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/* Copyright (C) 2002 MySQL AB
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; version 2 of the License.
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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA */
/*
Implementation of AES Encryption for MySQL
Initial version by Peter Zaitsev June 2002
*/
#include <my_global.h>
#include <m_string.h>
#include "my_aes.h"
enum encrypt_dir { AES_ENCRYPT, AES_DECRYPT };
#define AES_BLOCK_SIZE 16 /* Block size in bytes */
#define AES_BAD_DATA -1 /* If bad data discovered during decoding */
/* The structure for key information */
typedef struct {
int nr; /* Number of rounds */
uint32 rk[4*(AES_MAXNR + 1)]; /* key schedule */
} KEYINSTANCE;
/*
This is internal function just keeps joint code of Key generation
SYNOPSIS
my_aes_create_key()
aes_key Address of Key Instance to be created
direction Direction (are we encoding or decoding)
key Key to use for real key creation
key_length Length of the key
DESCRIPTION
RESULT
0 ok
-1 Error Note: The current impementation never returns this
*/
static int my_aes_create_key(KEYINSTANCE *aes_key,
enum encrypt_dir direction, const char *key,
int key_length)
{
uint8 rkey[AES_KEY_LENGTH/8]; /* The real key to be used for encryption */
uint8 *rkey_end=rkey+AES_KEY_LENGTH/8; /* Real key boundary */
uint8 *ptr; /* Start of the real key*/
const char *sptr; /* Start of the working key */
const char *key_end=key+key_length; /* Working key boundary*/
bzero((char*) rkey,AES_KEY_LENGTH/8); /* Set initial key */
for (ptr= rkey, sptr= key; sptr < key_end; ptr++,sptr++)
{
if (ptr == rkey_end)
ptr= rkey; /* Just loop over tmp_key until we used all key */
*ptr^= (uint8) *sptr;
}
#ifdef AES_USE_KEY_BITS
/*
This block is intended to allow more weak encryption if application
build with libmysqld needs to correspond to export regulations
It should be never used in normal distribution as does not give
any speed improvement.
To get worse security define AES_USE_KEY_BITS to number of bits
you want key to be. It should be divisible by 8
WARNING: Changing this value results in changing of enryption for
all key lengths so altering this value will result in impossibility
to decrypt data encrypted with previous value
*/
#define AES_USE_KEY_BYTES (AES_USE_KEY_BITS/8)
/*
To get weaker key we use first AES_USE_KEY_BYTES bytes of created key
and cyclically copy them until we created all required key length
*/
for (ptr= rkey+AES_USE_KEY_BYTES, sptr=rkey ; ptr < rkey_end;
ptr++,sptr++)
{
if (sptr == rkey+AES_USE_KEY_BYTES)
sptr=rkey;
*ptr=*sptr;
}
#endif
if (direction == AES_DECRYPT)
aes_key->nr = rijndaelKeySetupDec(aes_key->rk, rkey, AES_KEY_LENGTH);
else
aes_key->nr = rijndaelKeySetupEnc(aes_key->rk, rkey, AES_KEY_LENGTH);
return 0;
}
/*
Crypt buffer with AES encryption algorithm.
SYNOPSIS
my_aes_encrypt()
source Pointer to data for encryption
source_length Size of encryption data
dest Buffer to place encrypted data (must be large enough)
key Key to be used for encryption
key_length Length of the key. Will handle keys of any length
RETURN
>= 0 Size of encrypted data
< 0 Error
*/
int my_aes_encrypt(const char* source, int source_length, char* dest,
const char* key, int key_length)
{
KEYINSTANCE aes_key;
uint8 block[AES_BLOCK_SIZE]; /* 128 bit block used for padding */
int rc; /* result codes */
int num_blocks; /* number of complete blocks */
char pad_len; /* pad size for the last block */
int i;
if ((rc= my_aes_create_key(&aes_key,AES_ENCRYPT,key,key_length)))
return rc;
num_blocks = source_length/AES_BLOCK_SIZE;
for (i = num_blocks; i > 0; i--) /* Encode complete blocks */
{
rijndaelEncrypt(aes_key.rk, aes_key.nr, (const uint8*) source,
(uint8*) dest);
source+= AES_BLOCK_SIZE;
dest+= AES_BLOCK_SIZE;
}
/* Encode the rest. We always have incomplete block */
pad_len = AES_BLOCK_SIZE - (source_length - AES_BLOCK_SIZE*num_blocks);
memcpy(block, source, 16 - pad_len);
bfill(block + AES_BLOCK_SIZE - pad_len, pad_len, pad_len);
rijndaelEncrypt(aes_key.rk, aes_key.nr, block, (uint8*) dest);
return AES_BLOCK_SIZE*(num_blocks + 1);
}
/*
DeCrypt buffer with AES encryption algorithm.
SYNOPSIS
my_aes_decrypt()
source Pointer to data for decryption
source_length Size of encrypted data
dest Buffer to place decrypted data (must be large enough)
key Key to be used for decryption
key_length Length of the key. Will handle keys of any length
RETURN
>= 0 Size of encrypted data
< 0 Error
*/
int my_aes_decrypt(const char *source, int source_length, char *dest,
const char *key, int key_length)
{
KEYINSTANCE aes_key;
uint8 block[AES_BLOCK_SIZE]; /* 128 bit block used for padding */
int rc; /* Result codes */
int num_blocks; /* Number of complete blocks */
uint pad_len; /* Pad size for the last block */
int i;
if ((rc=my_aes_create_key(&aes_key,AES_DECRYPT,key,key_length)))
return rc;
num_blocks = source_length/AES_BLOCK_SIZE;
if ((source_length != num_blocks*AES_BLOCK_SIZE) || num_blocks ==0 )
return AES_BAD_DATA; /* Input size has to be even and at least one block */
for (i = num_blocks-1; i > 0; i--) /* Decode all but last blocks */
{
rijndaelDecrypt(aes_key.rk, aes_key.nr, (const uint8*) source,
(uint8*) dest);
source+= AES_BLOCK_SIZE;
dest+= AES_BLOCK_SIZE;
}
rijndaelDecrypt(aes_key.rk, aes_key.nr, (const uint8*) source, block);
/* Use last char in the block as size */
pad_len = (uint) (uchar) block[AES_BLOCK_SIZE-1];
if (pad_len > AES_BLOCK_SIZE)
return AES_BAD_DATA;
/* We could also check whole padding but we do not really need this */
memcpy(dest, block, AES_BLOCK_SIZE - pad_len);
return AES_BLOCK_SIZE*num_blocks - pad_len;
}
/*
Get size of buffer which will be large enough for encrypted data
SYNOPSIS
my_aes_get_size()
source_length Length of data to be encrypted
RETURN
Size of buffer required to store encrypted data
*/
int my_aes_get_size(int source_length)
{
return AES_BLOCK_SIZE*(source_length/AES_BLOCK_SIZE)+AES_BLOCK_SIZE;
}
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