raw
smg_comms_raw_types     1  -- raw types for the communication protocol
smg_comms_raw_types     2  -- these are used throughout at the lowest level of the protocol
smg_comms_raw_types     3  -- essentially they are the units of packets and of messages
smg_comms_raw_types     4  -- SMG.Comms has only 2 types of packets: RSA and Serpent
smg_comms_raw_types     5  -- a message is the decrypted content of a packet
smg_comms_raw_types     6  -- S.MG, 2018
smg_comms_raw_types     7 
smg_comms_raw_types     8 with Interfaces; use Interfaces; -- Unsigned_n and Integer_n
smg_comms_raw_types     9 with Ada.Unchecked_Conversion;
smg_comms_raw_types    10 
smg_comms_raw_types    11 package Raw_Types is
smg_comms_packing...   12   -- no side effects or internal state
smg_comms_packing...   13   Pragma Pure(Raw_Types);
smg_comms_raw_types    14 
smg_comms_packing...   15   -- raw, low-level type
smg_comms_packing...   16   -- all messages and packets are simply arrays of octets at low level/raw
smg_comms_packing...   17   type Octets is array( Natural range <> ) of Interfaces.Unsigned_8;
smg_comms_packing...   18 
smg_comms_raw_types    19   -- constants from SMG.COMMS standard specification
smg_comms_rsa_oaep     20 
smg_comms_rsa_oaep     21     -- RSA key size in octets
smg_comms_rsa_oaep     22     -- NB: this should MATCH the size of RSA key 
smg_comms_rsa_oaep     23     -- as defined in the rsa implementation in C!
smg_comms_rsa_oaep     24     -- NOT imported here because:
smg_comms_rsa_oaep     25     -- a. it's C code that should import this, not the other way around.
smg_comms_rsa_oaep     26     -- b. it needs to be static here.
smg_comms_rsa_oaep     27   RSA_KEY_OCTETS : constant Positive := 490;
smg_comms_packing...   28     
smg_comms_packing...   29     -- OAEP constants: defined here as still part of standard spec.
smg_comms_packing...   30     -- OAEP package will use those values when using Raw_Types
smg_comms_packing...   31     -- (NOT the other way around since dependency is oaep on types.)
smg_comms_packing...   32   OAEP_R_STR     : constant String  := "TMSR-RSA";
smg_comms_packing...   33     -- "TMSR-RSA" as unsigned_8 values:
smg_comms_packing...   34   OAEP_RESERVED  : constant Octets  := (84,77,83,82,45,82,83,65);
smg_comms_packing...   35     -- max length of useful payload in a OAEP-encrypted entity
smg_comms_packing...   36   OAEP_MAX_LEN   : constant Natural := RSA_KEY_OCTETS / 2 - 
smg_comms_packing...   37                                            OAEP_R_STR'Length - 3;
smg_comms_rsa_oaep     38 
smg_comms_packing...   39     -- size of a RSA-encrypted packet and message in octets and bits
smg_comms_packing...   40   RSA_PKT_OCTETS : constant Positive := 1470;
smg_comms_packing...   41   RSA_MSG_OCTETS : constant Positive := RSA_PKT_OCTETS / 
smg_comms_packing...   42                                           RSA_KEY_OCTETS *
smg_comms_packing...   43                                             OAEP_MAX_LEN;
smg_comms_packing...   44   RSA_MSG_BITS   : constant Positive := RSA_MSG_OCTETS * 8; 
smg_comms_rsa_oaep     45 
smg_comms_raw_types    46     -- size of a serpent-encrypted packet and message, in octets
smg_comms_raw_types    47     -- note that this corresponds to 1472/16 = 92 Serpent blocks
smg_comms_packing...   48     -- NB: lengths are the same!
smg_comms_packing...   49   SERPENT_OCTETS : constant Positive := 1472;
smg_comms_raw_types    50 
smg_comms_raw_types    51   -- raw representations of basic types (with fixed, well-defined sizes)
smg_comms_raw_types    52   subtype Octets_1 is Octets( 1 .. 1 );
smg_comms_raw_types    53   subtype Octets_2 is Octets( 1 .. 2 );
smg_comms_raw_types    54   subtype Octets_4 is Octets( 1 .. 4 );
smg_comms_raw_types    55   subtype Octets_8 is Octets( 1 .. 8 );
smg_comms_raw_types    56 
smg_comms_rsa_oaep     57   -- raw representations of RSA key components
smg_comms_rsa_oaep     58   subtype RSA_len is Octets ( 1 .. RSA_KEY_OCTETS);
smg_comms_rsa_oaep     59   subtype RSA_half is Octets( 1 .. RSA_KEY_OCTETS/2);
smg_comms_rsa_oaep     60 
smg_comms_raw_types    61   -- RSA packets and contained raw messages
smg_comms_raw_types    62   subtype RSA_Pkt is Octets( 1 .. RSA_PKT_OCTETS );
smg_comms_raw_types    63   subtype RSA_Msg is Octets( 1 .. RSA_MSG_OCTETS );
smg_comms_raw_types    64 
smg_comms_raw_types    65   -- Serpent packets and contained raw messages
smg_comms_raw_types    66   -- NB: length is the same but the distinction makes the code clearer
smg_comms_packing...   67   subtype Serpent_Pkt is Octets( 1 .. SERPENT_OCTETS );
smg_comms_packing...   68   subtype Serpent_Msg is Octets( 1 .. SERPENT_OCTETS );
smg_comms_raw_types    69 
smg_comms_raw_types    70   -- blind, unchecked casts ( memcpy style )
smg_comms_raw_types    71   function Cast is new Ada.Unchecked_Conversion( Integer_8  , Octets_1 );
smg_comms_raw_types    72   function Cast is new Ada.Unchecked_Conversion( Octets_1   , Integer_8 );
smg_comms_raw_types    73   function Cast is new Ada.Unchecked_Conversion( Unsigned_8 , Octets_1 );
smg_comms_raw_types    74   function Cast is new Ada.Unchecked_Conversion( Octets_1   , Unsigned_8 );
smg_comms_raw_types    75 
smg_comms_raw_types    76   function Cast is new Ada.Unchecked_Conversion( Integer_16 , Octets_2 );
smg_comms_raw_types    77   function Cast is new Ada.Unchecked_Conversion( Octets_2   , Integer_16 );
smg_comms_raw_types    78   function Cast is new Ada.Unchecked_Conversion( Unsigned_16, Octets_2 );
smg_comms_raw_types    79   function Cast is new Ada.Unchecked_Conversion( Octets_2   , Unsigned_16 );
smg_comms_raw_types    80 
smg_comms_raw_types    81   function Cast is new Ada.Unchecked_Conversion( Integer_32 , Octets_4 );
smg_comms_raw_types    82   function Cast is new Ada.Unchecked_Conversion( Octets_4   , Integer_32 );
smg_comms_raw_types    83   function Cast is new Ada.Unchecked_Conversion( Unsigned_32, Octets_4 );
smg_comms_raw_types    84   function Cast is new Ada.Unchecked_Conversion( Octets_4   , Unsigned_32 );
smg_comms_raw_types    85 
smg_comms_raw_types    86   -- Gnat's Float has 32 bits but this might be different with other compilers
smg_comms_raw_types    87   function Cast is new Ada.Unchecked_Conversion( Float, Octets_4 );
smg_comms_raw_types    88   function Cast is new Ada.Unchecked_Conversion( Octets_4, Float );
smg_comms_raw_types    89 
smg_comms_raw_types    90   function Cast is new Ada.Unchecked_Conversion( Integer_64, Octets_8 );
smg_comms_raw_types    91   function Cast is new Ada.Unchecked_Conversion( Octets_8, Integer_64 );
smg_comms_raw_types    92   function Cast is new Ada.Unchecked_Conversion( Unsigned_64, Octets_8 );
smg_comms_raw_types    93   function Cast is new Ada.Unchecked_Conversion( Octets_8, Unsigned_64 );
smg_comms_raw_types    94 
smg_comms_raw_types    95 end Raw_Types;