Add examples

CMakeLists.txt

@@ -112,7 +112,7 @@ if(NOT USE_SOFTWARE_CRYPTO_SHA256)
     add_compile_definitions(NO_SOFTWARE_CRYPTO_SHA256)
 endif()
 
-option(USE_SOFTWARE_CRYPTO_SHA512 "include software SHA512" OFF)
+option(USE_SOFTWARE_CRYPTO_SHA512 "include software SHA512" ON)
 if(NOT USE_SOFTWARE_CRYPTO_SHA512)
     add_compile_definitions(NO_SOFTWARE_CRYPTO_SHA512)
 endif()

cmake/linker-map.cmake

@@ -0,0 +1,12 @@
+set(command ${CMAKE_C_COMPILER} ${flags} -Wl,--version)
+
+
+function(add_linker_map_for_target TARGET)
+    if (APPLE)
+        # LLVM only understands this flag.
+        # The map output differs from GNU ld.
+        target_link_options(${TARGET} PRIVATE "-Wl,-map,${TARGET}.map")
+    else()
+        target_link_options(${TARGET} PRIVATE "-Wl,-Map=${TARGET}.map")
+    endif()
+endfunction()

examples/CMakeLists.txt

@@ -1,11 +1,16 @@
+include(../cmake/linker-map.cmake)
 #######################################
 # NFC example
 
 add_executable(nfc nfc.c)
+add_linker_map_for_target(nfc)
 target_link_libraries(nfc ${PRODUCT_NAME})
 
+add_executable(nfc_simulator nfc_simulator.c stateless_rp.c)
+add_linker_map_for_target(nfc_simulator)
+target_link_libraries(nfc_simulator ${PRODUCT_NAME})
+
 #######################################
-# FIDO2 authenticator simulator example
+# Test applications
 
-add_executable(nfc_simulator nfc_simulator.c)
-target_link_libraries(nfc_simulator ${PRODUCT_NAME})
+add_subdirectory(measurements)

examples/measurements/CMakeLists.txt

@@ -0,0 +1,15 @@
+include(../../cmake/linker-map.cmake)
+
+set(measurement_dependencies gpio.c)
+
+function(add_measurement name)
+    add_executable(${name} "${name}.c" ${measurement_dependencies})
+    add_linker_map_for_target(${name})
+    target_link_libraries(${name} ${PRODUCT_NAME})
+endfunction()
+
+add_measurement("aes_gcm_measure")
+add_measurement("ed25519_measure")
+add_measurement("sha256_measure")
+add_measurement("sha512_measure")
+add_measurement("inflate_measure")

examples/measurements/aes_gcm_measure.c

@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2022 Felix Gohla, Konrad Hanff, Tobias Kantusch,
+ *                    Quentin Kuth, Felix Roth. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+#include "fido.h"
+#include "gpio.h"
+
+#define SAMPLES 20
+
+// See scripts/gen_aes_gcm.py
+static const uint8_t key[] = { 0x7d, 0x1a, 0x22, 0xe8, 0x33, 0x8c, 0xf9, 0x8c, 0x18, 0x4a, 0x36, 0xd7, 0x1f, 0x53, 0x57, 0x06, 0xe7, 0x61, 0xab, 0x8c, 0xe9, 0xe3, 0xca, 0xde, 0x0e, 0x18, 0x60, 0xdf, 0xa9, 0xb2, 0x6f, 0x36 };
+static const uint8_t associated_data[12] = "fidoonmicros";
+static const uint8_t nonce[] = { 0xb7, 0x3a, 0x1b, 0x33, 0x1e, 0xe7, 0xef, 0x59, 0x44, 0xf8, 0x50, 0x73 };
+static const uint8_t ciphertext[] = { 0x20, 0x21, 0x93, 0x59, 0x35, 0x51, 0xec, 0xaa, 0x5c, 0x63, 0xe2, 0x31, 0xbb, 0x1b, 0x12, 0x29, 0x1d, 0x12, 0x24, 0xe5, 0x63, 0x28, 0xfd, 0xcd, 0x8a, 0x3a, 0xee, 0x45, 0x9c, 0x22, 0x32, 0xcb, 0xba, 0x34, 0x2e, 0x18, 0xad, 0xe5, 0xd0, 0xfa, 0x8f, 0x4f, 0xfe, 0x3d, 0xfb, 0xe6, 0xd0, 0x84, 0x4f, 0xcd, 0x1d, 0xfd, 0x34, 0xec, 0x75, 0x7f, 0xef, 0x86, 0x71, 0x37, 0x3c, 0x4b, 0xf1, 0x68, 0x64, 0x21, 0x70, 0x65, 0x82, 0x2c, 0xe6, 0xfb, 0x81, 0x55, 0xfa, 0x87, 0x12, 0xd5, 0x43, 0xfa, 0x41, 0x75, 0x36, 0x47, 0xf3, 0xfe, 0x94, 0x8e, 0xb9, 0x6d, 0xa4, 0x9d, 0x84, 0x7e, 0xb0, 0x81, 0x45, 0x19, 0x78, 0xa2, 0x79, 0x91, 0x41, 0x45, 0x08, 0x04, 0x37, 0xf5, 0xa2, 0x1c, 0xdd, 0x24, 0x90, 0xda, 0xab, 0x76, 0x4e, 0xfb, 0xdc, 0x4f, 0x59, 0x3b, 0x55, 0xd8, 0x30, 0x50, 0xcf, 0x66, 0xe9, 0x7e, 0x42, 0x79, 0xe0, 0x5d, 0x95, 0x8a, 0x59, 0x94, 0xe3, 0x02, 0xfa, 0xcf, 0xf1, 0x10, 0x0e, 0xd1, 0x9d, 0xef, 0x01, 0x53, 0x51, 0x1d, 0xeb, 0xc8, 0x5c, 0x88, 0x74, 0xb5, 0xce, 0x8d, 0x64, 0x9b, 0x55, 0x45, 0xd2, 0xcb, 0xbf, 0xce, 0x62, 0xc2, 0x86, 0x91, 0x05, 0xca, 0xca, 0x63, 0xa3, 0x56, 0x48, 0x0d, 0x14, 0x27, 0x20, 0x0a, 0xa2, 0xfe, 0x14, 0x3b, 0x15, 0x90, 0x83, 0x97, 0xa4, 0x98, 0x07, 0xeb, 0x23, 0xa2, 0x36, 0x16, 0x2c, 0x8d, 0xb6, 0x38, 0xb5, 0xa8, 0x46, 0x1d, 0xde, 0x6e, 0x6e, 0xbd, 0xeb, 0x31, 0xd1, 0x8a, 0xa9, 0x3d, 0xee, 0x10, 0x79, 0xc7, 0x2a, 0xbc, 0xa4, 0x83, 0xe7, 0xae, 0xd9, 0xaa, 0xdd, 0xef, 0x3d, 0x37, 0x1d, 0x73, 0x73, 0x19, 0x4f, 0x94, 0x2d, 0xb1, 0xa6, 0x24, 0x70, 0x36, 0x35, 0xb9, 0x10, 0x2b, 0x81, 0x2e, 0x21, 0x8c, 0x41, 0xef, 0x7b, 0x76, 0xd1, 0x49, 0x10, 0x0d, 0x18, 0x8f, 0x1e, 0x9d, 0xb6, 0x40, 0xef, 0x76, 0xf5, 0xb6, 0xc1, 0xf8, 0xc5, 0x25, 0x1c, 0x34, 0x90, 0xa2, 0xb5, 0x38, 0xa8, 0x7e, 0x27, 0x44, 0xe6, 0x21, 0xb5, 0x4b, 0xca, 0x47, 0x60, 0x42, 0x40, 0xb2, 0x61, 0x3c, 0xb7, 0x10, 0xa6, 0xaa, 0x96, 0x91, 0xc9, 0x91, 0xdc, 0xbd, 0x79, 0xdd, 0xa4, 0xf7, 0xa7, 0x5b, 0x6c, 0x41, 0x89, 0x9e, 0x82, 0xbd, 0x13, 0x01, 0x8b, 0x5b, 0xf0, 0x2f, 0xd7, 0x96, 0xa0, 0x13, 0xad, 0x07, 0x75, 0x09, 0xc7, 0x4a, 0x87, 0xe1, 0x5e, 0x5e, 0xd3, 0xb5, 0xd1, 0xd1, 0xf1, 0xc6, 0xd6, 0x9c, 0x95, 0x77, 0xa6, 0x45, 0x4c, 0x2e, 0xce, 0x12, 0xd5, 0x90, 0xbe, 0x5c, 0x12, 0x76, 0xc3, 0x3c, 0x0d, 0x49, 0x66, 0x04, 0x0a, 0xc2, 0x5e, 0x7a, 0x35, 0xd4, 0xec, 0x7c, 0x2d, 0xc1, 0xba, 0x1f, 0x6d, 0x5b, 0x3d, 0x78, 0x09, 0xf2, 0xdc, 0x6b, 0x06, 0x20, 0x2c, 0x3b, 0x57, 0x5e, 0xb2, 0xec, 0x96, 0x87, 0x27, 0x07, 0x62, 0x51, 0xa6, 0x66, 0xd0, 0x61, 0xaf, 0x8f, 0x6d, 0xea, 0x67, 0xef, 0xcb, 0xb7, 0x99, 0xf4, 0xe6, 0xe5, 0x42, 0x30, 0x44, 0xf6, 0x9f, 0xc2, 0x27, 0x0d, 0x55, 0x4b, 0xc2, 0x97, 0x15, 0x68, 0x9b, 0x13, 0x93, 0x47, 0xf5, 0x0b, 0xd0, 0x28, 0xe5, 0x3a, 0x10, 0x2f, 0xb6, 0x8d, 0xc3, 0x9c, 0x2e, 0x10, 0x35, 0xc6, 0x9c, 0x23, 0xa0, 0xf1, 0x84, 0x21, 0x9f, 0x40, 0x78, 0x67, 0x6b, 0xf8, 0x3c, 0xeb, 0x3c, 0x9b, 0xa7, 0x30, 0x50, 0xcd, 0xf5, 0x5d, 0x73, 0x38, 0x7c, 0x9a, 0xfa, 0x21, 0xbf, 0xb9, 0xa4, 0xa3, 0xa3, 0x63, 0x49, 0xe5, 0x15, 0x23, 0x0d, 0x55, 0xb0, 0xf2, 0x28, 0xb3, 0xb2, 0x81, 0x47, 0x57, 0xea, 0x66, 0x08, 0x4e, 0xd0, 0x09, 0x1e, 0xf0, 0x21, 0xc2, 0x4f, 0x8b, 0x2b, 0x1f, 0x30, 0x2a, 0x48, 0x9f, 0xd5, 0x55, 0xb9, 0xde, 0x4d, 0xf6, 0xe2, 0x3a, 0xc9, 0x9b, 0xbf, 0xbe, 0xb1, 0xd4, 0x3c, 0x74, 0x09, 0x8d, 0x98, 0xa5, 0x51, 0x98, 0x5f, 0x19, 0x39, 0x82, 0xde, 0x19, 0x97, 0xa2, 0x95, 0x2a, 0x2e, 0x2f, 0x0e, 0xe3, 0x3a, 0xdb, 0x54, 0x37, 0x17, 0x84, 0xba, 0xb5, 0x44, 0xbb, 0xed, 0xfb, 0x57, 0xb4, 0xe6, 0xc4, 0x8d, 0xe4, 0x01, 0xb7, 0x84, 0x5f };
+static const uint8_t tag[] = { 0x65, 0xc0, 0xe6, 0x07, 0x14, 0x30, 0x93, 0xde, 0x16, 0xc4, 0xa3, 0x28, 0x59, 0x54, 0x47, 0x09 };
+
+int main(void) {
+    // Wait until the microcontroller booted up to remove increased power consumption in the measurements at the beginning.
+    delay(3000);
+
+    uint8_t plain[576] = {0};
+
+    setup_pin();
+    pin_off();
+
+    int e = 0;
+
+    // Test AES GCM decryption.
+    for (size_t i = 0; i < SAMPLES; ++i) {
+        pin_on();
+        e = fido_aes_gcm_decrypt(
+            key,
+            sizeof(key),
+            nonce,
+            sizeof(nonce),
+            ciphertext,
+            sizeof(ciphertext),
+            associated_data,
+            sizeof(associated_data),
+            tag,
+            plain
+        );
+        pin_off();
+
+        delay(500);
+    }
+
+    delay(1000);
+    pin_on();
+    for (size_t i = 0; i < SAMPLES; ++i) {
+        e = fido_aes_gcm_decrypt(
+            key,
+            sizeof(key),
+            nonce,
+            sizeof(nonce),
+            ciphertext,
+            sizeof(ciphertext),
+            associated_data,
+            sizeof(associated_data),
+            tag,
+            plain
+        );
+    }
+    pin_off();
+
+    return e;
+}

examples/measurements/ed25519_measure.c

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2022 Felix Gohla, Konrad Hanff, Tobias Kantusch,
+ *                    Quentin Kuth, Felix Roth. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+#include "fido.h"
+#include "gpio.h"
+
+#include <string.h>
+
+#define SAMPLES 20
+
+// See scripts/gen_ed25519.py
+// This is the DEMO private key corresponding to the public key below.
+// static const uint8_t private_key[] = { 0x5b, 0x35, 0xd2, 0x98, 0x87, 0xd9, 0x2d, 0xd7, 0x8b, 0xc9, 0xf2, 0x5f, 0x19, 0xa3, 0xdf, 0xb1, 0x7c, 0xe5, 0x4d, 0x72, 0xd7, 0xe5, 0xdb, 0x29, 0xa7, 0x69, 0xe9, 0x45, 0x14, 0xc9, 0x44, 0xb3 };
+static const uint8_t public_key[] = { 0x5e, 0x51, 0x78, 0x80, 0xf9, 0x31, 0x4f, 0x44, 0x57, 0x6a, 0xfc, 0xe8, 0xd4, 0x1d, 0x77, 0xef, 0xb9, 0xd8, 0x94, 0x5a, 0x57, 0x27, 0xb6, 0x5e, 0x0f, 0xea, 0x41, 0x49, 0x2d, 0x7d, 0x68, 0x80 };
+
+// 576 * 'f'
+static const uint8_t message[] = { 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66 };
+static const uint8_t signature[] = { 0x2e, 0x55, 0x1a, 0x75, 0xf6, 0x48, 0x01, 0xc0, 0x1f, 0x56, 0x81, 0x22, 0xb3, 0x7a, 0xc2, 0xf5, 0x43, 0xa7, 0x9a, 0x5e, 0x0a, 0xc0, 0xba, 0x9c, 0xbe, 0xdd, 0xc8, 0x71, 0x95, 0xc6, 0x74, 0x82, 0x11, 0x66, 0xea, 0xaf, 0x17, 0x30, 0xb5, 0xbc, 0xf3, 0xef, 0x2b, 0x2c, 0xa1, 0xf0, 0xe7, 0xa4, 0x0c, 0x8a, 0x9b, 0xad, 0x55, 0x06, 0x28, 0x46, 0x2f, 0xdf, 0x51, 0x56, 0xc7, 0x51, 0x88, 0x08 };
+
+int main(void) {
+    // Wait until the microcontroller booted up to remove increased power consumption in the measurements at the beginning.
+    delay(3000);
+
+    setup_pin();
+    pin_off();
+
+    int e = 0;
+
+    // Test ed25519 verification.
+    for (size_t i = 0; i < SAMPLES; ++i) {
+        pin_on();
+        e = fido_ed25519_verify(
+            signature,
+            public_key,
+            message,
+            sizeof(message)
+        );
+        pin_off();
+
+        delay(500);
+    }
+
+    delay(1000);
+    pin_on();
+    for (size_t i = 0; i < SAMPLES; ++i) {
+        e = fido_ed25519_verify(
+            signature,
+            public_key,
+            message,
+            sizeof(message)
+        );
+    }
+    pin_off();
+
+    return e;
+}

examples/measurements/gpio.c

@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2022 Felix Gohla, Konrad Hanff, Tobias Kantusch,
+ *                    Quentin Kuth, Felix Roth. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+#if defined(__AVR__)
+
+#include <avr/io.h>
+#include <util/delay.h>
+
+#define PIN PB5
+
+void setup_pin() {
+    DDRB |= _BV(PIN);
+}
+
+void pin_on() {
+    PORTB |= _BV(PIN);
+}
+
+void pin_off() {
+    PORTB &= ~_BV(PIN);
+}
+
+void delay(double ms) {
+    for (double i = 0; i < ms; i++) {
+        _delay_ms(1);
+    }
+}
+
+#else
+// To make the examples compile, default to NOOP.
+#warning GPIO does not work on this system, defaulting to nop
+void setup_pin() {}
+void pin_on() {}
+void pin_off() {}
+void delay(double ms) {}
+#endif

examples/measurements/gpio.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2022 Felix Gohla, Konrad Hanff, Tobias Kantusch,
+ *                    Quentin Kuth, Felix Roth. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+/**
+ * @brief Setup the logical PPK2 output pin.
+ */
+void setup_pin();
+
+/**
+ * @brief Turn the logical PPK2 output pin on.
+ */
+void pin_on();
+
+/**
+ * @brief Turn the logical PPK2 output pin off.
+ */
+void pin_off();
+
+/**
+ * @brief Delay program execution by given milliseconds.
+ *
+ * @param ms Milliseconds to delay program execution
+ */
+void delay(double ms);