xref: /freebsd/sys/contrib/openzfs/module/icp/algs/modes/gcm_generic.c (revision 8ddb146abcdf061be9f2c0db7e391697dafad85c)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or https://opensource.org/licenses/CDDL-1.0.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
23  */
24 
25 #include <modes/gcm_impl.h>
26 
27 struct aes_block {
28 	uint64_t a;
29 	uint64_t b;
30 };
31 
32 /*
33  * Perform a carry-less multiplication (that is, use XOR instead of the
34  * multiply operator) on *x_in and *y and place the result in *res.
35  *
36  * Byte swap the input (*x_in and *y) and the output (*res).
37  *
38  * Note: x_in, y, and res all point to 16-byte numbers (an array of two
39  * 64-bit integers).
40  */
41 static void
42 gcm_generic_mul(uint64_t *x_in, uint64_t *y, uint64_t *res)
43 {
44 	static const uint64_t R = 0xe100000000000000ULL;
45 	struct aes_block z = {0, 0};
46 	struct aes_block v;
47 	uint64_t x;
48 	int i, j;
49 
50 	v.a = ntohll(y[0]);
51 	v.b = ntohll(y[1]);
52 
53 	for (j = 0; j < 2; j++) {
54 		x = ntohll(x_in[j]);
55 		for (i = 0; i < 64; i++, x <<= 1) {
56 			if (x & 0x8000000000000000ULL) {
57 				z.a ^= v.a;
58 				z.b ^= v.b;
59 			}
60 			if (v.b & 1ULL) {
61 				v.b = (v.a << 63)|(v.b >> 1);
62 				v.a = (v.a >> 1) ^ R;
63 			} else {
64 				v.b = (v.a << 63)|(v.b >> 1);
65 				v.a = v.a >> 1;
66 			}
67 		}
68 	}
69 	res[0] = htonll(z.a);
70 	res[1] = htonll(z.b);
71 }
72 
73 static boolean_t
74 gcm_generic_will_work(void)
75 {
76 	return (B_TRUE);
77 }
78 
79 const gcm_impl_ops_t gcm_generic_impl = {
80 	.mul = &gcm_generic_mul,
81 	.is_supported = &gcm_generic_will_work,
82 	.name = "generic"
83 };
84