LU501215B1 - Communication method of covert channel with feedback - Google Patents

Communication method of covert channel with feedback Download PDF

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Publication number
LU501215B1
LU501215B1 LU501215A LU501215A LU501215B1 LU 501215 B1 LU501215 B1 LU 501215B1 LU 501215 A LU501215 A LU 501215A LU 501215 A LU501215 A LU 501215A LU 501215 B1 LU501215 B1 LU 501215B1
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LU
Luxembourg
Prior art keywords
covert
secret information
data packets
channel
timing channel
Prior art date
Application number
LU501215A
Other languages
German (de)
Inventor
Linhong Guo
Xiaosong Zhang
Original Assignee
Univ Tangshan
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Publication date
Application filed by Univ Tangshan filed Critical Univ Tangshan
Priority to LU501215A priority Critical patent/LU501215B1/en
Application granted granted Critical
Publication of LU501215B1 publication Critical patent/LU501215B1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0251—Power saving arrangements in terminal devices using monitoring of local events, e.g. events related to user activity
    • H04W52/0258—Power saving arrangements in terminal devices using monitoring of local events, e.g. events related to user activity controlling an operation mode according to history or models of usage information, e.g. activity schedule or time of day
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H04L47/24—Traffic characterised by specific attributes, e.g. priority or QoS
    • H04L47/2416—Real-time traffic
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L47/00—Traffic control in data switching networks
    • H04L47/10—Flow control; Congestion control
    • H04L47/43—Assembling or disassembling of packets, e.g. segmentation and reassembly [SAR]
    • H04L47/431—Assembling or disassembling of packets, e.g. segmentation and reassembly [SAR] using padding or de-padding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L63/00—Network architectures or network communication protocols for network security
    • H04L63/04—Network architectures or network communication protocols for network security for providing a confidential data exchange among entities communicating through data packet networks

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Computer Security & Cryptography (AREA)
  • Computer Hardware Design (AREA)
  • Computing Systems (AREA)
  • General Engineering & Computer Science (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The present invention relates to a communication method of a covert channel with feedback, including: acquiring the number of SID (Silence Insertion Descriptor) data packets in the current silence period of the covert timing channel and the receiving situation of a receiver of the covert timing channel for secret information; determining the maximum number of digit of hidden secret information in the current silence period of the covert timing channel according to the number of the SID data packets in the current silence period; determining feedback information of RTCP (Real-Time Transport Control Protocol) data packets of a backward covert storage channel according to the receiving situation of the receiver of the covert timing channel for the secret information; and adjusting communication of the covert timing channel according to the feedback information of the RTCP data packets and the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel.

Description

BL-5359 1 LU501215
COMMUNICATION METHOD OF COVERT CHANNEL WITH FEEDBACK TECHNICAL FIELD
[01] The present invention relates to the field of data communication, and particularly relates to a communication method of covert channel with feedback.
BACKGROUND ART
[02] A covert channel generally includes two types: a covert storage channel and a covert timing channel. The covert storage channel means that a sender is configured to directly or indirectly write information into storage locations such as a memory unit, a resource state or a network data packet and the like, and a receiver is configured to recover secret information from the sender through observing the storage locations. The covert timing channel means that the receiver 1s configured to observe affection of the sender on system events such as performances, behaviors and the like, and the receiver and the sender are configured to send a secret message by utilizing the sequence, interval and frequency of the events and other time factors.
[03] At present, the research on a network covert channel used for real-time interaction is mainly concentrated on construction of the covert channel of voice and video traffic of VoIP (Voice over Internet Protocol). With the rapid development and popularization of LTE (Long Term Evolution) network, VoLTE (Voice over Long Term Evolution) provides a mixed network voice service and a ubiquitous smooth transition path of voices of the whole LTE network. The user experience and the service quality of the VOLTE are superior to application of the VoIP. Additionally, the mobile network is about to enter the SG (Fifth-generation) era, the VOLTE is in a good fit for 5G from the technical perspective, so that the VOLTE becomes the basis of carrier-class voice and video calling services in the SG network. Mobile communication brings many benefits, but also brings threats such as leakage of information and the like, and however, the covert channel can become an effective means of transmitting confidential information in the mobile network. Therefore, it is very necessary to research a communication method of the VOLTE covert channel.
[04] In order to enable the covert channel to communicate effectively, many researches and solutions have been proposed. However, the existing communication solution of the covert channel based on IPD (Inter-packet Delay) cannot be directly applied to the VOLTE, because IPD of traffic of the VOLTE is limited within a smaller scope and has strong regularity, and it is very difficult to hide secret information into the IPD of the traffic of the VoLTE. The voice service of the VoLTE has two states: talk period and silence period. The differences between the talk period and the silence period are that the size of the voice packet is bigger than that of the SID (Silence Insertion 40 Descriptor) packet, and an obvious difference exists between the time interval of two adjacent voice packets and the time interval of two adjacent SID packets. Therefore, the existing covert channel cannot be configured to adapt to a real-time interactive environment of the mobile network by adjusting parameters of the covert channel
BL-5359 2 according to the receiving situation of the receiver and cannot be configured to weigh LUS01215 the relationship between the robustness of confronting the active attack of an opponent and other performances of the covert timing channel, and has weak adaptive ability to the complicated environment of the mobile network.
SUMMARY
[05] The present invention provides a communication method of a covert channel with feedback. The covert channel includes a covert timing channel and a backward covert storage channel. The communication method includes the following steps:
[06] acquiring the number of SID (Silence Insertion Descriptor) data packets in the current silence period of the covert timing channel and a receiving situation of the receiver of the covert timing channel for secret information;
[07] determining the maximum number of digit of hidden secret information in the current silence period of the covert timing channel according to the number of the SID data packets in the current silence period;
[08] determining feedback information of RTCP (Real-Time Transport Control Protocol) data packets of the backward covert storage channel according to the receiving situation of the receiver of the covert timing channel for the secret information; and
[09] adjusting communication of the covert timing channel according to the feedback information of the RTCP data packets and the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel.
[10] Optionally, the step of determining the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel according to the number of the SID data packets in the current silence period specifically includes:
[11] determining the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel by adopting the formula: log2:N-1<I<log2N, wherein N is the number of the SID data packets.
[12] Optionally, the step of adjusting the communication of the covert timing channel according to the feedback information of the RTCP data packets and the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel specifically includes:
[13] determining the current network quality grade according to the feedback information of the RTCP data packets;
[14] reducing the maximum number of digit of the hidden secret information if the current network quality grade is less than the threshold of the network quality grade;
[15] determining the Gray value according to the maximum number of digit of the hidden secret information and the Gray code rule if the current network quality grade is not less than the threshold of the network quality grade; 40 [16] discarding redundant SID data packets if the Gray value is less than the number of the SID data packets in the current silence period;
[17] modifying the interval of SID tail packets in the current silence period to mark the number of digit of the hidden secret information;
[18] adjusting the communication of the covert timing channel according to the digit
BL-5359 3 of the embedded hidden secret information; LU501215
[19] adjusting the communication of the covert timing channel according to the maximum number of digit of the hidden secret information if the Gray value is not less than the number of the SID data packets in the current silence period.
[20] Optionally, the step of adjusting the communication of the covert timing channel according to the maximum number of digit of the hidden secret information if the Gray value is not less than the number of the SID data packets in the current silence period, afterwards also includes:
[21] judging whether all the hidden secret information is embedded or not;
[22] ending the communication if all the hidden secret information is embedded; and
[23] entering the next silence period if not all the hidden secret information is embedded and returning to the step of acquiring the number of the SID data packets in the current silence period of the covert timing channel and the receiving situation of the receiver of the covert timing channel for the secret information.
[24] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:
[25] According to the communication method of the covert channel with feedback, which is provided by the present invention, the feedback information of the RTCP data packets of the backward covert storage channel is determined according to the receiving situation of the receiver of the covert timing channel for the secret information; and the communication of the covert timing channel is adjusted according to the feedback information of the RTCP data packets and the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel. The communication method of the covert channel with feedback, which is provided by the present invention, has the advantage that the adaptive ability to the complicated environment of the mobile network is improved.
BRIEFT DESCRIPTION OF THE DRAWINGS
[26] FIG 1 is the schematic diagram of the flow of a communication method of a covert channel with feedback, which is provided by the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[27] The present invention aims to provide a communication method of a covert channel with feedback, which has the advantage that the adaptive ability to the complicated environment of the mobile network is improved.
[28] FIG 1 is the schematic diagram of the flow of the communication method of the covert channel with feedback, which is provided by the present invention. As shown in FIG. 1, in the communication method of the covert channel with feedback, which is provided by the present invention, the covert channel with feedback includes a covert 40 timing channel and a backward covert storage channel. The communication method includes the following steps:
[29] S101, acquiring the number of SID (Silence Insertion Descriptor) data packets in a current silence period of the covert timing channel and a receiving situation of a receiver of the covert timing channel for secret information, wherein
BL-5359 4
[30] the receiving situation refers to some digits of secret information extracted by LUS01215 the receiver at the time; the receiver is configured to write the contents serving as feedback information into RTCP (Real-Time Transport Control Protocol) data packets and send the contents back (i.e. the backward covert storage channel); the sender is configured to determine the current network quality grade according to the bit error rate of the received feedback information; the higher the bit error rate is, the lower the network quality grade is; and if the network quality grade is below a certain threshold, the sender is configured to reduce an embedding digit of the secret information of the covert timing channel, so as to adapt to the current network environment;
[31] S102, determining the maximum number of digit of hidden secret information in the current silence period of the covert timing channel according to the number of the SID data packets in the current silence period, wherein the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel is determined by adopting the formula: log,N-1<I<log2N, and N is the number of the SID data packets;
[32] S103, determining the feedback information of the RTCP data packets of the backward covert storage channel according to the receiving situation of the receiver of the covert timing channel for the secret information; and
[33] S104, adjusting communication of the covert timing channel according to the feedback information of the RTCP data packets and the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel; and the covert storage channel with a feedback function can provide the current mobile network conditions, so that the sender is enabled to modify parameters to control hiding capacity according to the real-time network conditions, so as to achieve adaptivity to the network environment.
[34] The current network quality grade is determined according to the feedback information of the RTCP data packets.
[35] The maximum number of digit of the hidden secret information is reduced if the current network quality grade is less than the threshold of the network quality grade.
[36] The Gray value is determined according to the maximum number of digit of the hidden secret information and the Gray code rule if the current network quality grade is not less than the threshold of the network quality grade.
[37] Redundant SID data packets are discarded if the Gray value is less than the number of the SID data packets in the current silence period.
[38] The interval of SID tail packets in the current silence period is modified to mark the number of digit of the hidden secret information. The SID data packets in the silence period are modulated, and the proper adjustment for the silence period cannot be detected to be abnormal by an opponent, so as to ensure the undetectability of the covert channel.
40 [39] The communication of the covert timing channel is adjusted according to the number of digit of the hidden secret information.
[40] The communication of the covert timing channel is adjusted according to the maximum number of digit of the hidden secret information if the Gray value is not less than the number of the SID data packets in the current silence period.
BL-5359 5
[41] The step of adjusting the communication of the covert timing channel according LUS01215 to the maximum number of digit of the hidden secret information if the Gray value is not less than the number of the SID data packets in the current silence period later also includes:
[42] judging whether all the hidden secret information is embedded or not;
[43] ending the communication if all the hidden secret information is embedded; and
[44] entering the next silence period if not all the hidden secret information is embedded and returning to the step of acquiring the number of the SID data packets in the current silence period of the covert timing channel and the receiving situation of the receiver of the covert timing channel for the secret information.
[45] The covert channel with feedback is composed of the covert timing channel from the sender to the receiver and the backward covert storage channel. On one hand, the covert timing channel from the sender to the receiver is realized by actively discarding the data packets in the silence period, and the secret information is modulated into the number of the SID data packets in the silence period. The silence period is a normal phenomenon in voice communication, and the moderate change of the silence period is not easily detected. Meanwhile, the use of the Gray code ensures that the covert channel can confront and attack on-purpose packet loss of the opponent and keep the robustness. The change of the silence period may affect the undetectability ofthe covert channel and reduce the call voice quality, and therefore, the Gray code is adopted for meeting the requirements on the undetectability and the voice quality. On the other hand, the covert storage channel is constructed for feedback from the receiver to the sender, and the confirmation feedback of the covert storage channel for receiving the secret information is hidden into a feedback control information field of the RTCP data packets and is sent back to the sender. Some bits of the field are selected as confirmation bits for transmission of the secret information. The sender evaluates the current network condition or the severity degree of attacking of the opponent according to the feedback, and adjusts the real-time parameter (the network quality grade) of the covert timing channel to weigh the relationship between the robustness of confronting an active attack of the opponent and other performances of the covert timing channel. Through several rounds of feedback, the secure covert communication capable of being adaptive to the current network environment is finally realized.

Claims (1)

BL-5359 6 CLAIMS LU501215
1. A communication method of a covert channel with feedback, characterized in that the covert channel comprises a covert timing channel and a backward covert storage channel, and the communication method comprises: acquiring the number of SID (Silence Insertion Descriptor) data packets in the current silence period of the covert timing channel and the receiving situation of the receiver of the covert timing channel for secret information; determining the maximum number of digit of hidden secret information in the current silence period of the covert timing channel according to the number of the SID data packets in the current silence period; determining feedback information of RTCP (Real-Time Transport Control Protocol) data packets of the backward covert storage channel according to the receiving situation of the receiver of the covert timing channel for the secret information; adjusting communication of the covert timing channel according to the feedback information of the RTCP data packets and the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel; the step of adjusting the communication of the covert timing channel according to the feedback information of the RTCP data packets and the maximum number of digit of the hidden secret information in the current silence period of the covert timing channel specifically comprises: determining a current network quality grade according to the feedback information of the RTCP data packets; reducing the maximum number of digit of the hidden secret information if the current network quality grade is less than a threshold of a network quality grade; determining the Gray value according to the maximum number of digit of the hidden secret information and the Gray code rule if the current network quality grade is not less than the threshold of the network quality grade; discarding redundant SID data packets if the Gray value is less than the number of the SID data packets in the current silence period; modifying the interval of SID tail packets in the current silence period to mark the number of digit of the hidden secret information; adjusting the communication of the covert timing channel according to the number of digit of the hidden secret information; and adjusting the communication of the covert timing channel according to the maximum number of digit of the hidden secret information if the Gray value is not less than the number of the SID data packets in the current silence period.
LU501215A 2022-01-06 2022-01-06 Communication method of covert channel with feedback LU501215B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
LU501215A LU501215B1 (en) 2022-01-06 2022-01-06 Communication method of covert channel with feedback

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Application Number Priority Date Filing Date Title
LU501215A LU501215B1 (en) 2022-01-06 2022-01-06 Communication method of covert channel with feedback

Publications (1)

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LU501215B1 true LU501215B1 (en) 2022-07-06

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Effective date: 20220706