Handbook of Applied Cryptography - chap12

... use of number of ↓ Protocol timestamps messages point-to-point key update none optional 1-3 Shamir’s no-key protocol none no 3 Kerberos KDC yes 4 Needham-Schroeder shared-key KDC no 5 Otway-Rees ... possibility of precomputation to reduce on-line computational complexity. 6. third party requirements. Considerations include (see §13.2.4): (a) requirement of an on-line (real-time), of...

Ngày tải lên: 24/10/2013, 01:15

... problem of preserving the integrity of a potentially large message is thus reduced to that of a small fixed-size hash- value. Since the existence of collisions is guaranteed in many-to-one mappings, ... security of a subset of the MDCs subsequently discussed in this section. Similar to the case of block ciphers for encryption (e.g. 8- or 1 2- round DES vs. 16-round DES), se...

Ngày tải lên: 17/10/2013, 16:15

... attacks, 5 5 Both chosen-ciphertext and chosen-plaintext attacks are of concern for challenge-response techniques based on symmetric-key encryption. Handbook of Applied Cryptography by A. Menezes, ... entropy) Suppose passwords consist of strings of 7-bit ASCII char- acters. Each has a numeric value in the range 0-1 27. (When 8-bit characters are used, val- ues 12 8-2 55comp...

Ngày tải lên: 20/10/2013, 03:15

... while digital signatures with appendix are applied to messages of arbitrary length. The one-way function h in Algorithm 11.5 is Handbook of Applied Cryptography by A. Menezes, P. van Oorschot ... ratio of the logarithm(base2) of the size of the signingspaceM S to the logarithm (base 2) of the size of M R , the image space of the redundancy function. Hence, the bandwidt...

Ngày tải lên: 20/10/2013, 03:15

... protocol run (c) off-line on-line [optional] [optional] A A A in-line TTP TTP TTP off-line Figure 13.2: In-line, on-line, and off-line third parties. In-line third parties are of particular interest ... properties of escrow systems include: 1. applicability to store-and-forward vs. real-time user communications 2. capability of real-time decryption of user traffic 3. requirement of t...

Ngày tải lên: 28/10/2013, 09:15

... non-repudiation of origin (denial of being the originator of a message), non-repudiation of delivery (denial of having received a mes- sage), and non-repudiation associated with the actions of ... draft 10118–4 includes MASH-1 and MASH-2 (see Algorithm 9.56). ISO/IEC 11770: This multi-part standard addresses generic key management and spe- Handbook of Applied Cryptography...

Ngày tải lên: 28/10/2013, 09:15

... applications. The ef - ciency of a particular cryptographic scheme based on any one of these algebraic structures will dependonanumberoffactors, such as parametersize, time-memorytradeoffs,process- ing power ... the case of the additive group Z m , the time required to do modular multiplication can be im- proved at the expense of precomputing a table of residues modulo m. For a l...

Ngày tải lên: 06/11/2013, 23:15

... fac- tored is of a special form; these are called special-purpose factoring algorithms. The run- ning times of such algorithmstypically depend on certain properties of the factors of n. Ex- amples ... one having a worst-case running time of O(lg 3 n) bit operations, and a sec- ond having an average-case running time of O(lg 2 n) bit operations. A more recent algo- rithm of Berns...

Ngày tải lên: 14/12/2013, 00:22

Ngày tải lên: 16/01/2014, 16:33

... originator. 1.8 Public-key cryptography The concept of public-key encryption is simple and elegant, but has far-reaching conse- quences. 1.8.1 Public-key encryption Let {E e : e ∈K}be a set of encryption ... abstract concepts of this section in mind as concrete methods are presented. Handbook of Applied Cryptography by A. Menezes, P. van Oorschot and S. Vanstone. 10 Ch. 1 Over...

Ngày tải lên: 26/01/2014, 00:20