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- /*
- * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of the
- * License, or any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-
- FILE_LICENCE ( GPL2_OR_LATER );
-
- #include <string.h>
- #include <errno.h>
- #include <byteswap.h>
- #include <gpxe/crypto.h>
- #include <gpxe/cbc.h>
- #include <gpxe/aes.h>
- #include "crypto/axtls/crypto.h"
-
- /** @file
- *
- * AES algorithm
- *
- */
-
- /** Basic AES blocksize */
- #define AES_BLOCKSIZE 16
-
- /** AES context */
- struct aes_context {
- /** AES context for AXTLS */
- AES_CTX axtls_ctx;
- /** Cipher is being used for decrypting */
- int decrypting;
- };
-
- /**
- * Set key
- *
- * @v ctx Context
- * @v key Key
- * @v keylen Key length
- * @ret rc Return status code
- */
- static int aes_setkey ( void *ctx, const void *key, size_t keylen ) {
- struct aes_context *aes_ctx = ctx;
- AES_MODE mode;
- void *iv;
-
- switch ( keylen ) {
- case ( 128 / 8 ):
- mode = AES_MODE_128;
- break;
- case ( 256 / 8 ):
- mode = AES_MODE_256;
- break;
- default:
- return -EINVAL;
- }
-
- /* IV is not a relevant concept at this stage; use a dummy
- * value that will have no side-effects.
- */
- iv = &aes_ctx->axtls_ctx.iv;
-
- AES_set_key ( &aes_ctx->axtls_ctx, key, iv, mode );
-
- aes_ctx->decrypting = 0;
-
- return 0;
- }
-
- /**
- * Set initialisation vector
- *
- * @v ctx Context
- * @v iv Initialisation vector
- */
- static void aes_setiv ( void *ctx __unused, const void *iv __unused ) {
- /* Nothing to do */
- }
-
- /**
- * Call AXTLS' AES_encrypt() or AES_decrypt() functions
- *
- * @v axtls_ctx AXTLS AES context
- * @v src Data to process
- * @v dst Buffer for output
- * @v func AXTLS AES function to call
- */
- static void aes_call_axtls ( AES_CTX *axtls_ctx, const void *src, void *dst,
- void ( * func ) ( const AES_CTX *axtls_ctx,
- uint32_t *data ) ){
- const uint32_t *srcl = src;
- uint32_t *dstl = dst;
- unsigned int i;
-
- /* AXTLS' AES_encrypt() and AES_decrypt() functions both
- * expect to deal with an array of four dwords in host-endian
- * order.
- */
- for ( i = 0 ; i < 4 ; i++ )
- dstl[i] = ntohl ( srcl[i] );
- func ( axtls_ctx, dstl );
- for ( i = 0 ; i < 4 ; i++ )
- dstl[i] = htonl ( dstl[i] );
- }
-
- /**
- * Encrypt data
- *
- * @v ctx Context
- * @v src Data to encrypt
- * @v dst Buffer for encrypted data
- * @v len Length of data
- */
- static void aes_encrypt ( void *ctx, const void *src, void *dst,
- size_t len ) {
- struct aes_context *aes_ctx = ctx;
-
- assert ( len == AES_BLOCKSIZE );
- if ( aes_ctx->decrypting )
- assert ( 0 );
- aes_call_axtls ( &aes_ctx->axtls_ctx, src, dst, AES_encrypt );
- }
-
- /**
- * Decrypt data
- *
- * @v ctx Context
- * @v src Data to decrypt
- * @v dst Buffer for decrypted data
- * @v len Length of data
- */
- static void aes_decrypt ( void *ctx, const void *src, void *dst,
- size_t len ) {
- struct aes_context *aes_ctx = ctx;
-
- assert ( len == AES_BLOCKSIZE );
- if ( ! aes_ctx->decrypting ) {
- AES_convert_key ( &aes_ctx->axtls_ctx );
- aes_ctx->decrypting = 1;
- }
- aes_call_axtls ( &aes_ctx->axtls_ctx, src, dst, AES_decrypt );
- }
-
- /** Basic AES algorithm */
- static struct cipher_algorithm aes_algorithm = {
- .name = "aes",
- .ctxsize = sizeof ( struct aes_context ),
- .blocksize = AES_BLOCKSIZE,
- .setkey = aes_setkey,
- .setiv = aes_setiv,
- .encrypt = aes_encrypt,
- .decrypt = aes_decrypt,
- };
-
- /* AES with cipher-block chaining */
- CBC_CIPHER ( aes_cbc, aes_cbc_algorithm,
- aes_algorithm, struct aes_context, AES_BLOCKSIZE );
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