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[crypto] Add our own general-purpose cipher-block chaining routines
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Michael Brown committed Feb 19, 2009
1 parent b4d3d68 commit e950dc0
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Showing 5 changed files with 363 additions and 29 deletions.
10 changes: 4 additions & 6 deletions src/crypto/axtls/aes.c
Expand Up @@ -152,10 +152,6 @@ static const unsigned char Rcon[30]=
0xb3,0x7d,0xfa,0xef,0xc5,0x91,
};

/* ----- static functions ----- */
static void AES_encrypt(const AES_CTX *ctx, uint32_t *data);
static void AES_decrypt(const AES_CTX *ctx, uint32_t *data);

/* Perform doubling in Galois Field GF(2^8) using the irreducible polynomial
x^8+x^4+x^3+x+1 */
static unsigned char AES_xtime(uint32_t x)
Expand Down Expand Up @@ -257,6 +253,7 @@ void AES_convert_key(AES_CTX *ctx)
}
}

#if 0
/**
* Encrypt a byte sequence (with a block size 16) using the AES cipher.
*/
Expand Down Expand Up @@ -358,11 +355,12 @@ void AES_cbc_decrypt(AES_CTX *ctx, const uint8_t *msg, uint8_t *out, int length)
l2n(xor2, iv);
l2n(xor3, iv);
}
#endif

/**
* Encrypt a single block (16 bytes) of data
*/
static void AES_encrypt(const AES_CTX *ctx, uint32_t *data)
void AES_encrypt(const AES_CTX *ctx, uint32_t *data)
{
/* To make this code smaller, generate the sbox entries on the fly.
* This will have a really heavy effect upon performance.
Expand Down Expand Up @@ -418,7 +416,7 @@ static void AES_encrypt(const AES_CTX *ctx, uint32_t *data)
/**
* Decrypt a single block (16 bytes) of data
*/
static void AES_decrypt(const AES_CTX *ctx, uint32_t *data)
void AES_decrypt(const AES_CTX *ctx, uint32_t *data)
{
uint32_t tmp[4];
uint32_t xt0,xt1,xt2,xt3,xt4,xt5,xt6;
Expand Down
2 changes: 2 additions & 0 deletions src/crypto/axtls/crypto.h
Expand Up @@ -55,6 +55,8 @@ void AES_cbc_encrypt(AES_CTX *ctx, const uint8_t *msg,
uint8_t *out, int length);
void AES_cbc_decrypt(AES_CTX *ks, const uint8_t *in, uint8_t *out, int length);
void AES_convert_key(AES_CTX *ctx);
void AES_encrypt(const AES_CTX *ctx, uint32_t *data);
void AES_decrypt(const AES_CTX *ctx, uint32_t *data);

/**************************************************************************
* RC4 declarations
Expand Down
231 changes: 208 additions & 23 deletions src/crypto/axtls_aes.c
@@ -1,17 +1,65 @@
#include "crypto/axtls/crypto.h"
/*
* 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.
*/

#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"

struct aes_cbc_context {
AES_CTX ctx;
/** @file
*
* AES algorithm
*
*/

/** Basic AES blocksize */
#define AES_BLOCKSIZE 16

/****************************************************************************
*
* Basic AES algorithm (independent of mode of operation)
*
****************************************************************************
*/

/** AES context */
struct aes_context {
/** AES context for AXTLS */
AES_CTX axtls_ctx;
/** Cipher is being used for decrypting */
int decrypting;
};

static int aes_cbc_setkey ( void *ctx, const void *key, size_t keylen ) {
struct aes_cbc_context *aesctx = ctx;
/**
* 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 ):
Expand All @@ -24,45 +72,182 @@ static int aes_cbc_setkey ( void *ctx, const void *key, size_t keylen ) {
return -EINVAL;
}

AES_set_key ( &aesctx->ctx, key, aesctx->ctx.iv, mode );
/* 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 );

aesctx->decrypting = 0;
aes_ctx->decrypting = 0;

return 0;
}

static void aes_cbc_setiv ( void *ctx, const void *iv ) {
struct aes_cbc_context *aesctx = ctx;
/**
* Set initialisation vector
*
* @v ctx Context
* @v iv Initialisation vector
*/
static void aes_setiv ( void *ctx __unused, const void *iv __unused ) {
/* Nothing to do */
}

memcpy ( aesctx->ctx.iv, iv, sizeof ( aesctx->ctx.iv ) );
/**
* 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] );
}

static void aes_cbc_encrypt ( void *ctx, const void *data, void *dst,
size_t len ) {
struct aes_cbc_context *aesctx = ctx;
/**
* 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;

if ( aesctx->decrypting )
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)
*
****************************************************************************
*/

/** AES with CBC context */
struct aes_cbc_context {
/** AES context */
struct aes_context aes_ctx;
/** CBC context */
uint8_t cbc_ctx[AES_BLOCKSIZE];
};

/**
* Set key
*
* @v ctx Context
* @v key Key
* @v keylen Key length
* @ret rc Return status code
*/
static int aes_cbc_setkey ( void *ctx, const void *key, size_t keylen ) {
struct aes_cbc_context *aes_cbc_ctx = ctx;

AES_cbc_encrypt ( &aesctx->ctx, data, dst, len );
return cbc_setkey ( ctx, key, keylen, &aes_algorithm,
&aes_cbc_ctx->cbc_ctx );
}

static void aes_cbc_decrypt ( void *ctx, const void *data, void *dst,
/**
* Set initialisation vector
*
* @v ctx Context
* @v iv Initialisation vector
*/
static void aes_cbc_setiv ( void *ctx, const void *iv ) {
struct aes_cbc_context *aes_cbc_ctx = ctx;

cbc_setiv ( ctx, iv, &aes_algorithm, &aes_cbc_ctx->cbc_ctx );
}

/**
* Encrypt data
*
* @v ctx Context
* @v src Data to encrypt
* @v dst Buffer for encrypted data
* @v len Length of data
*/
static void aes_cbc_encrypt ( void *ctx, const void *src, void *dst,
size_t len ) {
struct aes_cbc_context *aesctx = ctx;
struct aes_cbc_context *aes_cbc_ctx = ctx;

if ( ! aesctx->decrypting ) {
AES_convert_key ( &aesctx->ctx );
aesctx->decrypting = 1;
}
cbc_encrypt ( &aes_cbc_ctx->aes_ctx, src, dst, len,
&aes_algorithm, &aes_cbc_ctx->cbc_ctx );
}

/**
* Decrypt data
*
* @v ctx Context
* @v src Data to decrypt
* @v dst Buffer for decrypted data
* @v len Length of data
*/
static void aes_cbc_decrypt ( void *ctx, const void *src, void *dst,
size_t len ) {
struct aes_cbc_context *aes_cbc_ctx = ctx;

AES_cbc_decrypt ( &aesctx->ctx, data, dst, len );
cbc_decrypt ( &aes_cbc_ctx->aes_ctx, src, dst, len,
&aes_algorithm, &aes_cbc_ctx->cbc_ctx );
}

/* AES with cipher-block chaining */
struct cipher_algorithm aes_cbc_algorithm = {
.name = "aes_cbc",
.ctxsize = sizeof ( struct aes_cbc_context ),
.blocksize = 16,
.blocksize = AES_BLOCKSIZE,
.setkey = aes_cbc_setkey,
.setiv = aes_cbc_setiv,
.encrypt = aes_cbc_encrypt,
Expand Down

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