smg_comms_skeys_s...  189     end if;
smg_comms_skeys_s...  190 
smg_comms_skeys_s...  191     -- read count of keys and check
smg_comms_skeys_s...  192     if Msg(Pos) in Keys_Count'Range then
smg_comms_skeys_s...  193       declare
smg_comms_skeys_s...  194         N     : Keys_Count := Keys_Count(Msg(Pos));
smg_comms_skeys_s...  195         KS    : Serpent_Keyset(N);
smg_comms_skeys_s...  196         K     : Serpent.Key;
smg_comms_skeys_s...  197         Check : CRC32.CRC32;
smg_comms_skeys_s...  198         O4    : Raw_Types.Octets_4; 
smg_comms_skeys_s...  199         O2    : Raw_Types.Octets_2;
smg_comms_skeys_s...  200       begin
smg_comms_skeys_s...  201         Pos := Pos + 1;
smg_comms_skeys_s...  202         --read keys and check crc for each
smg_comms_skeys_s...  203         for I in 1 .. N loop
smg_comms_skeys_s...  204           -- read key and advance pos
smg_comms_skeys_s...  205           K := Msg(Pos..Pos+K'Length-1);
smg_comms_skeys_s...  206           Cast_LE(K);
smg_comms_skeys_s...  207           Pos := Pos + K'Length;
smg_comms_skeys_s...  208           -- read crc and compare to crc32(key)
smg_comms_skeys_s...  209           O4 := Msg(Pos..Pos+3);
smg_comms_skeys_s...  210           Cast_LE(O4);
smg_comms_skeys_s...  211           Check   := Raw_Types.Cast(O4);
smg_comms_skeys_s...  212           Pos := Pos + 4;
smg_comms_skeys_s...  213           if Check /= CRC32.CRC(K) then
smg_comms_skeys_s...  214             raise Invalid_Msg;
smg_comms_skeys_s...  215           end if;
smg_comms_skeys_s...  216           -- if it got here, key is fine so add to set
smg_comms_skeys_s...  217           KS.Keys(KS.Keys'First + I -1) := K;
smg_comms_skeys_s...  218         end loop;
smg_comms_skeys_s...  219         -- read and set flag
smg_comms_skeys_s...  220         KS.Flag := Msg(Pos);
smg_comms_skeys_s...  221         Pos := Pos + 1;
smg_comms_skeys_s...  222         -- read and set message counter
smg_comms_skeys_s...  223         O2 := Msg(Pos..Pos+1);
smg_comms_skeys_s...  224         Cast_LE(O2);
smg_comms_skeys_s...  225         Counter := Raw_Types.Cast(O2);
smg_comms_skeys_s...  226         -- rest of message is padding so it's ignored
smg_comms_skeys_s...  227         -- copy keyset to output variable
smg_comms_skeys_s...  228         Keyset := KS;
smg_comms_skeys_s...  229       end;
smg_comms_skeys_s...  230     else
smg_comms_skeys_s...  231       raise Invalid_Msg;
smg_comms_skeys_s...  232     end if;
smg_comms_keymgm      233   end Read_SKeys;
smg_comms_skeys_s...  234 
smg_comms_keymgm      235   -- writes given key management structure to the given octets array
smg_comms_keymgm      236   procedure Write_KMgm( KMgm    : in Keys_Mgm;
smg_comms_keymgm      237                         Counter : in Interfaces.Unsigned_16;
smg_comms_keymgm      238                         Type_ID : in Interfaces.Unsigned_8;
smg_comms_keymgm      239                         Msg     : out Raw_Types.Octets) is
smg_comms_keymgm      240     Pos   : Integer := Msg'First;
smg_comms_skeys_s...  241   begin
smg_comms_keymgm      242     -- write given type id
smg_comms_keymgm      243     Msg(Pos) := Type_ID;
smg_comms_keymgm      244     Pos := Pos + 1;
smg_comms_keymgm      245 
smg_comms_keymgm      246     -- write count of server keys requested
smg_comms_keymgm      247     Msg(Pos) := KMgm.N_Server;
smg_comms_keymgm      248     Pos := Pos + 1;
smg_comms_keymgm      249 
smg_comms_keymgm      250     -- write count of client keys requested
smg_comms_keymgm      251     Msg(Pos) := KMgm.N_Client;
smg_comms_keymgm      252     Pos := Pos + 1;
smg_comms_keymgm      253 
smg_comms_keymgm      254     -- write id of key preferred for further inbound Serpent messages
smg_comms_keymgm      255     Msg(Pos) := KMgm.Key_ID;
smg_comms_keymgm      256     Pos := Pos + 1;
smg_comms_keymgm      257 
smg_comms_keymgm      258     -- write count of burnt keys in this message
smg_comms_keymgm      259     Msg(Pos..Pos) := Cast( KMgm.N_Burnt );
smg_comms_keymgm      260     Pos := Pos + 1;
smg_comms_keymgm      261 
smg_comms_keymgm      262     -- if there are any burnt keys, write their ids
smg_comms_keymgm      263     if KMgm.N_Burnt > 0 then
smg_comms_keymgm      264       Msg( Pos .. Pos + KMgm.Burnt'Length - 1 ) := KMgm.Burnt;
smg_comms_keymgm      265       Pos := Pos + KMgm.Burnt'Length;
smg_comms_skeys_s...  266     end if;
smg_comms_keymgm      267 
smg_comms_keymgm      268     -- write the message count
smg_comms_keymgm      269     Msg(Pos..Pos+1) := Raw_Types.Cast( Counter );
smg_comms_keymgm      270     Cast_LE( Msg(Pos..Pos+1) );
smg_comms_keymgm      271     Pos := Pos + 2;
smg_comms_keymgm      272 
smg_comms_keymgm      273     -- pad with random octets until the end of Msg
smg_comms_keymgm      274     RNG.Get_Octets( Msg(Pos..Msg'Last) );
smg_comms_keymgm      275 
smg_comms_keymgm      276   end Write_KMgm;
smg_comms_keymgm      277 
smg_comms_keymgm      278   -- attempts to read from the given array of octets a key management structure
smg_comms_keymgm      279   procedure Read_KMgm( Msg     : in Raw_Types.Octets;
smg_comms_keymgm      280                        Counter : out Interfaces.Unsigned_16;
smg_comms_keymgm      281                        KMgm    : out Keys_Mgm) is
smg_comms_keymgm      282     Pos       : Integer := Msg'First;
smg_comms_keymgm      283     Burnt_Pos : Integer := Msg'First + 4;
smg_comms_keymgm      284   begin
smg_comms_keymgm      285     -- read type and check
smg_comms_keymgm      286     if Msg(Pos) = Key_Mgm_S_Type or 
smg_comms_keymgm      287        Msg(Pos) = Key_Mgm_R_Type then
smg_comms_keymgm      288       Pos := Pos + 1;
smg_comms_keymgm      289     else
smg_comms_keymgm      290       raise Invalid_Msg;
smg_comms_keymgm      291     end if;
smg_comms_keymgm      292 
smg_comms_keymgm      293     -- read the count of burnt keys and check
smg_comms_keymgm      294     -- NB: Burnt_Pos IS in range of Counter_8bits since it's an octet
smg_comms_keymgm      295     declare
smg_comms_keymgm      296       N_Burnt : Counter_8bits := Counter_8bits(Msg(Burnt_Pos));
smg_comms_keymgm      297       Mgm     : Keys_Mgm(N_Burnt);
smg_comms_keymgm      298       O2      : Raw_Types.Octets_2;
smg_comms_keymgm      299     begin
smg_comms_keymgm      300       -- read count of server keys requested
smg_comms_keymgm      301       Mgm.N_Server := Msg(Pos);
smg_comms_keymgm      302       Pos := Pos + 1;
smg_comms_keymgm      303 
smg_comms_keymgm      304       -- read count of client keys requested
smg_comms_keymgm      305       Mgm.N_Client := Msg(Pos);
smg_comms_keymgm      306       Pos := Pos + 1;
smg_comms_keymgm      307 
smg_comms_keymgm      308       -- read ID of Serpent key preferred for further inbound messages
smg_comms_keymgm      309       Mgm.Key_ID   := Msg(Pos);
smg_comms_keymgm      310       Pos := Pos + 2; --skip the count of burnt keys as it's read already
smg_comms_keymgm      311 
smg_comms_keymgm      312       -- read ids of burnt keys, if any
smg_comms_keymgm      313       if N_Burnt > 0 then
smg_comms_keymgm      314         Mgm.Burnt := Msg(Pos..Pos+N_Burnt-1);
smg_comms_keymgm      315         Pos := Pos + N_Burnt;
smg_comms_keymgm      316       end if;
smg_comms_keymgm      317 
smg_comms_keymgm      318       -- read and set message counter
smg_comms_keymgm      319       O2 := Msg(Pos..Pos+1);
smg_comms_keymgm      320       Cast_LE(O2);
smg_comms_keymgm      321       Counter := Raw_Types.Cast(O2);
smg_comms_keymgm      322       -- rest of message is padding so it's ignored
smg_comms_keymgm      323       -- copy the keys mgm structure to output param
smg_comms_keymgm      324       KMgm := Mgm;
smg_comms_keymgm      325     end;
smg_comms_keymgm      326   end Read_KMgm;
smg_comms_keymgm      327 
smg_comms_skeys_s...  328 
smg_comms_skeys_s...  329 end Messages;