On the security of public key protocols (original) (raw)

Public-Key Cryptography Theory and Practice

Viele haben auf die eine oder andere Weise dazu beigetragen, dass diese Dissertation so entstehen konnte, wie sie nun vorliegt. Der Versuch einer vollständigen Aufzählung müsste scheitern; hier seien zunächst die erwähnt, die nicht mit Namen genannt werden können, weil sie als anonyme Gutachter für Konferenzen tätig waren und dabei Anregungen zur Darstellung einiger der hier präsentierten Ergebnisse beigetragen haben. Außerdem zu nennen ist David Hopwood, der in einer früheren Fassung der Ausführungen zur beweisbaren Sicherheit des Mix-Verfahrens (hier in Abschnitt 4.2) eine Lücke aufgespürt hat. Prof. Johannes Buchmann hat es auf bemerkenswerte Weise verstanden, die Arbeitsbedingungen zu schaffen, in denen diese Dissertation gedeihen konnte, und hat wertvolle Anregungen geliefert. Auch alle anderen am Fachgebiet Theoretische Informatik hatten teil daran, eine angenehme und fruchtbare Arbeitsatmosphäre zu schaffen. Danke!

Public Key Cryptology – An Art of Keeping Secrecy and Authenticity

Cryptology consists of several mechanisms which ensure confidentiality and authenticity of the data. The fundamental objective of cryptology is the secure communication between sender and receiver through insecure channel. Modern cryptosystems can be broadly categorized in to secret key (symmetric) and public key (asymmetric) cryptosystems based up on the key which is used for data transmission. This paper focuses on the discussion of different categories of public key cryptosystems with its merits and demerits.

Public-Key Cryptography (Dagstuhl Seminar 11391)}}

From September 25th till September 30th, 2011, the Dagstuhl Seminar 11391 about "Public-Key Cryptography" took place at Schloss Dagstuhl. The meeting hosted 33 international researchers and incited active discussions about recent developments in this area. Seminar 25.-30. September, 2011 -www.dagstuhl.de/11391 1998 ACM Subject Classification D.4.6 Security and Protection

A Note on Public Key Cryptosystems

International Journal of Advanced Networking and Applications

Public key or asymmetric cryptosystems use public-private key pair for the secure transmission of data. RSA and ECC (Elliptic Curve Cryptography/Cryptosystems) are widely used cryptosystems in this category. Public key cryptosystems rely on mathematical problems known as hard problems. The security of these cryptosystems is based on these hard problems. Public key cryptosystems solve the key transportation problem of symmetric key cryptosystems and able to provides digital signatures also.

Encryption: Strengths and Weaknesses of Public-key Cryptography

Public key cryptography has become an important means of ensuring confidentiality, notably through its use of key distribution, where users seeking private communication exchange encryption keys. It also features digital signatures which allow users to sign keys to verify their identities. This research presents the innovations in the field of public-key cryptography while also analyzing their shortcomings. We present methods of improving upon the weaknesses that include techniques involving double encryption and mutual authentication. These contributions introduce new levels of security to the subject with ideas to combat man in the middle attacks and other hacker scenarios. Public-key encryption with digital signatures offers both security and data integrity against most attackers.

On the security of public key cryptosystems with a double decryption mechanism

Information Processing Letters, 2008

In public key encryption schemes with a double decryption mechanism (DD-PKE), decryption can be done in either of two ways: by the user owning the secret/public key pair corresponding to the ciphertext, or by a trusted party holding a sort of master secret-key. In this note we argue that the classical security notion for standard public key encryption schemes does not suffice for DD-PKE schemes, and propose a new natural definition. Additionally, we illustrate the usefulness of the new security definition by showing that a DD-PKE scheme presented in the workshop Selected Areas in Cryptography 2005 is insecure under this augmented security notion.

A New Security Definition for Public Key Encryption Schemes and Its Applications

The strongest security definition for public key encryption (PKE) schemes is indistinguishability against adaptive chosen ciphertext attacks (IND-CCA). A practical IND-CCA secure PKE scheme in the standard model is well-known to be difficult to construct given the fact that there are only a few such kind of PKE schemes available. From another perspective, we observe that for a large class of PKE-based applications, although IND-CCA security is sufficient, it is not a necessary requirement. Examples are Key Encapsulation Mechanism (KEM), MT-authenticator, providing pseudorandomness with a-priori information, and so on. This observation leads us to propose a slightly weaker version of IND-CCA, which requires ciphertexts of two randomly selected messages are indistinguishable under chosen ciphertext attacks. Under this new security notion, we show that highly efficient schemes proven secure in the standard model can be built in a straightforward way. We also demonstrate that such a security definition is already sufficient for the applications above.

On the Security Notions for Public-Key Encryption Schemes

2004

In this paper, we revisit the security notions for public-key encryption, and namely indistinguishability. We indeed achieve the surprising result that no decryption query before receiving the challenge ciphertext can be replaced by queries (whatever the number is) after having received the challenge, and vice-versa. This remark leads to a stricter and more complex hierarchy for security notions in the public-key setting: the (i, j)-IND level, in which an adversary can ask at most i (j resp.) queries before (after resp.) receiving the challenge. Excepted the trivial implications, all the other relations are strict gaps, with no polynomial reduction (under the assumption that IND-CCA2 secure encryption schemes exist.) Similarly, we define different levels for non-malleability (denoted (i, j)-NM.)

On Constructions and Security Notions of Public-key Cryptosystems

Book Chapter, Contemporary Topics in Mathematics and Statistics with Applications, Volume-I, Asian Books Pvt Ltd., 2012

From its inception, public-key cryptosystems have been an area of active research. Various aspects of public-key encryption like constructions, security notions, adversarial models, hardness assumptions, proof-methodology, efficiency, compatibility etc. have been analysed and re-analysed in the last three and half decades by numerous cryptographers. Some of them are good enough to survive while some of them, though broken, provides meaningful insights towards the subject. In this article, our aim is to provide an expository as well as technical (as far as possible, keeping in mind its brevity) overview of the subject as it has progressed over the years, along with some open problems and suitable references.

Public key cryptography

1987

We are going to devote most of our attention in this talk to the RSA Public Key Cryptosystem because it not only remains unbroken but it has some other useful features for digital signatures and authentication. We will briefly mention some other methods which have been compromised to some degree, and one, McEliece's which has not, but which are still valid when both keys are kept secret and some have other features which may be useful.