Tags: SGARD video communication
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I. Introduction
The rapid development of high-definition video communication technology has brought us unprecedented video quality, but how is network security guaranteed during the communication process? We are trying our best to improve the quality of video communication while in IP communication technology. Today, with rapid development, security is also the focus of our attention.
The use of information encryption technology is an effective means to protect network security. It is protected by an encryption algorithm that converts the data into a readable password that is decrypted, so that unauthorized access even if data is obtained. It is difficult to decrypt. The existing encryption technologies mainly include symmetric encryption technology and asymmetric encryption technology.
In the ITU-T standard for video communication, there is already an encryption chapter for video communication - the H.235 encryption standard. With the continuous development of H.235, its version has been updated to the V4 version so far. H.235 is a standard for security aspects of the ITU-T series of standards for video communication systems. It provides security procedures for systems based on H.323-, H.225.0-, H.245- and H.460-. H.235 can be applied to any point-to-point conference and multipoint conference with H.245 as the control protocol. H.235 mainly provides identity authentication, data encryption and integrity functions, can negotiate the required services and functions in the common mode, and select encryption technology and other functions. This particular approach is associated with system capabilities, application requirements, and specific security policy restrictions. H.235 supports various encryption algorithms and supports different encryption options for different purposes. The encryption algorithms used in the encryption communication on both sides are generally DES 56 and AES 128. Since these two encryption algorithms are commercial encryption algorithms, they are not widely recognized in some specific fields or industries in China.
Second, SGARD encryption technology introduction
Digital Video Corporation is deeply aware that users' requirements for video communication are shifting from focusing on connectivity and clarity to high quality, reliability, security and stability. Therefore, the company attaches great importance to video communication security. After years of efforts in video technology, the digital video has successfully developed the video coding encryption technology SGARD, which has been successfully applied to video communication systems, enabling the system to create a new encryption strategy for video communication. The era of information security in video communications.
SGARD encryption technology completes the authorization control and key generation, encryption, transmission, and video codec control for video terminal users, ensuring that only authenticated video terminal users can access the system for communication, and ensure that data streams are not stolen by illegal users. Is a new video communication security certification system.
Third, the application process
In the digital video communication system, audio and video data packets are sent through the codec device. First, the terminal internal control word generator generates a control word and supplies it to the encryption component. According to the control word provided by the control word generator, the H.264 high-definition video stream transmitted by the encoder is encrypted. At this time, the output of the encryption is a disturbed H.264 high-definition video stream, and the control word is the key used for encryption. . After receiving the control word from the control word generator, the video terminal system encrypts the control word according to the service key provided by the user authorization system to generate authorization control information. Finally, the encrypted audio and video data packets are packaged and transmitted to a remote video conference terminal or a multipoint control unit (MCU system). At the beginning of the decoded encrypted audio and video stream, the control word has not recovered. The encrypted data stream is sent out by the terminal decryptor without decryption, thereby restoring the control word. The process of restoring the control word is very short, and once the video terminal receives the recovered correct control word, the encrypted video bit stream is restored to the normal video stream. Thereby implementing the communication encryption process.
From this, we can see that the entire SGARD encryption system provides multiple layers of protection for video communication security: the first layer of protection uses the control word to encrypt the image, sound and data signal bit streams output by the codec, disrupting normal The audio and video stream can not obtain image, sound and data information without decrypting at the receiving end of the video communication; the second layer of protection is to encrypt the control word by the key, even if the control word is illegally intercepted during transmission, It is also impossible to decrypt the encrypted control word; the third layer of protection is to encrypt the service key by the personal distribution key, which further improves the security of the entire system, so that the unauthorized user can obtain the encrypted service key even if it is obtained. Underneath, it can't be easily decrypted, because the correct control word can't be obtained without the business key, and the normal signal stream can't be solved without the correct control word.
The security strategy for video communication system encryption should adopt a three-dimensional encryption system combining multi-level keys and algorithms to avoid the disadvantages caused by using a key or algorithm encryption system alone.
Fourth, SGARD technical analysis
Algorithm
Starting with the algorithm is the most direct way to crack the encrypted audio and video data packets. The digital video SGARD system generally uses two measures to deal with algorithmic cracking. First, the key is lengthened. According to Shannon's theorem, the capacity of the information is exponentially related to its length. The larger the information volume of the ciphertext, the more difficult it is to crack. The second is to use multiple algorithms. According to the principle of cryptography, the encryption system has four elements, namely ciphertext = algorithm (plain text, key). In most encryption applications, plaintext and keys are protected objects, and half of the four elements are unknown, and security is relatively high.
However, in the practical application of IP video communication, plaintext and ciphertext can be intercepted, and the algorithm used by a reliable encryption system should be public, so the encryption system using a single algorithm has only one unknown element and is relatively easy to be parsed. Or exhaustive methods to crack. But if multiple algorithms are used, the situation is completely different, because ciphertext = algorithm 2 (algorithm 1 (plain text, key 1), key 2), so there are six elements in the whole system, three of which are unknown. This greatly enhances the security, making the parsing of the analytic method almost impossible. If the long key and time factor are combined, the exhaustive method is very difficult to crack.
When selecting the encryption algorithm for encrypting SGARD data, taking into account the current status of security algorithms supported by the communications industry, if the internationally popular commercial algorithms (such as DES, AES, RSA) are fully adopted, it does not comply with China's relevant security regulations. Therefore, in order to comply with China's national conditions, the SGARD system of the digital video communication system uses its own patented special encryption and decryption algorithm (SVAS). The strength of all symmetric algorithms is not lower than 3DES or AES, and the strength of the asymmetric algorithm cannot be lower than RSA.
2. Encryption system
The algorithms used in the SGARD video communication encryption system are in line with the National Commerce Commission's commercial algorithm standard, and a variety of algorithms are used in various combinations. For example, using 64 algorithms, we have 264 combinations, and each time The number of combinations used is variable, which increases the difficulty of cracking and makes it completely based on the encryption strength of the algorithm.
In summary, SGARD encryption technology ensures the security of users when using video communication to the greatest extent, ensuring that the system can always be in the best security state, thus ensuring security and QoS in user video applications, and greatly improving the use of video communication. quality.
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