File : g-sehash.adb
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT LIBRARY COMPONENTS --
4 -- --
5 -- G N A T . S E C U R E _ H A S H E S . S H A 1 --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 2002-2009, 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 -- --
19 -- --
20 -- --
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
32 package body GNAT.Secure_Hashes.SHA1 is
33
34 use Interfaces;
35 use GNAT.Byte_Swapping;
36
37 -- The following functions are the four elementary components of each
38 -- of the four round groups (0 .. 19, 20 .. 39, 40 .. 59, and 60 .. 79)
39 -- defined in RFC 3174.
40
41 function F0 (B, C, D : Unsigned_32) return Unsigned_32;
42 pragma Inline (F0);
43
44 function F1 (B, C, D : Unsigned_32) return Unsigned_32;
45 pragma Inline (F1);
46
47 function F2 (B, C, D : Unsigned_32) return Unsigned_32;
48 pragma Inline (F2);
49
50 function F3 (B, C, D : Unsigned_32) return Unsigned_32;
51 pragma Inline (F3);
52
53 --------
54 -- F0 --
55 --------
56
57 function F0
58 (B, C, D : Interfaces.Unsigned_32) return Interfaces.Unsigned_32
59 is
60 begin
61 return (B and C) or ((not B) and D);
62 end F0;
63
64 --------
65 -- F1 --
66 --------
67
68 function F1
69 (B, C, D : Interfaces.Unsigned_32) return Interfaces.Unsigned_32
70 is
71 begin
72 return B xor C xor D;
73 end F1;
74
75 --------
76 -- F2 --
77 --------
78
79 function F2
80 (B, C, D : Interfaces.Unsigned_32) return Interfaces.Unsigned_32
81 is
82 begin
83 return (B and C) or (B and D) or (C and D);
84 end F2;
85
86 --------
87 -- F3 --
88 --------
89
90 function F3
91 (B, C, D : Interfaces.Unsigned_32) return Interfaces.Unsigned_32
92 renames F1;
93
94 ---------------
95 -- Transform --
96 ---------------
97
98 procedure Transform
99 (H : in out Hash_State.State;
100 M : in out Message_State)
101 is
102 use System;
103
104 type Words is array (Natural range <>) of Interfaces.Unsigned_32;
105
106 X : Words (0 .. 15);
107 for X'Address use M.Buffer'Address;
108 pragma Import (Ada, X);
109
110 W : Words (0 .. 79);
111
112 A, B, C, D, E, Temp : Interfaces.Unsigned_32;
113
114 begin
115 if Default_Bit_Order /= High_Order_First then
116 for J in X'Range loop
117 Swap4 (X (J)'Address);
118 end loop;
119 end if;
120
121 -- a. Divide data block into sixteen words
122
123 W (0 .. 15) := X;
124
125 -- b. Prepare working block of 80 words
126
127 for T in 16 .. 79 loop
128
129 -- W(t) = S^1(W(t-3) XOR W(t-8) XOR W(t-14) XOR W(t-16))
130
131 W (T) := Rotate_Left
132 (W (T - 3) xor W (T - 8) xor W (T - 14) xor W (T - 16), 1);
133
134 end loop;
135
136 -- c. Set up transformation variables
137
138 A := H (0);
139 B := H (1);
140 C := H (2);
141 D := H (3);
142 E := H (4);
143
144 -- d. For each of the 80 rounds, compute:
145
146 -- TEMP = S^5(A) + f(t;B,C,D) + E + W(t) + K(t);
147 -- E = D; D = C; C = S^30(B); B = A; A = TEMP;
148
149 for T in 0 .. 19 loop
150 Temp := Rotate_Left (A, 5) + F0 (B, C, D) + E + W (T) + 16#5A827999#;
151 E := D; D := C; C := Rotate_Left (B, 30); B := A; A := Temp;
152 end loop;
153
154 for T in 20 .. 39 loop
155 Temp := Rotate_Left (A, 5) + F1 (B, C, D) + E + W (T) + 16#6ED9EBA1#;
156 E := D; D := C; C := Rotate_Left (B, 30); B := A; A := Temp;
157 end loop;
158
159 for T in 40 .. 59 loop
160 Temp := Rotate_Left (A, 5) + F2 (B, C, D) + E + W (T) + 16#8F1BBCDC#;
161 E := D; D := C; C := Rotate_Left (B, 30); B := A; A := Temp;
162 end loop;
163
164 for T in 60 .. 79 loop
165 Temp := Rotate_Left (A, 5) + F3 (B, C, D) + E + W (T) + 16#CA62C1D6#;
166 E := D; D := C; C := Rotate_Left (B, 30); B := A; A := Temp;
167 end loop;
168
169 -- e. Update context:
170 -- H0 = H0 + A, H1 = H1 + B, H2 = H2 + C, H3 = H3 + D, H4 = H4 + E
171
172 H (0) := H (0) + A;
173 H (1) := H (1) + B;
174 H (2) := H (2) + C;
175 H (3) := H (3) + D;
176 H (4) := H (4) + E;
177 end Transform;
178
179 end GNAT.Secure_Hashes.SHA1;