Selective Encryption Research Articles

Smart selective encryption of H.264/AVC videos using confidentiality metrics

In the field of video protection, selective encryption (SE) is a scheme which ensures the visual security of a video by encrypting only a small part of the data. This paper presents a new SE algorithm for H.264/AVC videos in context-adaptive variable-length coding mode. This algorithm controls the amount of encrypted alternative coefficients (ACs) of the integer transform in the entropic encoder. Two visual quality measures, the peak signal-to-noise ratio (PSNR) and the structural similarity (SSIM), are used to measure the visual confidentiality level of each video frame and to control the amount of encrypted ACs. Moreover, a new psychovisual metric to measure the flickering is introduced, the so-called temporal structural similarity (TSSIM). This method can be applied on intra and inter frame video sequences. Several experimental results show the efficiency of the proposed method.

Visual Protection of HEVC Video by Selective Encryption of CABAC Binstrings

This paper presents one of the first methods allowing the protection of the newly emerging video codec HEVC (High Efficiency Video Coding). Visual protection is achieved through selective encryption (SE) of HEVC-CABAC binstrings in a format compliant manner. The SE approach developed for HEVC is different from that of H.264/AVC in several aspects. Truncated rice code is introduced for binarization of quantized transform coefficients (QTCs) instead of truncated unary code. The encryption space (ES) of binstrings of truncated rice codes is not always dyadic and cannot be represented by an integer number of bits. Hence they cannot be concatenated together to create plaintext for the CFB (Cipher Feedback) mode of AES, which is a self-synchronizing stream cipher for so-called AES-CFB. Another challenge for SE in HEVC concerns the introduction of context, which is adaptive to QTC. This work presents a thorough investigation of HEVC-CABAC from an encryption standpoint. An algorithm is devised for conversion of non-dyadic ES to dyadic, which can be concatenated to form plaintext for AES-CFB. For selectively encrypted binstrings, the context of truncated rice code for binarization of future syntax elements is guaranteed to remain unchanged. Hence the encrypted bitstream is format-compliant and has exactly the same bit-rate. The proposed technique requires very little processing power and is ideal for playback on hand held devices. The proposed scheme is acceptable for DRM of a wide range of applications, since it protects the contour and motion information, along with texture. Several benchmark video sequences of different resolutions and diverse contents were used for experimental evaluation of the proposed algorithm. A detailed security analysis of the proposed scheme verified the validity of the proposed encryption scheme for content protection in a wide range of applications.

Selective Encryption of Plaintext Using Multiple Indexing

Selective Encryption is one of the encryption algorithm in the field of multimedia security. They are used for the purpose of hiding image, video or audio files. The main feature of selective encryption is that the resource and time taken to encrypt the files is lower than any other encryption algorithm. We propose an algorithm that will exploit this feature of selective encryption to encrypt plaintext instead of multimedia file. Our purpose is to design an encryption algorithm that will be computationally faster than any hard encryption algorithm such as Advanced Encryption Standard (AES) while providing the basic cipher complexity.

An efficient technique for secure transmission of the region of interest in medical images

In this paper, we propose three ROI (Region of Interest) selective encryption schemes to achieve secure access for medical images. The security in the region of interest is ensured by using inversion or/and permutation function as cryptographic tools. The three schemes are performed during compression. Only few selected MSBs (Most Significant Bit-Planes) of the ROI’s codeblocks are concerned by the encryption. The first permutation scheme incurs a little loss on compression efficiency. The second scheme, inverts a set of important bit-planes of each ROI codeblock with no compression overhead. The third scheme combines the two schemes performing inversion and permutation of the selected ROI’s MSBs. The size of encrypted bit-stream is not changed. Moreover, the JPEG 2000 codestream resulting from the encryption process remains compliant with the JPEG 2000 format. Decryption is provided of course by our decoder which requires the same function to recover the original medical image.

Confidentiality of a selectively encrypted H.264 coded video bit-stream

It is an assumption that selective encryption does not strongly protect confidentiality owing to the partial visibility of some video data. This is because, though encryption keys may be difficult to derive, an enhanced version of selectively encrypted video sequence might be found from knowledge of the unencrypted parts of the sequence. An efficient selective encryption method for syntax elements of H.264 encoded video was recently proposed at the entropy coding stage of an H.264 encoder. Using this recent scheme as an example, the purpose of this paper is a comprehensive cryptanalysis of selectively encrypted H.264 bit-streams to contradict the previous assumption that selective encryption is vulnerable. The novel cryptanalysis methods presented in this paper analyze the ability of an attacker to improve the quality of the encrypted video stream to make it watchable. The conclusion is drawn that if the syntax elements for selective encryption are chosen using statistical and structural characteristics of the video, then the selective encryption method is secure. The cryptanalysis is performed by taking into account the probability distribution of syntax elements within the video sequence, the relationship of syntax elements with linear regression analysis and the probability of successfully attacking them in order to enhance the visual quality. The results demonstrate the preservation of distorted video quality even after considering many possible attacks on: the whole video sequence; each video frame; and on small video segments known as slices.

Application-Aware Client-Side Data Reduction and Encryption of Personal Data in Cloud Backup Services

Cloud backup has been an important issue ever since large quantities of valuable data have been stored on the personal computing devices. Data reduction techniques, such as deduplication, delta encoding, and Lempel-Ziv (LZ) compression, performed at the client side before data transfer can help ease cloud backup by saving network bandwidth and reducing cloud storage space. However, client-side data reduction in cloud backup services faces efficiency and privacy challenges. In this paper, we present Pangolin, a secure and efficient cloud backup service for personal data storage by exploiting application awareness. It can speedup backup operations by application-aware client-side data reduction technique, and mitigate data security risks by integrating selective encryption into data reduction for sensitive applications. Our experimental evaluation, based on a prototype implementation, shows that our scheme can improve data reduction efficiency over the state-of-the-art methods by shortening the backup window size to 33%~75%, and its security mechanism for sensitive applications has negligible impact on backup window size.

Securing Multimedia Content Using Joint Compression and Encryption

Algorithmic parameterization and hardware architectures can ensure secure transmission of multimedia data in resource-constrained environments such as wireless video surveillance networks, telemedicine frameworks for distant health care support in rural areas, and Internet video streaming. Joint multimedia compression and encryption techniques can significantly reduce the computational requirements of video processing systems. The authors present an approach to reduce the computational cost of multimedia encryption while also preserving the properties of compressed video. A hardware-amenable design of the proposed algorithms makes them suitable for real-time embedded multimedia systems. This approach alleviates the need for additional hardware for encryption in resource-constrained scenarios and can be otherwise used to augment existing encryption methods used for content delivery on the Internet or in other applications. This work shows how two compression blocks for video coding--a modified frequency transform (called a secure wavelet transform or SWT) and a modified entropy coding scheme (called a chaotic arithmetic coding or CAC)--can be used for video encryption. Experimental results are shown for selective encryption using the proposed schemes.

Study of Selective Video Encryption for the H.264 Standard

Video encryption has been widely researched in digital right management in recent years, especially selective video encryption. Selective video encryption has been the main trend with the development of compression coding methods, which selects an important subset of the comparative large compressed video data to encrypt in order to satisfy the real-time features and ensure the security of the video at the same time. In this paper, according to a particular evaluation criterion we proposed, we mainly analyze several selective video encryption algorithms based on the H.264 standard. Through the analysis we find out how to select the different vital data sets of the video to encrypt according to various security levels and applications.

An image joint compression-encryption algorithm based on adaptive arithmetic coding

Through a series of studies on arithmetic coding and arithmetic encryption, a novel image joint compression-encryption algorithm based on adaptive arithmetic coding is proposed. The contexts produced in the process of image compression are modified by keys in order to achieve image joint compression encryption. Combined with the bit-plane coding technique, the discrete wavelet transform coefficients in different resolutions can be encrypted respectively with different keys, so that the resolution selective encryption is realized to meet different application needs. Zero-tree coding is improved, and adaptive arithmetic coding is introduced. Then, the proposed joint compression-encryption algorithm is simulated. The simulation results show that as long as the parameters are selected appropriately, the compression efficiency of proposed image joint compression-encryption algorithm is basically identical to that of the original image compression algorithm, and the security of the proposed algorithm is better than the joint encryption algorithm based on interval splitting.

A Tunable Encryption Scheme and Analysis of Fast Selective Encryption for CAVLC and CABAC in H.264/AVC

Recently, two fast selective encryption methods for context-adaptive variable length coding and context-adaptive binary arithmetic coding in H.264/AVC were proposed by Shahid In this paper, it was demonstrated that these two methods are not as efficient as only encrypting the sign bits of nonzero coefficients. Experimental results showed that without encrypting the sign bits of nonzero coefficients, these two methods can not provide a perceptual scrambling effect. If a much stronger scrambling effect is required, intra prediction modes, and the sign bits of motion vectors can be encrypted together with the sign bits of nonzero coefficients. For practical applications, the required encryption scheme should be customized according to a user's specified requirement on the perceptual scrambling effect and the computational cost. Thus, a tunable encryption scheme combining these three methods is proposed for H.264/AVC. To simplify its implementation and reduce the computational cost, a simple control mechanism is proposed to adjust the control factors. Experimental results show that this scheme can provide different scrambling levels by adjusting three control factors with no or very little impact on the compression performance. The proposed scheme can run in real-time and its computational cost is minimal. The security of the proposed scheme is also discussed. It is secure against the replacement attack when all three control factors are set to one.

A selective encryption and energy efficient clustering scheme for video streaming in wireless sensor networks

The past few years have witnessed increased interest in the potential use of wireless sensor networks (WSNs) in applications such as battlefield assistance, adversary intrusion detection, distributed signal processing, etc. In these applications, multimedia semantic information and video content are extremely sensitive to malicious attacks, including eavesdropping/intercepting of ongoing traffic, and manipulating/counterfeiting of the existing media flows. From a security standpoint, it is very important to transmit authentic and accurate data to surrounding sensor nodes and to the sink. However, securing sensor networks poses unique challenges because these tiny wireless devices are deployed in large numbers, usually in unattended environments, and are severely limited in their capabilities and resources like power, computational capacity, and memory. In this work, a secure and selective encryption framework is proposed so as to optimize network lifetime and video distortion for an energy constrained wireless video sensor network (WVSN).

Chaos-based selective encryption for H.264/AVC

Encryption techniques are usually employed to maintain the secrecy of the video streams transmitted via a public network. However, full encryption using strong cryptographic algorithms is usually not necessary if the purpose is to destroy the commercial value by preventing pleasant viewing. For this purpose, selective encryption is preferred as its operating efficiency is higher. Here, a chaos-based selective encryption scheme implemented on the H.264/AVC standard is proposed. The scheme employs multiple Rényi chaotic maps to generate a pseudorandom bit sequence which is used to mask the selected H.264/AVC syntax elements. It provides sufficient protection against full reconstruction while keeping the format compliance property so as not to cause decoding error without the key. The operating efficiency is high due to the low computational complexity of the Rényi chaotic map, as justified by the simulation results using video clips at various resolutions. Moreover, the security analyses show that the proposed algorithm is highly sensitive to the secret key and possesses good perceptual security.

Use of elliptic curve cryptography for multimedia encryption

The unique characteristics of the elliptic curve cryptography (ECC) such as the small key size, fast computations and bandwidth saving make its use attractive for multimedia encryption. In this study, the ECC is used to perform encryption along with multimedia compression, and two ECC-based encryption algorithms are introduced and applied before and during compression. The first algorithm performs selective encryption on the transform coefficients during compression, whereas the second algorithm achieves perceptual encryption based on selective bit-plane encryption before compression. The results of applying ECC to multimedia encryption are presented and analysed with respect to the requirements of multimedia encryption: the encryption efficiency, compression efficiency, codec compliance and security level. It is shown that ECC is highly efficient and does not affect the compression efficiency, and accordingly can meet the multimedia encryption requirements.

Implementing Encryption Algorithms to Enhance Data Security of Cloud in Cloud Computing

In Cloud computing technology there are a set of important policy issues, which include issues of privacy, security, anonymity, telecommunications capacity, government surveillance, reliability, and liability, among others. But the most important between them is security and how cloud provider assures it. Generally, Cloud computing has several customers such as ordinary users, academia, and enterprises who have different motivation to move to cloud. If cloud clients are academia, security effect on performance of computing and for them cloud providers have to find a way to combine security and performance. For enterprises the most important problem is also security but with different vision. For them high performance may be not as critical as academia. This paper discusses to which degree this scepticismis justified, by presenting the Cipher Cloud. The Cipher Cloud is a framework that lets users keep their data confidentially on public cloud frameworks. To achieve this, the Cipher Cloud uses a two-step encryption process, in by which all the data sent from a client to a cloud server or vice versa is kept totally encrypted and confidential. The most thorough security controls needed to protect the most sensitive data may not be guaranteed in public cloud computing architectures, while they can be realized in private cloud computing architectures. As the most promising cloud computing approach, this paper suggests selective encryption techniques, which almost gives the data confidentiality just like private cloud models.

An Effective Selective Encryption Scheme for H.264 Video based on Chaotic Qi System

With the wide use of H.264 in Internet and wireless network, many concerns have been made to the security of it. Aiming at providing an effective content protection method for H.264 video, a novel selective encryption scheme based on chaotic Qi system is proposed in this paper. The unpredictability of chaotic system is implemented to construct a pseudo-random number generator based on the 3-dimensional chaotic Qi system, and then some key data such as intra-prediction modes, residual coefficients and MVD are encrypted by the generated key stream. Experimental results and analysis show that the proposed scheme can achieve a good encryption result, a low computational complexity, little impact on compression ratio, and good format compatibility. It has a great potential to be applied in some real-time applications.

Enforcing dynamic write privileges in data outsourcing

Users and companies are more and more resorting to external providers for storing their data and making them available to others. Since data sharing is typically selective (i.e., accesses to certain data should be allowed only to authorized users), there is the problem of enforcing authorizations on the outsourced data. Recently proposed approaches based on selective encryption provide convenient enforcement of read privileges, but are not directly applicable for supporting write privileges.In this paper, we extend selective encryption approaches to the support of write privileges. Our proposal enriches the approach based on key derivation of existing solutions and complements it with a hash-based approach for supporting write privileges. Enforcement of write privileges and of possible policy updates relies on the – controlled – cooperation of the external provider. Our solution also allows the data owner and the users to verify the integrity of the outsourced data.

An Efficient Security System for CABAC Bin-Strings of H.264/SVC

The distribution of copyrighted scalable video content to differing digital devices requires protection during rendering and transmission. In this paper, we propose a complete security system for H.264/scalable video coding (SVC) video codec and present a solution for the bit-rate and format compliance problems by careful selection of entropy coder syntax elements (bin-strings) for selective encryption (SE), and the problem of managing multiple layer encryption keys for scalable video distribution. A standard key management protocol, multimedia Internet keying protocol, is implemented for the hierarchical key generation mechanism, in which a subscriber has only one encryption key to unlock all scalable layers that have been subscribed to. The evaluation demonstrates the resulting video quality degradation arising from SE for many <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CIF</i> and 4 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CIF</i> test video sequences, without there being any impact upon the bit-rate or format compliancy, and with small computational delay. The security and statistical analysis performed further verify the effectiveness of the proposed security system for H.264/SVC. The proposed system is highly suitable for video distribution to users who have subscribed to a varying degree of video quality on devices with medium to high computational resources.

A Very Compact AES-SPIHT Selective Encryption Computer Architecture Design with Improved S-Box

The “S-box” algorithm is a key component in the Advanced Encryption Standard (AES) due to its nonlinear property. Various implementation approaches have been researched and discussed meeting stringent application goals (such as low power, high throughput, low area), but the ultimate goal for many researchers is to find a compact and small hardware footprint for the S-box circuit. In this paper, we present our version of minimized S-box with two separate proposals and improvements in the overall gate count. The compact S-box is adopted with a compact and optimum processor architecture specifically tailored for the AES, namely, the compact instruction set architecture (CISA). To further justify and strengthen the purpose of the compact crypto-processor’s application, we have also presented a selective encryption architecture (SEA) which incorporates the CISA as a part of the encryption core, accompanied by the set partitioning in hierarchical trees (SPIHT) algorithm as a complete selective encryption system.

SecureAccess to Outsourced Databases

Data security is one of the fundamental security requirement for outsourced databases in a cloud computing environment. Existing solutions usually suffer from problems such as information leakage, key management, revocation handling and user authentication. In this paper to overcome these security challenges, the proposed scheme uses a modified row- based encryption technique where each row of the database is encrypted using a separate key. The proposed scheme also uses client side memory, and selective encryption to increase performance of the system. The proposed approach also uses a modified Diffie-Hellman key exchange algorithm for establishing secure communication between cloud service provider and the user, inhibiting malicious outsiders.

A joint compression and encryption scheme for color JPEG image

To research the encryption algorithm for color joint photographic expert group (JPEG) image, by comprehensively choosing the selective encryption and the joint compression and encryption, an encryption algorithm combining with spatial domain and frequent domain for color JPEG image is proposed. The 8×8 blocks are first diffused on spatial domain, then the edge-detection method is utilized to find out the significant blocks containing abundant details. After encrypting all the direct current coefficients, part of alternating current (AC) coefficients in significant blocks are chosen to be encrypted. Finally the information about marking the significance of the blocks is embedded into AC coefficients for transmission. Theoretical analyses and experimental results show that the proposed algorithm is compatible with JPEG format. The cipher image has good visual quality and uniform color distribution. The algorithm possesses huge key space, strong key-sensitivity and good security.