getting-started: Align with getting_started.md snippets

The getting started guide in Mbed Crypto was recently changed to make it
more obvious that `AES_KEY` and `RSA_KEY` were shorthand for key
material. The guide did this by using function parameters instead of
all-caps shorthand. In order to better match what is in our getting
started guide with this getting started example, we make the same
function parameter changes here, passing global key data in via
`main()`.

Passing global key data in via `main()` has the additional benefit of
reducing stack usage of each example snippet function. This enables the
example to run on more boards, those with more limited stack space.

Author: Patater

getting-started/main.cpp

@@ -35,64 +35,68 @@
 /* This key is present as a global define for the purpose of example. In
  * real-world applications, you would not have a key hardcoded in source like
  * this. */
-#define AES_KEY \
-{ \
-0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, \
-0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, \
-}
+static const uint8_t AES_KEY[] =
+{
+    0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
+    0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa, 0xaa,
+};
 /* This key is present as a global define for the purpose of example. In
  * real-world applications, you would not have a key hardcoded in source like
  * this. */
-#define RSA_KEY \
-{ \
-0x30, 0x82, 0x02, 0x5e, 0x02, 0x01, 0x00, 0x02, 0x81, 0x81, 0x00, 0xaf, 0x05, \
-0x7d, 0x39, 0x6e, 0xe8, 0x4f, 0xb7, 0x5f, 0xdb, 0xb5, 0xc2, 0xb1, 0x3c, 0x7f, \
-0xe5, 0xa6, 0x54, 0xaa, 0x8a, 0xa2, 0x47, 0x0b, 0x54, 0x1e, 0xe1, 0xfe, 0xb0, \
-0xb1, 0x2d, 0x25, 0xc7, 0x97, 0x11, 0x53, 0x12, 0x49, 0xe1, 0x12, 0x96, 0x28, \
-0x04, 0x2d, 0xbb, 0xb6, 0xc1, 0x20, 0xd1, 0x44, 0x35, 0x24, 0xef, 0x4c, 0x0e, \
-0x6e, 0x1d, 0x89, 0x56, 0xee, 0xb2, 0x07, 0x7a, 0xf1, 0x23, 0x49, 0xdd, 0xee, \
-0xe5, 0x44, 0x83, 0xbc, 0x06, 0xc2, 0xc6, 0x19, 0x48, 0xcd, 0x02, 0xb2, 0x02, \
-0xe7, 0x96, 0xae, 0xbd, 0x94, 0xd3, 0xa7, 0xcb, 0xf8, 0x59, 0xc2, 0xc1, 0x81, \
-0x9c, 0x32, 0x4c, 0xb8, 0x2b, 0x9c, 0xd3, 0x4e, 0xde, 0x26, 0x3a, 0x2a, 0xbf, \
-0xfe, 0x47, 0x33, 0xf0, 0x77, 0x86, 0x9e, 0x86, 0x60, 0xf7, 0xd6, 0x83, 0x4d, \
-0xa5, 0x3d, 0x69, 0x0e, 0xf7, 0x98, 0x5f, 0x6b, 0xc3, 0x02, 0x03, 0x01, 0x00, \
-0x01, 0x02, 0x81, 0x81, 0x00, 0x87, 0x4b, 0xf0, 0xff, 0xc2, 0xf2, 0xa7, 0x1d, \
-0x14, 0x67, 0x1d, 0xdd, 0x01, 0x71, 0xc9, 0x54, 0xd7, 0xfd, 0xbf, 0x50, 0x28, \
-0x1e, 0x4f, 0x6d, 0x99, 0xea, 0x0e, 0x1e, 0xbc, 0xf8, 0x2f, 0xaa, 0x58, 0xe7, \
-0xb5, 0x95, 0xff, 0xb2, 0x93, 0xd1, 0xab, 0xe1, 0x7f, 0x11, 0x0b, 0x37, 0xc4, \
-0x8c, 0xc0, 0xf3, 0x6c, 0x37, 0xe8, 0x4d, 0x87, 0x66, 0x21, 0xd3, 0x27, 0xf6, \
-0x4b, 0xbe, 0x08, 0x45, 0x7d, 0x3e, 0xc4, 0x09, 0x8b, 0xa2, 0xfa, 0x0a, 0x31, \
-0x9f, 0xba, 0x41, 0x1c, 0x28, 0x41, 0xed, 0x7b, 0xe8, 0x31, 0x96, 0xa8, 0xcd, \
-0xf9, 0xda, 0xa5, 0xd0, 0x06, 0x94, 0xbc, 0x33, 0x5f, 0xc4, 0xc3, 0x22, 0x17, \
-0xfe, 0x04, 0x88, 0xbc, 0xe9, 0xcb, 0x72, 0x02, 0xe5, 0x94, 0x68, 0xb1, 0xea, \
-0xd1, 0x19, 0x00, 0x04, 0x77, 0xdb, 0x2c, 0xa7, 0x97, 0xfa, 0xc1, 0x9e, 0xda, \
-0x3f, 0x58, 0xc1, 0x02, 0x41, 0x00, 0xe2, 0xab, 0x76, 0x08, 0x41, 0xbb, 0x9d, \
-0x30, 0xa8, 0x1d, 0x22, 0x2d, 0xe1, 0xeb, 0x73, 0x81, 0xd8, 0x22, 0x14, 0x40, \
-0x7f, 0x1b, 0x97, 0x5c, 0xbb, 0xfe, 0x4e, 0x1a, 0x94, 0x67, 0xfd, 0x98, 0xad, \
-0xbd, 0x78, 0xf6, 0x07, 0x83, 0x6c, 0xa5, 0xbe, 0x19, 0x28, 0xb9, 0xd1, 0x60, \
-0xd9, 0x7f, 0xd4, 0x5c, 0x12, 0xd6, 0xb5, 0x2e, 0x2c, 0x98, 0x71, 0xa1, 0x74, \
-0xc6, 0x6b, 0x48, 0x81, 0x13, 0x02, 0x41, 0x00, 0xc5, 0xab, 0x27, 0x60, 0x21, \
-0x59, 0xae, 0x7d, 0x6f, 0x20, 0xc3, 0xc2, 0xee, 0x85, 0x1e, 0x46, 0xdc, 0x11, \
-0x2e, 0x68, 0x9e, 0x28, 0xd5, 0xfc, 0xbb, 0xf9, 0x90, 0xa9, 0x9e, 0xf8, 0xa9, \
-0x0b, 0x8b, 0xb4, 0x4f, 0xd3, 0x64, 0x67, 0xe7, 0xfc, 0x17, 0x89, 0xce, 0xb6, \
-0x63, 0xab, 0xda, 0x33, 0x86, 0x52, 0xc3, 0xc7, 0x3f, 0x11, 0x17, 0x74, 0x90, \
-0x2e, 0x84, 0x05, 0x65, 0x92, 0x70, 0x91, 0x02, 0x41, 0x00, 0xb6, 0xcd, 0xbd, \
-0x35, 0x4f, 0x7d, 0xf5, 0x79, 0xa6, 0x3b, 0x48, 0xb3, 0x64, 0x3e, 0x35, 0x3b, \
-0x84, 0x89, 0x87, 0x77, 0xb4, 0x8b, 0x15, 0xf9, 0x4e, 0x0b, 0xfc, 0x05, 0x67, \
-0xa6, 0xae, 0x59, 0x11, 0xd5, 0x7a, 0xd6, 0x40, 0x9c, 0xf7, 0x64, 0x7b, 0xf9, \
-0x62, 0x64, 0xe9, 0xbd, 0x87, 0xeb, 0x95, 0xe2, 0x63, 0xb7, 0x11, 0x0b, 0x9a, \
-0x1f, 0x9f, 0x94, 0xac, 0xce, 0xd0, 0xfa, 0xfa, 0x4d, 0x02, 0x40, 0x71, 0x19, \
-0x5e, 0xec, 0x37, 0xe8, 0xd2, 0x57, 0xde, 0xcf, 0xc6, 0x72, 0xb0, 0x7a, 0xe6, \
-0x39, 0xf1, 0x0c, 0xbb, 0x9b, 0x0c, 0x73, 0x9d, 0x0c, 0x80, 0x99, 0x68, 0xd6, \
-0x44, 0xa9, 0x4e, 0x3f, 0xd6, 0xed, 0x92, 0x87, 0x07, 0x7a, 0x14, 0x58, 0x3f, \
-0x37, 0x90, 0x58, 0xf7, 0x6a, 0x8a, 0xec, 0xd4, 0x3c, 0x62, 0xdc, 0x8c, 0x0f, \
-0x41, 0x76, 0x66, 0x50, 0xd7, 0x25, 0x27, 0x5a, 0xc4, 0xa1, 0x02, 0x41, 0x00, \
-0xbb, 0x32, 0xd1, 0x33, 0xed, 0xc2, 0xe0, 0x48, 0xd4, 0x63, 0x38, 0x8b, 0x7b, \
-0xe9, 0xcb, 0x4b, 0xe2, 0x9f, 0x4b, 0x62, 0x50, 0xbe, 0x60, 0x3e, 0x70, 0xe3, \
-0x64, 0x75, 0x01, 0xc9, 0x7d, 0xdd, 0xe2, 0x0a, 0x4e, 0x71, 0xbe, 0x95, 0xfd, \
-0x5e, 0x71, 0x78, 0x4e, 0x25, 0xac, 0xa4, 0xba, 0xf2, 0x5b, 0xe5, 0x73, 0x8a, \
-0xae, 0x59, 0xbb, 0xfe, 0x1c, 0x99, 0x77, 0x81, 0x44, 0x7a, 0x2b, 0x24, \
-}
+static const uint8_t RSA_KEY[] =
+{
+    0x30, 0x82, 0x02, 0x5e, 0x02, 0x01, 0x00, 0x02, 0x81, 0x81, 0x00, 0xaf,
+    0x05, 0x7d, 0x39, 0x6e, 0xe8, 0x4f, 0xb7, 0x5f, 0xdb, 0xb5, 0xc2, 0xb1,
+    0x3c, 0x7f, 0xe5, 0xa6, 0x54, 0xaa, 0x8a, 0xa2, 0x47, 0x0b, 0x54, 0x1e,
+    0xe1, 0xfe, 0xb0, 0xb1, 0x2d, 0x25, 0xc7, 0x97, 0x11, 0x53, 0x12, 0x49,
+    0xe1, 0x12, 0x96, 0x28, 0x04, 0x2d, 0xbb, 0xb6, 0xc1, 0x20, 0xd1, 0x44,
+    0x35, 0x24, 0xef, 0x4c, 0x0e, 0x6e, 0x1d, 0x89, 0x56, 0xee, 0xb2, 0x07,
+    0x7a, 0xf1, 0x23, 0x49, 0xdd, 0xee, 0xe5, 0x44, 0x83, 0xbc, 0x06, 0xc2,
+    0xc6, 0x19, 0x48, 0xcd, 0x02, 0xb2, 0x02, 0xe7, 0x96, 0xae, 0xbd, 0x94,
+    0xd3, 0xa7, 0xcb, 0xf8, 0x59, 0xc2, 0xc1, 0x81, 0x9c, 0x32, 0x4c, 0xb8,
+    0x2b, 0x9c, 0xd3, 0x4e, 0xde, 0x26, 0x3a, 0x2a, 0xbf, 0xfe, 0x47, 0x33,
+    0xf0, 0x77, 0x86, 0x9e, 0x86, 0x60, 0xf7, 0xd6, 0x83, 0x4d, 0xa5, 0x3d,
+    0x69, 0x0e, 0xf7, 0x98, 0x5f, 0x6b, 0xc3, 0x02, 0x03, 0x01, 0x00, 0x01,
+    0x02, 0x81, 0x81, 0x00, 0x87, 0x4b, 0xf0, 0xff, 0xc2, 0xf2, 0xa7, 0x1d,
+    0x14, 0x67, 0x1d, 0xdd, 0x01, 0x71, 0xc9, 0x54, 0xd7, 0xfd, 0xbf, 0x50,
+    0x28, 0x1e, 0x4f, 0x6d, 0x99, 0xea, 0x0e, 0x1e, 0xbc, 0xf8, 0x2f, 0xaa,
+    0x58, 0xe7, 0xb5, 0x95, 0xff, 0xb2, 0x93, 0xd1, 0xab, 0xe1, 0x7f, 0x11,
+    0x0b, 0x37, 0xc4, 0x8c, 0xc0, 0xf3, 0x6c, 0x37, 0xe8, 0x4d, 0x87, 0x66,
+    0x21, 0xd3, 0x27, 0xf6, 0x4b, 0xbe, 0x08, 0x45, 0x7d, 0x3e, 0xc4, 0x09,
+    0x8b, 0xa2, 0xfa, 0x0a, 0x31, 0x9f, 0xba, 0x41, 0x1c, 0x28, 0x41, 0xed,
+    0x7b, 0xe8, 0x31, 0x96, 0xa8, 0xcd, 0xf9, 0xda, 0xa5, 0xd0, 0x06, 0x94,
+    0xbc, 0x33, 0x5f, 0xc4, 0xc3, 0x22, 0x17, 0xfe, 0x04, 0x88, 0xbc, 0xe9,
+    0xcb, 0x72, 0x02, 0xe5, 0x94, 0x68, 0xb1, 0xea, 0xd1, 0x19, 0x00, 0x04,
+    0x77, 0xdb, 0x2c, 0xa7, 0x97, 0xfa, 0xc1, 0x9e, 0xda, 0x3f, 0x58, 0xc1,
+    0x02, 0x41, 0x00, 0xe2, 0xab, 0x76, 0x08, 0x41, 0xbb, 0x9d, 0x30, 0xa8,
+    0x1d, 0x22, 0x2d, 0xe1, 0xeb, 0x73, 0x81, 0xd8, 0x22, 0x14, 0x40, 0x7f,
+    0x1b, 0x97, 0x5c, 0xbb, 0xfe, 0x4e, 0x1a, 0x94, 0x67, 0xfd, 0x98, 0xad,
+    0xbd, 0x78, 0xf6, 0x07, 0x83, 0x6c, 0xa5, 0xbe, 0x19, 0x28, 0xb9, 0xd1,
+    0x60, 0xd9, 0x7f, 0xd4, 0x5c, 0x12, 0xd6, 0xb5, 0x2e, 0x2c, 0x98, 0x71,
+    0xa1, 0x74, 0xc6, 0x6b, 0x48, 0x81, 0x13, 0x02, 0x41, 0x00, 0xc5, 0xab,
+    0x27, 0x60, 0x21, 0x59, 0xae, 0x7d, 0x6f, 0x20, 0xc3, 0xc2, 0xee, 0x85,
+    0x1e, 0x46, 0xdc, 0x11, 0x2e, 0x68, 0x9e, 0x28, 0xd5, 0xfc, 0xbb, 0xf9,
+    0x90, 0xa9, 0x9e, 0xf8, 0xa9, 0x0b, 0x8b, 0xb4, 0x4f, 0xd3, 0x64, 0x67,
+    0xe7, 0xfc, 0x17, 0x89, 0xce, 0xb6, 0x63, 0xab, 0xda, 0x33, 0x86, 0x52,
+    0xc3, 0xc7, 0x3f, 0x11, 0x17, 0x74, 0x90, 0x2e, 0x84, 0x05, 0x65, 0x92,
+    0x70, 0x91, 0x02, 0x41, 0x00, 0xb6, 0xcd, 0xbd, 0x35, 0x4f, 0x7d, 0xf5,
+    0x79, 0xa6, 0x3b, 0x48, 0xb3, 0x64, 0x3e, 0x35, 0x3b, 0x84, 0x89, 0x87,
+    0x77, 0xb4, 0x8b, 0x15, 0xf9, 0x4e, 0x0b, 0xfc, 0x05, 0x67, 0xa6, 0xae,
+    0x59, 0x11, 0xd5, 0x7a, 0xd6, 0x40, 0x9c, 0xf7, 0x64, 0x7b, 0xf9, 0x62,
+    0x64, 0xe9, 0xbd, 0x87, 0xeb, 0x95, 0xe2, 0x63, 0xb7, 0x11, 0x0b, 0x9a,
+    0x1f, 0x9f, 0x94, 0xac, 0xce, 0xd0, 0xfa, 0xfa, 0x4d, 0x02, 0x40, 0x71,
+    0x19, 0x5e, 0xec, 0x37, 0xe8, 0xd2, 0x57, 0xde, 0xcf, 0xc6, 0x72, 0xb0,
+    0x7a, 0xe6, 0x39, 0xf1, 0x0c, 0xbb, 0x9b, 0x0c, 0x73, 0x9d, 0x0c, 0x80,
+    0x99, 0x68, 0xd6, 0x44, 0xa9, 0x4e, 0x3f, 0xd6, 0xed, 0x92, 0x87, 0x07,
+    0x7a, 0x14, 0x58, 0x3f, 0x37, 0x90, 0x58, 0xf7, 0x6a, 0x8a, 0xec, 0xd4,
+    0x3c, 0x62, 0xdc, 0x8c, 0x0f, 0x41, 0x76, 0x66, 0x50, 0xd7, 0x25, 0x27,
+    0x5a, 0xc4, 0xa1, 0x02, 0x41, 0x00, 0xbb, 0x32, 0xd1, 0x33, 0xed, 0xc2,
+    0xe0, 0x48, 0xd4, 0x63, 0x38, 0x8b, 0x7b, 0xe9, 0xcb, 0x4b, 0xe2, 0x9f,
+    0x4b, 0x62, 0x50, 0xbe, 0x60, 0x3e, 0x70, 0xe3, 0x64, 0x75, 0x01, 0xc9,
+    0x7d, 0xdd, 0xe2, 0x0a, 0x4e, 0x71, 0xbe, 0x95, 0xfd, 0x5e, 0x71, 0x78,
+    0x4e, 0x25, 0xac, 0xa4, 0xba, 0xf2, 0x5b, 0xe5, 0x73, 0x8a, 0xae, 0x59,
+    0xbb, 0xfe, 0x1c, 0x99, 0x77, 0x81, 0x44, 0x7a, 0x2b, 0x24,
+};
 
 #if !defined(MBEDTLS_PSA_CRYPTO_C) || (MBEDTLS_VERSION_NUMBER < 0x02130000)
 int main(void)
@@ -104,11 +108,10 @@ int main(void)
 }
 #else
 
-static void import_a_key(void)
+static void import_a_key(const uint8_t *key, size_t key_len)
 {
     psa_status_t status;
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    uint8_t data[] = AES_KEY;
     psa_key_handle_t handle;
 
     printf("Import an AES key...\t");
@@ -128,7 +131,7 @@ static void import_a_key(void)
     psa_set_key_bits(&attributes, 128);
 
     /* Import the key */
-    status = psa_import_key(&attributes, data, sizeof(data), &handle);
+    status = psa_import_key(&attributes, key, key_len, &handle);
     if (status != PSA_SUCCESS) {
         printf("Failed to import key\n");
         return;
@@ -144,11 +147,10 @@ static void import_a_key(void)
     mbedtls_psa_crypto_free();
 }
 
-static void sign_a_message_using_rsa(void)
+static void sign_a_message_using_rsa(const uint8_t *key, size_t key_len)
 {
     psa_status_t status;
     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
-    uint8_t key[] = RSA_KEY;
     uint8_t hash[] = "INPUT_FOR_SIGN";
     uint8_t signature[PSA_ASYMMETRIC_SIGNATURE_MAX_SIZE] = {0};
     size_t signature_length;
@@ -171,7 +173,7 @@ static void sign_a_message_using_rsa(void)
     psa_set_key_bits(&attributes, 1024);
 
     /* Import the key */
-    status = psa_import_key(&attributes, key, sizeof(key), &handle);
+    status = psa_import_key(&attributes, key, key_len, &handle);
     if (status != PSA_SUCCESS) {
         printf("Failed to import key\n");
         return;
@@ -198,7 +200,7 @@ static void sign_a_message_using_rsa(void)
     mbedtls_psa_crypto_free();
 }
 
-static void encrypt_with_symmetric_ciphers(void)
+static void encrypt_with_symmetric_ciphers(const uint8_t *key, size_t key_len)
 {
     enum {
         block_size = PSA_BLOCK_CIPHER_BLOCK_SIZE(PSA_KEY_TYPE_AES),
@@ -209,7 +211,6 @@ static void encrypt_with_symmetric_ciphers(void)
     uint8_t plaintext[block_size] = SOME_PLAINTEXT;
     uint8_t iv[block_size];
     size_t iv_len;
-    uint8_t key[] = AES_KEY;
     uint8_t output[block_size];
     size_t output_len;
     psa_key_handle_t handle;
@@ -231,7 +232,7 @@ static void encrypt_with_symmetric_ciphers(void)
     psa_set_key_algorithm(&attributes, alg);
     psa_set_key_type(&attributes, PSA_KEY_TYPE_AES);
     psa_set_key_bits(&attributes, 128);
-    status = psa_import_key(&attributes, key, sizeof(key), &handle);
+    status = psa_import_key(&attributes, key, key_len, &handle);
     if (status != PSA_SUCCESS) {
         printf("Failed to import a key\n");
         return;
@@ -272,7 +273,7 @@ static void encrypt_with_symmetric_ciphers(void)
     mbedtls_psa_crypto_free();
 }
 
-static void decrypt_with_symmetric_ciphers(void)
+static void decrypt_with_symmetric_ciphers(const uint8_t *key, size_t key_len)
 {
     enum {
         block_size = PSA_BLOCK_CIPHER_BLOCK_SIZE(PSA_KEY_TYPE_AES),
@@ -283,7 +284,6 @@ static void decrypt_with_symmetric_ciphers(void)
     psa_cipher_operation_t operation = PSA_CIPHER_OPERATION_INIT;
     uint8_t ciphertext[block_size] = SOME_CIPHERTEXT;
     uint8_t iv[block_size] = ENCRYPTED_WITH_IV;
-    uint8_t key[] = AES_KEY;
     uint8_t output[block_size];
     size_t output_len;
     psa_key_handle_t handle;
@@ -304,7 +304,7 @@ static void decrypt_with_symmetric_ciphers(void)
     psa_set_key_algorithm(&attributes, alg);
     psa_set_key_type(&attributes, PSA_KEY_TYPE_AES);
     psa_set_key_bits(&attributes, 128);
-    status = psa_import_key(&attributes, key, sizeof(key), &handle);
+    status = psa_import_key(&attributes, key, key_len, &handle);
     if (status != PSA_SUCCESS) {
         printf("Failed to import a key\n");
         return;
@@ -765,10 +765,10 @@ int main(void)
 {
     printf("-- Begin Mbed Crypto Getting Started --\n\n");
 
-    import_a_key();
-    sign_a_message_using_rsa();
-    encrypt_with_symmetric_ciphers();
-    decrypt_with_symmetric_ciphers();
+    import_a_key(AES_KEY, sizeof(AES_KEY));
+    sign_a_message_using_rsa(RSA_KEY, sizeof(RSA_KEY));
+    encrypt_with_symmetric_ciphers(AES_KEY, sizeof(AES_KEY));
+    decrypt_with_symmetric_ciphers(AES_KEY, sizeof(AES_KEY));
     hash_a_message();
     verify_a_hash();
     generate_a_random_value();