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[crypto] Add AES key-wrap mode (RFC 3394)

The unwrapping half is used by WPA2 code; the wrapping half is currently
unused.

Signed-off-by: Marty Connor <mdc@etherboot.org>
tags/v1.0.0-rc1
Joshua Oreman hace 15 años
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6c6db8647b
Se han modificado 2 ficheros con 126 adiciones y 0 borrados
  1. 123
    0
      src/crypto/aes_wrap.c
  2. 3
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      src/include/gpxe/aes.h

+ 123
- 0
src/crypto/aes_wrap.c Ver fichero

@@ -0,0 +1,123 @@
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+/*
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+ * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License as
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+ * published by the Free Software Foundation; either version 2 of the
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+ * License, or any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful, but
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+ * WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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+ * General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with this program; if not, write to the Free Software
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+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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+ */
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+
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+FILE_LICENCE ( GPL2_OR_LATER );
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+
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+#include <stdlib.h>
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+#include <string.h>
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+#include <gpxe/crypto.h>
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+#include <gpxe/aes.h>
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+
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+/**
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+ * Wrap a key or other data using AES Key Wrap (RFC 3394)
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+ *
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+ * @v kek	Key Encryption Key, 16 bytes
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+ * @v src	Data to encrypt
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+ * @v nblk	Number of 8-byte blocks in @a data
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+ * @ret dest	Encrypted data (8 bytes longer than input)
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+ *
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+ * The algorithm is implemented such that @a src and @a dest may point
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+ * to the same buffer.
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+ */
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+int aes_wrap ( const void *kek, const void *src, void *dest, int nblk )
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+{
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+	u8 *A = dest;
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+	u8 B[16];
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+	u8 *R;
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+	int i, j;
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+	void *aes_ctx = malloc ( AES_CTX_SIZE );
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+
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+	if ( ! aes_ctx )
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+		return -1;
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+
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+	cipher_setkey ( &aes_algorithm, aes_ctx, kek, 16 );
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+
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+	/* Set up */
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+	memset ( A, 0xA6, sizeof ( A ) );
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+	memmove ( dest + 8, src, nblk * 8 );
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+
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+	/* Wrap */
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+	for ( j = 0; j < 6; j++ ) {
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+		R = dest + 8;
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+		for ( i = 1; i <= nblk; i++ ) {
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+			memcpy ( B, A, 8 );
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+			memcpy ( B + 8, R, 8 );
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+			cipher_encrypt ( &aes_algorithm, aes_ctx, B, B, 16 );
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+			memcpy ( A, B, 8 );
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+			A[7] ^= ( nblk * j ) + i;
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+			memcpy ( R, B + 8, 8 );
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+			R += 8;
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+		}
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+	}
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+
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+	free ( aes_ctx );
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+	return 0;
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+}
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+
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+/**
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+ * Unwrap a key or other data using AES Key Wrap (RFC 3394)
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+ *
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+ * @v kek	Key Encryption Key, 16 bytes
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+ * @v src	Data to decrypt
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+ * @v nblk	Number of 8-byte blocks in @e plaintext key
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+ * @ret dest	Decrypted data (8 bytes shorter than input)
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+ * @ret rc	Zero on success, nonzero on IV mismatch
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+ *
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+ * The algorithm is implemented such that @a src and @a dest may point
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+ * to the same buffer.
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+ */
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+int aes_unwrap ( const void *kek, const void *src, void *dest, int nblk )
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+{
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+	u8 A[8], B[16];
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+	u8 *R;
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+	int i, j;
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+	void *aes_ctx = malloc ( AES_CTX_SIZE );
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+
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+	if ( ! aes_ctx )
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+		return -1;
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+
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+	cipher_setkey ( &aes_algorithm, aes_ctx, kek, 16 );
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+
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+	/* Set up */
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+	memcpy ( A, src, 8 );
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+	memmove ( dest, src + 8, nblk * 8 );
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+
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+	/* Unwrap */
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+	for ( j = 5; j >= 0; j-- ) {
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+		R = dest + ( nblk - 1 ) * 8;
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+		for ( i = nblk; i >= 1; i-- ) {
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+			memcpy ( B, A, 8 );
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+			memcpy ( B + 8, R, 8 );
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+			B[7] ^= ( nblk * j ) + i;
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+			cipher_decrypt ( &aes_algorithm, aes_ctx, B, B, 16 );
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+			memcpy ( A, B, 8 );
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+			memcpy ( R, B + 8, 8 );
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+			R -= 8;
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+		}
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+	}
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+
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+	free ( aes_ctx );
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+
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+	/* Check IV */
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+	for ( i = 0; i < 8; i++ ) {
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+		if ( A[i] != 0xA6 )
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+			return -1;
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+	}
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+
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+	return 0;
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+}

+ 3
- 0
src/include/gpxe/aes.h Ver fichero

@@ -24,4 +24,7 @@ struct aes_context {
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 extern struct cipher_algorithm aes_algorithm;
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 extern struct cipher_algorithm aes_cbc_algorithm;
26 26
 
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+int aes_wrap ( const void *kek, const void *src, void *dest, int nblk );
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+int aes_unwrap ( const void *kek, const void *src, void *dest, int nblk );
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+
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 #endif /* _GPXE_AES_H */

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