-- reading a RSA key pair from a file
 -- NB: this is for TESTING purposes only, NOT a production IO package!
 -- S.MG, 2018

with Raw_Types;
with RSA_OAEP;

package IO_RSA is

  Incorrect_E_Len: exception;
  Incorrect_D_Len: exception;

  -- reads a full private key from specified file, in Hex format
  -- one component per line, in order: n, e, d, p, q, u
  -- NB: length of each component has to match *precisely* the expected length
  -- e (public exponent) has the length given as argument
  -- if E_Len < RSA_half'Length then e is stored 0-led in Key.e
  -- if E_Len > RSA_half'Length then this will FAIL. 
  -- specifically, using Raw_Types: 
  --   n is RSA_len'Length octets (so *2 chars read); 
  --   p, q, u are RSA_half'Length (so *2 chars read);
  --   e is RSA_half'Length but E_Len_Chars chars will be read;
  --   d is RSA_len'Length but D_Len_Chars chars will be read;
  procedure ReadRSAKey( Filename    : in String; 
                        E_Len_Chars : in Positive;
                        D_Len_Chars : in Positive;
                        Key         : out RSA_OAEP.RSA_skey );

  -- convert hexadecimal strings to octets representation
  procedure Hex2Octets( Hex: in String; O: out Raw_Types.Octets );

end IO_RSA;