crypto: add initial Crypto module with AESCipher

This adds initial support for the PyCrypto AESCipher module.  This
implementation supports only a subset of AESCipher modes, namely
ECB, CBC, and CTR modes.

Example usage adapted from the PyCrypto README for AES:

```
>>> from Crypto.Cipher import AES
>>>
>>> key = b'Sixteen byte key'
>>> cipher = AES.new(key, AES.MODE_ECB)
>>> cipher.encrypt(b'Circuit Python!!')
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

@@ -136,6 +136,9 @@ endif
 ifeq ($(CIRCUITPY_BUSIO),1)
 SRC_PATTERNS += busio/% bitbangio/OneWire.%
 endif
+ifeq ($(CIRCUITPY_CRYPTO),1)
+SRC_PATTERNS += crypto/%
+endif
 ifeq ($(CIRCUITPY_DIGITALIO),1)
 SRC_PATTERNS += digitalio/%
 endif
@@ -342,6 +345,8 @@ SRC_SHARED_MODULE_ALL = \
 	bitbangio/__init__.c \
 	board/__init__.c \
 	busio/OneWire.c \
+	crypto/__init__.c \
+	crypto/aes.c \
 	displayio/Bitmap.c \
 	displayio/ColorConverter.c \
 	displayio/Display.c \

py/circuitpy_mpconfig.h

@@ -314,6 +314,13 @@ extern const struct _mp_obj_module_t busio_module;
 #define BUSIO_MODULE
 #endif
 
+#if CIRCUITPY_CRYPTO
+extern const struct _mp_obj_module_t crypto_module;
+#define CRYPTO_MODULE       { MP_OBJ_NEW_QSTR(MP_QSTR_Crypto), (mp_obj_t)&crypto_module },
+#else
+#define CRYPTO_MODULE
+#endif
+
 #if CIRCUITPY_DIGITALIO
 extern const struct _mp_obj_module_t digitalio_module;
 #define DIGITALIO_MODULE       { MP_OBJ_NEW_QSTR(MP_QSTR_digitalio), (mp_obj_t)&digitalio_module },
@@ -630,6 +637,7 @@ extern const struct _mp_obj_module_t ustack_module;
     BLEIO_MODULE \
     BOARD_MODULE \
     BUSIO_MODULE \
+    CRYPTO_MODULE \
     DIGITALIO_MODULE \
     DISPLAYIO_MODULE \
       FONTIO_MODULE \

py/circuitpy_mpconfig.mk

@@ -104,6 +104,11 @@ CIRCUITPY_BUSIO = 1
 endif
 CFLAGS += -DCIRCUITPY_BUSIO=$(CIRCUITPY_BUSIO)
 
+ifndef CIRCUITPY_CRYPTO
+CIRCUITPY_CRYPTO = 0
+endif
+CFLAGS += -DCIRCUITPY_CRYPTO=$(CIRCUITPY_CRYPTO)
+
 ifndef CIRCUITPY_DIGITALIO
 CIRCUITPY_DIGITALIO = 1
 endif

shared-bindings/crypto/__init__.c

@@ -0,0 +1,86 @@
+/*
+ * 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:`Crypto.Cipher` --- Cipher encryption and decryption routines
+//| ==================================================================
+//|
+//| .. module:: Crypto.Cipher
+//|   :synopsis: Embedded implementation of PyCrypto
+//|
+//| The `Crypto.Cipher` submodule contains classes used to implement
+//| encryption and decryption routines.
+//|
+//| Libraries
+//|
+//| .. toctree::
+//|     :maxdepth: 3
+//|
+//|     aes
+//|
+
+
+STATIC const mp_rom_map_elem_t cipher_module_globals_table[] = {
+    {MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_Cipher)},
+    {MP_OBJ_NEW_QSTR(MP_QSTR_AES), MP_ROM_PTR(&aes_module)},
+};
+
+STATIC MP_DEFINE_CONST_DICT(cipher_module_globals, cipher_module_globals_table);
+
+
+const mp_obj_module_t cipher_module = {
+    {&mp_type_module},
+    .globals = (mp_obj_dict_t *)&cipher_module_globals,
+};
+
+//| :mod:`Crypto` --- Cryptographic routines
+//| ========================================
+//|
+//| .. module:: Crypto
+//|   :synopsis: Embedded implementation of PyCrypto
+//|
+//| The `Crypto` module contains classes used to implement cryptography.
+//| It aims to be API-compatible with the PyCrypto project.
+//|
+//|
+
+STATIC const mp_rom_map_elem_t crypto_module_globals_table[] = {
+    {MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_Crypto)},
+    {MP_OBJ_NEW_QSTR(MP_QSTR_Cipher), MP_ROM_PTR(&cipher_module)},
+};
+
+STATIC MP_DEFINE_CONST_DICT(crypto_module_globals, crypto_module_globals_table);
+
+const mp_obj_module_t crypto_module = {
+    .base = {&mp_type_module},
+    .globals = (mp_obj_dict_t *)&crypto_module_globals,
+};

shared-bindings/crypto/__init__.h

@@ -0,0 +1,48 @@
+/*
+ * 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_CRYPTO_H
+#define MICROPY_INCLUDED_SHARED_BINDINGS_CRYPTO_H
+
+#include "shared-module/crypto/__init__.h"
+
+extern const mp_obj_module_t crypto_module;
+extern const mp_obj_module_t aes_module;
+
+void common_hal_aes_construct(aes_obj_t* self,
+                              const uint8_t* key,
+                              uint32_t key_length,
+                              const uint8_t* iv,
+                              int mode,
+                              int counter);
+void common_hal_aes_encrypt(aes_obj_t* self,
+                            uint8_t* buffer,
+                            size_t len);
+void common_hal_aes_decrypt(aes_obj_t* self,
+                            uint8_t* buffer,
+                            size_t len);
+
+#endif // MICROPY_INCLUDED_SHARED_BINDINGS_CRYPTO_H