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smg_comms_rsa_oaep      1  -- Ada implementation of RSA with OAEP according to TMSR and Eulora spec
smg_comms_rsa_oaep      2  -- Uses: 
smg_comms_rsa_oaep      3  --   - Eulora's raw types (Ada, raw_types.ads)
smg_comms_rsa_oaep      4  --   - Keccak hashes (Ada, keccak.ads/adb)
smg_comms_rsa_oaep      5  --   - OAEP schema (Ada, oaep.ads/adb)
smg_comms_rsa_oaep      6  --   - RNG (Ada, rng.ads/adb) for true random padding
smg_comms_rsa_oaep      7  --   - C wrappers lib (C, c_wrappers/) for:
smg_comms_rsa_oaep      8  --       - MPI (C, mpi/)
smg_comms_rsa_oaep      9  --       - RSA (C, rsa/rsa.c)
smg_comms_rsa_oaep     10  -- 
smg_comms_rsa_oaep     11  -- S.MG, 2018
smg_comms_rsa_oaep     12 
smg_comms_rsa_oaep     13 with Raw_Types;
smg_comms_rsa_oaep     14 with Interfaces.C; use Interfaces.C;
smg_comms_rsa_oaep     15 
smg_comms_rsa_oaep     16 package RSA_OAEP is
smg_comms_rsa_oaep     17   -- exception for mismatched lengths when converting octets <-> char arrays
smg_comms_rsa_oaep     18   Mismatched_Lengths_Error: exception;
smg_comms_rsa_oaep     19 
smg_comms_rsa_oaep     20   -- public RSA key with n,e stored as raw octets
smg_comms_rsa_oaep     21   type RSA_pkey is
smg_comms_rsa_oaep     22     record
smg_comms_rsa_oaep     23       n : Raw_Types.RSA_len; --public modulus
smg_comms_rsa_oaep     24       e : Raw_Types.RSA_half; --public exponent
smg_comms_rsa_oaep     25     end record; --RSA_pkey
smg_comms_rsa_oaep     26 
smg_comms_rsa_oaep     27   -- private (secret) RSA key with components stored as raw octets
smg_comms_rsa_oaep     28   type RSA_skey is
smg_comms_rsa_oaep     29     record
smg_comms_rsa_oaep     30       n : Raw_Types.RSA_len;  --public modulus
smg_comms_rsa_oaep     31       e : Raw_Types.RSA_half; --public exponent
smg_comms_rsa_oaep     32       d : Raw_Types.RSA_len;  --secret exponent e*d=1 mod phi; phi=(p-1)*(q-1)
smg_comms_rsa_oaep     33       p : Raw_Types.RSA_half; --prime p
smg_comms_rsa_oaep     34       q : Raw_Types.RSA_half; --prime q
smg_comms_rsa_oaep     35       u : Raw_Types.RSA_half;  --inverse of p mod q; for faster calculations
smg_comms_rsa_oaep     36     end record; --RSA_skey
smg_comms_rsa_oaep     37 
smg_comms_rsa_oaep     38   -- Encryption RSA+OAEP (i.e. using public key)
smg_comms_rsa_oaep     39   -- NB: at most OAEP.MAX_LEN_MSG octets from Plain will be encrypted!
smg_comms_rsa_oaep     40   -- Relies directly on: 
smg_comms_rsa_oaep     41   --   oaep.adb/ads
smg_comms_rsa_oaep     42   --   c_wrappers.c ( RSA )
smg_comms_rsa_oaep     43   --   rng.adb/ads ( random padding )
smg_comms_rsa_oaep     44   procedure Encrypt( Plain: in Raw_Types.Octets;
smg_comms_rsa_oaep     45                      Key  : in RSA_pkey;
smg_comms_rsa_oaep     46                      Encr : out Raw_Types.RSA_len );
smg_comms_rsa_oaep     47 
smg_comms_rsa_oaep     48   -- Decryption RSA+OAEP (i.e. using private/secret key)
smg_comms_rsa_oaep     49   -- The opposite of Encrypt above.
smg_comms_rsa_oaep     50   -- NB: Plain has to have ENOUGH space for result!
smg_comms_rsa_oaep     51   -- Result can be at most OAEP.MAX_LEN_MSG octets.
smg_comms_rsa_oaep     52   -- Relies directly on:
smg_comms_rsa_oaep     53   --   oaep.adb/ads
smg_comms_rsa_oaep     54   --   c_wrappers.c (RSA)
smg_comms_rsa_oaep     55   -- Plain_Len gives the length in OCTETS of the decrypted message.
smg_comms_rsa_oaep     56   procedure Decrypt( Encr      : in Raw_Types.RSA_len;
smg_comms_rsa_oaep     57                      Key       : in RSA_skey;
smg_comms_rsa_oaep     58                      Plain     : out Raw_Types.Octets;
smg_comms_rsa_oaep     59                      Plain_Len : out Natural;
smg_comms_rsa_oaep     60                      Success   : out Boolean);
smg_comms_rsa_oaep     61 
smg_comms_rsa_oaep     62  --helper methods:
smg_comms_rsa_oaep     63  -- mainly conversions to/from C's char* and imports from C_wrappers
smg_comms_rsa_oaep     64   -- encrypt with public RSA key given as struct, Ada style
smg_comms_rsa_oaep     65   -- NB: result is potentially 0-led (i.e. at end of Encr not at start!)
smg_comms_rsa_oaep     66   procedure Public_RSA( Plain: in Raw_Types.Octets;
smg_comms_rsa_oaep     67                         Key  : in RSA_pkey;
smg_comms_rsa_oaep     68                         Encr : out Raw_Types.RSA_len);
smg_comms_rsa_oaep     69 
smg_comms_rsa_oaep     70   -- encrypt with public RSA key given as char arrays, via C_Wrappers
smg_comms_rsa_oaep     71   -- this returns the length of result because C functions trim leading 0s!
smg_comms_rsa_oaep     72   function Public_RSA_C( Encr      : out Interfaces.C.char_array; 
smg_comms_rsa_oaep     73                          Encr_Len  : in Integer;
smg_comms_rsa_oaep     74                          Plain     : in Interfaces.C.char_array;
smg_comms_rsa_oaep     75                          Plain_Len : in Integer;
smg_comms_rsa_oaep     76                          RSA_N     : in Interfaces.C.char_array;
smg_comms_rsa_oaep     77                          N_Len     : in Integer;
smg_comms_rsa_oaep     78                          RSA_E     : in Interfaces.C.char_array;
smg_comms_rsa_oaep     79                          E_Len     : in Integer)
smg_comms_rsa_oaep     80                      return Integer;
smg_comms_rsa_oaep     81    pragma Import(C, Public_RSA_C, "public_rsa_octets"); 
smg_comms_rsa_oaep     82 
smg_comms_rsa_oaep     83   -- decrypt with private RSA key given as struct, Ada style
smg_comms_rsa_oaep     84   -- NB: Plain has to have ENOUGH space!
smg_comms_rsa_oaep     85   -- NB: Result is potentially 0-led (i.e. at the end of Plain, not at start!)
smg_comms_rsa_oaep     86   -- @return actual length of result
smg_comms_rsa_oaep     87   procedure Private_RSA( Encr  : in Raw_Types.RSA_len;
smg_comms_rsa_oaep     88                          Key   : in RSA_skey;
smg_comms_rsa_oaep     89                          Plain : out Raw_Types.Octets);
smg_comms_rsa_oaep     90 
smg_comms_rsa_oaep     91   -- encrypt with private/secret RSA key given as char arrays (via C_wrappers)
smg_comms_rsa_oaep     92   -- this returns length because C methods trim leading 0s
smg_comms_rsa_oaep     93   function Private_RSA_C( Plain     : out Interfaces.C.char_array;
smg_comms_rsa_oaep     94                           Plain_Len : in Integer;
smg_comms_rsa_oaep     95                           Encr      : in Interfaces.C.char_array;
smg_comms_rsa_oaep     96                           Encr_Len  : in Integer;
smg_comms_rsa_oaep     97                           RSA_N     : in Interfaces.C.char_array;
smg_comms_rsa_oaep     98                           N_Len     : in Integer;
smg_comms_rsa_oaep     99                           RSA_E     : in Interfaces.C.char_array;
smg_comms_rsa_oaep    100                           E_Len     : in Integer;
smg_comms_rsa_oaep    101                           RSA_D     : in Interfaces.C.char_array;
smg_comms_rsa_oaep    102                           D_Len     : in Integer;
smg_comms_rsa_oaep    103                           RSA_P     : in Interfaces.C.char_array;
smg_comms_rsa_oaep    104                           P_Len     : in Integer;
smg_comms_rsa_oaep    105                           RSA_Q     : in Interfaces.C.char_array;
smg_comms_rsa_oaep    106                           Q_Len     : in Integer;
smg_comms_rsa_oaep    107                           RSA_U     : in Interfaces.C.char_array;
smg_comms_rsa_oaep    108                           U_Len     : in Integer)
smg_comms_rsa_oaep    109                       return Integer;
smg_comms_rsa_oaep    110   pragma Import( C, Private_RSA_C, "private_rsa_octets" );
smg_comms_rsa_oaep    111 
smg_comms_rsa_oaep    112   -- convert from Ada's Octets (array of octets) to C's char* (char_array)
smg_comms_rsa_oaep    113 
smg_comms_rsa_oaep    114   -- This copies the octets from O to the beginning of A
smg_comms_rsa_oaep    115   -- NB: there are NO checks or memory allocations here!
smg_comms_rsa_oaep    116   -- Caller has to make sure that:
smg_comms_rsa_oaep    117   --   A has allocated space for at least O'Length octets!
smg_comms_rsa_oaep    118   procedure Octets_To_Char_Array( O   : in Raw_Types.Octets;
smg_comms_rsa_oaep    119                                   A   : out Interfaces.C.char_array);
smg_comms_rsa_oaep    120 
smg_comms_rsa_oaep    121 
smg_comms_rsa_oaep    122   -- This copies first O'Length characters from A to O
smg_comms_rsa_oaep    123   -- NB: this does NOT allocate /check memory!
smg_comms_rsa_oaep    124   -- Caller has to ensure that:
smg_comms_rsa_oaep    125   --    A has space at least O'Length characters
smg_comms_rsa_oaep    126   procedure Char_Array_To_Octets( A   : in Interfaces.C.char_array;
smg_comms_rsa_oaep    127                                   O   : out Raw_Types.Octets);
smg_comms_rsa_oaep    128 
smg_comms_rsa_oaep    129 end RSA_OAEP;