diff --git a/content.tex b/content.tex
index 4b45678..ab75f78 100644
--- a/content.tex
+++ b/content.tex
@@ -5750,6 +5750,8 @@ descriptor for the \field{sense_len}, \field{residual},
 \field{status_qualifier}, \field{status}, \field{response} and
 \field{sense} fields.
 
+\input{virtio-crypto.tex}
+
 \chapter{Reserved Feature Bits}\label{sec:Reserved Feature Bits}
 
 Currently there are three device-independent feature bits defined:
diff --git a/virtio-crypto.tex b/virtio-crypto.tex
new file mode 100644
index 0000000..491fc25
--- /dev/null
+++ b/virtio-crypto.tex
@@ -0,0 +1,835 @@
+\section{Crypto Device}\label{sec:Device Types / Crypto Device}
+
+The virtio crypto device is a virtual crypto device, and is a kind of
+virtual hardware accelerators for virtual machine.  The encryption and
+decryption requests of are placed in the data queue, and handled by the
+real crypto accelerators finally. The second queue is the control queue,
+which is used to create or destroy session for symmetric algorithms, and
+control some advanced features in the future. The virtio crypto
+device can provide seven crypto services: CIPHER, MAC, HASH, AEAD,
+KDF, ASYM, PRIMITIVE.
+
+\subsection{Device ID}\label{sec:Device Types / Crypto Device / Device ID}
+
+20
+
+\subsection{Virtqueues}\label{sec:Device Types / Crypto Device / Virtqueues}
+
+\begin{description}
+\item[0] dataq1
+\item[\ldots]
+\item[N-1] dataqN
+\item[N] controlq
+\end{description}
+
+N is set by \field{max_dataqueues} (\field{max_dataqueues} >= 1).
+
+\subsection{Feature bits}\label{sec:Device Types / Crypto Device / Feature bits}
+  None currently defined
+
+\subsection{Device configuration layout}\label{sec:Device Types / Crypto Device / Device configuration layout}
+
+Thirteen driver-read-only configuration fields are currently defined.
+
+\begin{lstlisting}
+struct virtio_crypto_config {
+    le16  status;
+    le16  max_dataqueues;
+    le32  crypto_services;
+    /* detailed algorithms mask */
+    le32 cipher_algo_l;
+    le32 cipher_algo_h;
+    le32 hash_algo;
+    le32 mac_algo_l;
+    le32 mac_algo_h;
+    le32 asym_algo;
+    le32 kdf_algo;
+    le32 aead_algo;
+    le32 primitive_algo;
+};
+\end{lstlisting}
+
+The first field, \field{status} is currently defined: VIRTIO_CRYPTO_S_HW_READY.
+
+\begin{lstlisting}
+#define VIRTIO_CRYPTO_S_HW_READY  (1 << 0)
+\end{lstlisting}
+
+The following driver-read-only field, \field{max_dataqueuess} specifies the
+maximum number of data virtqueues (dataq1\ldots dataqN). The crypto_services
+shows the crypto services the virtio crypto supports. The service currently
+defined are:
+
+\begin{lstlisting}
+#define VIRTIO_CRYPTO_NO_SERVICE (0) /* cipher services */
+#define VIRTIO_CRYPTO_SERVICE_CIPHER (1) /* cipher services */
+#define VIRTIO_CRYPTO_SERVICE_HASH  (2) /* hash service */
+#define VIRTIO_CRYPTO_SERVICE_MAC   (3) /* MAC (Message Authentication Codes) service */
+#define VIRTIO_CRYPTO_SERVICE_AEAD  (4) /* AEAD(Authenticated Encryption with Associated Data) service */
+\end{lstlisting}
+
+The last driver-read-only fields specify detailed algorithms mask which
+the device offered for corresponding service. The below CIPHER algorithms
+are defined currently:
+
+\begin{lstlisting}
+#define VIRTIO_CRYPTO_NO_CIPHER                 0
+#define VIRTIO_CRYPTO_CIPHER_ARC4               1
+#define VIRTIO_CRYPTO_CIPHER_AES_ECB            2
+#define VIRTIO_CRYPTO_CIPHER_AES_CBC            3
+#define VIRTIO_CRYPTO_CIPHER_AES_CTR            4
+#define VIRTIO_CRYPTO_CIPHER_DES_ECB            5
+#define VIRTIO_CRYPTO_CIPHER_DES_CBC            6
+#define VIRTIO_CRYPTO_CIPHER_3DES_ECB           7
+#define VIRTIO_CRYPTO_CIPHER_3DES_CBC           8
+#define VIRTIO_CRYPTO_CIPHER_3DES_CTR           9
+#define VIRTIO_CRYPTO_CIPHER_KASUMI_F8          10
+#define VIRTIO_CRYPTO_CIPHER_SNOW3G_UEA2        11
+#define VIRTIO_CRYPTO_CIPHER_AES_F8             12
+#define VIRTIO_CRYPTO_CIPHER_AES_XTS            13
+#define VIRTIO_CRYPTO_CIPHER_ZUC_EEA3           14
+\end{lstlisting}
+
+The below HASH algorithms are defined currently:
+
+\begin{lstlisting}
+#define VIRTIO_CRYPTO_NO_HASH            0
+#define VIRTIO_CRYPTO_HASH_MD5           1
+#define VIRTIO_CRYPTO_HASH_SHA1          2
+#define VIRTIO_CRYPTO_HASH_SHA_224       3
+#define VIRTIO_CRYPTO_HASH_SHA_256       4
+#define VIRTIO_CRYPTO_HASH_SHA_384       5
+#define VIRTIO_CRYPTO_HASH_SHA_512       6
+#define VIRTIO_CRYPTO_HASH_SHA3_224      7
+#define VIRTIO_CRYPTO_HASH_SHA3_256      8
+#define VIRTIO_CRYPTO_HASH_SHA3_384      9
+#define VIRTIO_CRYPTO_HASH_SHA3_512      10
+#define VIRTIO_CRYPTO_HASH_SHA3_SHAKE128      11
+#define VIRTIO_CRYPTO_HASH_SHA3_SHAKE256      12
+\end{lstlisting}
+
+The below MAC algorithms are defined currently:
+
+\begin{lstlisting}
+#define VIRTIO_CRYPTO_NO_MAC                       0
+#define VIRTIO_CRYPTO_MAC_HMAC_MD5                 1
+#define VIRTIO_CRYPTO_MAC_HMAC_SHA1                2
+#define VIRTIO_CRYPTO_MAC_HMAC_SHA_224             3
+#define VIRTIO_CRYPTO_MAC_HMAC_SHA_256             4
+#define VIRTIO_CRYPTO_MAC_HMAC_SHA_384             5
+#define VIRTIO_CRYPTO_MAC_HMAC_SHA_512             6
+#define VIRTIO_CRYPTO_MAC_CMAC_3DES                25
+#define VIRTIO_CRYPTO_MAC_CMAC_AES                 26
+#define VIRTIO_CRYPTO_MAC_CMAC_KASUMI_F9           27
+#define VIRTIO_CRYPTO_MAC_CMAC_SNOW3G_UIA2         28
+#define VIRTIO_CRYPTO_MAC_GMAC_AES                 41
+#define VIRTIO_CRYPTO_MAC_GMAC_TWOFISH             42
+#define VIRTIO_CRYPTO_MAC_CBCMAC_AES               49
+#define VIRTIO_CRYPTO_MAC_CBCMAC_KASUMI_F9         50
+#define VIRTIO_CRYPTO_MAC_XCBC_AES                 53
+#define VIRTIO_CRYPTO_MAC_ZUC_EIA3                 54
+\end{lstlisting}
+
+The below AEAD algorithms are defined currently:
+
+\begin{lstlisting}
+#define VIRTIO_CRYPTO_NO_AEAD     0
+#define VIRTIO_CRYPTO_AEAD_GCM    1
+#define VIRTIO_CRYPTO_AEAD_CCM    2
+#define VIRTIO_CRYPTO_AEAD_CHACHA20_POLY1305  3
+\end{lstlisting}
+
+\subsubsection{Device Requirements: Device configuration layout}\label{sec:Device Types / Crypto Device / Device configuration layout / Device Requirements: Device configuration layout}
+
+\begin{itemize*}
+\item The device MUST set \field{max_dataqueues} to between 1 and 65535 inclusive.
+\item The device SHOULD set \field{status} according to the status of the hardware-backed implementation.
+\item The device MUST set \field{crypto_services} according to the crypto services which the device offered.
+\item The device MUST set detailed algorithms mask according to \field{crypto_services} field.
+\end{itemize*}
+
+\subsubsection{Driver Requirements: Device configuration layout}\label{sec:Device Types / Crypto Device / Device configuration layout / Driver Requirements: Device configuration layout}
+
+\begin{itemize*}
+\item The driver MUST read the ready \field{status} from the bottom bit of status to
+      check whether the hardware-backed implementation is ready or not.
+\item The driver MAY read \field{max_dataqueues} field to discover how many data queues the device supports.
+\item The driver MUST read \field{crypto_services} field to discover which services the device is able to offer.
+\item The driver MUST read detail \field{algorithms} field according to \field{crypto_services} field.
+\end{itemize*}
+
+\subsection{Device Initialization}\label{sec:Device Types / Crypto Device / Device Initialization}
+
+\subsubsection{Driver Requirements: Device Initialization}\label{sec:Device Types / Crypto Device / Device Initialization / Driver Requirements: Device Initialization}
+
+\begin{itemize*}
+\item The driver MUST identify and initialize data virtqueue, up to \field{max_dataqueues}.
+\item The driver MUST identify the control virtqueue.
+\item The driver MUST identify the ready status of hardware-backend from \field{status} field.
+\item The driver MUST read the supported crypto services from bits of \field{crypto_servies}. 
+\item The driver MUST read the supported algorithms according to \field{crypto_services} field.
+\end{itemize*}
+
+\subsubsection{Device Requirements: Device Initialization}\label{sec:Device Types / Crypto Device / Device Initialization / Device Requirements: Device Initialization}
+
+\begin{itemize*}
+\item The device MUST be configured at least one real accelerator as the backend accelerator which executes real crypto operations.
+\item The device MUST write the \field{crypto_services} field according to the capacities of the backend accelerator.
+\item The device MUST write the corresponding algorithms field according to the \field{crypto_services} field.
+\end{itemize*}
+
+\subsection{Device Operation}\label{sec:Device Types / Crypto Device / Device Operation}
+
+Packets can be transmitted by placing them in both the controlq and dataq.
+The packet are consisted of general header and services specific request,
+Where 'general header' is for all crypto request, 'service specific request'
+is composed of operation parameter + output data + input data in generally.
+Operation parameters are algorithm-specific parameters, output data is the
+data should be operated, input data is the "operation result + result buffer".
+The general header of controlq:
+
+\begin{lstlisting}
+#define VIRTIO_CRYPTO_OPCODE(service, op)   ((service << 8) | (op))
+
+struct virtio_crypto_ctrl_header{
+#define VIRTIO_CRYPTO_CIPHER_CREATE_SESSION   VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_CIPHER, 0x02)
+#define VIRTIO_CRYPTO_CIPHER_DESTROY_SESSION  VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_CIPHER, 0x03)
+#define VIRTIO_CRYPTO_HASH_CREATE_SESSION     VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_HASH, 0x02)
+#define VIRTIO_CRYPTO_HASH_DESTROY_SESSION    VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_HASH, 0x03)
+#define VIRTIO_CRYPTO_MAC_CREATE_SESSION      VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_MAC, 0x02)
+#define VIRTIO_CRYPTO_MAC_DESTROY_SESSION     VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_MAC, 0x03)
+#define VIRTIO_CRYPTO_AEAD_CREATE_SESSION     VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_AEAD, 0x02)
+#define VIRTIO_CRYPTO_AEAD_DESTROY_SESSION    VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_AEAD, 0x03)
+    le32 opcode;
+    /* algo should be service-specific algorithms */
+    le32 algo;
+    /* control flag to control the request */
+    le16 flag;
+    /* data virtqeueu id */
+    le16 queue_id;
+};
+\end{lstlisting}
+
+The general header of dataq:
+
+\begin{lstlisting}
+struct virtio_crypto_op_header {
+#define VIRTIO_CRYPTO_CIPHER_ENCRYPT    VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_CIPHER, 0x00)
+#define VIRTIO_CRYPTO_CIPHER_DECRYPT    VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_CIPHER, 0x01)
+#define VIRTIO_CRYPTO_HASH              VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_HASH, 0x00)
+#define VIRTIO_CRYPTO_MAC               VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_MAC, 0x00)
+#define VIRTIO_CRYPTO_AEAD_ENCRYPT      VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_AEAD, 0x00)
+#define VIRTIO_CRYPTO_AEAD_DECRYPT      VIRTIO_CRYPTO_OPCODE(VIRTIO_CRYPTO_SERVICE_AEAD, 0x01)
+    le32 opcode;
+    /* algo should be service-specific algorithms */
+    le32 algo;
+    /* control flag to control the request */
+    le16 flag;
+    /* data virtqeueu id */
+    le16 queue_id;
+    /* session_id should be service-specific algorithms */
+    le64 session_id;
+};
+\end{lstlisting}
+
+\subsubsection{Control virtqueue}\label{sec:Device Types / Crypto Device / Device Operation / Control virtqueue}
+
+The driver uses the control virtqueue to send control commands to the
+device which finish the non-data plane operations, such as session
+operations (see \ref{sec:Device Types / Crypto Device / Device Operation / Session operation}).
+The packet of controlq:
+
+\begin{lstlisting}
+struct virtio_crypto_op_ctrl_req {
+    struct virtio_crypto_ctrl_header header;
+
+    union {
+        struct virtio_crypto_sym_create_session_req   sym_create_session;
+        struct virtio_crypto_hash_create_session_req  hash_create_session;
+        struct virtio_crypto_mac_create_session_req   mac_create_session;
+        struct virtio_crypto_aead_create_session_req  aead_create_session;
+        struct virtio_crypto_destroy_session_req      sym_destroy_session;
+    } u;
+};
+\end{lstlisting}
+
+The header is the general header, the union is algorithm-specific type,
+which is set by the driver. All the properties in the union will be shown as follow.
+
+\subsubsection{Session operation}\label{sec:Device Types / Crypto Device / Device Operation / Session operation}
+
+The symmetric algorithms have the concept of sessions. A session is a
+handle which describes the cryptographic parameters to be applied to
+a number of buffers. The data within a session handle includes the following:
+
+\begin{enumerate}
+\item The operation (cipher, hash/mac or both, and if both, the order in
+      which the algorithms should be applied).
+\item The cipher setup data, including the cipher algorithm and mode,
+      the key and its length, and the direction (encrypt or decrypt).
+\item The hash/mac setup data, including the hash algorithm or mac algorithm,
+      and digest result length (to allow for truncation).
+\begin{itemize*}
+\item Authenticated mode can refer to MAC, which requires that the key and
+      its length are also specified.
+\item For nested mode, the inner and outer prefix data and length are specified,
+      as well as the outer hash algorithm.
+\end{itemize*}
+\end{enumerate}
+
+\paragraph{Session operation: HASH session}\label{sec:Device Types / Crypto Device / Device Operation / Session operation / Session operation: HASH session}
+
+The packet of HASH session is:
+
+\begin{lstlisting}
+struct virtio_crypto_hash_session_para {
+    /* See VIRTIO_CRYPTO_HASH_* above */
+    le32 algo;
+    /* hash result length */
+    le32 hash_result_len;
+};
+struct virtio_crypto_hash_create_session_req {
+    // Device-readable part
+    struct virtio_crypto_hash_session_para parameter;
+    // Device-writable part
+    le64    session_id;
+    u8     status;
+};
+\end{lstlisting}
+
+\paragraph{Session operation: MAC session}\label{sec:Device Types / Crypto Device / Device
+Operation / Session operation / Session operation: MAC session}
+
+The packet of MAC session is:
+
+\begin{lstlisting}
+struct virtio_crypto_mac_session_para {
+    /* See VIRTIO_CRYPTO_MAC_* above */
+    le32 algo;
+    /* hash result length */
+    le32 hash_result_len;
+    /* length of authenticated key */
+    le32 auth_key_len;
+};
+struct virtio_crypto_mac_create_session_req {
+    // Device-readable part
+    struct virtio_crypto_mac_session_para  parameter;
+    // Device-writable part
+    le64    session_id;
+    u8     status;
+};
+\end{lstlisting}
+
+\paragraph{Session operation: Symmetric algorithms session}\label{sec:Device Types / Crypto Device / Device
+Operation / Session operation / Session operation: Symmetric algorithms session}
+
+The request of symmetric session includes two parts, CIPHER algorithms and chain
+algorithms (chaining cipher and hash/mac). The packet of symmetric session is:
+
+\begin{lstlisting}
+struct virtio_crypto_cipher_session_para {
+    /* See VIRTIO_CRYPTO_CIPHER* above */
+    le32 algo;
+    /* length of key */
+    le32 keylen;
+    /* encrypt or decrypt */
+    u8 op;
+};
+struct virtio_crypto_sym_create_session_req {
+    // Device-readable part
+/* No operation */
+#define VIRTIO_CRYPTO_SYM_OP_NONE  0
+/* Cipher only operation on the data */
+#define VIRTIO_CRYPTO_SYM_OP_CIPHER  1
+/* Chain any cipher with any hash or mac operation. The order
+   depends on the value of alg_chain_order param */
+#define VIRTIO_CRYPTO_SYM_OP_ALGORITHM_CHAINING  2
+    u8 op_type;
+
+    union {
+        struct virtio_crypto_cipher_session_para cipher_param;
+        struct virtio_crypto_alg_chain_param {
+#define VIRTIO_CRYPTO_SYM_ALG_CHAIN_ORDER_HASH_THEN_CIPHER  1
+#define VIRTIO_CRYPTO_SYM_ALG_CHAIN_ORDER_CIPHER_THEN_HASH  2
+            u8 alg_chain_order;
+/* Plain hash */
+#define VIRTIO_CRYPTO_SYM_HASH_MODE_PLAIN    1
+/* Authenticated hash (mac) */
+#define VIRTIO_CRYPTO_SYM_HASH_MODE_AUTH     2
+/* Nested hash */
+#define VIRTIO_CRYPTO_SYM_HASH_MODE_NESTED   3
+            u8 hash_mode;
+            struct virtio_crypto_cipher_session_para cipher_param;
+            union {
+                struct virtio_crypto_hash_session_para hash_param;
+                struct virtio_crypto_mac_session_para mac_param;
+            } u;
+        } chain;
+    } sym;
+
+    // Device-writable part
+    le64    session_id;
+    u8     status;
+};
+\end{lstlisting}
+
+\paragraph{Session operation: AEAD session}\label{sec:Device Types / Crypto Device / Device
+Operation / Session operation / Session operation: AEAD session}
+
+The packet of AEAD session is:
+
+\begin{lstlisting}
+struct virtio_crypto_aead_session_para {
+    /* See VIRTIO_CRYPTO_AEAD_* above*/
+    u8 algo;
+    /* length of key */
+    le32 key_len;
+    /* digest result length */
+    le32 digest_result_len;
+    /* The length of the additional authenticated data (AAD) in bytes */
+    le32 aad_len;
+    /* encrypt or decrypt */
+    u8 op;
+};
+struct virtio_crypto_aead_create_session_req {
+    // Device-readable part
+    struct virtio_crypto_aead_session_para parameter;
+    // Device-writable part
+    le64    session_id;
+    u8     status;
+};
+\end{lstlisting}
+
+\paragraph{Session operation: create session}\label{sec:Device Types / Crypto Device / Device
+Operation / Session operation / Session operation: create session}
+
+A request of creating a session including the following information:
+
+\begin{lstlisting}
+struct virtio_crypto_op_ctrl_req {
+    struct virtio_crypto_ctrl_header header;
+
+    union {
+        struct virtio_crypto_sym_create_session_req   sym_create_session;
+        struct virtio_crypto_hash_create_session_req  hash_create_session;
+        struct virtio_crypto_mac_create_session_req   mac_create_session;
+        struct virtio_crypto_aead_create_session_req  aead_create_session;
+        struct virtio_crypto_destroy_session_req      sym_destroy_session;
+    } u;
+};
+\end{lstlisting}
+
+\subparagraph{Driver Requirements: Session operation: create session}\label{sec:Device Types / Crypto Device / Device
+Operation / Session operation / Session operation: create session / Driver Requirements: Session operation: create session}
+
+The driver MUST set the control general header and corresponding property
+of union in structure virtio_crypto_op_ctrl_req. See \ref{sec:Device Types / Crypto Device / Device Operation}.
+Take the example of MAC service, the driver MUST set VIRTIO_CRYPTO_MAC_CREATE_SESSION
+for \field{opcode} field in struct virtio_crypto_op_ctrl_req, and set the \field{queue_id}
+to show dataq used.
+
+\subparagraph{Device Requirements: Session operation: create session}\label{sec:Device Types / Crypto Device / Device
+Operation / Session operation / Session operation: create session / Device Requirements: Session operation: create session}
+
+The device MUST return a session identifier to the driver when the device
+finishes the processing of session creation. The session creation request
+MUST end by a \field{status} field and a \field{session_id} field:
+
+Both \field{status} and \field{session_id} are written by the device: either VIRTIO_CRYPTO_OP_OK for success,
+VIRTIO_CRYPTO_OP_ERR for creation failed or device error, VIRTIO_CRYPTO_OP_NOTSUPP for not support,
+VIRTIO_CRYPTO_OP_INVSESS for invalid session id when executing crypto operations.
+
+\begin{lstlisting}
+#define VIRTIO_CRYPTO_OP_OK        0
+#define VIRTIO_CRYPTO_OP_ERR       1
+#define VIRTIO_CRYPTO_OP_BADMSG    2
+#define VIRTIO_CRYPTO_OP_NOTSUPP   3
+#define VIRTIO_CRYPTO_OP_INVSESS   4
+\end{lstlisting}
+
+\paragraph{Session operation: destroy session}\label{sec:Device Types / Crypto Device / Device
+Operation / Session operation / Session operation: destroy session}
+
+A request which destroy a session including the following information:
+
+\begin{lstlisting}
+struct virtio_crypto_destroy_session_req {
+    // Device-readable part
+    le64    session_id;
+    // Device-writable part
+    u8     status;
+};
+struct virtio_crypto_op_ctrl_req {
+    struct virtio_crypto_ctrl_header header;
+
+    union {
+        struct virtio_crypto_sym_create_session_req   sym_create_session;
+        struct virtio_crypto_hash_create_session_req  hash_create_session;
+        struct virtio_crypto_mac_create_session_req   mac_create_session;
+        struct virtio_crypto_aead_create_session_req  aead_create_session;
+        struct virtio_crypto_destroy_session_req      sym_destroy_session;
+    } u;
+};
+\end{lstlisting}
+
+\subparagraph{Driver Requirements: Session operation: destroy session}\label{sec:Device Types / Crypto Device / Device
+Operation / Session operation / Session operation: destroy session / Driver Requirements: Session operation: destroy session}
+
+The driver MUST set the control general header and corresponding property
+of union in struct virtio_crypto_op_ctrl_req. See \ref{sec:Device Types / Crypto Device / Device Operation}.
+Take the example of MAC service, the driver MUST set VIRTIO_CRYPTO_MAC_DESTROY_SESSION
+for \field{opcode} field in struct virtio_crypto_op_ctrl_req, and set the \field{queue_id} shows dataq used.
+The driver MUST set the \field{session_id} which MUST be a valid value which assigned by the
+device when a session was created.
+
+\subparagraph{Device Requirements: Session operation: destroy session}\label{sec:Device Types / Crypto Device / Device
+Operation / Session operation / Session operation: destroy session / Device Requirements: Session operation: destroy session}
+
+Status is written by the device: either VIRTIO_CRYPTO_OP_OK for success, VIRTIO_CRYPTO_OP_ERR for failure or device error.
+
+\subsubsection{Crypto operation}\label{sec:Device Types / Crypto Device / Device Operation / Crypto operation}
+
+The driver uses the dataq to finish the data plane operations (such as crypto operation).
+The packet of dataq:
+
+\begin{lstlisting}
+struct virtio_crypto_op_data_req {
+    struct virtio_crypto_op_header header;
+
+    union {
+        struct virtio_crypto_sym_data_req   sym_req;
+        struct virtio_crypto_hash_data_req  hash_req;
+        struct virtio_crypto_mac_data_req   mac_req;
+        struct virtio_crypto_aead_data_req  aead_req;
+    } u;
+};
+\end{lstlisting}
+
+The header is the general header, the union is algorithm-specific type,
+which are set by the driver. All properties in the union will be shown as follow.
+
+\paragraph{Crypto operation: HASH operation}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: HASH operation}
+
+\begin{lstlisting}
+struct virtio_crypto_hash_input {
+    le64 digest_result_addr; /* digest result guest physical address */
+    u8    status;
+};
+
+struct virtio_crypto_hash_output {
+    /* length of source data */
+    le32 src_data_len;
+    /* source data guest physical address */
+    le64 src_data_addr;
+};
+
+struct virtio_crypto_hash_data_req {
+    // Device-readable part
+    struct virtio_crypto_hash_output odata;
+    // Device-writable part
+    struct virtio_crypto_hash_input idata;
+};
+\end{lstlisting}
+
+Each data request uses virtio_crypto_hash_data_req structure to store informations,
+which are used to execute one HASH operation. The request only occupies one entry
+of the Vring descriptor table in virtio crypto device's dataq, which improves
+the throughput of data transferring for HASH service, so that the virtio crypto
+device CAN get the better result of acceleration.
+
+The informations include the source data guest physical address stored by \field{src_data_addr},
+length of source data stored by \field{src_data_len}, digest result guest physical address
+stored by \field{digest_result_addr} which is used to save the result of HASH operation.
+The address and length CAN determine the specific content in the guest memory.
+
+Note: The guest memory MUST be guaranteed to be allocated and physically-contiguous
+pointed by \field{digest_result_addr} in struct virtio_crypto_hash_input and
+\field{src_data_addr} in struct virtio_crypto_hash_output.
+
+\subparagraph{Driver Requirements: Crypto operation: HASH operation}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: HASH operation / Driver Requirements: Crypto operation: HASH operation}
+
+The driver MUST set the \field{opcode}, \field{session_id} in struct virtio_crypto_op_header.
+The \field{opcode} is set to VIRTIO_CRYPTO_HASH, \field{session_id} MUST be a valid value
+which assigned by the device when a session was created.
+The driver SHOULD set the \field{queue_id} field to show dataq used in struct virtio_crypto_op_header.
+The driver MUST fill out all fields in struct virtio_crypto_hash_data_req, including \field{parameter},
+\field{odata} and \field{idata} sub structures.
+
+\subparagraph{Device Requirements: Crypto operation: HASH operation}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: HASH operation / Device Requirements: Crypto operation: HASH operation}
+
+The device MUST copy the result of hash operation recorded by \field{digest_result_addr}
+filed in struct virtio_crypto_hash_input.
+The device MUST set the \field{status} in strut virtio_crypto_hash_input: either VIRTIO_CRYPTO_OP_OK for success,
+VIRTIO_CRYPTO_OP_ERR for creation failed or device error, VIRTIO_CRYPTO_OP_NOTSUPP for not support.
+
+\paragraph{Crypto operation: MAC operation}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: MAC operation}
+
+\begin{lstlisting}
+struct virtio_crypto_mac_input {
+    struct virtio_crypto_hash_input hash_input;
+};
+
+struct virtio_crypto_mac_output {
+    struct virtio_crypto_hash_output hash_output;
+};
+
+struct virtio_crypto_mac_data_req {
+    // Device-readable part
+    struct virtio_crypto_mac_output odata;
+    // Device-writable part
+    struct virtio_crypto_mac_input idata;
+};
+\end{lstlisting}
+
+Each data request uses virtio_crypto_mac_data_req structure to store informations,
+which are used to execute one MAC operation. The request only occupies one entry
+of the Vring descriptor table in virtio crypto device's dataq, which improves
+the throughput of data transferring for MAC service, so that the virtio crypto
+device CAN get the better result of acceleration.
+
+The informations include the source data guest physical address stored by \field{src_data_addr},
+length of source data stored by \field{src_data_len}, digest result guest physical address
+stored by \field{digest_result_addr} which is used to save the result of MAC operation.
+The address and length CAN determine the specific content in the guest memory.
+
+Note: The guest memory MUST be guaranteed to be allocated and physically-contiguous
+pointed by \field{digest_result_addr} in struct virtio_crypto_hash_input and
+\field{src_data_addr} in struct virtio_crypto_hash_output.
+
+\subparagraph{Driver Requirements: Crypto operation: MAC operation}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: MAC operation / Driver Requirements: Crypto operation: MAC operation}
+
+Refer to the hash operation.
+The driver MUST set the \field{opcode} field to VIRTIO_CRYPTO_MAC.
+
+\subparagraph{Device Requirements: Crypto operation: MAC operation}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: MAC operation / Device Requirements: Crypto operation: MAC operation}
+
+Refer to the hash operation.
+
+\paragraph{Crypto operation: Symmetric algorithms operation}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: Symmetric algorithms operation}
+
+\begin{lstlisting}
+struct virtio_crypto_cipher_para {
+    le32 iv_len;
+    /* length of source data */
+    le32 src_data_len;
+    /* length of dst data */
+    le32 dst_data_len;
+};
+struct virtio_crypto_cipher_input {
+    le64 dst_data_addr; /* destination data guest physical address */
+    u8    status;
+};
+
+struct virtio_crypto_cipher_output {
+    le64 iv_addr; /* iv guest physical address */
+    le64 src_data_addr; /* source data guest physical address */
+};
+struct virtio_crypto_cipher_data_req {
+    // Device-readable part
+    struct virtio_crypto_cipher_para parameter;
+    struct virtio_crypto_cipher_output odata;
+    // Device-writable part
+    struct virtio_crypto_cipher_input idata;
+};
+struct virtio_crypto_sym_data_req {
+    struct virtio_crypto_cipher_data_req cipher_req;
+    union {
+        struct virtio_crypto_hash_data_req hash_req;
+        struct virtio_crypto_mac_data_req mac_req;
+    } u;
+};
+\end{lstlisting}
+
+Each data request uses virtio_crypto_cipher_data_req structure to store informations,
+which are used to execute one CIPHER operation. The request only occupies one entry
+of the Vring descriptor table in virtio crypto device's dataq, which improves
+the throughput of data transferring for CIPHER service, so that the virtio crypto
+device CAN get the better result of acceleration.
+
+In the first virtio_crypto_cipher_para structure, \field{iv_len} specifics the length of initialization vector,
+\field{src_data_len} specifics the length of source data, \field{dst_data_len} specifics the
+length of destination data.
+
+In the following virtio_crypto_cipher_input structure, \field{dst_data_addr} specifics destination
+data guest physical address which is used to store the result of CIPHER operation. \field{status} special
+the status of CIPHER operation, See \ref{sec:Device Types / Crypto Device / Device Operation / Session operation /
+Session operation: create session / Device Requirements: Session operation: create session}. 
+
+In the virtio_crypto_cipher_output structure, \field{iv_addr} specifics guest physical address of initialization vector,
+\field{src_data_addr} specifics source data guest physical address.
+
+The addresses and length CAN determine the specific content in the guest memory.
+
+Note: The guest memory MUST be guaranteed to be allocated and physically-contiguous
+pointed by \field{dst_data_addr} in struct virtio_crypto_cipher_input, 
+\field{iv_addr} and \field{src_data_addr} in struct virtio_crypto_cipher_output.
+
+\subparagraph{Driver Requirements: Crypto operation: Symmetric algorithms encryption}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: Symmetric algorithms operation / Driver Requirements: Crypto operation: Symmetric algorithms encryption}
+
+Refer to the hash operation.
+
+The driver MUST set the \field{opcode} field to VIRTIO_CRYPTO_CIPHER_ENCRYPT.
+The driver MUST fill out the fields in struct virtio_crypto_sym_data_req according to
+the operation type of the session. 
+
+The driver SHOULD fill out fields of struct virtio_crypto_cipher_data_req in struct virtio_crypto_sym_data_req
+if the created session is based on VIRTIO_CRYPTO_SYM_OP_CIPHER
+
+The driver SHOULD fill out fields of both struct virtio_crypto_cipher_data_req and struct
+virtio_crypto_mac_data_req mac_req in struct virtio_crypto_sym_data_req if the created session
+is VIRTIO_CRYPTO_SYM_OP_ALGORITHM_CHAINING type and VIRTIO_CRYPTO_SYM_HASH_MODE_AUTH mode.
+
+\subparagraph{Device Requirements: Crypto operation: Symmetric algorithms encryption}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: Symmetric algorithms operation / Device Requirements: Crypto operation: Symmetric algorithms encryption}
+
+The device MUST parse the virtio_crypto_sym_data_req according to the session_id in general header.
+
+The device SHOULD only parsed fields of struct virtio_crypto_cipher_data_req in
+struct virtio_crypto_sym_data_req if the created session is VIRTIO_CRYPTO_SYM_OP_CIPHER type.
+
+The driver SHOULD parse fields of both struct virtio_crypto_cipher_data_req and struct
+virtio_crypto_mac_data_req mac_req in struct virtio_crypto_sym_data_req if the created
+session is VIRTIO_CRYPTO_SYM_OP_ALGORITHM_CHAINING operation type and VIRTIO_CRYPTO_SYM_HASH_MODE_AUTH mode.
+
+The device MUST copy the result of encryption operation recorded by \filed{dst_data_addr} filed in struct virtio_crypto_cipher_input in plain cipher mode.
+The device MUST copy the result of hash operation recorded by \filed{digest_result_addr} filed in struct virtio_crypto_hash_input in chain hash/mac mode.
+The device MUST set the \filed{status} field in strut virtio_crypto_cipher_input: either VIRTIO_CRYPTO_OP_OK for success, VIRTIO_CRYPTO_OP_ERR for creation
+failed or device error, VIRTIO_CRYPTO_OP_NOTSUPP for not support.
+
+\subparagraph{Crypto operation: Steps of encryption}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: Symmetric algorithms operation / Crypto operation: Steps of encryption}
+
+Step1: Creating a session:
+\begin{enumerate}
+\item The driver fills out informations in struct virtio_crypto_op_ctrl_req, including algorithm name, key, keylen etc;
+\item The driver puts the request of session creation into the controlq's Vring descriptor table;
+\item The driver kicks the device;
+\item The device gets the request from controlq;
+\item The device parses informations of the request, determines the informations of the backend crypto accelerator;
+\item The device packages informations according to the API of the backend crypto accelerator;
+\item The device invokes the session creation API of the backend crypto accelerator to create a session;
+\item The device returns the session id to the driver.
+\end{enumerate}
+
+Step2: Executing the detail encryption operation:
+\begin{enumerate}
+\item The driver fills out informations in struct virtio_crypto_op_data_req, including struct virtio_crypto_op_header and struct virtio_crypto_sym_data_req, See \ref{sec:Device Types / Crypto Device / Device
+      Operation / Crypto operation / Crypto operation: Symmetric algorithms operation / Driver Requirements: Crypto operation: Symmetric algorithms encryption};
+\item The driver puts the request of encryption into the dataq's Vring descriptor table;
+\item The driver kicks the device (Or the device polls the dataq's Vring descriptor table actively);
+\item The device gets the request from dataq;
+\item The device parses informations of the request, determines the identifying informations of the backend crypto accelerator.
+      For example, changing guest physical addresses to host physical addresses;
+\item The device packages identifying informations according to the API of the backend crypto accelerator;
+\item The device invokes the encryption API of the backend crypto accelerator;
+\item The backend crypto accelerator executes the encryption operation implicitly;
+\item The device gets the encryption result from the backend crypto accelerator (synchronous or asynchronous);
+\item The device set the \field{status} in struct virtio_crypto_cipher_input;
+\tiem The device updates and flushes the Vring used table to return the encryption result to the driver;
+\item The device notifies the driver (Or the driver polls the dataq's Vring used table actively);
+\item The driver handles the encryption result.
+\end{enumerate}
+
+Note: 
+\begin{itemize*}
+\item The driver MAY support both synchronous and asynchronous encryption. Then the performance
+      is poor in synchronous operation because frequent context switching and virtualization overhead.
+      The driver SHOULD by preference use asynchronous encryption.
+\item For better performance, the device SHOULD by preference use vhost scheme (user space or kernel space)
+      as the backend crypto accelerator in real production environment.
+\end{itemize*}
+
+\paragraph{Crypto operation: AEAD operation}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: AEAD operation}
+
+\begin{lstlisting}
+struct virtio_crypto_aead_para {
+    le32 iv_len;
+    /* length of additional auth data */
+    le32 aad_len;
+    /* length of source data */
+    le32 src_data_len;
+    /* length of dst data */
+    le32 dst_data_len;
+};
+
+struct virtio_crypto_aead_input {
+    le64 dst_data_addr; /* destination data guest physical address */
+    le64 digest_result_addr; /* digest result guest physical address */
+    u8    status;
+};
+
+struct virtio_crypto_aead_output {
+    le64 iv_addr; /* iv guest physical address */
+    le64 src_data_addr; /* source data guest physical address */
+    le64 add_data_addr; /* additional auth data guest physical address */
+};
+struct virtio_crypto_aead_data_req {
+    // Device-readable part
+    struct virtio_crypto_aead_para parameter;
+    struct virtio_crypto_aead_output odata;
+    // Device-writable part
+    struct virtio_crypto_aead_input idata;
+};
+\end{lstlisting}
+
+Each data request uses virtio_crypto_aead_data_req structure to store informations,
+which are used to execute one CIPHER operation. The request only occupies one entry
+of the Vring descriptor table in virtio crypto device's dataq, which improves
+the throughput of data transferring for AEAD service, so that the virtio crypto
+device CAN get the better result of acceleration.
+
+In the first virtio_crypto_aead_para structure, \field{iv_len} specifics the length of initialization vector,
+\field{aad_len} specifics the length of additional authentication data, \field{src_data_len} specifics the
+length of source data, \field{dst_data_len} specifics the length of destination data.
+
+In the following virtio_crypto_aead_input structure, \field{dst_data_addr} specifics destination
+data guest physical address which is used to store the result of CIPHER operation. \field{digest_result_addr} specifics
+digest result guest physical address which is used to store the result of HASH/MAC operation. \field{status} special
+the status of AEAD operation, See \ref{sec:Device Types / Crypto Device / Device Operation / Session operation /
+Session operation: create session / Device Requirements: Session operation: create session}. 
+
+In the virtio_crypto_aead_output structure, \field{iv_addr} specifics guest physical address of initialization vector,
+\field{src_data_addr} specifics source data guest physical address, \field{add_data_addr} specifics the guest physical address
+of additional authentication data.
+
+The addresses and length CAN determine the specific content in the guest memory.
+
+Note: The guest memory MUST be gauranted to be allocated and physically-contiguous
+pointed by \field{dst_data_addr} and \field{digest_result_addr} in struct virtio_crypto_aead_input, 
+\field{iv_addr}, \field{add_data_addr} and \field{src_data_addr} in struct virtio_crypto_aead_output.
+
+\subparagraph{Driver Requirements: Crypto operation: AEAD encryption}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: AEAD operation / Driver Requirements: Crypto operation: AEAD encryption}
+
+Refer to the symmetric algorithms encryption operation (See \ref{sec:Device Types / Crypto Device / Device Operation / Crypto
+                        operation / Crypto operation: Symmetric algorithms operation / Crypto operation: Steps of encryption}).
+The driver MUST set the \field{opcode} field to VIRTIO_CRYPTO_AEAD_ENCRYPT.
+
+\subparagraph{Device Requirements: Crypto operation: AEAD encryption}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: AEAD operation / Device Requirements: Crypto operation: AEAD encryption}
+
+Refer to the symmetric algorithms encryption operation (See \ref{sec:Device Types / Crypto Device / Device Operation / Crypto
+                        operation / Crypto operation: Symmetric algorithms operation / Crypto operation: Steps of encryption}).
+
+\subparagraph{Driver Requirements: Crypto operation: AEAD decryption}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: AEAD operation / Driver Requirements: Crypto operation: AEAD decryption}
+
+Refer to the symmetric algorithms encryption operation (See \ref{sec:Device Types / Crypto Device / Device Operation / Crypto
+                        operation / Crypto operation: Symmetric algorithms operation / Crypto operation: Steps of encryption}).
+The driver MUST set the \field{opcode} field to VIRTIO_CRYPTO_AEAD_DECRYPT.
+
+\subparagraph{Device Requirements: Crypto operation: AEAD decryption}\label{sec:Device Types / Crypto Device / Device
+Operation / Crypto operation / Crypto operation: AEAD operation / Device Requirements: Crypto operation: AEAD decryption}
+
+The device MUST verify and return the verify result to the driver.
+If the verify result is not correct, VIRTIO_CRYPTO_OP_BADMSG (bad message)
+MUST be returned the driver.
