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In cryptography, a scytale (, rhymes approximately with Italy ; also transliterated skytale, Greek σκυτάλη " baton ") is a tool used to perform a transposition cipher, consisting of a cylinder with a strip of parchment wound around it on which is written a message.
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The Biuro Szyfrów (, Polish for " Cipher Bureau ") was the interwar Polish General Staff's agency charged with both cryptography ( the use of ciphers and codes ) and cryptology ( the study of ciphers and codes, particularly for the purpose of " breaking " them ).
cryptography and with
UHF, VHF Tactical ( 30-88 MHz ) and SatCom systems combined with ECCM methods, and cryptography secure the communications.
In cryptography, a block cipher is a deterministic algorithm operating on fixed-length groups of bits, called blocks, with an unvarying transformation that is specified by a symmetric key.
Most early vector CPUs, such as the Cray-1, were associated almost exclusively with scientific research and cryptography applications.
No asymmetric-key algorithms with this property are known ; elliptic curve cryptography comes the closest with an effective security of roughly half its key length.
One of the asymmetric algorithm types, elliptic curve cryptography, or ECC, appears to be secure with shorter keys than those needed by other asymmetric key algorithms.
There are now many active academic cryptologists, mathematics departments with strong programs in cryptography, and commercial information security companies and consultants.
" An astonishing share of the open literature in cryptography in the 1970s and 1980s dealt with the DES, and the DES is the standard against which every symmetric key algorithm since has been compared.
The need to break German codes in World War II led to advances in cryptography and theoretical computer science, with the first programmable digital electronic computer being developed at England's Bletchley Park.
The Cold War meant that cryptography remained important, with fundamental advances such as public-key cryptography being developed in the following decades.
In 2001 the Temporary Committee on the ECHELON Interception System recommended to the European Parliament that citizens of member states routinely use cryptography in their communications to protect their privacy, because economic espionage with ECHELON has been conducted by the US intelligence agences.
The sensation Poe created with his cryptography stunt played a major role in popularizing cryptograms in newspapers and magazines.
* Interactive introduction to elliptic curves and elliptic curve cryptography with SAGE
Although related, the distinctions among these measures mean that a random variable with high Shannon entropy is not necessarily satisfactory for use in an extractor and so for cryptography uses.
SHA-1 HMAC Generation. In cryptography, a hash-based message authentication code ( HMAC ) is a specific construction for calculating a message authentication code ( MAC ) involving a cryptographic hash function in combination with a secret cryptographic key.
This was followed by Cryptonomicon in 1999, a novel concerned with concepts ranging from computing and Alan Turing's research into codebreaking and cryptography during the Second World War at Bletchley Park, to a modern attempt to set up a data haven.
In 1991, he wrote the popular Pretty Good Privacy ( PGP ) program, and made it available ( together with its source code ) through public FTP for download, the first widely available program implementing public-key cryptography.
A central problem with the use of public-key cryptography is confidence ( ideally, proof ) that a particular public key is correct, and belongs to the person or entity claimed ( i. e. is " authentic "), and has not been tampered with, or replaced by, a malicious third party ( a " man-in-the-middle ").
As with most cryptography applications, the protocols used to establish and verify this binding are critically important.
Leading cryptography scholar Martin Hellman discusses the circumstances and fundamental insights of his invention of public key cryptography with collaborators Whitfield Diffie and Ralph Merkle at Stanford University in the mid-1970s.
Hellman describes his invention of public key cryptography with collaborators Whitfield Diffie and Ralph Merkle at Stanford University in the mid-1970s.
He also relates his subsequent work in cryptography with Steve Pohlig ( the Pohlig – Hellman system ) and others.
cryptography and Italy
In April 1945, while posted to a cryptography position in Italy, she began a relationship with an officer, William J. Murray, Jr. Murray was a married Roman Catholic, and he refused to divorce his wife.
cryptography and ;
Historically, cryptography was split into a dichotomy of codes and ciphers ; and coding had its own terminology, analogous to that for ciphers: " encoding, codetext, decoding " and so on.
Information security uses cryptography to transform usable information into a form that renders it unusable by anyone other than an authorized user ; this process is called encryption.
PGP encryption uses a serial combination of hashing, data compression, symmetric-key cryptography, and, finally, public-key cryptography ; each step uses one of several supported algorithms.
There are several other techniques in use ; see cryptography.
Utopias original edition included the symmetrical " Utopian alphabet " that was omitted from later editions ; it is a notable, early attempt at cryptography that might have influenced the development of shorthand.
To some extent, the cryptography list acts as a successor to cypherpunks ; it has many of the people and continues some of the same discussions.
In cryptography, a substitution cipher is a method of encryption by which units of plaintext are replaced with ciphertext, according to a regular system ; the " units " may be single letters ( the most common ), pairs of letters, triplets of letters, mixtures of the above, and so forth.
In other words, two successive applications of ROT13 restore the original text ( in mathematics, this is sometimes called an involution ; in cryptography, a reciprocal cipher ).
Keeping keys secret is one of the most difficult problems in practical cryptography ; see key management.
Modern cryptography, on the other hand, is implemented in software or hardware and is used for a diverse range of applications ; for many cases, a chosen-plaintext attack is often very feasible.
Introduced by Jacobi in 1837, it is of theoretical interest in modular arithmetic and other branches of number theory, but its main use is in computational number theory, especially primality testing and integer factorization ; these in turn are important in cryptography.
This was a small work on cryptography ; it may well have been influenced by Godwin's Nuncius inanimatus ( 1629 ).
** First United States Department of Defense workshop on quantum computing and quantum cryptography is organized by United States Army physicists Charles M. Bowden, Jonathan P. Dowling, and Henry O. Everitt ; it takes place in February at the University of Arizona in Tucson.
In practical cryptography, it is not sufficient to choose just any semiprime ; a good number must evade a number of well-known special-purpose algorithms that can factor numbers of certain form.
In computational complexity theory and cryptography, an index set is a set for which there exists an algorithm I that can sample the set efficiently ; i. e., on input 1 < sup > n </ sup >, I can efficiently select a poly ( n )- bit long element from the set.
; Public-key cryptography:
Some of the following algorithms are used often in cryptography ; consult the article for each specific algorithm for more information on the status of each algorithm.
Higher-layer processes may specify keys to perform symmetric cryptography to protect the payload and restrict it to a group of devices or just a point-to-point link ; these groups of devices can be specified in access control lists.
Many early cryptographic works were esoteric, mystical, and / or reputation-promoting ; cryptography being mysterious, there was much opportunity for such things.
Public / private key pairs used in asymmetric encryption ( public key cryptography ) must be much longer than 128 bits for security ; see key size for more details.
The book was republished in 1996, and this new edition includes an additional chapter briefly covering the events since the original publication ; see the " Books on cryptography " article for other works which cover this later history in more detail.
Herodotus tells us of secret messages physically concealed beneath wax on wooden tablets or as a tattoo on a slave's head concealed by regrown hair, though these are not properly examples of cryptography per se as the message, once known, is directly readable ; this is known as steganography.
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