diff -r 4816d766a08a -r f345bda72bc4 Symbian3/PDK/Source/GUID-7B6073BF-6D8C-5F00-98EC-966573777677.dita --- a/Symbian3/PDK/Source/GUID-7B6073BF-6D8C-5F00-98EC-966573777677.dita Tue Mar 30 11:42:04 2010 +0100 +++ b/Symbian3/PDK/Source/GUID-7B6073BF-6D8C-5F00-98EC-966573777677.dita Tue Mar 30 11:56:28 2010 +0100 @@ -1,109 +1,109 @@ - - - - - -Managing -Master Key

The Secure Real-Time Transport Protocol (SRTP) stream requires -the sender and receiver to maintain the cryptographic context of the packets. -SRTP uses two types of keys: master keys and session keys for packet encryption -and decryption. Master key is a random bit string. The session keys are derived -from the master key. The Session key is used directly in cryptographic transform -for encryption or message authentication.

A single master key provides -keying material for confidentiality and integrity protection of both SRTP -and the corresponding SRTCP stream. For each master key, a count of processed -packets is maintained. There is a limit on the number of packets processed -by a single master key. SRTCP maintains a separate counter for master key -even if the master key is the same as that for SRTP. The counter counts the -number of SRTCP packets processed with the key.

The SRTP stack checks -for the count of packet processed when the RTP/RTCP packets are encrypted -or decrypted. If the number of packets processed is maximum, the master key -status is identified as stale. The SRTP notifies the SRTP client of the master -key status. This is Notifying the Master Key Expiry.

The SRTP stack -can request for a new master key(ReKey) even before the master key status -is identified as stale.This is ReKey request.

 -

An SRTP session -must be created and initialized before an application requests for a RTP/RTCP -packet decryption and encryption.

The two variants of the API SRTPMasterKeyStaleEvent() must be -implemented by the application.

- -An RTP/RTCP packet -is encrypted or decrypted . - -The SRTP uses the -current master key to check the count of packet processed. If the number of -packets processed is not the maximum permissible value, the count is increased. -If the number of packets processed has reached maximum permissible value, -the SRTP DLL notifies the expiry(stale) state of the current master key. - -The SRTP DLL notifies -the master key status using the API's SRTPMasterKeyStaleEvent() of -the class MSRTPReKeyingObserver .The -notification can be initiated by MSRTPReKeyingObserver or CSRTPSession. - - -The prototypes for both the variants of SRTPMasterKeyStaleEvent() are -described below: -
    -
  • virtual void SRTPMasterKeyStaleEvent(const CSRTPStream& aStream)=0; - -

    This API is called -by the SRTP Stream initiated with MSRTPReKeyingObserver, if a master key is -identified as stale and needs to be refreshed.

    aStream is the input -parameter. It contains the stream of the master key that needs to be refreshed.

    • -
 -
    -
  • virtual void SRTPMasterKeyStaleEvent(const CSRTPSession& aSession)=0; - -

    This API is called -by SRTP Stream initiated with CSRTPSession if a master key is identified as -stale and needs to be refreshed.

    aSession is the input parameter. -It contains the session of the master key that needs to be refreshed.

    • -
 - - - -The SRTP DLL requests -for a new master key using the API - ReKeyNeeded() of the classCSRTPSession. - - -The prototype of the API is as described below: -
    -
  • void ReKeyNeeded(const CSRTPStream& aStream, TBool aIsStrmCrypto); - -

    This API requests -for ReKey.

    aStream is the input parameter that needs the Rekey.

    aIsStrmCrypto -is the boolean input parameter. It contains true if stream has its own cryptographic -context. Else the value is false.

    • -
 - - - - -

SRTP stack notifies the SRTP client of the master key expiry state.

SRTP -stack requests for ReKey.

- -Creating -an SRTP Session -Creating -a Cryptographic Context -Creating -an SRTP Stream -Encrypting - RTCP Packet Data -Encrypting -RTP Packet Data -Decrypting -RTP Packet Data -Decrypting - RTCP Packet Data -Updating -Master Key + + + + + +Managing +Master Key

The Secure Real-Time Transport Protocol (SRTP) stream requires +the sender and receiver to maintain the cryptographic context of the packets. +SRTP uses two types of keys: master keys and session keys for packet encryption +and decryption. Master key is a random bit string. The session keys are derived +from the master key. The Session key is used directly in cryptographic transform +for encryption or message authentication.

A single master key provides +keying material for confidentiality and integrity protection of both SRTP +and the corresponding SRTCP stream. For each master key, a count of processed +packets is maintained. There is a limit on the number of packets processed +by a single master key. SRTCP maintains a separate counter for master key +even if the master key is the same as that for SRTP. The counter counts the +number of SRTCP packets processed with the key.

The SRTP stack checks +for the count of packet processed when the RTP/RTCP packets are encrypted +or decrypted. If the number of packets processed is maximum, the master key +status is identified as stale. The SRTP notifies the SRTP client of the master +key status. This is Notifying the Master Key Expiry.

The SRTP stack +can request for a new master key(ReKey) even before the master key status +is identified as stale.This is ReKey request.

 +

An SRTP session +must be created and initialized before an application requests for a RTP/RTCP +packet decryption and encryption.

The two variants of the API SRTPMasterKeyStaleEvent() must be +implemented by the application.

+ +An RTP/RTCP packet +is encrypted or decrypted . + +The SRTP uses the +current master key to check the count of packet processed. If the number of +packets processed is not the maximum permissible value, the count is increased. +If the number of packets processed has reached maximum permissible value, +the SRTP DLL notifies the expiry(stale) state of the current master key. + +The SRTP DLL notifies +the master key status using the API's SRTPMasterKeyStaleEvent() of +the class MSRTPReKeyingObserver .The +notification can be initiated by MSRTPReKeyingObserver or CSRTPSession. + + +The prototypes for both the variants of SRTPMasterKeyStaleEvent() are +described below: +
    +
  • virtual void SRTPMasterKeyStaleEvent(const CSRTPStream& aStream)=0; + +

    This API is called +by the SRTP Stream initiated with MSRTPReKeyingObserver, if a master key is +identified as stale and needs to be refreshed.

    aStream is the input +parameter. It contains the stream of the master key that needs to be refreshed.

    • +
 +
    +
  • virtual void SRTPMasterKeyStaleEvent(const CSRTPSession& aSession)=0; + +

    This API is called +by SRTP Stream initiated with CSRTPSession if a master key is identified as +stale and needs to be refreshed.

    aSession is the input parameter. +It contains the session of the master key that needs to be refreshed.

    • +
 + + + +The SRTP DLL requests +for a new master key using the API + ReKeyNeeded() of the classCSRTPSession. + + +The prototype of the API is as described below: +
    +
  • void ReKeyNeeded(const CSRTPStream& aStream, TBool aIsStrmCrypto); + +

    This API requests +for ReKey.

    aStream is the input parameter that needs the Rekey.

    aIsStrmCrypto +is the boolean input parameter. It contains true if stream has its own cryptographic +context. Else the value is false.

    • +
 + + + + +

SRTP stack notifies the SRTP client of the master key expiry state.

SRTP +stack requests for ReKey.

+ +Creating +an SRTP Session +Creating +a Cryptographic Context +Creating +an SRTP Stream +Encrypting + RTCP Packet Data +Encrypting +RTP Packet Data +Decrypting +RTP Packet Data +Decrypting + RTCP Packet Data +Updating +Master Key \ No newline at end of file