1------------------------------------------------------------------------------ 2-- -- 3-- GNAT LIBRARY COMPONENTS -- 4-- -- 5-- G N A T . S E C U R E _ H A S H E S -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 2009-2014, Free Software Foundation, Inc. -- 10-- -- 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. -- 17-- -- 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. -- 21-- -- 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/>. -- 26-- -- 27-- GNAT was originally developed by the GNAT team at New York University. -- 28-- Extensive contributions were provided by Ada Core Technologies Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32with System; use System; 33with Interfaces; use Interfaces; 34 35package body GNAT.Secure_Hashes is 36 37 Hex_Digit : constant array (Stream_Element range 0 .. 15) of Character := 38 "0123456789abcdef"; 39 40 type Fill_Buffer_Access is 41 access procedure 42 (M : in out Message_State; 43 S : String; 44 First : Natural; 45 Last : out Natural); 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 48 -- consumed. 49 50 procedure Fill_Buffer_Copy 51 (M : in out Message_State; 52 S : String; 53 First : Natural; 54 Last : out Natural); 55 -- Transfer procedure which just copies data from S to M 56 57 procedure Fill_Buffer_Swap 58 (M : in out Message_State; 59 S : String; 60 First : Natural; 61 Last : out Natural); 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 67 -- S (S'First). 68 69 procedure To_String (SEA : Stream_Element_Array; S : out String); 70 -- Return the hexadecimal representation of SEA 71 72 ---------------------- 73 -- Fill_Buffer_Copy -- 74 ---------------------- 75 76 procedure Fill_Buffer_Copy 77 (M : in out Message_State; 78 S : String; 79 First : Natural; 80 Last : out Natural) 81 is 82 Buf_String : String (M.Buffer'Range); 83 for Buf_String'Address use M.Buffer'Address; 84 pragma Import (Ada, Buf_String); 85 86 Length : constant Natural := 87 Natural'Min (M.Block_Length - M.Last, S'Last - First + 1); 88 89 begin 90 pragma Assert (Length > 0); 91 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; 96 end Fill_Buffer_Copy; 97 98 ---------------------- 99 -- Fill_Buffer_Swap -- 100 ---------------------- 101 102 procedure Fill_Buffer_Swap 103 (M : in out Message_State; 104 S : String; 105 First : Natural; 106 Last : out Natural) 107 is 108 pragma Assert (S'Length mod 2 = 0); 109 Length : constant Natural := 110 Natural'Min (M.Block_Length - M.Last, S'Last - First + 1); 111 begin 112 Last := First; 113 while Last - First < Length loop 114 M.Buffer (M.Last + 1 + Last - First) := 115 (if (Last - S'First) mod 2 = 0 116 then S (Last + 1) 117 else S (Last - 1)); 118 Last := Last + 1; 119 end loop; 120 M.Last := M.Last + Length; 121 Last := First + Length - 1; 122 end Fill_Buffer_Swap; 123 124 --------------- 125 -- To_String -- 126 --------------- 127 128 procedure To_String (SEA : Stream_Element_Array; S : out String) is 129 pragma Assert (S'Length = 2 * SEA'Length); 130 begin 131 for J in SEA'Range loop 132 declare 133 S_J : constant Natural := 1 + Natural (J - SEA'First) * 2; 134 begin 135 S (S_J) := Hex_Digit (SEA (J) / 16); 136 S (S_J + 1) := Hex_Digit (SEA (J) mod 16); 137 end; 138 end loop; 139 end To_String; 140 141 ------- 142 -- H -- 143 ------- 144 145 package body H is 146 147 procedure Update 148 (C : in out Context; 149 S : String; 150 Fill_Buffer : Fill_Buffer_Access); 151 -- Internal common routine for all Update procedures 152 153 procedure Final 154 (C : Context; 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. 158 159 ------------ 160 -- Digest -- 161 ------------ 162 163 function Digest (C : Context) return Message_Digest is 164 Hash_Bits : Stream_Element_Array 165 (1 .. Stream_Element_Offset (Hash_Length)); 166 begin 167 Final (C, Hash_Bits); 168 return MD : Message_Digest do 169 To_String (Hash_Bits, MD); 170 end return; 171 end Digest; 172 173 function Digest (S : String) return Message_Digest is 174 C : Context; 175 begin 176 Update (C, S); 177 return Digest (C); 178 end Digest; 179 180 function Digest (A : Stream_Element_Array) return Message_Digest is 181 C : Context; 182 begin 183 Update (C, A); 184 return Digest (C); 185 end Digest; 186 187 function Digest (C : Context) return Binary_Message_Digest is 188 Hash_Bits : Stream_Element_Array 189 (1 .. Stream_Element_Offset (Hash_Length)); 190 begin 191 Final (C, Hash_Bits); 192 return Hash_Bits; 193 end Digest; 194 195 function Digest (S : String) return Binary_Message_Digest is 196 C : Context; 197 begin 198 Update (C, S); 199 return Digest (C); 200 end Digest; 201 202 function Digest 203 (A : Stream_Element_Array) return Binary_Message_Digest 204 is 205 C : Context; 206 begin 207 Update (C, A); 208 return Digest (C); 209 end Digest; 210 211 ----------- 212 -- Final -- 213 ----------- 214 215 -- 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). 219 220 procedure Final 221 (C : Context; 222 Hash_Bits : out Stream_Element_Array) 223 is 224 FC : Context := C; 225 226 Zeroes : Natural; 227 -- Number of 0 bytes in padding 228 229 Message_Length : Unsigned_64 := FC.M_State.Length; 230 -- Message length in bytes 231 232 Size_Length : constant Natural := 233 2 * Hash_State.Word'Size / 8; 234 -- Length in bytes of the size representation 235 236 begin 237 Zeroes := (Block_Length - 1 - Size_Length - FC.M_State.Last) 238 mod FC.M_State.Block_Length; 239 declare 240 Pad : String (1 .. 1 + Zeroes + Size_Length) := 241 (1 => Character'Val (128), others => ASCII.NUL); 242 243 Index : Natural; 244 First_Index : Natural; 245 246 begin 247 First_Index := (if Hash_Bit_Order = Low_Order_First 248 then Pad'Last - Size_Length + 1 249 else Pad'Last); 250 251 Index := First_Index; 252 while Message_Length > 0 loop 253 if Index = First_Index then 254 255 -- Message_Length is in bytes, but we need to store it as 256 -- a bit count). 257 258 Pad (Index) := Character'Val 259 (Shift_Left (Message_Length and 16#1f#, 3)); 260 Message_Length := Shift_Right (Message_Length, 5); 261 262 else 263 Pad (Index) := Character'Val (Message_Length and 16#ff#); 264 Message_Length := Shift_Right (Message_Length, 8); 265 end if; 266 267 Index := Index + 268 (if Hash_Bit_Order = Low_Order_First then 1 else -1); 269 end loop; 270 271 Update (FC, Pad); 272 end; 273 274 pragma Assert (FC.M_State.Last = 0); 275 276 Hash_State.To_Hash (FC.H_State, Hash_Bits); 277 278 -- HMAC case: hash outer pad 279 280 if C.KL /= 0 then 281 declare 282 Outer_C : Context; 283 Opad : Stream_Element_Array := 284 (1 .. Stream_Element_Offset (Block_Length) => 16#5c#); 285 286 begin 287 for J in C.Key'Range loop 288 Opad (J) := Opad (J) xor C.Key (J); 289 end loop; 290 291 Update (Outer_C, Opad); 292 Update (Outer_C, Hash_Bits); 293 294 Final (Outer_C, Hash_Bits); 295 end; 296 end if; 297 end Final; 298 299 -------------------------- 300 -- HMAC_Initial_Context -- 301 -------------------------- 302 303 function HMAC_Initial_Context (Key : String) return Context is 304 begin 305 if Key'Length = 0 then 306 raise Constraint_Error with "null key"; 307 end if; 308 309 return C : Context (KL => (if Key'Length <= Key_Length'Last 310 then Key'Length 311 else Stream_Element_Offset (Hash_Length))) 312 do 313 -- Set Key (if longer than block length, first hash it) 314 315 if C.KL = Key'Length then 316 declare 317 SK : String (1 .. Key'Length); 318 for SK'Address use C.Key'Address; 319 pragma Import (Ada, SK); 320 begin 321 SK := Key; 322 end; 323 324 else 325 C.Key := Digest (Key); 326 end if; 327 328 -- Hash inner pad 329 330 declare 331 Ipad : Stream_Element_Array := 332 (1 .. Stream_Element_Offset (Block_Length) => 16#36#); 333 334 begin 335 for J in C.Key'Range loop 336 Ipad (J) := Ipad (J) xor C.Key (J); 337 end loop; 338 339 Update (C, Ipad); 340 end; 341 end return; 342 end HMAC_Initial_Context; 343 344 ------------ 345 -- Update -- 346 ------------ 347 348 procedure Update 349 (C : in out Context; 350 S : String; 351 Fill_Buffer : Fill_Buffer_Access) 352 is 353 Last : Natural; 354 355 begin 356 C.M_State.Length := C.M_State.Length + S'Length; 357 358 Last := S'First - 1; 359 while Last < S'Last loop 360 Fill_Buffer (C.M_State, S, Last + 1, Last); 361 362 if C.M_State.Last = Block_Length then 363 Transform (C.H_State, C.M_State); 364 C.M_State.Last := 0; 365 end if; 366 end loop; 367 368 end Update; 369 370 ------------ 371 -- Update -- 372 ------------ 373 374 procedure Update (C : in out Context; Input : String) is 375 begin 376 Update (C, Input, Fill_Buffer_Copy'Access); 377 end Update; 378 379 ------------ 380 -- Update -- 381 ------------ 382 383 procedure Update (C : in out Context; Input : Stream_Element_Array) is 384 S : String (1 .. Input'Length); 385 for S'Address use Input'Address; 386 pragma Import (Ada, S); 387 begin 388 Update (C, S, Fill_Buffer_Copy'Access); 389 end Update; 390 391 ----------------- 392 -- Wide_Update -- 393 ----------------- 394 395 procedure Wide_Update (C : in out Context; Input : Wide_String) is 396 S : String (1 .. 2 * Input'Length); 397 for S'Address use Input'Address; 398 pragma Import (Ada, S); 399 begin 400 Update 401 (C, S, 402 (if System.Default_Bit_Order /= Low_Order_First 403 then Fill_Buffer_Swap'Access 404 else Fill_Buffer_Copy'Access)); 405 end Wide_Update; 406 407 ----------------- 408 -- Wide_Digest -- 409 ----------------- 410 411 function Wide_Digest (W : Wide_String) return Message_Digest is 412 C : Context; 413 begin 414 Wide_Update (C, W); 415 return Digest (C); 416 end Wide_Digest; 417 418 function Wide_Digest (W : Wide_String) return Binary_Message_Digest is 419 C : Context; 420 begin 421 Wide_Update (C, W); 422 return Digest (C); 423 end Wide_Digest; 424 425 end H; 426 427 ------------------------- 428 -- Hash_Function_State -- 429 ------------------------- 430 431 package body Hash_Function_State is 432 433 ------------- 434 -- To_Hash -- 435 ------------- 436 437 procedure To_Hash (H : State; H_Bits : out Stream_Element_Array) is 438 Hash_Words : constant Natural := H'Size / Word'Size; 439 Result : State (1 .. Hash_Words) := 440 H (H'Last - Hash_Words + 1 .. H'Last); 441 442 R_SEA : Stream_Element_Array (1 .. Result'Size / 8); 443 for R_SEA'Address use Result'Address; 444 pragma Import (Ada, R_SEA); 445 446 begin 447 if System.Default_Bit_Order /= Hash_Bit_Order then 448 for J in Result'Range loop 449 Swap (Result (J)'Address); 450 end loop; 451 end if; 452 453 -- Return truncated hash 454 455 pragma Assert (H_Bits'Length <= R_SEA'Length); 456 H_Bits := R_SEA (R_SEA'First .. R_SEA'First + H_Bits'Length - 1); 457 end To_Hash; 458 459 end Hash_Function_State; 460 461end GNAT.Secure_Hashes; 462