blob: ec95d7ceb15daf8a62b720ab7c3f8f2c094697a8 [file] [log] [blame]
Yen Lin2a6f0362012-04-02 13:18:48 +00001/*
2 * Copyright (c) 2011 The Chromium OS Authors.
3 * (C) Copyright 2010 - 2011 NVIDIA Corporation <www.nvidia.com>
4 *
Wolfgang Denk1a459662013-07-08 09:37:19 +02005 * SPDX-License-Identifier: GPL-2.0+
Yen Lin2a6f0362012-04-02 13:18:48 +00006 */
7
8#include <common.h>
9#include <asm/errno.h>
10#include "crypto.h"
11#include "aes.h"
12
13static u8 zero_key[16];
14
15#define AES_CMAC_CONST_RB 0x87 /* from RFC 4493, Figure 2.2 */
16
17enum security_op {
18 SECURITY_SIGN = 1 << 0, /* Sign the data */
19 SECURITY_ENCRYPT = 1 << 1, /* Encrypt the data */
20};
21
Yen Lin2a6f0362012-04-02 13:18:48 +000022/**
23 * Shift a vector left by one bit
24 *
25 * \param in Input vector
26 * \param out Output vector
27 * \param size Length of vector in bytes
28 */
29static void left_shift_vector(u8 *in, u8 *out, int size)
30{
31 int carry = 0;
32 int i;
33
34 for (i = size - 1; i >= 0; i--) {
35 out[i] = (in[i] << 1) | carry;
36 carry = in[i] >> 7; /* get most significant bit */
37 }
38}
39
40/**
41 * Sign a block of data, putting the result into dst.
42 *
43 * \param key Input AES key, length AES_KEY_LENGTH
44 * \param key_schedule Expanded key to use
45 * \param src Source data of length 'num_aes_blocks' blocks
46 * \param dst Destination buffer, length AES_KEY_LENGTH
47 * \param num_aes_blocks Number of AES blocks to encrypt
48 */
49static void sign_object(u8 *key, u8 *key_schedule, u8 *src, u8 *dst,
50 u32 num_aes_blocks)
51{
52 u8 tmp_data[AES_KEY_LENGTH];
53 u8 left[AES_KEY_LENGTH];
54 u8 k1[AES_KEY_LENGTH];
55 u8 *cbc_chain_data;
56 unsigned i;
57
58 cbc_chain_data = zero_key; /* Convenient array of 0's for IV */
59
60 /* compute K1 constant needed by AES-CMAC calculation */
61 for (i = 0; i < AES_KEY_LENGTH; i++)
62 tmp_data[i] = 0;
63
Marek Vasut6e7b9f42014-03-05 19:58:37 +010064 aes_cbc_encrypt_blocks(key_schedule, tmp_data, left, 1);
Yen Lin2a6f0362012-04-02 13:18:48 +000065
66 left_shift_vector(left, k1, sizeof(left));
Yen Lin2a6f0362012-04-02 13:18:48 +000067
68 if ((left[0] >> 7) != 0) /* get MSB of L */
69 k1[AES_KEY_LENGTH-1] ^= AES_CMAC_CONST_RB;
Yen Lin2a6f0362012-04-02 13:18:48 +000070
71 /* compute the AES-CMAC value */
72 for (i = 0; i < num_aes_blocks; i++) {
73 /* Apply the chain data */
Stephen Warren53eb7682014-04-18 10:28:58 -060074 aes_apply_cbc_chain_data(cbc_chain_data, src, tmp_data);
Yen Lin2a6f0362012-04-02 13:18:48 +000075
76 /* for the final block, XOR K1 into the IV */
77 if (i == num_aes_blocks - 1)
Stephen Warren53eb7682014-04-18 10:28:58 -060078 aes_apply_cbc_chain_data(tmp_data, k1, tmp_data);
Yen Lin2a6f0362012-04-02 13:18:48 +000079
80 /* encrypt the AES block */
81 aes_encrypt(tmp_data, key_schedule, dst);
82
83 debug("sign_obj: block %d of %d\n", i, num_aes_blocks);
Yen Lin2a6f0362012-04-02 13:18:48 +000084
85 /* Update pointers for next loop. */
86 cbc_chain_data = dst;
87 src += AES_KEY_LENGTH;
88 }
Yen Lin2a6f0362012-04-02 13:18:48 +000089}
90
91/**
92 * Encrypt and sign a block of data (depending on security mode).
93 *
94 * \param key Input AES key, length AES_KEY_LENGTH
95 * \param oper Security operations mask to perform (enum security_op)
96 * \param src Source data
97 * \param length Size of source data
98 * \param sig_dst Destination address for signature, AES_KEY_LENGTH bytes
99 */
100static int encrypt_and_sign(u8 *key, enum security_op oper, u8 *src,
101 u32 length, u8 *sig_dst)
102{
103 u32 num_aes_blocks;
104 u8 key_schedule[AES_EXPAND_KEY_LENGTH];
105
106 debug("encrypt_and_sign: length = %d\n", length);
Yen Lin2a6f0362012-04-02 13:18:48 +0000107
108 /*
109 * The only need for a key is for signing/checksum purposes, so
110 * if not encrypting, expand a key of 0s.
111 */
112 aes_expand_key(oper & SECURITY_ENCRYPT ? key : zero_key, key_schedule);
113
114 num_aes_blocks = (length + AES_KEY_LENGTH - 1) / AES_KEY_LENGTH;
115
116 if (oper & SECURITY_ENCRYPT) {
117 /* Perform this in place, resulting in src being encrypted. */
118 debug("encrypt_and_sign: begin encryption\n");
Marek Vasut6e7b9f42014-03-05 19:58:37 +0100119 aes_cbc_encrypt_blocks(key_schedule, src, src, num_aes_blocks);
Yen Lin2a6f0362012-04-02 13:18:48 +0000120 debug("encrypt_and_sign: end encryption\n");
121 }
122
123 if (oper & SECURITY_SIGN) {
124 /* encrypt the data, overwriting the result in signature. */
125 debug("encrypt_and_sign: begin signing\n");
126 sign_object(key, key_schedule, src, sig_dst, num_aes_blocks);
127 debug("encrypt_and_sign: end signing\n");
128 }
129
130 return 0;
131}
132
133int sign_data_block(u8 *source, unsigned length, u8 *signature)
134{
135 return encrypt_and_sign(zero_key, SECURITY_SIGN, source,
136 length, signature);
137}