Key Agreement Clause Samples

Key Agreement. The agreement of symmetric key is accomplished by public key system. As shown in Figure 4, ▇▇▇▇▇ encodes her public key kp into acoustic signal and transmits the signal to Bob. The encoded acoustic signal from ▇▇▇▇▇ should preserve the channel ACR features. Bob decodes ▇▇▇▇▇’s public key after verified whether it is from ▇▇▇▇▇ using ACR features. The message coding should be efficient and be able to tolerate errors in the channel. Then, Bob generates a session key ks and encrypts it using ▇▇▇▇▇’s public key kp. Assume the encrypted session key is Ekp (ks), Bob encodes Ekp (ks) into acoustic signal and transmits the signal to ▇▇▇▇▇. ▇▇▇▇▇ verifies the signal source is from Bob. Then she decodes Ekp (ks) and uses her private key to obtain ks. Then the session key ks can be used by ▇▇▇▇▇ and ▇▇▇ for further communication. In this progress, the attackers have no opportunity for spoofing due to the identity verification by ACR, and the public key system prevents attackers from deriving the session key ks.

Key Agreement. ‌ In this report, key agreement means the idea sketched in Figure 11. Formal definitions are in Chapter 2. Key agreement is a generalization of basic Diffie–▇▇▇▇▇▇▇ key agreement, and is usually part of a larger system such as a secure handshake as a step for key distribution in a secure communication protocol. Key agreement allows two users to agree on a key by delivering each other information. Delivery is non-interactive: each delivery can be independently 1Douglas Stebila suggested the crossing of arrows in the figure to distinguish from key encapsulation. I since learned of similar but non-crossing rhombic diagram in an article of De Feo [Feo17]. generated, starting from some initial joint information. If the key agreement is secure, then the agreed key will be a secret known only to the agreeing parties. Adversaries may see the deliveries, but security depends on the adver- saries not modifying the deliveries. In other words, key agreement, as we define it, is unauthenticated. Generally, to avoid an man-in-the-middle at- tack, some extra security techniques must be applied, to authenticate the deliveries. For example, digital signatures might be applied to the deliveries. These extra mechanisms are not part of key agreement, but a necessary part of larger system. A few schemes for key agreement are • ▇▇▇▇▇▇ and ▇▇▇▇▇▇▇’▇ original (1978) modular exponentiation based key agreement, • ▇▇▇▇▇▇▇ (1987) and ▇▇▇▇▇▇’▇ (1985) elliptic curve variant of Diffie–▇▇▇▇▇▇▇ key agreement, • ▇▇▇▇▇▇▇, Qu and ▇▇▇▇▇▇▇▇’▇ (1995) double-key variant of Diffie–▇▇▇▇▇▇▇ key agreement, and • De Feo, Jao and Plut’s (2014) super-singular isogeny Diffie–▇▇▇▇▇▇▇. The few schemes above (and yet fewer variations) are widely conjectured to contribute significantly to security, at least when used correctly within a larger protocol. (Furthermore, some kinds of password-authenticated key exchange, such as SPEKE and SPAKE2, also fit this model of key agreement.) Other than these few schemes and similar ones, secure key agreement seem elusive. The key agreement schemes with well-established security are sim- ilar to those above.2 Obscurer key agreements do not have well-established security (although may well be secure nonetheless).

Key Agreement. Once the certificates are verified, a unique session-key kM = H(gUS, gS , eS, eU ) is derived from the contributions of both parties in Step 20 of Figures 2 and 5. Thus, no single party has complete control on the selection of the session-key, which is the main goal of a key agreement protocol [28].

Key Agreement. Key agreement as the name implies, is a process in which entities cooperate in order to establish a session key which is further used to encrypt the message. When it comes to peer to peer communication, key agreement becomes a necessity in order to transfer the data safely even in the presence of an intruder [1,2,3]. For communication security, symmetric cryptography, public key cryptography,

Key Agreement. The Setup algorithm is executed by the ID-PKG. This part of the key agreement proto- col is only performed once and creates both the master secrets P and Q as well as the public parameters. Setup - The Setup algorithm is executed by the ID-PKG. Input: k ∈ N Step 1: Choose an arbitrary integer R > 1 from Z .

Key Agreement. To establish the shared secret key between two users A and B with identities ID(k) and ID(l) registered with private key generators PKGk and PKGl respectively and possessing secret keys S(k) and S(l) respectively, the users engage in a session by exchanging components and eventually set up the shared secret key. Either user A or B could initiate the protocol. 1. (Partnered Sessions.) Let Π be a protocol and j a b

Key Agreement. To establish a common shared secret key, the three parties could naively perform the two-party key exchange protocol with each other, and as a result of this first round, establish three secret keys. Then, they will need three more passes to finally establish a common key. This approach would take nine passes in total. Here, we present our approach, described in previous section, that takes only four passes.

Key Agreement. ▇▇▇▇▇ and ▇▇▇, living in different places, would like to communicate pri- vately. There are two security requirements which ▇▇▇▇▇ and ▇▇▇ have in such a setting. First, the communication should be secret, meaning that a potential eavesdropper, commonly called “Eve”, will not get any infor- mation about their communication. Second, the communication should be authentic, which means that Eve cannot insert messages without being detected. If both these requirements are met we say that ▇▇▇▇▇ and ▇▇▇ can communicate securely. In this thesis, we make the basic assumption that ▇▇▇▇▇ and ▇▇▇ share an authentic channel, i.e., the second goal is already achieved by physical means or some underlying protocol. The term key agreement refers to the following task: given an authentic channel, ▇▇▇▇▇ and ▇▇▇ communicate and then agree on a bit string (called the key), about which ▇▇▇ has no information. It is not so hard to see that key agreement is equivalent to achieving secret communication from an authentic channel, and our goal from now on will be to obtain a key. For classical communication channels, key agreement is not possible unconditionally. But if we assume that ▇▇▇ is computationally bounded, i.e., if the computing time which ▇▇▇ has at her disposal is not very large, then this changes (or rather, it is commonly believed that this changes). Pro- tocols which are belived to achieve key agreement in this case were first proposed by Merkle [Mer79] (in a limited sense) and by Diffie and Hell- man [DH76], and are widely used in practice nowadays. However, we are currently unable to prove the security of any such protocol. Such a proof would imply a non-trivial lower bound for the computation of ▇▇▇, and to give such a lower bound is a notoriously hard problem in theoretical computer science (in particular, if ▇▇▇ needs superpolynomial computa- tion to break a protocol which runs in polynomial time, then P = NP). Consequently one makes assumptions under which such a protocol is se- cure. For example one assumes that computing discrete logarithms or factoring large numbers are intractable problems. The goal of this thesis is to make this assumption as weak as possible. A very strong result of this form would be to base a key agreement pro- tocol on an arbitrary one-way function (i.e., a function which is easy to evaluate but for which it is difficult to find a preimage of a given image). However, ▇▇▇▇▇▇▇▇▇▇▇ and ▇▇▇▇▇▇ [IR89] showed that this is not possible using bl...

Key Agreement. The City of Tenino will assign one Quarry House key to SSSS to be used exclusively during the hours of operation as specified in section III of this rental agreement. If an SSSS employee needs access to the Quarry House outside of lease hours, s/he must first receive permission from the City of Tenino.