a hash function which resists second preimage attacks (like MD5 [21]; namely: collision resistance is no longer required) and a commitment scheme. Other so- lutions such as MANA protocols [13,14] have been proposed. They can reduce the amount of information to be authenticated down to 20 bits, but they work as- suming a stronger hypothesis on the authenticated channel, namely that the au- thentication occurs without any latency for the delivery. Some protocols **based** on the Diffie-Hellman one were proposed [11,15] with an incomplete security analysis. A provably secure solution was finally proposed by Vaudenay [22]. This protocol can work with only 20 bits to authenticate and is **based** on a com- mitment scheme. Those authentication protocols can be pretty cheap (namely: without public-**key** **cryptography**) and provably secure (at least in the random oracle model). So, the remaining overwhelming cost is still the Diffie-Hellman protocol. Since **key** **agreement** is the foundation to public-**key** **cryptography**, it seems that setting up secure communications with an authenticated channel only cannot be solved at a lower expense than regular public-**key** algorithms.

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a hash function which resists second preimage attacks (like MD5 [21]; namely: collision resistance is no longer required) and a commitment scheme. Other so- lutions such as MANA protocols [13,14] have been proposed. They can reduce the amount of information to be authenticated down to 20 bits, but they work as- suming a stronger hypothesis on the authenticated channel, namely that the au- thentication occurs without any latency for the delivery. Some protocols **based** on the Diffie-Hellman one were proposed [11,15] with an incomplete security analysis. A provably secure solution was finally proposed by Vaudenay [22]. This protocol can work with only 20 bits to authenticate and is **based** on a com- mitment scheme. Those authentication protocols can be pretty cheap (namely: without public-**key** **cryptography**) and provably secure (at least in the random oracle model). So, the remaining overwhelming cost is still the Diffie-Hellman protocol. Since **key** **agreement** is the foundation to public-**key** **cryptography**, it seems that setting up secure communications with an authenticated channel only cannot be solved at a lower expense than regular public-**key** algorithms.

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Recently, some two-party Authenticated **Key** **Agreement** protocols over elliptic curve **based** algebraic groups, in the context of Identity-**Based** **cryptography** have been proposed. The main contribution of this category of protocols is to reduce the complexity of performing algebraic operations through eliminating the need to using Bilinear Pairings. In this paper, we proposed two novel Identity-**Based** Authenticated **Key** **Agreement** protocols over non-**symmetric** role participants without using Bilinear Pairings. The results show that our proposed schemes beside of supporting security requirements of **Key** **Agreement** protocols, require a subset of operations with low complexity in compare with related protocols in this scientific area.

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Related work Proxy re-encryption (PRE) is a research topic with increasing popularity, with new use cases arising in different contexts (e.g, data sharing in the cloud, **key** management, etc.). Although the vast majority of PRE schemes are **based** on public-**key** **cryptography** [1, 3, 6], there have been some proposals **based** on **symmetric** **cryptography**. Syalim et al. [26] propose a **symmetric** PRE scheme **based** on the All-Or-Nothing Transform, although it assumes that both sender and receiver share a common secret. Cook and Keromytis [9] present a solution **based** on a double-encryption approach, but as in the previous case, a priori shared keys are needed. The **key**-homomorphic PRF primitive by Boneh et al. [4] can be used to construct **symmetric** PRE schemes without the shared **key** requirement, although as noted by Garrison et al. [15], its computational cost is comparable or greater than traditional public-**key** **cryptography**. Sakazaki et al. [24] propose a **symmetric** PRE scheme that is essentially equivalent to the one of this paper; this is discussed further in Section 2.1.

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makes it possible to adapt the algorithm, if more sophist- icated attacks are discovered in the future. The encryption presented in Section 2.2 has undergone some evolution to resist all attacks which came to our mind. The version using a proof honest encryption has no vulnerabilities currently known to us, but of course much more crypto-analysis is needed and the reader is invited to devise stronger attacks to challenge and improve the algorithm. In particular, we have not proven that it is (NP-)hard to decipher a message without knowledge of the private **key**. It is the problem of deducing the private from the public **key** that is NP- hard, i.e. “post-quantum”, by construction. The same is true for the signature scheme presented in Section 5.2, which is independent of our encryption scheme. It is analogous to Blum’s well known scheme [2], adapted to our SAT scenario. A notable feature of our encryption is that, in principle, it is fully homomorpic, i.e. applying any function to the cipher bit vector and then decoding yields the same result as decoding and then applying the function. However, as discussed in Section 4, the cipher might become unfeasibly long if to many multiplications are applied to it, hence our scheme is effectively only somewhat homomorphic. The oracle attack mentioned in Section 3.4 is a stronger incarnation of malleability. It is a severe generic attack on any cipher consisting of Boolean functions. Enforcing honest encryption, as explained in Section 3.4.1, is a generic counter. The multi-**key** version of our scheme described in Ap- pendix D is another work around, however, not completely resistant. Although it only reveals much less information, the **key** pairs still need to be changed regularly, but here this could here be feasible. In some special situations, like using our scheme for homomorphic encryption, the multi- **key** version might be preferable. Encryption is considerably more complex than **key** generation and decryption, which in particular yields some protection against DOS attacks for multi-**key** schemes.

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Section 2.2 – Locks and Keys Digital security often begins with. physical security….[r]

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Playfair cipher: The best known multiple letter encryption cipher is the playfair, which treats digrams in the plaintext as single units and translates these units into cipher text digrams. The playfair algorithm is **based** on the use of 5x5 matrix of letters constructed using a keyword. Let the keyword be „monarchy‟. The matrix is constructed by filling in the letters of the keyword (minus duplicates) from left to right and from top to bottom, and then filling in the remainder of the matrix with the remaining letters in alphabetical order. The letter „i‟ and „j‟ count as one letter. Plaintext is encrypted two letters at a time.

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________________________________________________________________________________________________________ Abstract— The data security is a very important issue nowadays. Confidential data, financial documents, military information, secret data etc. is transmitted on the Internet. Internet is the primary source to transmit such secure information. In such cases, many techniques are involved to transmit data securely such as Encryption with the **key**, visual **cryptography**, Steganography. These techniques devoted to protect such kind of information and they play an important role in providing confidential and secure transmission over network. In this paper, we are suggesting one new method in which the **symmetric** secret **key** is used to encrypt the image and then cipher image is produced. Divide this cipher image into different unique parts and apply Novel secret sharing algorithm of steganography. Each unique part will conceal by another innocent image i.e. steganography. Use of secret **key** will ensure the security of scheme. At the receiver side among n parts only k (threshold) parts or greater than k parts are needed to reconstruct the original secret image.

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5 Discussion
The new ID-**based** SIP authentication mechanism and **key** **agreement** protocol proposed here meets the goal and requirements stated above. The cryptographic primitives used to provide the assurances are provably secure in the adversarial model of the BR93 model which assumes an all-powerful adversary that is in control of all communication links with the ability to manipulate any message sent and impersonate any other party. That is, the adversary is capable of performing Man-in-the-Middle and session hijacking attacks (i.e., known **key** security), as well as spoofing and identity-**based** attacks. Since the proposed protocol is proven secure in the BR93 model, it is capable of withstanding these attacks. The new authentication mechanism proposed in this paper introduces a new dialog for authentication, but only introduces one additional field into the existing authentication message, namely, the field to hold a signature. The additional changes involve how existing fields are interpreted by the parties involved and remain consistent in form with the appropriate RFC. Furthermore, the new **key** **agreement** protocol recommended in this paper does not introduce any new fields into the SDP message but makes use of existing fields in such a manner that is still within the bounds of their scope according to the RFC. It is expected that both of these changes will still be functional in the event that intermediary proxies have no understanding of the new additions.

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One of the approaches to increase the performance of **symmetric** **key** **cryptography** was carried by Praveen Dongara and T. N. Vijaykumar [3]. They were implementing Interleaved Cipher Block Chaining method on **Symmetric** Multiprocessors. This is the case where the effort to improve **symmetric** **key** **cryptography** is focused on the algorithm and hardware. Another related effort carried out by Jerome Burke, John McDonald and Todd Austin [4] adds instruction set support for fast substitutions, general permutations, rotates, and modular arithmetic. Their experiment has shown overall speedup to the **symmetric** **key** **cryptography**. While these two approaches also enhance the performance of **symmetric** **key** **cryptography**, our approach is scalable and cost-effective due to the use of a commodity-**based** high- performance computing platform.

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Nowadays big organizations have complex administrative structure with scattered offices to face with serious problems related to **key** management like financial and security problems **based** on **symmetric** encryption system. This project proposes an efficient solution related to **symmetric** **key** crypto system to solve this problem and provide the opportunity for the organization have a secure, affordable, efficient, easier and faster **symmetric** **key** crypto system. **Symmetric** **key** **cryptography** with the less **key** size have more secure in comparison to asymmetric **cryptography**. Therefore using **symmetric** **key** **cryptography** is more secure and Advantageous. The speed of processing **symmetric** **cryptography** is higher than asymmetric **cryptography**. The purpose of this project is to product the software for all of the employees in the organization to have the secret **symmetric** **key** **cryptography** to have communicatation to each other through the secret **key**. However, the security of **symmetric** **key** **cryptography** is higher than asymmetric **key** **cryptography**. **Key** derivations algorithm which used in this project is very important for **symmetric** cryptosystems in comparison with other algorithm because one **key** can be derived to the others. This Method is chosen by **key** derivation one-way function and implemented by Delphi programming language. This implemented method give the manager of the organization an opportunity to generate the secret **key** for all of the employees and so each employee has the **symmetric** secret **key** and if the employees need to communicate with each other their request will be sent to the manager. This project has been done in three phases and one of the outcomes of this project is an application which generates random **key**, according to hierarchy of organization.

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[NNL01, NNL02]. Almost every known **symmetric** **key** broadcast encryption scheme falls under this framework. It has three phases namely, initiation, encryption and decryption. In the initiation phase, a collection S of subsets of N is created. Each subset in S is assigned a secret **key**. A user gets the secret information which enables it to compute the secret keys of all subsets S of users such that it is a member of S and S ∈ S. Once this initiation phase is over, the system is ready for secured broadcasting. The broadcast messages are sent to the users in blocks. Each block goes with a new session. For each session, the center knows the set of revoked users R. It finds the set of subsets S c = {S i 1 , S i 2 , . . . , S i h } ⊂ S from the collection S such that each privileged user is in

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Apart from cost and efficiency, security is another important aspect of a cryp- tosystem. A new class of attack on **cryptography** known as side channel analysis (SCA) attacks [14], which monitors the side channel information (electromagnetic radiation, timing, power [13, 14, 15]) of a cryptosystem, has been developed to reveal the knowledge of the secret **key**. In this thesis, the security of the Tate pairing is considered. Several different attacks are applied on the Tate pairing designs to test their resistance against SCA attacks. For different kinds of protocols, the security is discussed. Against SCA attacks, several countermeasures are studied, including uti- lizing the bilinear property of the Tate pairing [16, 17], randomizing Miller variables in the algorithm [17], and using projective coordinates to mask the operations [18]. The proposed countermeasures are implemented in this work and the operation time and area costs of their implementations are evaluated, along with the consideration of the security aspects of the countermeasures.

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Cryptographic Technique implemented by AODV Routing Protocol throughput and end to end delay enhanced. **Cryptography** is an emerging technology, which is important for the network security. Security and attack aspect of the cryptographic technique. Related work has concluded the issues of security [7], Network Performance tests and characteristics of the cipher texts. The simulation **based** network performance tests is to be done such as throughput, end to end delay, jitter effect and packet delivery ratio. In the literature, there are many cryptographic algorithms in the mobile ad hoc network. By Jared cordasco and susanne wetzel [9] compare the security issues of the cryptographic and trust **based** method for routing security. A. santos, Edwards [10] have analyzed of the performance parameters, Throughput and end to end delay of the mobility for vehicular mechanism ad hoc network, and Wilson T.H. Woon [11] evaluate the performance of wireless 802.15.4 using simulation and test bed approach.

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Beginner‟s view about the algorithm was to make some use of the ASCII numbers & the Prime numbers. Considering a character as plain text & n as ASCII Value of character the Cipher Text can be nth Prime Number. But this had big flaw of no **Key** being used. So, easiest to decrypt. Certainly some **key** was to be used. Then different approaches were taken before finalizing the **Key** for the process.

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Abstract— Advances in communication technology have seen strong interest in digital data transmission. However, illegal data access has become more easy and prevalent in wireless and general communication networks. In order to protect the valuable data from illegal access, different kinds of cryptographic systems have been proposed. In this paper, a new integrating channel coding and **cryptography** design communication systems is proposed. So we use **cryptography** as an error detection tool. In order to preserve the advantages of encryption and to improve its disadvantages, we place the encryptor before the encoder. The hamming encoder is used to select the generator matrix to be used as a block code to form the new system .In this the security of common cryptographic primitive i.e a **key** stream generator **based** on LFSR can be strengthened by using the properties of a physical layer.So, a passive eaves dropping will experience great difficulty in cracking the LFSR **based** **cryptography** system as the computational complexity of discovering the secret **key** increases to large extent. The analysis indicates that the proposed design possesses the following feature. Its security is higher than the conventional one with the channel encoder only. Privacy is more due to unknown random codes. As the applied codes are unknown to a hostile user, this means that it is hardly possible to detect the message of another user. Anti-jam performance is good. It overcomes the disadvantage of Chaos **based** **cryptography** system as input data is not extended and hence bandwidth is not wasted. Moreover, the computer simulation shows that the proposed system has a good ability in error detection especially when the SNR per bit is moderate high, and the detection ability is enhanced when the increased length of Hamming code is employed.

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which technique performs better in multiple remote realms that are typical in an increasingly large network these days. It is very difficult to analyze the case of multiple remote realms due to the complexity of authentication message exchanges. The difficulty is in the complexity analysis of these protocols and the building and analysis of queueing network models that reflects the workload of authentication requests for these protocols in the case of multiple remote realms. Second, we explicit derive the formulas for calculating the computational and communication times of these protocols so as to easily determine which technique is better. Third, using a closed queueing network in Harbitter and Menasce [24] assumes there exist constant authentication requests in the queueing network. This means that the number of the client’s authentication requests remains unchanged with time, which is obviously an unrealistic assumption in a real-world computer application such as Web services. Rather, we adopted an open queueing network where the client requests authentication at a given rate, i.e., the number of authentication requests in a computing system under study is not constant; it can be dynamically changed with time. Fourth, in order to better understand the performance of the authentication technique, we distinguish the processing ordering of multiple authentication requests by using the preemptive-resume priority discipline. Fifth, due to a performance trade off between these two protocols according to our scalability analysis, we propose a new hybrid technique. Our analysis has showed that the new technique has better scalability than these two protocols in most cases. Finally, we must point out that the approach of using queueing networks is relatively complicated in the case of multiple remote realms but it is necessary. As is seen, the numbers n given in Table 8 **based** on the approach of counting the number of operations are smaller than the crossover numbers presented in Figure 14. The preliminary results of this research was published in [40].

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The **key** length argument goes like this. Assuming that the only feasible attack on DES is to try each **key** in turn until the right one is found, then 1,000,000 machines each capable of testing 1,000,000 keys per second would find (on average) one **key** every 12 hours. Most reasonable people might find this rather comforting and a good measure of the strength of the algorithm. Those who consider the exhaustive **key**-search attack to be a real possibility (and to be fair the technology to do such a search is becoming a reality) can overcome the problem by using double or triple length keys. In fact, double length keys have been recommended for the financial industry for many years.

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