Android APIs
public final class

MediaDrm.CryptoSession

extends Object
java.lang.Object
   ↳ android.media.MediaDrm.CryptoSession

Class Overview

In addition to supporting decryption of DASH Common Encrypted Media, the MediaDrm APIs provide the ability to securely deliver session keys from an operator's session key server to a client device, based on the factory-installed root of trust, and then perform encrypt, decrypt, sign and verify operations with the session key on arbitrary user data.

The CryptoSession class implements generic encrypt/decrypt/sign/verify methods based on the established session keys. These keys are exchanged using the getKeyRequest/provideKeyResponse methods.

Applications of this capability could include securing various types of purchased or private content, such as applications, books and other media, photos or media delivery protocols.

Operators can create session key servers that are functionally similar to a license key server, except that instead of receiving license key requests and providing encrypted content keys which are used specifically to decrypt A/V media content, the session key server receives session key requests and provides encrypted session keys which can be used for general purpose crypto operations.

A CryptoSession is obtained using getCryptoSession(byte[], String, String)

Summary

Public Methods
byte[] decrypt(byte[] keyid, byte[] input, byte[] iv)
Decrypt data using the CryptoSessions's cipher algorithm
byte[] encrypt(byte[] keyid, byte[] input, byte[] iv)
Encrypt data using the CryptoSession's cipher algorithm
byte[] sign(byte[] keyid, byte[] message)
Sign data using the CryptoSessions's mac algorithm.
boolean verify(byte[] keyid, byte[] message, byte[] signature)
Verify a signature using the CryptoSessions's mac algorithm.
[Expand]
Inherited Methods
From class java.lang.Object

Public Methods

public byte[] decrypt (byte[] keyid, byte[] input, byte[] iv)

Added in API level 18

Decrypt data using the CryptoSessions's cipher algorithm

Parameters
keyid specifies which key to use
input the data to encrypt
iv the initialization vector to use for the cipher
Returns
byte[]

public byte[] encrypt (byte[] keyid, byte[] input, byte[] iv)

Added in API level 18

Encrypt data using the CryptoSession's cipher algorithm

Parameters
keyid specifies which key to use
input the data to encrypt
iv the initialization vector to use for the cipher
Returns
byte[]

public byte[] sign (byte[] keyid, byte[] message)

Added in API level 18

Sign data using the CryptoSessions's mac algorithm.

Parameters
keyid specifies which key to use
message the data for which a signature is to be computed
Returns
byte[]

public boolean verify (byte[] keyid, byte[] message, byte[] signature)

Added in API level 18

Verify a signature using the CryptoSessions's mac algorithm. Return true if the signatures match, false if they do no.

Parameters
keyid specifies which key to use
message the data to verify
signature the reference signature which will be compared with the computed signature
Returns
boolean