1 ------------------------------------------------------------------------------
3 -- GNAT LIBRARY COMPONENTS --
5 -- G N A T . S E C U R E _ H A S H E S --
9 -- Copyright (C) 2009-2019, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
32 with System; use System;
33 with Interfaces; use Interfaces;
35 package body GNAT.Secure_Hashes is
37 Hex_Digit : constant array (Stream_Element range 0 .. 15) of Character :=
40 type Fill_Buffer_Access is
42 (M : in out Message_State;
46 -- A procedure to transfer data from S, starting at First, into M's block
47 -- buffer until either the block buffer is full or all data from S has been
50 procedure Fill_Buffer_Copy
51 (M : in out Message_State;
55 -- Transfer procedure which just copies data from S to M
57 procedure Fill_Buffer_Swap
58 (M : in out Message_State;
62 -- Transfer procedure which swaps bytes from S when copying into M. S must
63 -- have even length. Note that the swapping is performed considering pairs
64 -- starting at S'First, even if S'First /= First (that is, if
65 -- First = S'First then the first copied byte is always S (S'First + 1),
66 -- and if First = S'First + 1 then the first copied byte is always
69 procedure To_String (SEA : Stream_Element_Array; S : out String);
70 -- Return the hexadecimal representation of SEA
72 ----------------------
73 -- Fill_Buffer_Copy --
74 ----------------------
76 procedure Fill_Buffer_Copy
77 (M : in out Message_State;
82 Buf_String : String (M.Buffer'Range);
83 for Buf_String'Address use M.Buffer'Address;
84 pragma Import (Ada, Buf_String);
86 Length : constant Natural :=
87 Natural'Min (M.Block_Length - M.Last, S'Last - First + 1);
90 pragma Assert (Length > 0);
92 Buf_String (M.Last + 1 .. M.Last + Length) :=
93 S (First .. First + Length - 1);
94 M.Last := M.Last + Length;
95 Last := First + Length - 1;
98 ----------------------
99 -- Fill_Buffer_Swap --
100 ----------------------
102 procedure Fill_Buffer_Swap
103 (M : in out Message_State;
108 pragma Assert (S'Length mod 2 = 0);
109 Length : constant Natural :=
110 Natural'Min (M.Block_Length - M.Last, S'Last - First + 1);
113 while Last - First < Length loop
114 M.Buffer (M.Last + 1 + Last - First) :=
115 (if (Last - S'First) mod 2 = 0
120 M.Last := M.Last + Length;
121 Last := First + Length - 1;
122 end Fill_Buffer_Swap;
128 procedure To_String (SEA : Stream_Element_Array; S : out String) is
129 pragma Assert (S'Length = 2 * SEA'Length);
131 for J in SEA'Range loop
133 S_J : constant Natural := 1 + Natural (J - SEA'First) * 2;
135 S (S_J) := Hex_Digit (SEA (J) / 16);
136 S (S_J + 1) := Hex_Digit (SEA (J) mod 16);
150 Fill_Buffer : Fill_Buffer_Access);
151 -- Internal common routine for all Update procedures
155 Hash_Bits : out Ada.Streams.Stream_Element_Array);
156 -- Perform final hashing operations (data padding) and extract the
157 -- (possibly truncated) state of C into Hash_Bits.
163 function Digest (C : Context) return Message_Digest is
164 Hash_Bits : Stream_Element_Array
165 (1 .. Stream_Element_Offset (Hash_Length));
167 Final (C, Hash_Bits);
168 return MD : Message_Digest do
169 To_String (Hash_Bits, MD);
173 function Digest (S : String) return Message_Digest is
180 function Digest (A : Stream_Element_Array) return Message_Digest is
187 function Digest (C : Context) return Binary_Message_Digest is
188 Hash_Bits : Stream_Element_Array
189 (1 .. Stream_Element_Offset (Hash_Length));
191 Final (C, Hash_Bits);
195 function Digest (S : String) return Binary_Message_Digest is
203 (A : Stream_Element_Array) return Binary_Message_Digest
215 -- Once a complete message has been processed, it is padded with one 1
216 -- bit followed by enough 0 bits so that the last block is 2 * Word'Size
217 -- bits short of being completed. The last 2 * Word'Size bits are set to
218 -- the message size in bits (excluding padding).
222 Hash_Bits : out Stream_Element_Array)
227 -- Number of 0 bytes in padding
229 Message_Length : Unsigned_64 := FC.M_State.Length;
230 -- Message length in bytes
232 Size_Length : constant Natural :=
233 2 * Hash_State.Word'Size / 8;
234 -- Length in bytes of the size representation
237 Zeroes := (Block_Length - 1 - Size_Length - FC.M_State.Last)
238 mod FC.M_State.Block_Length;
240 Pad : String (1 .. 1 + Zeroes + Size_Length) :=
241 (1 => Character'Val (128), others => ASCII.NUL);
244 First_Index : Natural;
247 First_Index := (if Hash_Bit_Order = Low_Order_First
248 then Pad'Last - Size_Length + 1
251 Index := First_Index;
252 while Message_Length > 0 loop
253 if Index = First_Index then
255 -- Message_Length is in bytes, but we need to store it as
258 Pad (Index) := Character'Val
259 (Shift_Left (Message_Length and 16#1f#, 3));
260 Message_Length := Shift_Right (Message_Length, 5);
263 Pad (Index) := Character'Val (Message_Length and 16#ff#);
264 Message_Length := Shift_Right (Message_Length, 8);
268 (if Hash_Bit_Order = Low_Order_First then 1 else -1);
274 pragma Assert (FC.M_State.Last = 0);
276 Hash_State.To_Hash (FC.H_State, Hash_Bits);
278 -- HMAC case: hash outer pad
283 Opad : Stream_Element_Array :=
284 (1 .. Stream_Element_Offset (Block_Length) => 16#5c#);
287 for J in C.Key'Range loop
288 Opad (J) := Opad (J) xor C.Key (J);
291 Update (Outer_C, Opad);
292 Update (Outer_C, Hash_Bits);
294 Final (Outer_C, Hash_Bits);
299 --------------------------
300 -- HMAC_Initial_Context --
301 --------------------------
303 function HMAC_Initial_Context (Key : String) return Context is
305 if Key'Length = 0 then
306 raise Constraint_Error with "null key";
309 return C : Context (KL => (if Key'Length <= Key_Length'Last
311 else Stream_Element_Offset (Hash_Length)))
313 -- Set Key (if longer than block length, first hash it)
315 if C.KL = Key'Length then
317 SK : String (1 .. Key'Length);
318 for SK'Address use C.Key'Address;
319 pragma Import (Ada, SK);
325 C.Key := Digest (Key);
331 Ipad : Stream_Element_Array :=
332 (1 .. Stream_Element_Offset (Block_Length) => 16#36#);
335 for J in C.Key'Range loop
336 Ipad (J) := Ipad (J) xor C.Key (J);
342 end HMAC_Initial_Context;
349 (Stream : in out Hash_Stream;
350 Item : out Stream_Element_Array;
351 Last : out Stream_Element_Offset)
353 pragma Unreferenced (Stream, Item, Last);
355 raise Program_Error with "Hash_Stream is write-only";
365 Fill_Buffer : Fill_Buffer_Access)
370 C.M_State.Length := C.M_State.Length + S'Length;
373 while Last < S'Last loop
374 Fill_Buffer (C.M_State, S, Last + 1, Last);
376 if C.M_State.Last = Block_Length then
377 Transform (C.H_State, C.M_State);
387 procedure Update (C : in out Context; Input : String) is
389 Update (C, Input, Fill_Buffer_Copy'Access);
396 procedure Update (C : in out Context; Input : Stream_Element_Array) is
397 S : String (1 .. Input'Length);
398 for S'Address use Input'Address;
399 pragma Import (Ada, S);
401 Update (C, S, Fill_Buffer_Copy'Access);
408 procedure Wide_Update (C : in out Context; Input : Wide_String) is
409 S : String (1 .. 2 * Input'Length);
410 for S'Address use Input'Address;
411 pragma Import (Ada, S);
415 (if System.Default_Bit_Order /= Low_Order_First
416 then Fill_Buffer_Swap'Access
417 else Fill_Buffer_Copy'Access));
424 function Wide_Digest (W : Wide_String) return Message_Digest is
431 function Wide_Digest (W : Wide_String) return Binary_Message_Digest is
443 (Stream : in out Hash_Stream;
444 Item : Stream_Element_Array)
447 Update (Stream.C.all, Item);
452 -------------------------
453 -- Hash_Function_State --
454 -------------------------
456 package body Hash_Function_State is
462 procedure To_Hash (H : State; H_Bits : out Stream_Element_Array) is
463 Hash_Words : constant Natural := H'Size / Word'Size;
464 Result : State (1 .. Hash_Words) :=
465 H (H'Last - Hash_Words + 1 .. H'Last);
467 R_SEA : Stream_Element_Array (1 .. Result'Size / 8);
468 for R_SEA'Address use Result'Address;
469 pragma Import (Ada, R_SEA);
472 if System.Default_Bit_Order /= Hash_Bit_Order then
473 for J in Result'Range loop
474 Swap (Result (J)'Address);
478 -- Return truncated hash
480 pragma Assert (H_Bits'Length <= R_SEA'Length);
481 H_Bits := R_SEA (R_SEA'First .. R_SEA'First + H_Bits'Length - 1);
484 end Hash_Function_State;
486 end GNAT.Secure_Hashes;