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-rw-r--r--gpxe/src/crypto/cbc.c99
1 files changed, 99 insertions, 0 deletions
diff --git a/gpxe/src/crypto/cbc.c b/gpxe/src/crypto/cbc.c
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+/*
+ * Copyright (C) 2009 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.
+ */
+
+#include <string.h>
+#include <assert.h>
+#include <gpxe/crypto.h>
+#include <gpxe/cbc.h>
+
+/** @file
+ *
+ * Cipher-block chaining
+ *
+ */
+
+/**
+ * XOR data blocks
+ *
+ * @v src Input data
+ * @v dst Second input data and output data buffer
+ * @v len Length of data
+ */
+static void cbc_xor ( const void *src, void *dst, size_t len ) {
+ const uint32_t *srcl = src;
+ uint32_t *dstl = dst;
+ unsigned int i;
+
+ /* Assume that block sizes will always be dword-aligned, for speed */
+ assert ( ( len % sizeof ( *srcl ) ) == 0 );
+
+ for ( i = 0 ; i < ( len / sizeof ( *srcl ) ) ; i++ )
+ dstl[i] ^= srcl[i];
+}
+
+/**
+ * Encrypt data
+ *
+ * @v ctx Context
+ * @v src Data to encrypt
+ * @v dst Buffer for encrypted data
+ * @v len Length of data
+ * @v raw_cipher Underlying cipher algorithm
+ * @v cbc_ctx CBC context
+ */
+void cbc_encrypt ( void *ctx, const void *src, void *dst, size_t len,
+ struct cipher_algorithm *raw_cipher, void *cbc_ctx ) {
+ size_t blocksize = raw_cipher->blocksize;
+
+ assert ( ( len % blocksize ) == 0 );
+
+ while ( len ) {
+ cbc_xor ( src, cbc_ctx, blocksize );
+ cipher_encrypt ( raw_cipher, ctx, cbc_ctx, dst, blocksize );
+ memcpy ( cbc_ctx, dst, blocksize );
+ dst += blocksize;
+ src += blocksize;
+ len -= blocksize;
+ }
+}
+
+/**
+ * Decrypt data
+ *
+ * @v ctx Context
+ * @v src Data to decrypt
+ * @v dst Buffer for decrypted data
+ * @v len Length of data
+ * @v raw_cipher Underlying cipher algorithm
+ * @v cbc_ctx CBC context
+ */
+void cbc_decrypt ( void *ctx, const void *src, void *dst, size_t len,
+ struct cipher_algorithm *raw_cipher, void *cbc_ctx ) {
+ size_t blocksize = raw_cipher->blocksize;
+
+ assert ( ( len % blocksize ) == 0 );
+
+ while ( len ) {
+ cipher_decrypt ( raw_cipher, ctx, src, dst, blocksize );
+ cbc_xor ( cbc_ctx, dst, blocksize );
+ memcpy ( cbc_ctx, src, blocksize );
+ dst += blocksize;
+ src += blocksize;
+ len -= blocksize;
+ }
+}