/pdf/a-break-in-the-clouds-towards-a-cloud-definition-svovsw1r5a.pdf

A Break in the Clouds: Towards a Cloud Definition

In this paper, we define and explore proofs of retrievability (PORs). A POR scheme enables an archive or back-up service (prover) to produce a concise proof that a user (verifier) can retrieve a target file F, that is, that the archive retains and reliably transmits file data sufficient for the user to recover F in its entirety.A POR may be viewed as a kind of cryptographic proof of knowledge (POK), but one specially designed to handle a large file (or bitstring) F. We explore POR protocols here in which the communication costs, number of memory accesses for the prover, and storage requirements of the user (verifier) are small parameters essentially independent of the length of F. In addition to proposing new, practical POR constructions, we explore implementation considerations and optimizations that bear on previously explored, related schemes.In a POR, unlike a POK, neither the prover nor the verifier need actually have knowledge of F. PORs give rise to a new and unusual security definition whose formulation is another contribution of our work.We view PORs as an important tool for semi-trusted online archives. Existing cryptographic techniques help users ensure the privacy and integrity of files they retrieve. It is also natural, however, for users to want to verify that archives do not delete or modify files prior to retrieval. The goal of a POR is to accomplish these checks without users having to download the files themselves. A POR can also provide quality-of-service guarantees, i.e., show that a file is retrievable within a certain time bound.

PORs: Proofs of Retrievability for Large Files

An important open problem in the area of Traitor Tracing is designing a scheme with constant expansion of the size of keys (users' keys and the encryption key) and of the size of ciphertexts with respect to the size of the plaintext. This problem is known from the introduction of Traitor Tracing by Chor, Fiat and Naor. We refer to such schemes as traitor tracing with constant transmission rate. Here we present a general methodology and two protocol constructions that result in the first two public-key traitor tracing schemes with constant transmission rate in settings where plaintexts can be calibrated to be sufficiently large. Our starting point is the notion of copyrighted function which was presented by Naccache, Shamir and Stern. We first solve the open problem of discrete-log-based and public-key-based copyrighted function. Then, we observe the simple yet crucial relation between (public-key) copyrighted encryption and (public-key) traitor tracing, which we exploit by introducing a generic design paradigm for designing constant transmission rate traitor tracing schemes based on copyrighted encryption functions. Our first scheme achieves the same expansion efficiency as regular ElGamal encryption. The second scheme introduces only a slightly larger (constant) overhead, however, it additionally achieves efficient black-box traitor tracing (against any pirate construction).

Traitor Tracing with constant transmission rate

Im Jahre 1977 wurde der „Data Encryption Algorithm“ (DEA) vom „National Bureau of Standards“ (NBS, später „National Institute of Standards and Technology“ – NIST) zum amerikanischen Verschlüsselungsstandard für Bundesbehörden erklärt [NBS_77]. 1981 folgte die Verabschiedung der DEA-Spezifikation als ANSI-Standard „DES“ [ANSI_81]. Die Empfehlung des DES als StandardVerschlüsselungsverfahren wurde auf fünf Jahre befristet und 1983, 1988 und 1993 um jeweils weitere fünf Jahre verlängert. Derzeit liegt eine Neufassung des NISTStandards vor [NIST_99], in dem der DES für weitere fünf Jahre übergangsweise zugelassen sein soll, aber die Verwendung von Triple-DES empfohlen wird: eine dreifache Anwendung des DES mit drei verschiedenen Schlüsseln (effektive Schlüssellänge: 168 bit) [NIST_99]. Der DES basiert auf einer von Horst Feistel bei IBM entwickelten Blockchiffre („Lucipher“) mit einer Schlüssellänge von 128 bit. Da die amerikanische „National Security Agency“ (NSA) dafür gesorgt hatte, daß der DES eine Schlüssellänge von lediglich 64 bit besitzt, von denen nur 56 bit relevant sind, und spezielle Substitutionsboxen (den „kryptographischen Kern“ des Verfahrens) erhielt, deren Konstruktionskriterien von der NSA nicht veröffentlicht wurden, war das Verfahren von Beginn an umstritten. Kritiker nahmen an, daß es eine geheime „Trapdoor“ in dem Verfahren gäbe, die der NSA eine OnlineEntschlüsselung auch ohne Kenntnis des Schlüssels erlauben würde. Zwar ließ sich dieser Verdacht nicht erhärten, aber sowohl die Zunahme von Rechenleistung als auch die Parallelisierung von Suchalgorithmen machen heute eine Schlüssellänge von 56 bit zum Sicherheitsrisiko. Zuletzt konnte 1998 mit einer von der „Electronic Frontier Foundation“ (EFF) entwickelten Spezialmaschine mit 1.800 parallel arbeitenden, eigens entwickelten Krypto-Prozessoren ein DES-Schlüssel in einer Rekordzeit von 2,5 Tagen gefunden werden. Um einen Nachfolger für den DES zu finden, kündigte das NIST am 2. Januar 1997 die Suche nach einem „Advanced Encryption Standard“ (AES) an. Ziel dieser Initiative ist, in enger Kooperation mit Forschung und Industrie ein symmetrisches Verschlüsselungsverfahren zu finden, das geeignet ist, bis weit ins 21. Jahrhundert hinein amerikanische Behördendaten wirkungsvoll zu verschlüsseln. Dazu wurde am 12. September 1997 ein offizieller „Call for Algorithm“ ausgeschrieben. An die vorzuschlagenden symmetrischen Verschlüsselungsalgorithmen wurden die folgenden Anforderungen gestellt: nicht-klassifiziert und veröffentlicht, weltweit lizenzfrei verfügbar, effizient implementierbar in Hardund Software, Blockchiffren mit einer Blocklänge von 128 bit sowie Schlüssellängen von 128, 192 und 256 bit unterstützt. Auf der ersten „AES Candidate Conference“ (AES1) veröffentlichte das NIST am 20. August 1998 eine Liste von 15 vorgeschlagenen Algorithmen und forderte die Fachöffentlichkeit zu deren Analyse auf. Die Ergebnisse wurden auf der zweiten „AES Candidate Conference“ (22.-23. März 1999 in Rom, AES2) vorgestellt und unter internationalen Kryptologen diskutiert. Die Kommentierungsphase endete am 15. April 1999. Auf der Basis der eingegangenen Kommentare und Analysen wählte das NIST fünf Kandidaten aus, die es am 9. August 1999 öffentlich bekanntmachte: MARS (IBM) RC6 (RSA Lab.) Rijndael (Daemen, Rijmen) Serpent (Anderson, Biham, Knudsen) Twofish (Schneier, Kelsey, Whiting, Wagner, Hall, Ferguson).

Advanced Encryption Standard (AES).

１ インフラを構築する（ＡＷＳにおけるインフラ；ＶＰＣを構成する；ＶＰＣとオンプレミス環境とを接続する） ２ ファイルオブジェクトを保存・共有・公開する（オブジェクトストレージＳ３の機能；ファイルストレージとして利用する；Ｗｅｂサーバーを構築する；信頼性とコストのバランスをとりたい） ３ アプリケーションサーバーを構築する（Ａｍａｚｏｎ ＥＣ２とＡＷＳ Ｌａｍｂｄａ；スケーラビリティーを高める；サーバーレスでプログラムを動かす；データベースサービスを活用する） ４ ＡＷＳシステムを管理する（リソース監視と異常検知・通報；耐障害性を高める仕組みとバックアップ＆リカバリー；構成管理）

Amazon Web Services完全ソリューションガイド

A method, an apparatus, and a system for making a decision about virtual machine migration includes a source host platform, configured to send a migration request to a Migration Authority (MA), and to migrate the virtual machine to a target host platform according to a received migration decision-making result. The MA is configured to perform security checks on the source host platform and the target host platform, to obtain a first evaluation result of the source host platform and a second evaluation result of the target host platform, acquire a third evaluation result of the virtual machine, and return a corresponding migration decision-making result to the source host platform. The corresponding migration decision-making result indicates whether the virtual machine is permitted to be migrated; and the target host platform of the virtual machine to be migrated, is configured to accept the virtual machine to be migrated.

Method, apparatus and system for making a decision about virtual machine migration

Proxy re-encryption (PRE) allows the proxy to translate a ciphertext encrypted under Alice's public key into another ciphertext that can be decrypted by Bob's secret key. Identity-based proxy re-encryption (IB-PRE) is the development of identity-based encryption and proxy re-encryption, where ciphertexts are transformed from one identity to another. In this paper, we propose two novel unidirectional identity-based proxy re-encryption schemes, which are both non-interactive and proved secure in the standard model. The first scheme is a single-hop IB-PRE scheme and has master secret security, allows the encryptor to decide whether the ciphertext can be re-encrypted. The second scheme is a multi-hop IB-PRE scheme which allows the ciphertext re-encrypted multiple times but without the size of ciphertext growing linearly as previous multi-hop IB-PRE schemes.

Fully secure unidirectional identity-based proxy re-encryption

The invention is suitable for the technical field of computers, and provides a key generation, backup and migration method and system based on trusted computing. The method comprises the following steps of: receiving a key generation request input by a user; controlling a trusted platform module to generate a platform migratory key, encrypting the platform migratory key by a public key of a root key of the trusted platform module, and storing a cipher text key of the platform migratory key; controlling the trusted platform module to generate a user migratory key, encrypting the user migratory key by using the public key of the platform migratory key, and storing the cipher text key of the user migratory key; and controlling the trusted platform module to generate a binding key of the user, and encrypting the binding key by using the public key of the user migratory key, and storing the cipher text key of the binding key. According to the method and the system, the generation, backup, recovery and migration of the key are realized based on a trusted computing module in the trusted computing, and the security of the key in the generation, backup, recovery and migration processes is improved.

Key generation, backup and migration method and system based on trusted computing

The embodiment of the invention discloses a method for migration decision-making of a virtual machine, which comprises the following steps of: receiving a migration request from a source platform; determining a target platform according to the migration request; performing attribute inspection or integrity confirmation on the target platform so as to obtain a result of the attribute inspection or the integrity confirmation; and performing the migration decision-making according to the result of the attribute inspection or the integrity confirmation. The embodiment of the invention also provides a device and a system for the migration decision-making of the virtual machine. In the embodiment of the invention, the attribute inspection or the integrity confirmation of the target platform is performed before the migration of the virtual machine, so the safety and the reliability of the migration of the virtual machine are effectively ensured.

Qingni Shen

Papers

Method, apparatus and system for making a decision about virtual machine migration

Fully secure unidirectional identity-based proxy re-encryption

Key generation, backup and migration method and system based on trusted computing

Method, device and system for migration decision-making of virtual machine

Virtual machine migration decision-making method, device and system