File : tigertree.adb
------------------------------------------------------------------------------
-- ADAGIO - ADALID - AENEA. --
-- --
-- Copyright (C) 2003 --
-- A. Mosteo. --
-- --
-- Authors: A. Mosteo. (adagio@mosteo.com) --
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-- This program is free software; you can redistribute it and/or modify --
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-- General Public License for more details. --
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------------------------------------------------------------------------------
-- $Id: tigertree.adb,v 1.3 2004/01/21 21:05:47 Jano Exp $
-- Types and functions to instantiate a TigerTree using HashTree.ads
with Acf.Types;
with Bit_arrays;
with Bit_arrays.Numbers;
with Bit_arrays.Modular;
package body TigerTree is
package Tiger renames Acf.Hash.Algorithms.Tiger;
package Byte_bit is new Bit_arrays.Modular (Acf.Types.Byte);
------------------------------------------------------------------------
-- Begin_hash --
------------------------------------------------------------------------
procedure Begin_hash (Context : in out Hash_context) is
begin
Tiger.Hash_start (Context.Context'Access);
end Begin_hash;
------------------------------------------------------------------------
-- End_hash --
------------------------------------------------------------------------
function End_hash (Context : in Hash_context) return Hash_type is
Result : Hash_type;
begin
Result.Hash := Tiger.Hash_end (Context.Context'Unrestricted_access);
return Result;
end;
------------------------------------------------------------------------
-- Update_hash --
------------------------------------------------------------------------
procedure Update_hash (
Context : in out Hash_context;
Bytes : in Byte_array) is
begin
Tiger.Hash_update (Context.Context'Access, Bytes);
end Update_hash;
------------------------------------------------------------------------
-- Start_leaf_hash --
------------------------------------------------------------------------
procedure Start_leaf_hash (Context : in out Hash_context) is
begin
Tiger.Hash_update (
Context.Context'Access,
Acf.Types.Byte_array'(1 => 0));
end Start_leaf_hash;
------------------------------------------------------------------------
-- Start_intermediate_hash --
------------------------------------------------------------------------
procedure Start_intermediate_hash (Context : in out Hash_context) is
begin
Tiger.Hash_update (
Context.Context'Access,
Acf.Types.Byte_array'(1 => 1));
end Start_intermediate_hash;
------------------------------------------------------------------------
-- To_hash --
------------------------------------------------------------------------
-- Converts a byte array into a hash
function To_hash (Bytes : in Byte_array) return Hash_type is
B : Byte_array (Bytes'Range);
Hash : Hash_type;
begin
-- Reverse Bytes:
for N in 0 .. 7 loop
B (B'First + N) := Bytes (Bytes'First + 7 - N);
end loop;
for N in 8 .. 15 loop
B (B'First + N) := Bytes (Bytes'First + 15 - N + 8);
end loop;
for N in 16 .. 23 loop
B (B'First + N) := Bytes (Bytes'First + 23 - N + 16);
end loop;
Hash.Hash := Acf.Hash.Message_digests.To_message_digest (B);
return Hash;
end To_hash;
------------------------------------------------------------------------
-- To_byte_array --
------------------------------------------------------------------------
-- Returns a Hash as a Byte_array
-- We must reverse the byte orders because that's the way it is done
-- in gnutella (little endian instead of big endian)
function To_byte_array (This : in Hash_type) return Byte_array is
Bytes : Byte_array :=
Acf.Hash.Message_digests.To_byte_array (This.Hash);
B : Byte_array (Bytes'Range);
begin
-- Reverse Bytes:
for N in 0 .. 7 loop
B (B'First + N) := Bytes (Bytes'First + 7 - N);
end loop;
for N in 8 .. 15 loop
B (B'First + N) := Bytes (Bytes'First + 15 - N + 8);
end loop;
for N in 16 .. 23 loop
B (B'First + N) := Bytes (Bytes'First + 23 - N + 16);
end loop;
return B;
end To_byte_array;
------------------------------------------------------------------------
-- To_hex --
------------------------------------------------------------------------
-- Hex representation of a hash:
function To_hex (This : in Hash_type) return String is
begin
return Acf.Hash.Message_digests.To_hex_string (This.Hash);
end To_hex;
------------------------------------------------------------------------
-- To_base32 --
------------------------------------------------------------------------
-- Base32 representation of a hash:
function To_base32 (This : in Hash_type) return String is
Bytes : Acf.Types.Byte_array := To_byte_array (This);
use Bit_arrays;
Base32 : array (0 .. 31) of Character :=
"ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
Raw : Bit_array (1 .. 195) := (others => false);
Pos : Natural := Raw'First;
s : String (1 .. Raw'Length / 5);
begin
if Bytes'Length /= 24 then
raise Constraint_error;
end if;
for i in Bytes'range loop
Raw (Pos .. Pos + 7) := Byte_bit.To_bit_array_BE (Bytes (i));
Pos:= Pos + 8;
end loop;
-- Churn the base32 representation:
Pos := Raw'First;
for i in s'range loop
s (i) :=
Base32 (Bit_arrays.Numbers.To_number_BE (Raw (Pos .. Pos + 4)));
Pos := Pos + 5;
end loop;
return s;
end To_base32;
------------------------------------------------------------------------
-- To_char_array
------------------------------------------------------------------------
-- Returns a Hash as a string of bytes
function To_char_array (This : in Hash_type) return String is
B : Byte_array := To_byte_array (This);
S : String (B'range);
begin
for N in S'range loop
S (N) := Character'Val (Byte'Pos (B (N)));
end loop;
return S;
end To_char_array;
end TigerTree;