Creating +Cryptographic Context

SRTP library generates SRTP packets from the RTP or RTCP stream and forwards +the packets to the receiver. SRTP transforms incoming SRTP packets to RTP/RTCP +packets and passes them up the stack. The cryptographic state information +associated with each SRTP stream is termed the cryptographic context. The +state information is maintained by both the sender and receiver of SRTP streams.

A cryptographic context includes a session key used in encryption and message +authentication. A cryptographic context also includes a securely exchanged +random bit string used to derive session keys called the master key. In addition +to the session and master key the cryptographic context includes other working +session parameters.

Procedure

The following steps describe the steps +involved in creating a cryptographic context:

Create a cryptographic +context by invoking the API NewL() or NewLC() of the class CSRTPCryptoContext.
1. + IMPORT_C static CSRTPCryptoContext* NewL( const CSRTPMasterKey* aKey, + const CSRTPMasterSalt* aSalt, + const TSrtpCryptoParams& aCryptoParams);
  
  aKey +is the input parameter that contains the master key.
  
  aSalt is the +input parameter that contains the master salt key.
  
  aCryptoParams is +the input parameter that contains the Crypto Context parameters.
  
  The +API leaves with KErrNone if successfully executed, else returns a valid system-wide +error code.
2. + IMPORT_C static CSRTPCryptoContext* NewLC( const CSRTPMasterKey* aKey, + const CSRTPMasterSalt* aSalt, + const TSrtpCryptoParams& aCryptoParams );
  
  aKey +is the input parameter that contains the master key.
  
  aSalt is the +input parameter that contains the master salt key.
  
  aCryptoParams is +the input parameter that contains the Crypto Context parameters.
  
  The +API leaves with KErrNone if successfully executed, else returns a valid system-wide +error code.

Creating Master Key

The master key can be created using +the following API's:

IMPORT_C static CSRTPMasterKey* NewL( const TDesC8& aKey,const TDesC8& aMKI,TUint aN_E = KSRTPDefSessionEncryptionKeyLength,Uint aN_A = KSRTPDefSessionAuthenticationKeyLength );
IMPORT_C static CSRTPMasterKey* NewLC( const TDesC8& aKey,const TDesC8& aMKI,TUint aN_E = KSRTPDefSessionEncryptionKeyLength,TUint aN_A = KSRTPDefSessionAuthenticationKeyLength);
IMPORT_C static CSRTPMasterSalt* NewLC( const TDesC8& aKey, TUint aN_S = KSRTPDefSessionSaltingKeyLength );

Creating Master Salt Key

The master salt key can be created +using the following API's:

IMPORT_C static CSRTPMasterSalt* NewL( const TDesC8& aKey,TUint aN_S = KSRTPDefSessionSaltingKeyLength )

For more information on cryptographic context management also +refer:

MasterKey()

SetMasterKey()

MasterSalt()

SetMasterSalt()

SetRCCm3Sync()

CryptoParams()

AddCryptoChangeObserver()

RemoveCryptoChangeObserver()

UpdateCryptoParams()