aes-internal-dec.c File Reference

AES (Rijndael) cipher - decrypt. More...

#include "includes.h"
#include "common.h"
#include "crypto.h"
#include "aes_i.h"

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Defines
#define	ROUND(i, d, s)
Functions
void	rijndaelKeySetupDec (u32 rk[], const u8 cipherKey[])
void *	aes_decrypt_init (const u8 *key, size_t len)
	Initialize AES for decryption.
void	aes_decrypt (void *ctx, const u8 *crypt, u8 *plain)
	Decrypt one AES block.
void	aes_decrypt_deinit (void *ctx)
	Deinitialize AES decryption.

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Detailed Description

AES (Rijndael) cipher - decrypt.

Modifications to public domain implementation:

• support only 128-bit keys
• cleanup
• use C pre-processor to make it easier to change S table access
• added option (AES_SMALL_TABLES) for reducing code size by about 8 kB at cost of reduced throughput (quite small difference on Pentium 4, 10-25% when using -O1 or -O2 optimization)

Copyright

Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi>

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License version 2 as published by the Free Software Foundation.

Alternatively, this software may be distributed under the terms of BSD license.

See README and COPYING for more details.

Definition in file aes-internal-dec.c.

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Define Documentation

#define ROUND	(	i,
		d,
		s		)

Value:

d##0 = TD0(s##0) ^ TD1(s##3) ^ TD2(s##2) ^ TD3(s##1) ^ rk[4 * i]; \
d##1 = TD0(s##1) ^ TD1(s##0) ^ TD2(s##3) ^ TD3(s##2) ^ rk[4 * i + 1]; \
d##2 = TD0(s##2) ^ TD1(s##1) ^ TD2(s##0) ^ TD3(s##3) ^ rk[4 * i + 2]; \
d##3 = TD0(s##3) ^ TD1(s##2) ^ TD2(s##1) ^ TD3(s##0) ^ rk[4 * i + 3]

---

Function Documentation

void aes_decrypt	(	void *	ctx,
		const u8 *	crypt,
		u8 *	plain
	)

Decrypt one AES block.

Parameters:

	ctx	Context pointer from aes_encrypt_init()
	crypt	Encrypted data (16 bytes)
	plain	Buffer for the decrypted data (16 bytes)

Definition at line 142 of file aes-internal-dec.c.

void aes_decrypt_deinit

(

void *

ctx

)

Deinitialize AES decryption.

Parameters:

ctx

Context pointer from aes_encrypt_init()

Definition at line 148 of file aes-internal-dec.c.

void* aes_decrypt_init	(	const u8 *	key,
		size_t	len
	)

Initialize AES for decryption.

Parameters:

	key	Decryption key
	len	Key length in bytes (usually 16, i.e., 128 bits)

Returns:

Pointer to context data or NULL on failure

Definition at line 63 of file aes-internal-dec.c.

void rijndaelKeySetupDec	(	u32	rk[],
		const u8	cipherKey[]
	)

Expand the cipher key into the decryption key schedule.

Returns:

the number of rounds for the given cipher key size.

Definition at line 36 of file aes-internal-dec.c.

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