[PATCH 33/92] NAN: Add a function for encrypting the key data using the KEK

[Andrei Otcheretianski]

From: Avraham Stern <avraham.stern at intel.com>

Signed-off-by: Avraham Stern <avraham.stern at intel.com>
---
 src/nan/nan_crypto.c | 80 ++++++++++++++++++++++++++++++++++++++++++++
 src/nan/nan_i.h      |  3 +-
 2 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/src/nan/nan_crypto.c b/src/nan/nan_crypto.c
index f582830e8d..256ff23840 100644
--- a/src/nan/nan_crypto.c
+++ b/src/nan/nan_crypto.c
@@ -12,6 +12,7 @@
 #include "crypto/sha256.h"
 #include "crypto/sha384.h"
 #include "crypto/crypto.h"
+#include "crypto/aes_wrap.h"
 #include "nan_i.h"
 
 #define NAN_KCK_MAX_LEN 24
@@ -523,3 +524,82 @@ int nan_crypto_derive_kek(const u8 *kdk, size_t kdk_len,
 					  initiator_nmi, responder_nmi,
 					  ptk->kek, ptk->kek_len);
 }
+
+
+/*
+ * nan_crypto_encrypt_key - Encrypt key data using AES Key Wrap (RFC 3394)
+ *
+ * @key_data: Key data to be encrypted
+ * @kek: Key Encryption Key (KEK)
+ * @kek_len: Length of KEK in octets
+ *
+ * This function encrypts the provided key data using AES Key Wrap algorithm
+ * as defined in RFC 3394. The input data is padded to 8-byte alignment before
+ * encryption. The padding scheme uses 0xdd as the first padding byte followed
+ * by zeros.
+ *
+ * Returns: Encrypted key data in a newly allocated wpabuf, or NULL on failure.
+ * The caller is responsible for freeing the returned wpabuf.
+ */
+struct wpabuf *nan_crypto_encrypt_key_data(const struct wpabuf *key_data,
+					   const u8 *kek, size_t kek_len)
+{
+	size_t key_data_len;
+	size_t pad;
+	size_t padded_len;
+	u8 *padded_key_data;
+	struct wpabuf *encrypted_key_data;
+
+	if (!key_data || !kek || !kek_len) {
+		wpa_printf(MSG_ERROR,
+			   "NAN: Pairing: Invalid parameters for key data encryption");
+		return NULL;
+	}
+
+	key_data_len = wpabuf_len(key_data);
+	if (!key_data_len) {
+		wpa_printf(MSG_ERROR,
+			   "NAN: Pairing: Key data is empty for encryption");
+		return NULL;
+	}
+
+	wpa_hexdump_key(MSG_DEBUG, "NAN: Plain key data", wpabuf_head(key_data),
+			key_data_len);
+
+	/* Calculate padding to align to 8 bytes (AES block size) */
+	pad = key_data_len % 8;
+	if (pad)
+		pad = 8 - pad;
+
+	padded_len = key_data_len + pad;
+	padded_key_data = os_zalloc(padded_len);
+	if (!padded_key_data)
+		return NULL;
+
+	/* Copy key data and apply padding (0xdd followed by zeros) */
+	os_memcpy(padded_key_data, wpabuf_head(key_data), key_data_len);
+	if (pad)
+		padded_key_data[key_data_len] = 0xdd;
+
+	/* Allocate buffer for encrypted data (input length + 8 bytes for IV) */
+	encrypted_key_data = wpabuf_alloc(padded_len + 8);
+	if (!encrypted_key_data)
+		goto fail;
+
+	/* Encrypt the padded data using AES Key Wrap */
+	if (aes_wrap(kek, kek_len, padded_len / 8, padded_key_data,
+		     wpabuf_put(encrypted_key_data, padded_len + 8))) {
+		wpa_printf(MSG_ERROR, "NAN: Pairing: AES wrap failed");
+		wpabuf_free(encrypted_key_data);
+		encrypted_key_data = NULL;
+	} else {
+		wpa_hexdump_key(MSG_DEBUG, "NAN: Encrypted key data",
+				wpabuf_head(encrypted_key_data),
+				wpabuf_len(encrypted_key_data));
+	}
+
+fail:
+	os_memset(padded_key_data, 0, padded_len);
+	os_free(padded_key_data);
+	return encrypted_key_data;
+}
diff --git a/src/nan/nan_i.h b/src/nan/nan_i.h
index 07fa7a0e85..edfe28358a 100644
--- a/src/nan/nan_i.h
+++ b/src/nan/nan_i.h
@@ -727,7 +727,8 @@ int nan_crypto_derive_kek(const u8 *kdk, size_t kdk_len,
 			  enum nan_cipher_suite_id cipher,
 			  const u8 *initiator_nmi, const u8 *responder_nmi,
 			  struct wpa_ptk *ptk);
-
+struct wpabuf *nan_crypto_encrypt_key_data(const struct wpabuf *key_data,
+					   const u8 *kek, size_t kek_len);
 
 void nan_sec_reset(struct nan_data *nan, struct nan_ndp_sec *ndp_sec);
 int nan_sec_rx(struct nan_data *nan, struct nan_peer *peer,
-- 
2.53.0