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aesio: add basic AES encryption and decryption

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This adds initial support for an AES module named aesio.  This
implementation supports only a subset of AES modes, namely
ECB, CBC, and CTR modes.

Example usage:

```
>>> import aesio
>>>
>>> key = b'Sixteen byte key'
>>> cipher = aesio.AES(key, aesio.MODE_ECB)
>>> output = bytearray(16)
>>> cipher.encrypt_into(b'Circuit Python!!', output)
>>> output
bytearray(b'E\x14\x85\x18\x9a\x9c\r\x95>\xa7kV\xa2`\x8b\n')
>>>
```

This key is 16-bytes, so it uses AES128.  If your key is 24- or 32-
bytes long, it will switch to AES192 or AES256 respectively.

This has been tested with many of the official NIST test vectors,
such as those used in `pycryptodome` at
39626a5b01/lib/Crypto/SelfTest/Cipher/test_vectors/AES

CTR has not been tested as NIST does not provide test vectors for it.

Signed-off-by: Sean Cross <sean@xobs.io>
This commit is contained in:
Sean Cross 2020-04-14 11:18:45 +08:00
parent 90625d169a
commit b168784fa0
10 changed files with 1249 additions and 0 deletions
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5
py/circuitpy_defns.mk
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@ -99,6 +99,9 @@ endif
###
# Select which builtin modules to compile and include.
ifeq ($(CIRCUITPY_AESIO),1)
SRC_PATTERNS += aesio/%
endif
ifeq ($(CIRCUITPY_ANALOGIO),1)
SRC_PATTERNS += analogio/%
endif
@ -341,6 +344,8 @@ SRC_SHARED_MODULE_ALL = \
bitbangio/__init__.c \
board/__init__.c \
busio/OneWire.c \
aesio/__init__.c \
aesio/aes.c \
displayio/Bitmap.c \
displayio/ColorConverter.c \
displayio/Display.c \

8
py/circuitpy_mpconfig.h
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@ -223,6 +223,13 @@ typedef long mp_off_t;
// These CIRCUITPY_xxx values should all be defined in the *.mk files as being on or off.
// So if any are not defined in *.mk, they'll throw an error here.
#if CIRCUITPY_AESIO
extern const struct _mp_obj_module_t aesio_module;
#define AESIO_MODULE { MP_OBJ_NEW_QSTR(MP_QSTR_aesio), (mp_obj_t)&aesio_module },
#else
#define AESIO_MODULE
#endif
#if CIRCUITPY_ANALOGIO
#define ANALOGIO_MODULE { MP_OBJ_NEW_QSTR(MP_QSTR_analogio), (mp_obj_t)&analogio_module },
extern const struct _mp_obj_module_t analogio_module;
@ -619,6 +626,7 @@ extern const struct _mp_obj_module_t ustack_module;
// Some of these definitions will be blank depending on what is turned on and off.
// Some are omitted because they're in MICROPY_PORT_BUILTIN_MODULE_WEAK_LINKS above.
#define MICROPY_PORT_BUILTIN_MODULES_STRONG_LINKS \
AESIO_MODULE \
ANALOGIO_MODULE \
AUDIOBUSIO_MODULE \
AUDIOCORE_MODULE \

3
py/circuitpy_mpconfig.mk
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@ -33,6 +33,9 @@ CIRCUITPY_FULL_BUILD ?= 1
CFLAGS += -DCIRCUITPY_FULL_BUILD=$(CIRCUITPY_FULL_BUILD)
CIRCUITPY_AESIO ?= 0
CFLAGS += -DCIRCUITPY_AESIO=$(CIRCUITPY_AESIO)
CIRCUITPY_ANALOGIO ?= 1
CFLAGS += -DCIRCUITPY_ANALOGIO=$(CIRCUITPY_ANALOGIO)

79
shared-bindings/aesio/__init__.c Normal file
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@ -0,0 +1,79 @@
/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdint.h>
#include "py/obj.h"
#include "py/runtime.h"
#include "__init__.h"
//| :mod:`aesio` --- AES encryption routines
//| ========================================
//|
//| .. module:: aesio
//| :synopsis: Embedded implementation of AES
//|
//| The `AES` module contains classes used to implement encryption
//| and decryption. It aims to be low overhead in terms of memory.
//|
//|
//| Libraries
//|
//| .. toctree::
//| :maxdepth: 3
//|
//| aes
STATIC const mp_obj_tuple_t mp_aes_key_size_obj = {
{&mp_type_tuple},
3,
{
MP_OBJ_NEW_SMALL_INT(16),
MP_OBJ_NEW_SMALL_INT(24),
MP_OBJ_NEW_SMALL_INT(32),
}
};
STATIC const mp_rom_map_elem_t aesio_module_globals_table[] = {
{MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_aesio)},
{MP_ROM_QSTR(MP_QSTR_AES), MP_ROM_PTR(&aesio_aes_type) },
{MP_ROM_QSTR(MP_QSTR_MODE_ECB), MP_ROM_INT(AES_MODE_ECB)},
{MP_ROM_QSTR(MP_QSTR_MODE_CBC), MP_ROM_INT(AES_MODE_CBC)},
{MP_ROM_QSTR(MP_QSTR_MODE_CTR), MP_ROM_INT(AES_MODE_CTR)},
{MP_ROM_QSTR(MP_QSTR_block_size), MP_ROM_INT(AES_BLOCKLEN)},
{MP_ROM_QSTR(MP_QSTR_key_size), (mp_obj_t)&mp_aes_key_size_obj},
};
STATIC MP_DEFINE_CONST_DICT(aesio_module_globals, aesio_module_globals_table);
const mp_obj_module_t aesio_module = {
.base = {&mp_type_module},
.globals = (mp_obj_dict_t *)&aesio_module_globals,
};

53
shared-bindings/aesio/__init__.h Normal file
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@ -0,0 +1,53 @@
/*
* This file is part of the Micro Python project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef MICROPY_INCLUDED_SHARED_BINDINGS_AESIO_H
#define MICROPY_INCLUDED_SHARED_BINDINGS_AESIO_H
#include "shared-module/aesio/__init__.h"
extern const mp_obj_type_t aesio_aes_type;
void common_hal_aesio_aes_construct(aesio_aes_obj_t* self,
const uint8_t* key,
uint32_t key_length,
const uint8_t* iv,
int mode,
int counter);
void common_hal_aesio_aes_rekey(aesio_aes_obj_t* self,
const uint8_t* key,
uint32_t key_length,
const uint8_t* iv);
void common_hal_aesio_aes_set_mode(aesio_aes_obj_t* self,
int mode);
void common_hal_aesio_aes_encrypt(aesio_aes_obj_t* self,
uint8_t* buffer,
size_t len);
void common_hal_aesio_aes_decrypt(aesio_aes_obj_t* self,
uint8_t* buffer,
size_t len);
#endif // MICROPY_INCLUDED_SHARED_BINDINGS_AESIO_H

271
shared-bindings/aesio/aes.c Normal file
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@ -0,0 +1,271 @@
#include <stdint.h>
#include <string.h>
#include "py/obj.h"
#include "py/objproperty.h"
#include "py/runtime.h"
#include "shared-bindings/aesio/__init__.h"
// Defined at the end of this file
//| .. currentmodule:: aesio
//|
//| :class:`aesio` -- Encrypt and decrypt AES streams
//| =====================================================
//|
//| An object that represents an AES stream, including the current state.
//|
//| .. class:: AES(key, mode=0, iv=None, segment_size=8)
//|
//| Create a new AES state with the given key.
//|
//| :param bytearray key: A 16-, 24-, or 32-byte key
//| :param int mode: AES mode to use. One of: AES.MODE_ECB, AES.MODE_CBC, or
//| AES.MODE_CTR
//| :param bytearray iv: Initialization vector to use for CBC or CTR mode
//|
//| Additional arguments are supported for legacy reasons.
//|
//| Encrypting a string::
//|
//| import aesio
//| from binascii import hexlify
//|
//| key = b'Sixteen byte key'
//| inp = b'Circuit Python!!' # Note: 16-bytes long
//| outp = bytearray(len(inp))
//| cipher = aesio.AES(key, aesio.mode.MODE_ECB)
//| cipher.encrypt_into(inp, outp)
//| hexlify(outp)
//|
STATIC mp_obj_t aesio_aes_make_new(const mp_obj_type_t *type, size_t n_args,
const mp_obj_t *pos_args,
mp_map_t *kw_args) {
(void)type;
enum { ARG_key, ARG_mode, ARG_IV, ARG_counter, ARG_segment_size };
static const mp_arg_t allowed_args[] = {
{MP_QSTR_key, MP_ARG_OBJ | MP_ARG_REQUIRED},
{MP_QSTR_mode, MP_ARG_INT, {.u_int = AES_MODE_ECB}},
{MP_QSTR_IV, MP_ARG_OBJ},
{MP_QSTR_counter, MP_ARG_OBJ},
{MP_QSTR_segment_size, MP_ARG_INT, {.u_int = 8}},
};
mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args),
allowed_args, args);
aesio_aes_obj_t *self = m_new_obj(aesio_aes_obj_t);
self->base.type = &aesio_aes_type;
mp_buffer_info_t bufinfo;
const uint8_t *key = NULL;
uint32_t key_length = 0;
if (mp_get_buffer(args[ARG_key].u_obj, &bufinfo, MP_BUFFER_READ)) {
if ((bufinfo.len != 16) && (bufinfo.len != 24) && (bufinfo.len != 32)) {
mp_raise_TypeError(translate("Key must be 16, 24, or 32 bytes long"));
}
key = bufinfo.buf;
key_length = bufinfo.len;
} else {
mp_raise_TypeError(translate("No key was specified"));
}
int mode = args[ARG_mode].u_int;
switch (args[ARG_mode].u_int) {
case AES_MODE_CBC:
case AES_MODE_ECB:
case AES_MODE_CTR:
break;
default:
mp_raise_TypeError(translate("Requested AES mode is unsupported"));
}
// IV is required for CBC mode and is ignored for other modes.
const uint8_t *iv = NULL;
if (args[ARG_IV].u_obj != NULL &&
mp_get_buffer(args[ARG_IV].u_obj, &bufinfo, MP_BUFFER_READ)) {
if (bufinfo.len != AES_BLOCKLEN) {
mp_raise_TypeError_varg(translate("IV must be %d bytes long"),
AES_BLOCKLEN);
}
iv = bufinfo.buf;
}
common_hal_aesio_aes_construct(self, key, key_length, iv, mode,
args[ARG_counter].u_int);
return MP_OBJ_FROM_PTR(self);
}
STATIC mp_obj_t aesio_aes_rekey(size_t n_args, const mp_obj_t *pos_args) {
aesio_aes_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
size_t key_length = 0;
const uint8_t *key =
(const uint8_t *)mp_obj_str_get_data(pos_args[1], &key_length);
if (key == NULL) {
mp_raise_ValueError(translate("No key was specified"));
}
if ((key_length != 16) && (key_length != 24) && (key_length != 32)) {
mp_raise_TypeError(translate("Key must be 16, 24, or 32 bytes long"));
}
const uint8_t *iv = NULL;
if (n_args > 2) {
size_t iv_length = 0;
iv = (const uint8_t *)mp_obj_str_get_data(pos_args[2], &iv_length);
if (iv_length != AES_BLOCKLEN) {
mp_raise_TypeError_varg(translate("IV must be %d bytes long"),
AES_BLOCKLEN);
}
}
common_hal_aesio_aes_rekey(self, key, key_length, iv);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_VAR(aesio_aes_rekey_obj, 2, aesio_aes_rekey);
STATIC void validate_length(aesio_aes_obj_t *self, size_t src_length,
size_t dest_length) {
if (src_length != dest_length) {
mp_raise_ValueError(
translate("Source and destination buffers must be the same length"));
}
switch (self->mode) {
case AES_MODE_ECB:
if (src_length != 16) {
mp_raise_msg(&mp_type_ValueError,
translate("ECB only operates on 16 bytes at a time"));
}
break;
case AES_MODE_CBC:
if ((src_length & 15) != 0) {
mp_raise_msg(&mp_type_ValueError,
translate("CBC blocks must be multiples of 16 bytes"));
}
break;
case AES_MODE_CTR:
break;
}
}
//| .. method:: encrypt_into(src, dest)
//|
//| Encrypt the buffer from ``src`` into ``dest``.
//| For ECB mode, the buffers must be 16 bytes long. For CBC mode, the
//| buffers must be a multiple of 16 bytes, and must be equal length. For
//| CTX mode, there are no restrictions.
//|
STATIC mp_obj_t aesio_aes_encrypt_into(mp_obj_t aesio_obj, mp_obj_t src,
mp_obj_t dest) {
if (!MP_OBJ_IS_TYPE(aesio_obj, &aesio_aes_type)) {
mp_raise_TypeError_varg(translate("Expected a %q"), aesio_aes_type.name);
}
// Convert parameters into expected types.
aesio_aes_obj_t *aes = MP_OBJ_TO_PTR(aesio_obj);
mp_buffer_info_t srcbufinfo, destbufinfo;
mp_get_buffer_raise(src, &srcbufinfo, MP_BUFFER_READ);
mp_get_buffer_raise(dest, &destbufinfo, MP_BUFFER_READ);
validate_length(aes, srcbufinfo.len, destbufinfo.len);
memcpy(destbufinfo.buf, srcbufinfo.buf, srcbufinfo.len);
common_hal_aesio_aes_encrypt(aes, (uint8_t *)destbufinfo.buf,
destbufinfo.len);
return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_3(aesio_aes_encrypt_into_obj,
aesio_aes_encrypt_into);
//| .. method:: decrypt_into(src, dest)
//|
//| Decrypt the buffer from ``src`` into ``dest``.
//| For ECB mode, the buffers must be 16 bytes long. For CBC mode, the
//| buffers must be a multiple of 16 bytes, and must be equal length. For
//| CTX mode, there are no restrictions.
//|
STATIC mp_obj_t aesio_aes_decrypt_into(mp_obj_t aesio_obj, mp_obj_t src,
mp_obj_t dest) {
if (!MP_OBJ_IS_TYPE(aesio_obj, &aesio_aes_type)) {
mp_raise_TypeError_varg(translate("Expected a %q"), aesio_aes_type.name);
}
// Convert parameters into expected types.
aesio_aes_obj_t *aes = MP_OBJ_TO_PTR(aesio_obj);
mp_buffer_info_t srcbufinfo, destbufinfo;
mp_get_buffer_raise(src, &srcbufinfo, MP_BUFFER_READ);
mp_get_buffer_raise(dest, &destbufinfo, MP_BUFFER_READ);
validate_length(aes, srcbufinfo.len, destbufinfo.len);
memcpy(destbufinfo.buf, srcbufinfo.buf, srcbufinfo.len);
common_hal_aesio_aes_decrypt(aes, (uint8_t *)destbufinfo.buf,
destbufinfo.len);
return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_3(aesio_aes_decrypt_into_obj,
aesio_aes_decrypt_into);
STATIC mp_obj_t aesio_aes_get_mode(mp_obj_t aesio_obj) {
if (!MP_OBJ_IS_TYPE(aesio_obj, &aesio_aes_type)) {
mp_raise_TypeError_varg(translate("Expected a %q"), aesio_aes_type.name);
}
aesio_aes_obj_t *self = MP_OBJ_TO_PTR(aesio_obj);
return MP_OBJ_NEW_SMALL_INT(self->mode);
}
MP_DEFINE_CONST_FUN_OBJ_1(aesio_aes_get_mode_obj, aesio_aes_get_mode);
STATIC mp_obj_t aesio_aes_set_mode(mp_obj_t aesio_obj, mp_obj_t mode_obj) {
if (!MP_OBJ_IS_TYPE(aesio_obj, &aesio_aes_type)) {
mp_raise_TypeError_varg(translate("Expected a %q"), aesio_aes_type.name);
}
aesio_aes_obj_t *self = MP_OBJ_TO_PTR(aesio_obj);
int mode = mp_obj_get_int(mode_obj);
switch (mode) {
case AES_MODE_CBC:
case AES_MODE_ECB:
case AES_MODE_CTR:
break;
default:
mp_raise_TypeError(translate("Requested AES mode is unsupported"));
}
common_hal_aesio_aes_set_mode(self, mode);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_2(aesio_aes_set_mode_obj, aesio_aes_set_mode);
const mp_obj_property_t aesio_aes_mode_obj = {
.base.type = &mp_type_property,
.proxy = {
(mp_obj_t)&aesio_aes_get_mode_obj,
(mp_obj_t)&aesio_aes_set_mode_obj,
(mp_obj_t)&mp_const_none_obj
},
};
STATIC const mp_rom_map_elem_t aesio_locals_dict_table[] = {
// Methods
{MP_ROM_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR_AES)},
{MP_ROM_QSTR(MP_QSTR_encrypt_into), (mp_obj_t)&aesio_aes_encrypt_into_obj},
{MP_ROM_QSTR(MP_QSTR_decrypt_into), (mp_obj_t)&aesio_aes_decrypt_into_obj},
{MP_ROM_QSTR(MP_QSTR_rekey), (mp_obj_t)&aesio_aes_rekey_obj},
{MP_ROM_QSTR(MP_QSTR_mode), (mp_obj_t)&aesio_aes_mode_obj},
};
STATIC MP_DEFINE_CONST_DICT(aesio_locals_dict, aesio_locals_dict_table);
const mp_obj_type_t aesio_aes_type = {
{&mp_type_type},
.name = MP_QSTR_AES,
.make_new = aesio_aes_make_new,
.locals_dict = (mp_obj_dict_t *)&aesio_locals_dict,
};

58
shared-module/aesio/__init__.c Normal file
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@ -0,0 +1,58 @@
#include <string.h>
#include "py/runtime.h"
#include "shared-bindings/aesio/__init__.h"
#include "shared-module/aesio/__init__.h"
void common_hal_aesio_aes_construct(aesio_aes_obj_t *self, const uint8_t *key,
uint32_t key_length, const uint8_t *iv,
int mode, int counter) {
self->mode = mode;
self->counter = counter;
common_hal_aesio_aes_rekey(self, key, key_length, iv);
}
void common_hal_aesio_aes_rekey(aesio_aes_obj_t *self, const uint8_t *key,
uint32_t key_length, const uint8_t *iv) {
memset(&self->ctx, 0, sizeof(self->ctx));
if (iv != NULL) {
AES_init_ctx_iv(&self->ctx, key, key_length, iv);
} else {
AES_init_ctx(&self->ctx, key, key_length);
}
}
void common_hal_aesio_aes_set_mode(aesio_aes_obj_t *self, int mode) {
self->mode = mode;
}
void common_hal_aesio_aes_encrypt(aesio_aes_obj_t *self, uint8_t *buffer,
size_t length) {
switch (self->mode) {
case AES_MODE_ECB:
AES_ECB_encrypt(&self->ctx, buffer);
break;
case AES_MODE_CBC:
AES_CBC_encrypt_buffer(&self->ctx, buffer, length);
break;
case AES_MODE_CTR:
AES_CTR_xcrypt_buffer(&self->ctx, buffer, length);
break;
}
}
void common_hal_aesio_aes_decrypt(aesio_aes_obj_t *self, uint8_t *buffer,
size_t length) {
switch (self->mode) {
case AES_MODE_ECB:
AES_ECB_decrypt(&self->ctx, buffer);
break;
case AES_MODE_CBC:
AES_CBC_decrypt_buffer(&self->ctx, buffer, length);
break;
case AES_MODE_CTR:
AES_CTR_xcrypt_buffer(&self->ctx, buffer, length);
break;
}
}

59
shared-module/aesio/__init__.h Normal file
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@ -0,0 +1,59 @@
/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2018 Dan Halbert for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef MICROPY_INCLUDED_SHARED_MODULE_AESIO__INIT__H
#define MICROPY_INCLUDED_SHARED_MODULE_AESIO__INIT__H
#include <stdbool.h>
#include <stdint.h>
#include "py/obj.h"
#include "py/proto.h"
#include "shared-module/aesio/aes.h"
// These values were chosen to correspond with the values
// present in pycrypto.
enum AES_MODE {
AES_MODE_ECB = 1,
AES_MODE_CBC = 2,
AES_MODE_CTR = 6,
};
typedef struct {
mp_obj_base_t base;
// The tinyaes context
struct AES_ctx ctx;
// Which AES mode this instance of the object is configured to use
enum AES_MODE mode;
// Counter for running in CTR mode
uint32_t counter;
} aesio_aes_obj_t;
#endif // MICROPY_INCLUDED_SHARED_MODULE_AESIO__INIT__H

608
shared-module/aesio/aes.c Normal file
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@ -0,0 +1,608 @@
/*
This is an implementation of the AES algorithm, specifically ECB, CTR and CBC mode.
Block size can be chosen in aes.h - available choices are AES128, AES192, AES256.
The implementation is verified against the test vectors in:
National Institute of Standards and Technology Special Publication 800-38A 2001 ED
ECB-AES128
----------
plain-text:
6bc1bee22e409f96e93d7e117393172a
ae2d8a571e03ac9c9eb76fac45af8e51
30c81c46a35ce411e5fbc1191a0a52ef
f69f2445df4f9b17ad2b417be66c3710
key:
2b7e151628aed2a6abf7158809cf4f3c
resulting cipher
3ad77bb40d7a3660a89ecaf32466ef97
f5d3d58503b9699de785895a96fdbaaf
43b1cd7f598ece23881b00e3ed030688
7b0c785e27e8ad3f8223207104725dd4
NOTE: String length must be evenly divisible by 16byte (str_len % 16 == 0)
You should pad the end of the string with zeros if this is not the case.
For AES192/256 the key size is proportionally larger.
*/
/*****************************************************************************/
/* Includes: */
/*****************************************************************************/
#include <string.h> // CBC mode, for memset
#include "aes.h"
/*****************************************************************************/
/* Defines: */
/*****************************************************************************/
// The number of columns comprising a state in AES. This is a constant in AES.
// Value=4
#define Nb 4UL
#if defined(AES256) && (AES256 == 1)
#define Nk256 8UL
#define Nr256 14UL
#endif
#if defined(AES192) && (AES192 == 1)
#define Nk192 6UL
#define Nr192 12UL
#endif
#if defined(AES128) && (AES128 == 1)
#define Nk128 4UL // The number of 32 bit words in a key.
#define Nr128 10UL // The number of rounds in AES Cipher.
#endif
// jcallan@github points out that declaring Multiply as a function reduces code
// size considerably with the Keil ARM compiler. See this link for more
// information: https://github.com/kokke/tiny-AES-C/pull/3
#ifndef MULTIPLY_AS_A_FUNCTION
#define MULTIPLY_AS_A_FUNCTION 0
#endif
/*****************************************************************************/
/* Private variables: */
/*****************************************************************************/
// state - array holding the intermediate results during decryption.
typedef uint8_t state_t[4][4];
// The lookup-tables are marked const so they can be placed in read-only storage
// instead of RAM The numbers below can be computed dynamically trading ROM for
// RAM - This can be useful in (embedded) bootloader applications, where ROM is
// often limited.
static const uint8_t sbox[256] = {
//0 1 2 3 4 5 6 7 8 9 A B C D E F
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 };
static const uint8_t rsbox[256] = {
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d };
// The round constant word array, Rcon[i], contains the values given by x to the
// power (i-1) being powers of x (x is denoted as {02}) in the field GF(2^8)
static const uint8_t Rcon[11] = {
0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 };
/*
* Jordan Goulder points out in PR #12
* (https://github.com/kokke/tiny-AES-C/pull/12), that you can remove most of
* the elements in the Rcon array, because they are unused.
*
* From Wikipedia's article on the Rijndael key schedule @
* https://en.wikipedia.org/wiki/Rijndael_key_schedule#Rcon
*
* "Only the first some of these constants are actually used – up to rcon[10]
* for AES-128 (as 11 round keys are needed), up to rcon[8] for AES-192, up to
* rcon[7] for AES-256. rcon[0] is not used in AES algorithm."
*/
/*****************************************************************************/
/* Private functions: */
/*****************************************************************************/
static const uint8_t *GetRoundKey(const struct AES_ctx *ctx) {
switch (ctx->KeyLength) {
#if defined(AES128) && (AES128 == 1)
case 16: return ctx->RoundKey128;
#endif
#if defined(AES192) && (AES192 == 1)
case 24: return ctx->RoundKey192;
#endif
#if defined(AES256) && (AES256 == 1)
case 32: return ctx->RoundKey256;
#endif
}
return NULL;
}
/*
static uint8_t getSBoxValue(uint8_t num)
{
return sbox[num];
}
*/
#define getSBoxValue(num) (sbox[(num)])
/*
static uint8_t getSBoxInvert(uint8_t num)
{
return rsbox[num];
}
*/
#define getSBoxInvert(num) (rsbox[(num)])
// This function produces Nb(Nr+1) round keys. The round keys are used in each
// round to decrypt the states.
static void KeyExpansion(struct AES_ctx* ctx, const uint8_t* Key)
{
uint8_t* RoundKey = (uint8_t *)GetRoundKey(ctx);
unsigned i, j, k;
uint8_t tempa[4]; // Used for the column/row operations
// The first round key is the key itself.
for (i = 0; i < ctx->Nk; ++i)
{
RoundKey[(i * 4) + 0] = Key[(i * 4) + 0];
RoundKey[(i * 4) + 1] = Key[(i * 4) + 1];
RoundKey[(i * 4) + 2] = Key[(i * 4) + 2];
RoundKey[(i * 4) + 3] = Key[(i * 4) + 3];
}
// All other round keys are found from the previous round keys.
for (i = ctx->Nk; i < Nb * (ctx->Nr + 1); ++i)
{
{
k = (i - 1) * 4;
tempa[0]=RoundKey[k + 0];
tempa[1]=RoundKey[k + 1];
tempa[2]=RoundKey[k + 2];
tempa[3]=RoundKey[k + 3];
}
if (i % ctx->Nk == 0)
{
// This function shifts the 4 bytes in a word to the left once.
// [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
// Function RotWord()
{
const uint8_t u8tmp = tempa[0];
tempa[0] = tempa[1];
tempa[1] = tempa[2];
tempa[2] = tempa[3];
tempa[3] = u8tmp;
}
// SubWord() is a function that takes a four-byte input word and applies
// the S-box to each of the four bytes to produce an output word.
// Function Subword()
{
tempa[0] = getSBoxValue(tempa[0]);
tempa[1] = getSBoxValue(tempa[1]);
tempa[2] = getSBoxValue(tempa[2]);
tempa[3] = getSBoxValue(tempa[3]);
}
tempa[0] = tempa[0] ^ Rcon[i/ctx->Nk];
}
#if defined(AES256) && (AES256 == 1)
if (ctx->KeyLength == 32) {
if (i % ctx->Nk == 4)
{
// Function Subword()
{
tempa[0] = getSBoxValue(tempa[0]);
tempa[1] = getSBoxValue(tempa[1]);
tempa[2] = getSBoxValue(tempa[2]);
tempa[3] = getSBoxValue(tempa[3]);
}
}
}
#endif
j = i * 4; k=(i - ctx->Nk) * 4;
RoundKey[j + 0] = RoundKey[k + 0] ^ tempa[0];
RoundKey[j + 1] = RoundKey[k + 1] ^ tempa[1];
RoundKey[j + 2] = RoundKey[k + 2] ^ tempa[2];
RoundKey[j + 3] = RoundKey[k + 3] ^ tempa[3];
}
}
void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key, uint32_t keylen)
{
ctx->KeyLength = keylen;
switch (ctx->KeyLength) {
#if defined(AES128) && (AES128 == 1)
case 16: ctx->Nr = Nr128; ctx->Nk = Nk128; break;
#endif
#if defined(AES192) && (AES192 == 1)
case 24: ctx->Nr = Nr192; ctx->Nk = Nk192; break;
#endif
#if defined(AES256) && (AES256 == 1)
case 32: ctx->Nr = Nr256; ctx->Nk = Nk256; break;
#endif
default: ctx->Nr = 0; ctx->Nk = 0; break;
}
KeyExpansion(ctx, key);
}
#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, uint32_t keylen, const uint8_t* iv)
{
AES_init_ctx(ctx, key, keylen);
memcpy (ctx->Iv, iv, AES_BLOCKLEN);
}
void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv)
{
memcpy (ctx->Iv, iv, AES_BLOCKLEN);
}
#endif
// This function adds the round key to state. The round key is added to the
// state by an XOR function.
static void AddRoundKey(uint8_t round, state_t* state, const uint8_t* RoundKey)
{
uint8_t i,j;
for (i = 0; i < 4; ++i)
{
for (j = 0; j < 4; ++j)
{
(*state)[i][j] ^= RoundKey[(round * Nb * 4) + (i * Nb) + j];
}
}
}
// The SubBytes Function Substitutes the values in the state matrix with values
// in an S-box.
static void SubBytes(state_t* state)
{
uint8_t i, j;
for (i = 0; i < 4; ++i)
{
for (j = 0; j < 4; ++j)
{
(*state)[j][i] = getSBoxValue((*state)[j][i]);
}
}
}
// The ShiftRows() function shifts the rows in the state to the left. Each row
// is shifted with different offset. Offset = Row number. So the first row is
// not shifted.
static void ShiftRows(state_t* state)
{
uint8_t temp;
// Rotate first row 1 columns to left
temp = (*state)[0][1];
(*state)[0][1] = (*state)[1][1];
(*state)[1][1] = (*state)[2][1];
(*state)[2][1] = (*state)[3][1];
(*state)[3][1] = temp;
// Rotate second row 2 columns to left
temp = (*state)[0][2];
(*state)[0][2] = (*state)[2][2];
(*state)[2][2] = temp;
temp = (*state)[1][2];
(*state)[1][2] = (*state)[3][2];
(*state)[3][2] = temp;
// Rotate third row 3 columns to left
temp = (*state)[0][3];
(*state)[0][3] = (*state)[3][3];
(*state)[3][3] = (*state)[2][3];
(*state)[2][3] = (*state)[1][3];
(*state)[1][3] = temp;
}
static uint8_t xtime(uint8_t x)
{
return ((x<<1) ^ (((x>>7) & 1) * 0x1b));
}
// MixColumns function mixes the columns of the state matrix
static void MixColumns(state_t* state)
{
uint8_t i;
uint8_t Tmp, Tm, t;
for (i = 0; i < 4; ++i)
{
t = (*state)[i][0];
Tmp = (*state)[i][0] ^ (*state)[i][1] ^ (*state)[i][2] ^ (*state)[i][3] ;
Tm = (*state)[i][0] ^ (*state)[i][1] ; Tm = xtime(Tm); (*state)[i][0] ^= Tm ^ Tmp ;
Tm = (*state)[i][1] ^ (*state)[i][2] ; Tm = xtime(Tm); (*state)[i][1] ^= Tm ^ Tmp ;
Tm = (*state)[i][2] ^ (*state)[i][3] ; Tm = xtime(Tm); (*state)[i][2] ^= Tm ^ Tmp ;
Tm = (*state)[i][3] ^ t ; Tm = xtime(Tm); (*state)[i][3] ^= Tm ^ Tmp ;
}
}
// Multiply is used to multiply numbers in the field GF(2^8)
// Note: The last call to xtime() is unneeded, but often ends up generating a smaller binary
// The compiler seems to be able to vectorize the operation better this way.
// See https://github.com/kokke/tiny-AES-c/pull/34
#if MULTIPLY_AS_A_FUNCTION
static uint8_t Multiply(uint8_t x, uint8_t y)
{
return (((y & 1) * x) ^
((y>>1 & 1) * xtime(x)) ^
((y>>2 & 1) * xtime(xtime(x))) ^
((y>>3 & 1) * xtime(xtime(xtime(x)))) ^
((y>>4 & 1) * xtime(xtime(xtime(xtime(x)))))); /* this last call to xtime() can be omitted */
}
#else
#define Multiply(x, y) \
( ((y & 1) * x) ^ \
((y>>1 & 1) * xtime(x)) ^ \
((y>>2 & 1) * xtime(xtime(x))) ^ \
((y>>3 & 1) * xtime(xtime(xtime(x)))) ^ \
((y>>4 & 1) * xtime(xtime(xtime(xtime(x)))))) \
#endif
#if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
// MixColumns function mixes the columns of the state matrix. The method used to
// multiply may be difficult to understand for the inexperienced. Please use the
// references to gain more information.
static void InvMixColumns(state_t* state)
{
int i;
uint8_t a, b, c, d;
for (i = 0; i < 4; ++i)
{
a = (*state)[i][0];
b = (*state)[i][1];
c = (*state)[i][2];
d = (*state)[i][3];
(*state)[i][0] = Multiply(a, 0x0e) ^ Multiply(b, 0x0b) ^ Multiply(c, 0x0d) ^ Multiply(d, 0x09);
(*state)[i][1] = Multiply(a, 0x09) ^ Multiply(b, 0x0e) ^ Multiply(c, 0x0b) ^ Multiply(d, 0x0d);
(*state)[i][2] = Multiply(a, 0x0d) ^ Multiply(b, 0x09) ^ Multiply(c, 0x0e) ^ Multiply(d, 0x0b);
(*state)[i][3] = Multiply(a, 0x0b) ^ Multiply(b, 0x0d) ^ Multiply(c, 0x09) ^ Multiply(d, 0x0e);
}
}
// The SubBytes Function Substitutes the values in the state matrix with values
// in an S-box.
static void InvSubBytes(state_t* state)
{
uint8_t i, j;
for (i = 0; i < 4; ++i)
{
for (j = 0; j < 4; ++j)
{
(*state)[j][i] = getSBoxInvert((*state)[j][i]);
}
}
}
static void InvShiftRows(state_t* state)
{
uint8_t temp;
// Rotate first row 1 columns to right
temp = (*state)[3][1];
(*state)[3][1] = (*state)[2][1];
(*state)[2][1] = (*state)[1][1];
(*state)[1][1] = (*state)[0][1];
(*state)[0][1] = temp;
// Rotate second row 2 columns to right
temp = (*state)[0][2];
(*state)[0][2] = (*state)[2][2];
(*state)[2][2] = temp;
temp = (*state)[1][2];
(*state)[1][2] = (*state)[3][2];
(*state)[3][2] = temp;
// Rotate third row 3 columns to right
temp = (*state)[0][3];
(*state)[0][3] = (*state)[1][3];
(*state)[1][3] = (*state)[2][3];
(*state)[2][3] = (*state)[3][3];
(*state)[3][3] = temp;
}
#endif // #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
// Cipher is the main function that encrypts the PlainText.
static void Cipher(state_t* state, const struct AES_ctx* ctx)
{
const uint8_t* RoundKey = GetRoundKey(ctx);
uint8_t round = 0;
// Add the First round key to the state before starting the rounds.
AddRoundKey(0, state, RoundKey);
// There will be Nr rounds. The first Nr-1 rounds are identical. These Nr
// rounds are executed in the loop below. Last one without MixColumns()
for (round = 1; ; ++round)
{
SubBytes(state);
ShiftRows(state);
if (round == ctx->Nr) {
break;
}
MixColumns(state);
AddRoundKey(round, state, RoundKey);
}
// Add round key to last round
AddRoundKey(ctx->Nr, state, RoundKey);
}
#if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
static void InvCipher(state_t* state, const struct AES_ctx* ctx)
{
const uint8_t* RoundKey = GetRoundKey(ctx);
uint8_t round = 0;
// Add the First round key to the state before starting the rounds.
AddRoundKey(ctx->Nr, state, RoundKey);
// There will be Nr rounds. The first Nr-1 rounds are identical. These Nr
// rounds are executed in the loop below. Last one without InvMixColumn()
for (round = (ctx->Nr - 1); ; --round)
{
InvShiftRows(state);
InvSubBytes(state);
AddRoundKey(round, state, RoundKey);
if (round == 0) {
break;
}
InvMixColumns(state);
}
}
#endif // #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
/*****************************************************************************/
/* Public functions: */
/*****************************************************************************/
#if defined(ECB) && (ECB == 1)
void AES_ECB_encrypt(const struct AES_ctx* ctx, uint8_t* buf)
{
// The next function call encrypts the PlainText with the Key using AES
// algorithm.
Cipher((state_t*)buf, ctx);
}
void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf)
{
// The next function call decrypts the PlainText with the Key using AES
// algorithm.
InvCipher((state_t*)buf, ctx);
}
#endif // #if defined(ECB) && (ECB == 1)
#if defined(CBC) && (CBC == 1)
static void XorWithIv(uint8_t* buf, const uint8_t* Iv)
{
uint8_t i;
for (i = 0; i < AES_BLOCKLEN; ++i) // The block in AES is always 128bit no matter the key size
{
buf[i] ^= Iv[i];
}
}
void AES_CBC_encrypt_buffer(struct AES_ctx *ctx, uint8_t* buf, uint32_t length)
{
uintptr_t i;
uint8_t *Iv = ctx->Iv;
for (i = 0; i < length; i += AES_BLOCKLEN)
{
XorWithIv(buf, Iv);
Cipher((state_t*)buf, ctx);
Iv = buf;
buf += AES_BLOCKLEN;
}
/* store Iv in ctx for next call */
memcpy(ctx->Iv, Iv, AES_BLOCKLEN);
}
void AES_CBC_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length)
{
uintptr_t i;
uint8_t storeNextIv[AES_BLOCKLEN];
for (i = 0; i < length; i += AES_BLOCKLEN)
{
memcpy(storeNextIv, buf, AES_BLOCKLEN);
InvCipher((state_t*)buf, ctx);
XorWithIv(buf, ctx->Iv);
memcpy(ctx->Iv, storeNextIv, AES_BLOCKLEN);
buf += AES_BLOCKLEN;
}
}
#endif // #if defined(CBC) && (CBC == 1)
#if defined(CTR) && (CTR == 1)
/* Symmetrical operation: same function for encrypting as for decrypting. Note
any IV/nonce should never be reused with the same key */
void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length)
{
uint8_t buffer[AES_BLOCKLEN];
unsigned i;
int bi;
for (i = 0, bi = AES_BLOCKLEN; i < length; ++i, ++bi)
{
if (bi == AES_BLOCKLEN) /* we need to regen xor compliment in buffer */
{
memcpy(buffer, ctx->Iv, AES_BLOCKLEN);
Cipher((state_t*)buffer, ctx);
/* Increment Iv and handle overflow */
for (bi = (AES_BLOCKLEN - 1); bi >= 0; --bi)
{
/* inc will overflow */
if (ctx->Iv[bi] == 255)
{
ctx->Iv[bi] = 0;
continue;
}
ctx->Iv[bi] += 1;
break;
}
bi = 0;
}
buf[i] = (buf[i] ^ buffer[bi]);
}
}
#endif // #if defined(CTR) && (CTR == 1)

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#ifndef _AES_H_
#define _AES_H_
#include <stdint.h>
// #define the macros below to 1/0 to enable/disable the mode of operation.
//
// CBC enables AES encryption in CBC-mode of operation.
// CTR enables encryption in counter-mode.
// ECB enables the basic ECB 16-byte block algorithm. All can be enabled simultaneously.
// The #ifndef-guard allows it to be configured before #include'ing or at compile time.
#ifndef CBC
#define CBC 1
#endif
#ifndef ECB
#define ECB 1
#endif
#ifndef CTR
#define CTR 1
#endif
#define AES128 1
#define AES192 1
#define AES256 1
#define AES_BLOCKLEN 16 // Block length in bytes - AES is 128b block only
#if defined(AES256) && (AES256 == 1)
#define AES_KEYLEN256 32
#define AES_keyExpSize256 240
#endif
#if defined(AES192) && (AES192 == 1)
#define AES_KEYLEN192 24
#define AES_keyExpSize192 208
#endif
#if defined(AES128) && (AES128 == 1)
#define AES_KEYLEN128 16 // Key length in bytes
#define AES_keyExpSize128 176
#endif
struct AES_ctx
{
union {
#if defined(AES256) && (AES256 == 1)
uint8_t RoundKey256[AES_keyExpSize256];
#endif
#if defined(AES192) && (AES192 == 1)
uint8_t RoundKey192[AES_keyExpSize192];
#endif
#if defined(AES128) && (AES128 == 1)
uint8_t RoundKey128[AES_keyExpSize128];
#endif
};
#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
uint8_t Iv[AES_BLOCKLEN];
#endif
uint32_t KeyLength;
uint8_t Nr;
uint8_t Nk;
};
void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key, uint32_t keylen);
#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, uint32_t keylen, const uint8_t* iv);
void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv);
#endif
#if defined(ECB) && (ECB == 1)
// buffer size is exactly AES_BLOCKLEN bytes;
// you need only AES_init_ctx as IV is not used in ECB
// NB: ECB is considered insecure for most uses
void AES_ECB_encrypt(const struct AES_ctx* ctx, uint8_t* buf);
void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf);
#endif // #if defined(ECB) && (ECB == !)
#if defined(CBC) && (CBC == 1)
// buffer size MUST be mutile of AES_BLOCKLEN;
// Suggest https://en.wikipedia.org/wiki/Padding_(cryptography)#PKCS7 for padding scheme
// NOTES: you need to set IV in ctx via AES_init_ctx_iv() or AES_ctx_set_iv()
// no IV should ever be reused with the same key
void AES_CBC_encrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length);
void AES_CBC_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length);
#endif // #if defined(CBC) && (CBC == 1)
#if defined(CTR) && (CTR == 1)
// Same function for encrypting as for decrypting.
// IV is incremented for every block, and used after encryption as XOR-compliment for output
// Suggesting https://en.wikipedia.org/wiki/Padding_(cryptography)#PKCS7 for padding scheme
// NOTES: you need to set IV in ctx with AES_init_ctx_iv() or AES_ctx_set_iv()
// no IV should ever be reused with the same key
void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length);
#endif // #if defined(CTR) && (CTR == 1)
#endif // _AES_H_