| ------------------------------------------------------------------------------ |
| -- -- |
| -- 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) 2009-2021, 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 (Stream_Element_Offset (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; |
