Lossy Encryption Research Articles

Ring Signature With Unconditional Anonymity in the Plain Model

Ring signature allows a user to sign messages as a member of a set of users, which is called the ring. In addition to an unforgeability, ring signature ensures that nobody can detect which member in the ring signs the message. In this paper, we propose the first generic construction of ring signature with unconditional anonymity in the plain model based on the standard assumption. The plain model means that we do not need any setup procedure by trusted third party and not depends on a random oracle methodology. Our scheme is constructed based on a statistical ZAP argument, a lossy encryption scheme, and a standard signature scheme. It is known that all of our building blocks can be instantiated based on the quasi-polynomial learning with errors assumption.

Privacy preserving search services against online attack

Searchable functionality is provided in many online services such as mail services or outsourced data storage. To protect users privacy, data in these services is usually stored after being encrypted using searchable encryption. This enables the data user to securely search encrypted data from a remote server without leaking data and query information. Public key encryption with keyword search is one of the research branches of searchable encryption; this provides privacy-preserving searchable functionality for applications such as encrypted email systems. However, it has an inherent vulnerability in that the information of a query may be leaked using a keyword guessing attack. Most of existing works aim to make the system resistant to offline keyword guessing, but this does not protect against online attacks on real world services. In this paper, we move a step forward to present a generic framework able to resist online keyword guessing attack using a server-assisted model. Specifically, we design a novel primitive C mirrored all-but-one lossy encryption, which can prevent a specific user from generating valid encryptions. This primitive can be seen as an access control on encryption ability. Combining searchable encryption technique with the new primitive makes online keyword guessing attack impossible for the specified user, even if the attack is launched online. We further give formal security analysis for the generic framework, and a concrete implementation with efficiency analysis to show that our design is practical.

Oblivious Transfer via Lossy Encryption from Lattice‐Based Cryptography

Authentication is the first defence line to prevent malicious entities to access smart mobile devices (or SMD). Essentially, there exist many available cryptographic primitives to design authentication protocols. Oblivious transfer () protocol is one of the important cryptographic primitives to design authentication protocols. The first lattice‐based framework under universal composability (UC) model was designed by dual mode encryption and promoted us to find an alternative efficient scheme. We note that “lossy encryption” scheme is an extension of the dual mode encryption and can be used to design UC‐secure protocol, but the investigations of via lossy encryption over the lattice are absent. Hence, in order to obtain an efficient authentication protocol by improving the performance of the UC‐secure protocol, in this paper, we first design a multibit lossy encryption under the decisional learning with errors () assumption and then design a new variant of UC‐secure protocol for authenticated protocol via lossy encryption scheme. Additionally, our protocol is secure against semihonest (static) adversaries in the common reference string (CRS) model and within the UC framework.

웨이브렛 변환 계수의 특성을 이용한 생체 영상 암호화 알고리즘

Lossless encryption methods are more applicable than lossy encryption methods when marginal distortion is not tolerable. In this research, the author propose a novel lossless symmetric key encryption/decryption technique. In the proposed algorithm, the image is transformed into the frequency domain using the lifting wavelet transform, then the image sub-bands are encrypted in a such way that guarantees a secure, reliable, and an unbreakable form. The encryption involves scattering the distinguishable frequency data in the image using a reversible weighting factor amongst the rest of the frequencies. The algorithm is designed to shuffle and reverse the sign of each frequency in the transformed image before the image frequencies are transformed back to the pixel domain. The results show a total deviation in pixel values between the original and encrypted image. The decryption algorithm reverses the encryption process and restores the image to its original form. The proposed algorithm is evaluated using standard security and statistical methods; results show that the proposed work is resistant to most known attacks and more secure than other algorithms in the cryptography domain.

Algoritma Enkripsi Selektif Citra Digital dalam Ranah Frekuensi Berbasis Permutasi Chaos

This paper presents a selective image encryption in frequency domain. At first, the image is transformed into frequency domain with Discrete Cosine Transform (DCT), and then DCT coefficients are scanned in zigzag, and elements of the low-frequency sub-band are extracted. Encryption is performed only on selected elements by scrambling them using 2D chaos map, namely Arnold Cat Map. Next, IDCT is applied to obtain the encrypted image. The encryption algorithm is included in lossy encryption. Experiments on both grayscale images and color images show that the images can be encrypted succesfully. Histograms of the encrypted images differ significantly from histogram of the original images, and the pixels in the encrypted images are not longer correlated.

Image cryptographic algorithm based on the Haar wavelet transform

Lossless encryption methods are more applicable than lossy encryption methods when marginal distortion is not tolerable. In this research, the authors propose a novel lossless symmetric key encryption/decryption technique. In the proposed algorithm, the image is transformed into the frequency domain using the Haar wavelet transform, then the image sub-bands are encrypted in a such way that guarantees a secure, reliable, and an unbreakable form. The encryption involves scattering the distinguishable frequency data in the image using a reversible weighting factor amongst the rest of the frequencies. The algorithm is designed to shuffle and reverse the sign of each frequency in the transformed image before the image frequencies are transformed back to the pixel domain. The results show a total deviation in pixel values between the original and encrypted image. The decryption algorithm reverses the encryption process and restores the image to its original form. The proposed algorithm is evaluated using standard security and statistical methods; results show that the proposed work is resistant to most known attacks and more secure than other algorithms in the cryptography domain.

Non-interactive Equivocable Commitment from Lossy Encryption

Non-interactive Equivocable Commitment from Lossy Encryption