diff --git a/common/polarssl/libpcrypto.c b/common/polarssl/libpcrypto.c
index 6b3058c6..05c2ffe7 100644
--- a/common/polarssl/libpcrypto.c
+++ b/common/polarssl/libpcrypto.c
@@ -60,9 +60,16 @@ int aes_cmac(uint8_t *iv, uint8_t *key, uint8_t *input, uint8_t *mac, int length
 	data[length] = 0x80;
 	int datalen = (length & 0xfffffff0) + 0x10;
 	
+	
+//	int mbedtls_aes_cmac_prf_128( const unsigned char *key, size_t key_length,
+//                              const unsigned char *input, size_t in_len,
+//                              unsigned char *output )
+// mbedtls_aes_cmac_prf_128(key, 16, input, length, mac);
+
 	//  NIST 800-38B 
 	mbedtls_cipher_context_t ctx;
 	mbedtls_cipher_init(&ctx);
+	mbedtls_cipher_setup(&ctx, mbedtls_cipher_info_from_type(MBEDTLS_CIPHER_AES_128_ECB));
 	mbedtls_cipher_cmac_starts(&ctx, key, 128);
 	mbedtls_cipher_cmac_update(&ctx, data, datalen);
 	mbedtls_cipher_cmac_finish(&ctx, mac);