iPXE
cbc.c
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1 /*
2  * Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation; either version 2 of the
7  * License, or any later version.
8  *
9  * This program is distributed in the hope that it will be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17  * 02110-1301, USA.
18  *
19  * You can also choose to distribute this program under the terms of
20  * the Unmodified Binary Distribution Licence (as given in the file
21  * COPYING.UBDL), provided that you have satisfied its requirements.
22  */
23 
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25 
26 #include <string.h>
27 #include <assert.h>
28 #include <ipxe/crypto.h>
29 #include <ipxe/cbc.h>
30 
31 /** @file
32  *
33  * Cipher-block chaining
34  *
35  */
36 
37 /**
38  * XOR data blocks
39  *
40  * @v src Input data
41  * @v dst Second input data and output data buffer
42  * @v len Length of data
43  */
44 static void cbc_xor ( const void *src, void *dst, size_t len ) {
45  const uint32_t *srcl = src;
46  uint32_t *dstl = dst;
47  unsigned int i;
48 
49  /* Assume that block sizes will always be dword-aligned, for speed */
50  assert ( ( len % sizeof ( *srcl ) ) == 0 );
51 
52  for ( i = 0 ; i < ( len / sizeof ( *srcl ) ) ; i++ )
53  dstl[i] ^= srcl[i];
54 }
55 
56 /**
57  * Encrypt data
58  *
59  * @v ctx Context
60  * @v src Data to encrypt
61  * @v dst Buffer for encrypted data
62  * @v len Length of data
63  * @v raw_cipher Underlying cipher algorithm
64  * @v cbc_ctx CBC context
65  */
66 void cbc_encrypt ( void *ctx, const void *src, void *dst, size_t len,
67  struct cipher_algorithm *raw_cipher, void *cbc_ctx ) {
68  size_t blocksize = raw_cipher->blocksize;
69 
70  assert ( ( len % blocksize ) == 0 );
71 
72  while ( len ) {
73  cbc_xor ( src, cbc_ctx, blocksize );
74  cipher_encrypt ( raw_cipher, ctx, cbc_ctx, dst, blocksize );
75  memcpy ( cbc_ctx, dst, blocksize );
76  dst += blocksize;
77  src += blocksize;
78  len -= blocksize;
79  }
80 }
81 
82 /**
83  * Decrypt data
84  *
85  * @v ctx Context
86  * @v src Data to decrypt
87  * @v dst Buffer for decrypted data
88  * @v len Length of data
89  * @v raw_cipher Underlying cipher algorithm
90  * @v cbc_ctx CBC context
91  */
92 void cbc_decrypt ( void *ctx, const void *src, void *dst, size_t len,
93  struct cipher_algorithm *raw_cipher, void *cbc_ctx ) {
94  size_t blocksize = raw_cipher->blocksize;
95  uint8_t next_cbc_ctx[blocksize];
96 
97  assert ( ( len % blocksize ) == 0 );
98 
99  while ( len ) {
100  memcpy ( next_cbc_ctx, src, blocksize );
101  cipher_decrypt ( raw_cipher, ctx, src, dst, blocksize );
102  cbc_xor ( cbc_ctx, dst, blocksize );
103  memcpy ( cbc_ctx, next_cbc_ctx, blocksize );
104  dst += blocksize;
105  src += blocksize;
106  len -= blocksize;
107  }
108 }
size_t blocksize
Block size.
Definition: crypto.h:54
Cryptographic API.
struct golan_eq_context ctx
Definition: CIB_PRM.h:28
void cbc_decrypt(void *ctx, const void *src, void *dst, size_t len, struct cipher_algorithm *raw_cipher, void *cbc_ctx)
Decrypt data.
Definition: cbc.c:92
FILE_LICENCE(GPL2_OR_LATER_OR_UBDL)
static void cbc_xor(const void *src, void *dst, size_t len)
XOR data blocks.
Definition: cbc.c:44
#define cipher_encrypt(cipher, ctx, src, dst, len)
Definition: crypto.h:202
void * memcpy(void *dest, const void *src, size_t len) __nonnull
Assertions.
assert((readw(&hdr->flags) &(GTF_reading|GTF_writing))==0)
static __always_inline void off_t userptr_t src
Definition: efi_uaccess.h:66
unsigned char uint8_t
Definition: stdint.h:10
#define cipher_decrypt(cipher, ctx, src, dst, len)
Definition: crypto.h:212
Cipher-block chaining.
unsigned int uint32_t
Definition: stdint.h:12
void cbc_encrypt(void *ctx, const void *src, void *dst, size_t len, struct cipher_algorithm *raw_cipher, void *cbc_ctx)
Encrypt data.
Definition: cbc.c:66
uint32_t len
Length.
Definition: ena.h:14
A cipher algorithm.
Definition: crypto.h:48
String functions.