diff --git a/crypto/aes.c b/crypto/aes.c
index 4aa5cd1c137..371c0d26240 100644
--- a/crypto/aes.c
+++ b/crypto/aes.c
@@ -105,7 +105,7 @@ static const uint8_t g_rcon[11] =
   0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36
 };
 
-static uint8_t g_expanded_key[176];
+static aes_state_s g_aes_state;
 
 /****************************************************************************
  * Private Functions
@@ -543,6 +543,88 @@ static void aes_decr(FAR uint8_t *state, FAR const uint8_t *expanded_key)
  * Public Functions
  ****************************************************************************/
 
+/****************************************************************************
+ * Name: aes_setupkey
+ *
+ * Description:
+ *   Configure the given AES context for operation with the selected key.
+ *
+ * Input Parameters:
+ *  state  an AES context that can be used for AES operations
+ *  key    a pointer to a 16-byte buffer holding the AES-128 key
+ *  len    length of the key, must be 16
+ *
+ * TODO: Support other key lengths of 24 (AES-192) and 32 (AES-256)
+ *
+ * Returned Value:
+ *   0 if OK
+ *   -EINVAL if len is not 16
+ *
+ ****************************************************************************/
+
+int aes_setupkey(FAR struct aes_state_s *state, FAR const uint8_t *key, int len)
+{
+  if (len != 16)
+    {
+      return -EINVAL;
+    }
+
+  expand_key(state->expanded_key, key);
+  return 0;
+}
+
+/****************************************************************************
+ * Name: aes_encipher
+ *
+ * Description:
+ *   Encipher some 16-byte blocks (without any operation mode) using the
+ *   previously defined key. The function can be called multiple times with
+ *   the same state parameter.
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void aes_encipher(FAR struct aes_state_s *state, FAR uint8_t *blocks,
+                  int nblk)
+{
+  int i;
+  uint32_t off = 0;
+
+  for (i = 0; i < nblk; i++)
+    {
+      aes_encr(blocks + off, state->expanded_key);
+      off += 16;
+    }
+}
+
+/****************************************************************************
+ * Name: aes_decipher
+ *
+ * Description:
+ *   Decipher some 16-byte blocks (without any operation mode) using the
+ *   previously defined key. The function can be called multiple times with
+ *   the same state parameter.
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void aes_decipher(FAR struct aes_state_s *state, FAR uint8_t *blocks,
+                  int nblk)
+{
+  int i;
+  uint32_t off = 0;
+
+  for (i = 0; i < nblk; i++)
+    {
+      aes_decr(blocks + off, state->expanded_key);
+      off += 16;
+    }
+}
+
 /****************************************************************************
  * Name: aes_encrypt
  *
@@ -564,8 +646,8 @@ void aes_encrypt(FAR uint8_t *state, FAR const uint8_t *key)
 {
   /* Expand the key into 176 bytes */
 
-  expand_key(g_expanded_key, key);
-  aes_encr(state, g_expanded_key);
+  aes_setupkey(&g_aes_state->expanded_key, key, 16);
+  aes_encr(state, g_aes_state->expanded_key);
 }
 
 /****************************************************************************
@@ -589,6 +671,6 @@ void aes_decrypt(FAR uint8_t *state, FAR const uint8_t *key)
 {
   /* Expand the key into 176 bytes */
 
-  expand_key(g_expanded_key, key);
-  aes_decr(state, g_expanded_key);
+  aes_setupkey(&g_aes_state->expanded_key, key, 16);
+  aes_decr(state, g_aes_state->expanded_key);
 }
diff --git a/include/nuttx/crypto/aes.h b/include/nuttx/crypto/aes.h
index af97032e50d..f3fe9fc6fbe 100644
--- a/include/nuttx/crypto/aes.h
+++ b/include/nuttx/crypto/aes.h
@@ -50,6 +50,15 @@
 
 #define AES128_KEY_SIZE    16
 
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+struct aes_state_s
+{
+  uint8_t expanded_key[176];
+};
+
 /****************************************************************************
  * Public Data
  ****************************************************************************/
@@ -61,7 +70,7 @@ extern "C"
 
 /****************************************************************************
  * Public Function Prototypes
-/****************************************************************************
+ ****************************************************************************/
 
 /****************************************************************************
  * Name: aes_encrypt
@@ -101,6 +110,60 @@ void aes_encrypt(FAR uint8_t *state, FAR const uint8_t *key);
 
 void aes_decrypt(FAR uint8_t *state, FAR const uint8_t *key);
 
+/****************************************************************************
+ * Name: aes_setupkey
+ *
+ * Description:
+ *   Configure the given AES context for operation with the selected key.
+ *
+ * Input Parameters:
+ *  state  an AES context that can be used for AES operations
+ *  key    a pointer to a 16-byte buffer holding the AES-128 key
+ *  len    length of the key, must be 16
+ *
+ * TODO: Support other key lengths of 24 (AES-192) and 32 (AES-256)
+ *
+ * Returned Value:
+ *   0 if OK
+ *   -EINVAL if len is not 16
+ *
+ ****************************************************************************/
+
+int aes_setupkey(FAR struct aes_state_s *state, FAR const uint8_t *key,
+                 int len);
+
+/****************************************************************************
+ * Name: aes_encipher
+ *
+ * Description:
+ *   Encipher some 16-byte blocks (without any operation mode) using the
+ *   previously defined key. The function can be called multiple times with
+ *   the same state parameter.
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void aes_encipher(FAR struct aes_state_s *state, FAR uint8_t *blocks,
+                  int nblk);
+
+/****************************************************************************
+ * Name: aes_decipher
+ *
+ * Description:
+ *   Decipher some 16-byte blocks (without any operation mode) using the
+ *   previously defined key. The function can be called multiple times with
+ *   the same state parameter.
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void aes_decipher(FAR struct aes_state_s *state, FAR uint8_t *blocks,
+                  int nblk);
+
 #ifdef  __cplusplus
 }
 #endif /* __cplusplus */