samples: crypto: Add AES-GCM sample

Add sample for AES Galois/Counter Mode (GCM) of operation with a MACsec
GCM-AES test vector.
Also improve existing code by declaring expected ciphertext arrays as
constant.

Signed-off-by: Markus Fuchs <[email protected]>

Author: mrfuchs

samples/drivers/crypto/prj_mtls_shim.conf

@@ -5,6 +5,7 @@ CONFIG_MBEDTLS_BUILTIN=y
 CONFIG_MBEDTLS_CFG_FILE="config-tls-generic.h"
 CONFIG_MBEDTLS_HEAP_SIZE=512
 CONFIG_MBEDTLS_CIPHER_CCM_ENABLED=y
+CONFIG_MBEDTLS_CIPHER_MODE_GCM_ENABLED=y
 CONFIG_MAIN_STACK_SIZE=4096
 
 CONFIG_CRYPTO=y

samples/drivers/crypto/sample.yaml

@@ -18,6 +18,7 @@ tests:
         - ".*: CBC Mode"
         - ".*: CTR Mode"
         - ".*: CCM Mode"
+        - ".*: GCM Mode"
   sample.drivers.crypto.mbedtls.micro:
     tags: crypto
     harness_config:
@@ -27,6 +28,7 @@ tests:
         - ".*: CBC Mode"
         - ".*: CTR Mode"
         - ".*: CCM Mode"
+        - ".*: GCM Mode"
   sample.drivers.crypto.stm32:
     tags: crypto
     platform_whitelist: mikroe_mini_m4_for_stm32

samples/drivers/crypto/src/main.c

@@ -43,7 +43,7 @@ static u8_t plaintext[64] = {
 
 u32_t cap_flags;
 
-static void print_buffer_comparison(u8_t *wanted_result,
+static void print_buffer_comparison(const u8_t *wanted_result,
 				    u8_t *result, size_t length)
 {
 	int i, j;
@@ -113,7 +113,7 @@ void ecb_mode(struct device *dev)
 		0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
 		0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF
 	};
-	u8_t ecb_ciphertext[16] = {
+	const u8_t ecb_ciphertext[16] = {
 		0x69, 0xC4, 0xE0, 0xD8, 0x6A, 0x7B, 0x04, 0x30,
 		0xD8, 0xCD, 0xB7, 0x80, 0x70, 0xB4, 0xC5, 0x5A
 	};
@@ -188,7 +188,7 @@ void ecb_mode(struct device *dev)
 	cipher_free_session(dev, &ini);
 }
 
-static u8_t cbc_ciphertext[80] = {
+static const u8_t cbc_ciphertext[80] = {
 	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
 	0x0c, 0x0d, 0x0e, 0x0f, 0x76, 0x49, 0xab, 0xac, 0x81, 0x19, 0xb2, 0x46,
 	0xce, 0xe9, 0x8e, 0x9b, 0x12, 0xe9, 0x19, 0x7d, 0x50, 0x86, 0xcb, 0x9b,
@@ -276,7 +276,7 @@ void cbc_mode(struct device *dev)
 	cipher_free_session(dev, &ini);
 }
 
-static u8_t ctr_ciphertext[64] = {
+static const u8_t ctr_ciphertext[64] = {
 	0x22, 0xe5, 0x2f, 0xb1, 0x77, 0xd8, 0x65, 0xb2,
 	0xf7, 0xc6, 0xb5, 0x12, 0x69, 0x2d, 0x11, 0x4d,
 	0xed, 0x6c, 0x1c, 0x72, 0x25, 0xda, 0xf6, 0xa2,
@@ -381,7 +381,7 @@ static u8_t ccm_data[23] = {
 	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13,
 	0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e
 };
-static u8_t ccm_expected[31] = {
+static const u8_t ccm_expected[31] = {
 	0x58, 0x8c, 0x97, 0x9a, 0x61, 0xc6, 0x63, 0xd2, 0xf0, 0x66, 0xd0, 0xc2,
 	0xc0, 0xf9, 0x89, 0x80, 0x6d, 0x5f, 0x6b, 0x61, 0xda, 0xc3, 0x84, 0x17,
 	0xe8, 0xd1, 0x2c, 0xfd, 0xf9, 0x26, 0xe0
@@ -477,6 +477,123 @@ void ccm_mode(struct device *dev)
 	cipher_free_session(dev, &ini);
 }
 
+/*  MACsec GCM-AES test vector 2.4.1 */
+static u8_t gcm_key[16] = {
+	0x07, 0x1b, 0x11, 0x3b, 0x0c, 0xa7, 0x43, 0xfe, 0xcc, 0xcf, 0x3d, 0x05,
+	0x1f, 0x73, 0x73, 0x82
+};
+static u8_t gcm_nonce[12] = {
+	0xf0, 0x76, 0x1e, 0x8d, 0xcd, 0x3d, 0x00, 0x01, 0x76, 0xd4, 0x57, 0xed
+};
+static u8_t gcm_hdr[20] = {
+	0xe2, 0x01, 0x06, 0xd7, 0xcd, 0x0d, 0xf0, 0x76, 0x1e, 0x8d, 0xcd, 0x3d,
+	0x88, 0xe5, 0x4c, 0x2a, 0x76, 0xd4, 0x57, 0xed
+};
+static u8_t gcm_data[42] = {
+	0x08, 0x00, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
+	0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24,
+	0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
+	0x31, 0x32, 0x33, 0x34, 0x00, 0x04
+};
+static const u8_t gcm_expected[58] = {
+	0x13, 0xb4, 0xc7, 0x2b, 0x38, 0x9d, 0xc5, 0x01, 0x8e, 0x72, 0xa1, 0x71,
+	0xdd, 0x85, 0xa5, 0xd3, 0x75, 0x22, 0x74, 0xd3, 0xa0, 0x19, 0xfb, 0xca,
+	0xed, 0x09, 0xa4, 0x25, 0xcd, 0x9b, 0x2e, 0x1c, 0x9b, 0x72, 0xee, 0xe7,
+	0xc9, 0xde, 0x7d, 0x52, 0xb3, 0xf3,
+	0xd6, 0xa5, 0x28, 0x4f, 0x4a, 0x6d, 0x3f, 0xe2, 0x2a, 0x5d, 0x6c, 0x2b,
+	0x96, 0x04, 0x94, 0xc3
+};
+
+void gcm_mode(struct device *dev)
+{
+	u8_t encrypted[60] = {0};
+	u8_t decrypted[44] = {0};
+	struct cipher_ctx ini = {
+		.keylen = sizeof(gcm_key),
+		.key.bit_stream = gcm_key,
+		.mode_params.gcm_info = {
+			.nonce_len = sizeof(gcm_nonce),
+			.tag_len = 16,
+		},
+		.flags = cap_flags,
+	};
+	struct cipher_pkt encrypt = {
+		.in_buf = gcm_data,
+		.in_len = sizeof(gcm_data),
+		.out_buf_max = sizeof(encrypted),
+		.out_buf = encrypted,
+	};
+	struct cipher_aead_pkt gcm_op = {
+		.ad = gcm_hdr,
+		.ad_len = sizeof(gcm_hdr),
+		.pkt = &encrypt,
+		/* TinyCrypt always puts the tag at the end of the ciphered
+		 * text, but other library such as mbedtls might be more
+		 * flexible and can take a different buffer for it.  So to
+		 * make sure test passes on all backends: enforcing the tag
+		 * buffer to be after the ciphered text.
+		 */
+		.tag = encrypted + sizeof(gcm_data),
+	};
+	struct cipher_pkt decrypt = {
+		.in_buf = encrypted,
+		.in_len = sizeof(gcm_data),
+		.out_buf = decrypted,
+		.out_buf_max = sizeof(decrypted),
+	};
+
+	if (cipher_begin_session(dev, &ini, CRYPTO_CIPHER_ALGO_AES,
+				 CRYPTO_CIPHER_MODE_GCM,
+				 CRYPTO_CIPHER_OP_ENCRYPT)) {
+		return;
+	}
+
+	gcm_op.pkt = &encrypt;
+	if (cipher_gcm_op(&ini, &gcm_op, gcm_nonce)) {
+		LOG_ERR("GCM mode ENCRYPT - Failed");
+		goto out;
+	}
+
+	LOG_INF("Output length (encryption): %d", encrypt.out_len);
+
+	if (memcmp(encrypt.out_buf, gcm_expected, sizeof(gcm_expected))) {
+		LOG_ERR("GCM mode ENCRYPT - Mismatch between expected "
+			    "and returned cipher text");
+		print_buffer_comparison(gcm_expected,
+					encrypt.out_buf, sizeof(gcm_expected));
+		goto out;
+	}
+
+	LOG_INF("GCM mode ENCRYPT - Match");
+	cipher_free_session(dev, &ini);
+
+	if (cipher_begin_session(dev, &ini, CRYPTO_CIPHER_ALGO_AES,
+				 CRYPTO_CIPHER_MODE_GCM,
+				 CRYPTO_CIPHER_OP_DECRYPT)) {
+		return;
+	}
+
+	gcm_op.pkt = &decrypt;
+	if (cipher_gcm_op(&ini, &gcm_op, gcm_nonce)) {
+		LOG_ERR("GCM mode DECRYPT - Failed");
+		goto out;
+	}
+
+	LOG_INF("Output length (decryption): %d", decrypt.out_len);
+
+	if (memcmp(decrypt.out_buf, gcm_data, sizeof(gcm_data))) {
+		LOG_ERR("GCM mode DECRYPT - Mismatch between plaintext "
+			"and decrypted cipher text");
+		print_buffer_comparison(gcm_data,
+					decrypt.out_buf, sizeof(gcm_data));
+		goto out;
+	}
+
+	LOG_INF("GCM mode DECRYPT - Match");
+out:
+	cipher_free_session(dev, &ini);
+}
+
 struct mode_test {
 	const char *mode;
 	void (*mode_func)(struct device *dev);
@@ -490,6 +607,7 @@ void main(void)
 		{ .mode = "CBC Mode", .mode_func = cbc_mode },
 		{ .mode = "CTR Mode", .mode_func = ctr_mode },
 		{ .mode = "CCM Mode", .mode_func = ccm_mode },
+		{ .mode = "GCM Mode", .mode_func = gcm_mode },
 		{ },
 	};
 	int i;