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how to generate keystream segment for SRTP header
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how to generate keystream segment for SRTP header
by Yogesh Devidas Patil
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Hi I am implementing SRTP and have little confusion about it. as per my understanding of SRTP RFC3711, Initialization vector(IV) is generated as IV = (salt_key << 16) XOR (SSRC << 64) XOR (packet_index << 16) and keystream segment (required for AES ICM ) is generated as Keystream_seg = E(k,IV) where k=Session key i.e Keystream_seg = k XOR IV is my understanding correct wrt SRTP standard?? Wherein AES ICM RFC3686, keystream segment consists keystream_seg = NONCE || IV || Counter where Counter advances from initial val=0. I mean how to relate these keystream_seg forming units in AES ICM(NONCE,IV,Counter) with SRTP header fields & fields computed from them?? Second, how should i generate Master Key on sender side??And how to derive session keys from Master Key?? Thanks in advance!! Regards Yogesh Patil A R I C E N T "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." _______________________________________________ Ccrtp-devel mailing list Ccrtp-devel@... http://lists.gnu.org/mailman/listinfo/ccrtp-devel |
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Re: how to generate keystream segment for SRTP header
by Bugzilla from werner.dittmann@t-online.de
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Do you implement SRTP for this RTP stack? We already have SRTP
avaliable since some years. If you like to implement SRTP for some other project maybe you can have a look in the source files to see how this is implemented. Best Regards, Werner Yogesh Devidas Patil schrieb: > Hi > I am implementing SRTP and have little confusion about it. > > as per my understanding of SRTP RFC3711, > Initialization vector(IV) is generated as > > IV = (salt_key << 16) XOR (SSRC << 64) XOR (packet_index << 16) > > and keystream segment (required for AES ICM ) is generated as > > Keystream_seg = E(k,IV) where k=Session key > i.e Keystream_seg = k XOR IV > > is my understanding correct wrt SRTP standard?? > > Wherein AES ICM RFC3686, keystream segment consists > keystream_seg = NONCE || IV || Counter where Counter advances from initial val=0. > > I mean how to relate these keystream_seg forming units in AES ICM(NONCE,IV,Counter) with SRTP header fields & fields computed from them?? > > Second, how should i generate Master Key on sender side??And how to derive session keys from Master Key?? > > Thanks in advance!! > > > Regards > Yogesh Patil > > A R I C E N T > > "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." > > > _______________________________________________ > Ccrtp-devel mailing list > Ccrtp-devel@... > http://lists.gnu.org/mailman/listinfo/ccrtp-devel > _______________________________________________ Ccrtp-devel mailing list Ccrtp-devel@... http://lists.gnu.org/mailman/listinfo/ccrtp-devel |
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RE: how to generate keystream segment for SRTP header
by Yogesh Devidas Patil
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I am implementing it for differant project. I have looked through the source files and
found working of encryption algo as 16 bits * <-----> * +------+------+------+------+------+------+------+------+ * | nonce | pakcet index | ctr |---+ * +------+------+------+------+------+------+------+------+ | * | * +------+------+------+------+------+------+------+------+ v * | salt |000000|->(+) * +------+------+------+------+------+------+------+------+ | * | * +---------+ * | encrypt | * +---------+ * | * +------+------+------+------+------+------+------+------+ | * | keystream block |<--+ * +------+------+------+------+------+------+------+------+ Doesn't this daviates from SRTP RFC specification ? And how should i choose nonce value? Regards Yogesh Patil ________________________________________ From: Werner Dittmann [Werner.Dittmann@...] Sent: Tuesday, July 28, 2009 11:15 PM To: Yogesh Devidas Patil Cc: ccrtp-devel@... Subject: Re: [Ccrtp-devel] how to generate keystream segment for SRTP header Do you implement SRTP for this RTP stack? We already have SRTP avaliable since some years. If you like to implement SRTP for some other project maybe you can have a look in the source files to see how this is implemented. Best Regards, Werner Yogesh Devidas Patil schrieb: > Hi > I am implementing SRTP and have little confusion about it. > > as per my understanding of SRTP RFC3711, > Initialization vector(IV) is generated as > > IV = (salt_key << 16) XOR (SSRC << 64) XOR (packet_index << 16) > > and keystream segment (required for AES ICM ) is generated as > > Keystream_seg = E(k,IV) where k=Session key > i.e Keystream_seg = k XOR IV > > is my understanding correct wrt SRTP standard?? > > Wherein AES ICM RFC3686, keystream segment consists > keystream_seg = NONCE || IV || Counter where Counter advances from initial val=0. > > I mean how to relate these keystream_seg forming units in AES ICM(NONCE,IV,Counter) with SRTP header fields & fields computed from them?? > > Second, how should i generate Master Key on sender side??And how to derive session keys from Master Key?? > > Thanks in advance!! > > > Regards > Yogesh Patil > > A R I C E N T > > "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." > > > _______________________________________________ > Ccrtp-devel mailing list > Ccrtp-devel@... > http://lists.gnu.org/mailman/listinfo/ccrtp-devel > "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." _______________________________________________ Ccrtp-devel mailing list Ccrtp-devel@... http://lists.gnu.org/mailman/listinfo/ccrtp-devel |
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Re: how to generate keystream segment for SRTP header
by Bugzilla from werner.dittmann@t-online.de
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Where in the source of ccRTP did you find the below diagram?
In your first mail you refer to RFC 3686 - this RFC is in no way related to RFC 3711, no even referenced in RFC 3711. RFC 3711 describes the AES counter mode encryption that must be used for SRTP. The below diagram does not make sense for SRTP. Best Regards, Werner Yogesh Devidas Patil schrieb: > I am implementing it for differant project. I have looked through the source files and > found working of encryption algo as > > 16 bits > * <-----> > * +------+------+------+------+------+------+------+------+ > * | nonce | pakcet index | ctr |---+ > * +------+------+------+------+------+------+------+------+ | > * | > * +------+------+------+------+------+------+------+------+ v > * | salt |000000|->(+) > * +------+------+------+------+------+------+------+------+ | > * | > * +---------+ > * | encrypt | > * +---------+ > * | > * +------+------+------+------+------+------+------+------+ | > * | keystream block |<--+ > * +------+------+------+------+------+------+------+------+ > > Doesn't this daviates from SRTP RFC specification ? > And how should i choose nonce value? > > > > Regards > Yogesh Patil > > > ________________________________________ > From: Werner Dittmann [Werner.Dittmann@...] > Sent: Tuesday, July 28, 2009 11:15 PM > To: Yogesh Devidas Patil > Cc: ccrtp-devel@... > Subject: Re: [Ccrtp-devel] how to generate keystream segment for SRTP header > > Do you implement SRTP for this RTP stack? We already have SRTP > avaliable since some years. If you like to implement SRTP for some > other project maybe you can have a look in the source files to > see how this is implemented. > > Best Regards, > Werner > > Yogesh Devidas Patil schrieb: >> Hi >> I am implementing SRTP and have little confusion about it. >> >> as per my understanding of SRTP RFC3711, >> Initialization vector(IV) is generated as >> >> IV = (salt_key << 16) XOR (SSRC << 64) XOR (packet_index << 16) >> >> and keystream segment (required for AES ICM ) is generated as >> >> Keystream_seg = E(k,IV) where k=Session key >> i.e Keystream_seg = k XOR IV >> >> is my understanding correct wrt SRTP standard?? >> >> Wherein AES ICM RFC3686, keystream segment consists >> keystream_seg = NONCE || IV || Counter where Counter advances from initial val=0. >> >> I mean how to relate these keystream_seg forming units in AES ICM(NONCE,IV,Counter) with SRTP header fields & fields computed from them?? >> >> Second, how should i generate Master Key on sender side??And how to derive session keys from Master Key?? >> >> Thanks in advance!! >> >> >> Regards >> Yogesh Patil >> >> A R I C E N T >> >> "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." >> >> >> _______________________________________________ >> Ccrtp-devel mailing list >> Ccrtp-devel@... >> http://lists.gnu.org/mailman/listinfo/ccrtp-devel >> > > > "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." > _______________________________________________ Ccrtp-devel mailing list Ccrtp-devel@... http://lists.gnu.org/mailman/listinfo/ccrtp-devel |
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