❤️ Key (cryptography) 🐽

"In cryptography, a key is a piece of information (a parameter) that determines the functional output of a cryptographic algorithm. For encryption algorithms, a key specifies the transformation of plaintext into ciphertext, and vice versa for decryption algorithms. Keys also specify transformations in other cryptographic algorithms, such as digital signature schemes and message authentication codes. Need for secrecy In designing security systems, it is wise to assume that the details of the cryptographic algorithm are already available to the attacker. This is known as Kerckhoffs' principle — "only secrecy of the key provides security", or, reformulated as Shannon's maxim, "the enemy knows the system". The history of cryptography provides evidence that it can be difficult to keep the details of a widely used algorithm secret (see security through obscurity). A key is often easier to protect (it's typically a small piece of information) than an encryption algorithm, and easier to change if compromised. Thus, the security of an encryption system in most cases relies on some key being kept secret. Trying to keep keys secret is one of the most difficult problems in practical cryptography; see key management. An attacker who obtains the key (by, for example, theft, extortion, dumpster diving, assault, torture, or social engineering) can recover the original message from the encrypted data, and issue signatures. Key scope Keys are generated to be used with a given suite of algorithms, called a cryptosystem. Encryption algorithms which use the same key for both encryption and decryption are known as symmetric key algorithms. A newer class of "public key" cryptographic algorithms was invented in the 1970s. These asymmetric key algorithms use a pair of keys—or keypair—a public key and a private one. Public keys are used for encryption or signature verification; private ones decrypt and sign. The design is such that finding out the private key is extremely difficult, even if the corresponding public key is known. As that design involves lengthy computations, a keypair is often used to exchange an on-the-fly symmetric key, which will only be used for the current session. RSA and DSA are two popular public-key cryptosystems; DSA keys can only be used for signing and verifying, not for encryption. Ownership and revocation Part of the security brought about by cryptography concerns confidence about who signed a given document, or who replies at the other side of a connection. Assuming that keys are not compromised, that question consists of determining the owner of the relevant public key. To be able to tell a key's owner, public keys are often enriched with attributes such as names, addresses, and similar identifiers. The packed collection of a public key and its attributes can be digitally signed by one or more supporters. In the PKI model, the resulting object is called a certificate and is signed by a certificate authority (CA). In the PGP model, it is still called a "key", and is signed by various people who personally verified that the attributes match the subject. In both PKI and PGP models, compromised keys can be revoked. Revocation has the side effect of disrupting the relationship between a key's attributes and the subject, which may still be valid. In order to have a possibility to recover from such disruption, signers often use different keys for everyday tasks: Signing with an intermediate certificate (for PKI) or a subkey (for PGP) facilitates keeping the principal private key in an offline safe. Deleting a key on purpose to make the data inaccessible is called crypto-shredding. Key sizes For the one-time pad system the key must be at least as long as the message. In encryption systems that use a cipher algorithm, messages can be much longer than the key. The key must, however, be long enough so that an attacker cannot try all possible combinations. A key length of 80 bits is generally considered the minimum for strong security with symmetric encryption algorithms. 128-bit keys are commonly used and considered very strong. See the key size article for a more complete discussion. The keys used in public key cryptography have some mathematical structure. For example, public keys used in the RSA system are the product of two prime numbers. Thus public key systems require longer key lengths than symmetric systems for an equivalent level of security. 3072 bits is the suggested key length for systems based on factoring and integer discrete logarithms which aim to have security equivalent to a 128 bit symmetric cipher. Elliptic curve cryptography may allow smaller-size keys for equivalent security, but these algorithms have only been known for a relatively short time and current estimates of the difficulty of searching for their keys may not survive. As early as 2004, a message encrypted using a 109-bit key elliptic curve algorithm had been broken by brute force. The current rule of thumb is to use an ECC key twice as long as the symmetric key security level desired. Except for the random one-time pad, the security of these systems has not been proven mathematically , so a theoretical breakthrough could make everything one has encrypted an open book (see P versus NP problem). This is another reason to err on the side of choosing longer keys. Key choice To prevent a key from being guessed, keys need to be generated truly randomly and contain sufficient entropy. The problem of how to safely generate truly random keys is difficult, and has been addressed in many ways by various cryptographic systems. There is an RFC on generating randomness (RFC 4086, Randomness Requirements for Security). Some operating systems include tools for "collecting" entropy from the timing of unpredictable operations such as disk drive head movements. For the production of small amounts of keying material, ordinary dice provide a good source of high quality randomness. Key vs password For most computer security purposes and for most users, "key" is not synonymous with "password" (or "passphrase"), although a password can in fact be used as a key. The primary practical difference between keys and passwords is that the latter are intended to be generated, read, remembered, and reproduced by a human user (though the user may delegate those tasks to password management software). A key, by contrast, is intended for use by the software that is implementing the cryptographic algorithm, and so human readability etc. is not required. In fact, most users will, in most cases, be unaware of even the existence of the keys being used on their behalf by the security components of their everyday software applications. If a password is used as an encryption key, then in a well-designed crypto system it would not be used as such on its own. This is because passwords tend to be human-readable and, hence, may not be particularly strong. To compensate, a good crypto system will use the password-acting-as-key not to perform the primary encryption task itself, but rather to act as an input to a key derivation function (KDF). That KDF uses the password as a starting point from which it will then generate the actual secure encryption key itself. Various methods such as adding a salt and key stretching may be used in the generation. See also * Cryptographic key types classification according to their usage * Diceware describes a method of generating fairly easy-to-remember, yet fairly secure, passphrases, using only dice and a pencil. * EKMS * Group key * Keyed hash algorithm * Key authentication * Key derivation function * Key distribution center * Key escrow * Key exchange * Key generation * Key management * Key schedule * Key server * Key signature (cryptography) * Key signing party * Key stretching * Key-agreement protocol * glossary of concepts related to keys * Password psychology * Public key fingerprint * Random number generator * Session key * Tripcode * Machine-readable paper key * Weak key References Cryptography Key management "

❤️ Symmetric-key algorithm 🐽

"Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both encryption of plaintext and decryption of ciphertext. The keys may be identical or there may be a simple transformation to go between the two keys. The keys, in practice, represent a shared secret between two or more parties that can be used to maintain a private information link. This requirement that both parties have access to the secret key is one of the main drawbacks of symmetric key encryption, in comparison to public-key encryption (also known as asymmetric key encryption). Types Symmetric- key encryption can use either stream ciphers or block ciphers. * Stream ciphers encrypt the digits (typically bytes), or letters (in substitution ciphers) of a message one at a time. An example is the Vigenère Cipher. * Block ciphers take a number of bits and encrypt them as a single unit, padding the plaintext so that it is a multiple of the block size. The Advanced Encryption Standard (AES) algorithm, approved by NIST in December 2001, uses 128-bit blocks. Implementations Examples of popular symmetric-key algorithms include Twofish, Serpent, AES (Rijndael), Camellia, Salsa20, ChaCha20, Blowfish, CAST5, Kuznyechik, RC4, DES, 3DES, Skipjack, Safer, and IDEA. Cryptographic primitives based on symmetric ciphers Symmetric ciphers are commonly used to achieve other cryptographic primitives than just encryption. Encrypting a message does not guarantee that this message is not changed while encrypted. Hence often a message authentication code is added to a ciphertext to ensure that changes to the ciphertext will be noted by the receiver. Message authentication codes can be constructed from symmetric ciphers (e.g. CBC-MAC). However, symmetric ciphers cannot be used for non- repudiation purposes except by involving additional parties. See the ISO/IEC 13888-2 standard. Another application is to build hash functions from block ciphers. See one-way compression function for descriptions of several such methods. Construction of symmetric ciphers Many modern block ciphers are based on a construction proposed by Horst Feistel. Feistel's construction makes it possible to build invertible functions from other functions that are themselves not invertible. Security of symmetric ciphers Symmetric ciphers have historically been susceptible to known-plaintext attacks, chosen- plaintext attacks, differential cryptanalysis and linear cryptanalysis. Careful construction of the functions for each round can greatly reduce the chances of a successful attack. Key management Key establishment Symmetric-key algorithms require both the sender and the recipient of a message to have the same secret key. All early cryptographic systems required one of those people to somehow receive a copy of that secret key over a physically secure channel. Nearly all modern cryptographic systems still use symmetric-key algorithms internally to encrypt the bulk of the messages, but they eliminate the need for a physically secure channel by using Diffie–Hellman key exchange or some other public-key protocol to securely come to agreement on a fresh new secret key for each message (forward secrecy). Key generation When used with asymmetric ciphers for key transfer, pseudorandom key generators are nearly always used to generate the symmetric cipher session keys. However, lack of randomness in those generators or in their initialization vectors is disastrous and has led to cryptanalytic breaks in the past. Therefore, it is essential that an implementation use a source of high entropy for its initialization. Ian Goldberg and David Wagner. "Randomness and the Netscape Browser". January 1996 Dr. Dobb's Journal. quote: "it is vital that the secret keys be generated from an unpredictable random- number source." Thomas Ristenpart , Scott Yilek. "When Good Randomness Goes Bad: Virtual Machine Reset Vulnerabilities and Hedging Deployed Cryptography (2010)" quote from abstract: "Random number generators (RNGs) are consistently a weak link in the secure use of cryptography." Reciprocal cipher A reciprocal cipher is a cipher where, just as one enters the plaintext into the cryptography system to get the ciphertext, one could enter the ciphertext into the same place in the system to get the plaintext. A reciprocal cipher is also sometimes referred as self-reciprocal cipher. Practically all mechanical cipher machines implement a reciprocal cipher, a mathematical involution on each typed-in letter. Instead of designing two kinds of machines, one for encrypting and one for decrypting, all the machines can be identical and can be set up (keyed) the same way. Greg Goebel. "The Mechanization of Ciphers". 2018\. Examples of reciprocal ciphers include: * Atbash * Beaufort cipher "... the true Beaufort cipher. Notice that we have reciprocal encipherment; encipherment and decipherment are identically the same thing." Helen F. Gaines. "Cryptanalysis: A Study of Ciphers and Their Solution". 2014\. p. 121. * Enigma machine Greg Goebel. "The Mechanization of Ciphers". 2018\. * Marie Antoinette and Axel von Fersen communicated with a self-reciprocal cipher. Friedrich L. Bauer. "Decrypted Secrets: Methods and Maxims of Cryptology". 2006\. p. 144 * the Porta polyalphabetic cipher is self-reciprocal. David Salomon. "Coding for Data and Computer Communications". 2006\. p. 245 * Purple cipher Greg Goebel. "US Codebreakers In The Shadow Of War". 2018\. * RC4 * ROT13 * XOR cipher * Vatsyayana cipher Practically all modern ciphers can be classified as either a stream cipher, most of which use a reciprocol XOR cipher combiner, or a block cipher, most of which use a Feistel cipher or Lai–Massey scheme with a reciprocal transformation in each round. Notes References Cryptographic algorithms "

❤️ Lenin Peak 🐽

"Lenin Peak (, Lenin Çoqusu, لەنىن چوقۇسۇ; , Pik Lenina; , qulla‘i Lenin/qullaji Lenin, renamed қуллаи Абӯалӣ ибни Сино (qulla‘i Abûalî ibni Sino) in July 2006Government Resolution No. 297, July 4, 2006, Dushanbe (Tajik); for Russian text see .), or Ibn Sina (Avicenna) Peak, rises to 7,134 metres (23,406 ft) in Gorno-Badakhshan (GBAO) on the border of Tajikistan and Kyrgyzstan, and is the second-highest point of both countries. It is considered one of the less technical 7000 m peaks in the world to climb and it has by far the most ascents of any 7000 m or higher peak on Earth, with every year seeing hundreds of mountaineers make their way to the summit.Lenin Peak on summitpost.org retrieved 21-09-2011 Lenin Peak is the highest mountain in the Trans-Alay Range of Central Asia, and in the Pamir Mountains in Tajikistan it is exceeded only by Ismoil Somoni Peak (7,495 m). It was thought to be the highest point in the Pamirs in Tajikistan until 1933, when Ismoil Somoni Peak (known as Stalin Peak at the time) was climbed and found to be more than 300 metres higher. Two mountains in the Pamirs in China, Kongur Tagh (7,649 m) and Muztagh Ata (7,546 m), are higher than the Tajik summits. Names The peak was discovered in 1871 and originally named Mount Kaufmann after Konstantin Kaufman, the first Governor-General of Turkestan. In 1928, the mountain was renamed Lenin Peak after the Russian revolutionary and first leader of the Soviet Union, Vladimir Lenin. In Tajikistan, the peak was renamed again in July 2006, and today it is officially called in Tajik Qullai Abuali ibni Sino (қуллаи Абӯалӣ ибни Сино, Ibn Sina Peak or, alternatively, Avicenna Peak) after Abu Ali ibn Sina (Avicenna). In Kyrgyzstan, the peak is still officially called Lenin Chokusu (Ленин Чокусу, Lenin Peak). However, in October 2017, Kyrgyz president Almazbek Atambayev called for renaming the peak "Manas Peak", after the hero of the Epic of Manas. A peak named "Manas Peak" already exists in Kyrgyzstan; it is a mountain of in the Talas Alatau range in Talas Region. Local Kyrgyz names include Jel-Aidar ("Wind's God") and Achyk-Tash ("Open Rock"). Teiji Watanabe et al. (2013), Place Names as an Ecotourism Resource for the Alai Valley of the Kyrgyz Pamir, Geographical Studies, Vol. 88, No. 2, page 9Anarbaev, M. and Watanabe, T. (2008): Tourism in the Pamir-Alai Mountains, southern Kyrgyz Republic. Chiri (Geography), 55 (1), 56–59. (in Japanese) Achik-Tash, is also the name of a plateau and a base camp at an elevation of 3,600 m on a popular northern climbing route to Lenin Peak, which starts in the southern Kyrgyz city of Osh, a day's drive north of the border.Achik-Tash camp in Kyrgyzstan on the way to Lenin Peak Another suggested local name, Pik Kaman ("wild pig", "boar") probably belongs to an officially unnamed peak west of Lenin Peak. Climbing history and routes As it is now, in consideration of an existing infrastructure and BC/ABC location, there are three most attractive routes from the North (as it is approximately indicated on the Scheme): Lipkin's rocks route and NE Ridge; North Face classical route; Razdelnaya route and NW Ridge Lenin Peak Expedition. Climb Lenin Peak A climber poses on the summit of Lenin Peak next to the bust of Vladimir Lenin and the flag of Kyrgyzstan. Initial exploration of this part of Central Asia occurred in the period 1774–82. Arguably the first recorded travel through the region is the involuntary journey of the slave Filipp Efremov (an ethnic Russian), who escaped from slavery in Bukhara. He crossed the Fergana valley, then via Osh, the Chigirik Pass and Terekdavan Pass he reached the Kashgar and finally came over the Karakorum. He was the first European who crossed the Alai Mountains.Ф.С. Ефремов."Девятилетнее странствование и приключения в Бухарии, Хиве, Персии и Индии и возвращение оттуда через Англию в Россию" изд. Санкт-Петербург 1786Ефремов (филипп Сергеев) Scientific expeditions to the Alai Mountains began in 1871, when Alexei Pavlovich Fedchenko discovered the Trans-Alai (Zaalayskiy) Range and its main peak. The first geographical expedition which came nearest to the base of the future Lenin Peak in the early 20th century was arguably the expedition of Nikolai Leopol'dovich Korzhenevskiy. In September 1928, three mountaineers -the Germans and Karl Wien, and the Austrian - from a Soviet- German scientific expedition, made the first attempt to reach the highest point of the Trans-Alai Range, which at that time had the name Kaufman Peak. They started climbing upstream of the Saukdara river along the South slope of Trans-Alai Range also Trans-Alay Range. From the river head they continued climbing along the Greater Saukdara Glacier towards a saddle at an elevation of 5820 m (this saddle is also known as the Krilenko Pass). On September 25, 1928 they started climbing from the saddle along the NE Ridge and at 15.30 they reached the summit. At the time, Kaufman Peak was the highest summit reached by men. The title Lenin Peak was first applied to the highest point of the Trans-Alai Range in the same year (1928). When it was renamed after Lenin it was believed to be the highest point in the USSR. On September 8, 1934, at 16:20 Kasian Chernuha, Vitaly Abalakov and Ivan Lukin, three members of a Soviet expedition, reached the summit at an elevation of . Their attempt lasted for four days with three camps (5700 m, 6500 m and 7000 m). The expedition started climbing from the Achik-Tash canyon in the Alai valley. The summit attempt itself was started along the Western ice slope of the Lenin glacier. They continued climbing along the North Face, passing the rocks that were later given the name Lipkin's Rocks. At the end of the second day they reached the crest of the NE ridge at an elevation of about 6500 m. During the following day and a half they climbed along the NE Ridge and, utterly exhausted, reached the summit. The third ascent was three years later, in 1937, when eight Soviet climbers under the direction of Lev Barkhash reached the summit by the same route. This was at the beginning of mass political repressions in the Soviet Union and many of the most prominent Soviet climbers, including Lev Barkhash, were brought to trial. Subsequent attempts to climb Lenin Peak could not begin until 1950, when the USSR began to recover from the Second World War. On August 14, 1950, twelve climbers (V. Aksenov, K, Zaporojchenko, Y. Izrael, V. Kovalev, A. Kormshikov, Y. Maslov, E. Nagel, V. Narishkin, V. Nikonov, V. Nozdryuhin, I. Rojkov) under the direction of Vladimir Racek reached the summit for the fourth time. All three Soviet expeditions including Racec's expedition of 1950 were by almost the same route via the NE Ridge.http://www.skitalets.ru/books/pik_lenina/ The route which now is known as the classic route, via the Razdelnaya Peak and NW Ridge, was first climbed in 1954 by the team of Soviet climbers under the direction of V. Kovalev (P. Karpov, E. Nagel, V. Narishkin, V. Nozdryuhin). Jaan Künnap, a decorated Estonian mountaineer, at the top of Lenin Peak in 1989. This marked the first time an Estonian flag was flown at an altitude over 7000 m. In 1960, a group of eight Soviet climbers made a successful direct climb along the North Face (15.08.1960). There are 16 established routes, nine on the southern side and seven on the northern slopes. The peak is quite popular with climbers due to its easy access and some uncomplicated routes. However, the peak is not without its share of disasters. In 1974, an entire team of eight female climbers died high on the mountain in a storm. In 1987 Anatoli Boukreev achieved the first round trip speed ascent Base camp to Summit to Base camp in 14 hours. In 1989 The first solo ascent is achieved by the great high altitude mountaineer Anatoli Boukreev.Memorial to the victims of avalanche of 1990 An avalanche triggered by an earthquake killed 43 climbers in 1990. As it is now, considering the existing infrastructure and BC/ABC locations, there are three most attractive routes from the North (approximately indicated on the Scheme): Lipkin's rocks route and NE Ridge; the classic North Face route; the route via Razdelnaya Peak and the NW Ridge. References External links * Lenin Peak on summitpost * Description district Lenin Peak, climbing routes on Lenin Peak * Alternative 3D map of climbing routes * Climbing in Kyrgyzstan Mountains of Kyrgyzstan Mountains of Tajikistan Kyrgyzstan–Tajikistan border International mountains of Asia Seven-thousanders of the Pamir "