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Separate TEA encryption and decryption to separate files

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This commit is contained in:
Gregory Nutt 2016-01-19 16:46:25 -06:00
parent f4f931c2a5
commit a60a822ef2
3 changed files with 92 additions and 34 deletions
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3
libc/misc/Make.defs
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@ -35,7 +35,8 @@
# Add the internal C files to the build
CSRCS += lib_stream.c lib_filesem.c lib_utsname.c lib_tea.c
CSRCS += lib_stream.c lib_filesem.c lib_utsname.c
CSRCS += lib_tea_encrypt.c lib_tea_decrypt.c
# Add C files that depend on file OR socket descriptors

35
libc/misc/lib_tea.c → libc/misc/lib_tea_decrypt.c
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@ -1,6 +1,6 @@
/****************************************************************************
* libc/misc/lib_tea.c
* Tiny Encryption Algorithm
* libc/misc/lib_tea_decrypt.c
* Tiny Encryption Algorithm - Decryption support
*
* Copyright (C) 2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
@ -56,37 +56,6 @@
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: tea_encrypt
*
* Input Parameters:
* value = 2 x 32-bit value (input/output)
* key = 4 x 32-bit Cache key (input)
*
****************************************************************************/
void tea_encrypt(FAR uint32_t *value, FAR const uint32_t *key)
{
uint32_t v0 = value[0];
uint32_t v1 = value[1];
uint32_t sum = 0;
int i;
/* Basic cycle start */
for (i = 0; i < 32; i++)
{
sum += TEA_KEY_SCHEDULE_CONSTANT;
v0 += ((v1 << 4) + key[0]) ^ (v1 + sum) ^ ((v1 >> 5) + key[1]);
v1 += ((v0 << 4) + key[2]) ^ (v0 + sum) ^ ((v0 >> 5) + key[3]);
}
/* End cycle */
value[0] = v0;
value[1] = v1;
}
/****************************************************************************
* Name: tea_decrypt
*

88
libc/misc/lib_tea_encrypt.c Normal file
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@ -0,0 +1,88 @@
/****************************************************************************
* libc/misc/lib_tea_encrypt.c
* Tiny Encryption Algorithm - Encryption support
*
* Copyright (C) 2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm: "Following is
* an adaptation of the reference encryption and decryption routines in C,
* released into the public domain by David Wheeler and Roger Needham."
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <stdint.h>
#include <nuttx/crypto/tea.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define TEA_KEY_SCHEDULE_CONSTANT 0x9e3779b9
#define TEA_SUM_SETUP_CONSTANT 0xc6ef3720
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: tea_encrypt
*
* Input Parameters:
* value = 2 x 32-bit value (input/output)
* key = 4 x 32-bit Cache key (input)
*
****************************************************************************/
void tea_encrypt(FAR uint32_t *value, FAR const uint32_t *key)
{
uint32_t v0 = value[0];
uint32_t v1 = value[1];
uint32_t sum = 0;
int i;
/* Basic cycle start */
for (i = 0; i < 32; i++)
{
sum += TEA_KEY_SCHEDULE_CONSTANT;
v0 += ((v1 << 4) + key[0]) ^ (v1 + sum) ^ ((v1 >> 5) + key[1]);
v1 += ((v0 << 4) + key[2]) ^ (v0 + sum) ^ ((v0 >> 5) + key[3]);
}
/* End cycle */
value[0] = v0;
value[1] = v1;
}