examples: fix flash encryption example test

Commit 5e8795eebe has changed the partition table offset, which
has resulted in the ciphertext not matching the one expected in the
example test.
Fix by calculating the ciphertext using espsecure.py.

examples/security/flash_encryption/README.md

@@ -100,8 +100,8 @@ Reading with esp_partition_read:
 I (461) example: 0x3ffb4da0   00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 0e 0f  |................|
 I (471) example: 0x3ffb4db0   10 11 12 13 14 15 16 17  18 19 1a 1b 1c 1d 1e 1f  |................|
 Reading with spi_flash_read:
-I (491) example: 0x3ffb4da0   29 68 2e 13 88 a0 5b 7f  cc 6b 39 f9 d7 7b 32 2f  |)h....[..k9..{2/|
-I (491) example: 0x3ffb4db0   9f e6 55 37 4b 91 b0 83  cd a6 e9 4e cd fa b4 c7  |..U7K......N....|
+I (491) example: 0x3ffb4b30   35 9b f2 07 b4 6d 40 89  28 b4 1e 22 98 7b 4a 36  |5....m@.(..".{J6|
+I (491) example: 0x3ffb4b40   ba 89 81 67 77 a3 60 5e  0a e7 51 01 b3 58 c2 f6  |...gw.`^..Q..X..|
 ```
 
 ## Troubleshooting

examples/security/flash_encryption/example_test.py

@@ -1,5 +1,19 @@
 from __future__ import print_function
+import binascii
+from io import BytesIO
+from collections import namedtuple
+import os
+import sys
+
 import ttfw_idf
+try:
+    import espsecure
+except ImportError:
+    idf_path = os.getenv("IDF_PATH")
+    if not idf_path or not os.path.exists(idf_path):
+        raise
+    sys.path.insert(0, os.path.join(idf_path, "components", "esptool_py", "esptool"))
+    import espsecure
 
 
 # To prepare a test runner for this example:
@@ -14,15 +28,31 @@ def test_examples_security_flash_encryption(env, extra_data):
     dut = env.get_dut('flash_encryption', 'examples/security/flash_encryption', dut_class=ttfw_idf.ESP32DUT)
     # start test
     dut.start_app()
+
+    # calculate the expected ciphertext
+    flash_addr = dut.app.partition_table["storage"]["offset"]
+    plain_hex_str = '00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 0e 0f'
+    plain_data = binascii.unhexlify(plain_hex_str.replace(' ', ''))
+
+    # Emulate espsecure encrypt_flash_data command
+    EncryptFlashDataArgs = namedtuple('EncryptFlashDataArgs', ['output', 'plaintext_file', 'address', 'keyfile', 'flash_crypt_conf'])
+    args = EncryptFlashDataArgs(BytesIO(), BytesIO(plain_data), flash_addr, BytesIO(b'\x00' * 32), 0xF)
+    espsecure.encrypt_flash_data(args)
+
+    expected_ciphertext = args.output.getvalue()
+    hex_ciphertext = binascii.hexlify(expected_ciphertext).decode('ascii')
+    expected_str = (' '.join(hex_ciphertext[i:i + 2] for i in range(0, 16, 2)) + '  ' +
+                    ' '.join(hex_ciphertext[i:i + 2] for i in range(16, 32, 2)))
+
     lines = [
         'FLASH_CRYPT_CNT eFuse value is 1',
         'Flash encryption feature is enabled in DEVELOPMENT mode',
         'with esp_partition_write',
-        '00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 0e 0f',
+        plain_hex_str,
         'with esp_partition_read',
-        '00 01 02 03 04 05 06 07  08 09 0a 0b 0c 0d 0e 0f',
+        plain_hex_str,
         'with spi_flash_read',
-        '29 68 2e 13 88 a0 5b 7f  cc 6b 39 f9 d7 7b 32 2f'
+        expected_str
     ]
     for line in lines:
         dut.expect(line, timeout=2)