Month: December 2015

TalkTalk, a British phone and broadband provider with more than four million customers, disclosed Friday that intruders had hacked its Web site and may have stolen personal and financial data. Sources close to the investigation say the company has received a ransom demand of approximately £80,000 (~USD $122,000), with the attackers threatening to publish the TalkTalk’s customer data unless they are paid the amount in Bitcoin.
In a statement on its Web site, TalkTalk said a criminal investigation was launched by the Metropolitan Police Cyber Crime Unit following “a significant and sustained cyberattack on our website.”
“That investigation is ongoing, but unfortunately there is a chance that some of the following data has been compromised: names, addresses, date of birth, phone numbers, email addresses, TalkTalk account information, credit card details and/or bank details,” the statement continues. “We are continuing to work with leading cyber crime specialists and the Metropolitan Police to establish exactly what happened and the extent of any information accessed.”
A source close to the investigation who spoke on condition of anonymity told KrebsOnSecurity that the hacker group who demanded the £80,000 ransom provided TalkTalk with copies of the tables from its user database as evidence of the breach. The database in question, the source said, appears related to at least 400,000 people who have recently undergone credit checks for new service with the company. However, TalkTalk’s statement says it’s too early to say exactly how many customers were impacted. “Identifying the extent of information accessed is part of the investigation that’s underway,” the company said.
Separately, promises to post the stolen data have appeared on AlphaBay, a Deep Web black market that specialized in selling stolen goods and illicit drugs. The posting was made by someone using the nickname “Courvoisier.” This member, whose signature describes him as “Level 6 Fraud and Drugs seller,” appears to be an active participant in the AlphaBay market with many vouches from happy customers who’ve turned to him for illegal drugs and stolen credit cards, among other goods and services.

Homomorphism Encryption (HE) provides a solution to the problem of outsourcing computations privately to a cloud. There are a number of Somewhat Homomorphism Encryption (SHE) schemes that support many additions but only a limited number of multiplications. Though SHE schemes can evaluate only a limited set of circuits compared to FHE schemes, it is at rest motivating to believe them for application chiefly for competence motive. Those SHE schemes that support only a single operation on cipher texts – addition or multiplication – is called linearly homomorphism. That is, (additive) linearly-homomorphism encryption scheme can estimate barely linear function on top of cipher texts.

The major problem address in the present job is to allow assessment of degree-two function using linearly-homomorphism encryption scheme. To this end, the author offer a general conversion that extend an (additively-written) linearly-homomorphism format to carry a solitary development procedure so that it will now be able to evaluate a subset of functions of degree two. The only requirement of the underlying linearly-homomorphism scheme is that it should be public space, which means that the communication room must be a openly known limited commutative circle and that it is probable to efficiently sample a random element from this ring. This property seem to hold for nearly the entire recognized linearly-homomorphism encryption scheme or can be simply modified to become so.

Density is single of the three main materials of a (fully) HE system that say so as to the difficulty of decryption must exist autonomous of the complexity of the route evaluate the given function. The other two requirements are semantic safety and route solitude for the underlying plaintext mail. The latter means that it must not be possible to learn anything regarding the post in the code texts input to a occupation It is exposed that the proposed transformation conserve semantic safety and the distorted format will be leveled circuit private if the underlying scheme is circuit classified. The distorted system will be clever to compactly evaluate a subset of degree-two functions (represented as polynomials) [Math Processing Error] consisting of the following polynomials [Math Processing Error]
where [Math Processing Error], [Math Processing Error], [Math Processing Error] are linear polynomials. It turns out that the subclass [Math Processing Error] of quadratic polynomials is applicable, for example, SPDZ protocol for multi-party computation requires a HE scheme for [Math Processing Error] with [Math Processing. A transformation of the underlying HE scheme is given in this model that is similar to the previous alteration, using which it is now possible to evaluate any quadratic polynomial compactly. Interestingly, the former (single-server) change preserves other property such as zero-knowledge proof of plaintext information, threshold decryption, and multi-key homomorphicity.