aesio: add basic AES encryption and decryption

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
https://github.com/Legrandin/pycryptodome/tree/39626a5b01ce5c1cf51d022be166ad0aea722177/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 <[email protected]>

Author: xobs

py/circuitpy_defns.mk

@@ -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 \

py/circuitpy_mpconfig.h

@@ -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 \

py/circuitpy_mpconfig.mk

@@ -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)
 

shared-bindings/aesio/__init__.c

@@ -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,
+};
+

shared-bindings/aesio/__init__.h

@@ -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