drmaes.h

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/**@@@+++@@@@******************************************************************
**
** Microsoft Windows Media
** Copyright (C) Microsoft Corporation. All rights reserved.
**
***@@@---@@@@******************************************************************
*/

/*
 * DrmAes.h
 *
 * Header file for AES encryption of a single block sized buffer
 *
 * Each OEM is expected to implement its own version of these routines.
 *
 */

#ifndef _DRMAES_H_
#define _DRMAES_H_

#ifdef  __cplusplus
extern "C"
{
#endif

#include "drmcommon.h"

/*
 * Constants
 */
#define DRM_AES_BLOCKLEN    (16) /* Size (in bytes) of a single encrypted/decrypted block */
#define DRM_AES_KEYSIZE_128 (16) /* Size (in bytes) of a 128 bit key */


/*
 * AES secret key
 *
 * The actual contents of the structure is opaque.
 *
 * The opaque data is represented as a signle byte array below.
 * Don't access the array or assume the size of this structure.
 */
typedef struct {
    DRM_BYTE opaque[1];
} DRM_AES_KEY;

/*
 * Encrypt versus Decrypt enum
 */
typedef enum _DRM_AES_ENCRYPT_OPTION
{
    DRM_AES_DECRYPT = 0,
    DRM_AES_ENCRYPT = 1,
} DRM_AES_ENCRYPT_OPTION;


/*
 * The DrmAesSetKey routine allocates an AES secret key given the value of the key
 *
 * The returned opaque secret key structure is used as a parameter to all of the
 * other AES encryption routines.
 *
 * Parameters:
 *
 *      pbKey - Specifies the value of the key
 *          Only 128-bit, 192-bit, and 256-bit keys are supported
 *
 *      cbKey - Specifies the size (in bytes) of the key
 *
 * Return Value:
 *      A pointer to the allocated secret key.
 *      The returned key must be freed using DrmAesDeleteKey().
 */
DRM_AES_KEY *
OEM_DrmAesSetKey(
    IN DRM_BYTE *pbKey,
    IN DRM_DWORD cbKey
    );

/*
 * The DrmAesDeleteKey routine deletes an AES secret key
 *
 * Parameters:
 *
 *      pKey - Specifies the key to delete
 *
 * Return Value:
 *      None
 */
DRM_VOID
OEM_DrmAesDeleteKey(
    IN DRM_AES_KEY *pKey
    );

/*
 * The DrmAesKeySize routine returns the size in bytes of the AES secret key
 *
 * Note, this size is the size of the key and not the size of the passed in DRM_AES_KEY structure.
 *
 * Parameters:
 *
 *      pKey - Specifies the AES secret key to determine the size of
 *
 * Return Value:
 *  The key size in bytes.
 */
DRM_DWORD
OEM_DrmAesKeySize(
    IN DRM_AES_KEY *pKey
    );

/*
 * The DrmAesOne routine does one round of AES encryption or decryption
 *
 * Parameters:
 *
 *      pKey - Specifies the AES secret key used to encrypt or decrypt buffer
 *
 *      pbOut - Returns the encrypted data.
 *          The returned data is DRM_AES_BLOCKLEN bytes long
 *
 *      pbIn - Specifies the data to encrypt.
 *          The specified data is DRM_AES_BLOCKLEN bytes long.
 *
 *      Op - Specifies whether encryption or decryption should be done
 *
 * Return Value:
 *      None
 */
DRM_VOID
OEM_DrmAesOne(
    IN DRM_AES_KEY *pKey,
    OUT DRM_BYTE pbOut[DRM_AES_BLOCKLEN],
    IN DRM_BYTE pbIn[DRM_AES_BLOCKLEN],
    IN DRM_AES_ENCRYPT_OPTION Op
    );

#ifdef  __cplusplus
}
#endif

#endif /* _DRMAES_H_ */