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------------------------------------------------------------------------------ -- -- -- GNAT LIBRARY COMPONENTS -- -- -- -- G N A T . S E C U R E _ H A S H E S . S H A 2 _ C O M M O N -- -- -- -- B o d y -- -- -- -- Copyright (C) 2009, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. -- -- -- -- As a special exception under Section 7 of GPL version 3, you are granted -- -- additional permissions described in the GCC Runtime Library Exception, -- -- version 3.1, as published by the Free Software Foundation. -- -- -- -- You should have received a copy of the GNU General Public License and -- -- a copy of the GCC Runtime Library Exception along with this program; -- -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- -- <http://www.gnu.org/licenses/>. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ package body GNAT.Secure_Hashes.SHA2_Common is --------------- -- Transform -- --------------- procedure Transform (H_St : in out Hash_State.State; M_St : in out Message_State) is use System; subtype Word is Hash_State.Word; use type Hash_State.Word; function Ch (X, Y, Z : Word) return Word; function Maj (X, Y, Z : Word) return Word; pragma Inline (Ch, Maj); -- Elementary functions from FIPS PUB 180-3 -------- -- Ch -- -------- function Ch (X, Y, Z : Word) return Word is begin return (X and Y) xor ((not X) and Z); end Ch; --------- -- Maj -- --------- function Maj (X, Y, Z : Word) return Word is begin return (X and Y) xor (X and Z) xor (Y and Z); end Maj; type Words is array (Natural range <>) of Word; X : Words (0 .. 15); for X'Address use M_St.Buffer'Address; pragma Import (Ada, X); W : Words (0 .. Rounds - 1); A, B, C, D, E, F, G, H, T1, T2 : Word; -- Start of processing for Transform begin if Default_Bit_Order /= High_Order_First then for J in X'Range loop Hash_State.Swap (X (J)'Address); end loop; end if; -- 1. Prepare message schedule W (0 .. 15) := X; for T in 16 .. Rounds - 1 loop W (T) := S1 (W (T - 2)) + W (T - 7) + S0 (W (T - 15)) + W (T - 16); end loop; -- 2. Initialize working variables A := H_St (0); B := H_St (1); C := H_St (2); D := H_St (3); E := H_St (4); F := H_St (5); G := H_St (6); H := H_St (7); -- 3. Perform transformation rounds for T in 0 .. Rounds - 1 loop T1 := H + Sigma1 (E) + Ch (E, F, G) + K (T) + W (T); T2 := Sigma0 (A) + Maj (A, B, C); H := G; G := F; F := E; E := D + T1; D := C; C := B; B := A; A := T1 + T2; end loop; -- 4. Update hash state H_St (0) := A + H_St (0); H_St (1) := B + H_St (1); H_St (2) := C + H_St (2); H_St (3) := D + H_St (3); H_St (4) := E + H_St (4); H_St (5) := F + H_St (5); H_St (6) := G + H_St (6); H_St (7) := H + H_St (7); end Transform; end GNAT.Secure_Hashes.SHA2_Common;
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