In cryptography Cryptography is the practice and study of hiding information. Modern cryptography intersects the disciplines of mathematics, computer science, and engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce, plaintext is information a sender wishes to transmit to a receiver. Cleartext is, sometimes confusingly, often used as a synonym Synonyms are different words with identical or very similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn ("with") and onoma (ὄνομα) ("name"). The words car and automobile are synonyms. Similarly, if we talk about a. Before the computer era, plaintext most commonly meant message text in the language of the communicating parties. Plaintext has reference to the operation of cryptographic Cryptography is the practice and study of hiding information. Modern cryptography intersects the disciplines of mathematics, computer science, and engineering. Applications of cryptography include ATM cards, computer passwords, and electronic commerce algorithms, usually encryption In cryptography, encryption is the process of transforming information using an algorithm (called cipher) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information (in cryptography, referred to as ciphertext). In many contexts, the word encryption algorithms, and is the input upon which they operate. Cleartext, by contrast, refers to data that is transmitted or stored unencrypted (that is, 'in the clear').
Since computers became commonly available, the definition has also encompassed not only electronic representations of the traditional text, for instance, messages (e.g., email) and document content (e.g., word processor files), but also the computer representations of sound (e.g., speech or music), images (e.g., photos or videos), ATM and credit card transaction information, sensor data, and so forth. Few of these are directly meaningful to humans, being already transformed into computer manipulable forms. Basically, any information which the communicating parties wish to conceal from others can now be treated, and referred to, as plaintext. Thus, in a significant sense, plaintext is the 'normal' representation of data before any action has been taken to conceal, compress, or 'digest' A cryptographic hash function is a deterministic procedure that takes an arbitrary block of data and returns a fixed-size bit string, the hash value, such that an accidental or intentional change to the data will change the hash value. The data to be encoded is often called the "message", and the hash value is sometimes called the it. It need not represent text, and even if it does, the text may not be "plain".
Plaintext is used as input to an encryption algorithm; the output is usually termed ciphertext In cryptography, ciphertext is the result of the process of transforming information (referred to as plaintext) using an algorithm (called cipher) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. This result is also known as encrypted information. The process to read ciphertext is known as particularly when the algorithm is a cipher In cryptography, a cipher is an algorithm for performing encryption or decryption — a series of well-defined steps that can be followed as a procedure. An alternative, less common term is encipherment. In non-technical usage, a “cipher” is the same thing as a “code”; however, the concepts are distinct in cryptography. In classical. Codetext is less often used, and almost always only when the algorithm involved is actually a code A code is a rule for converting a piece of information into another form or representation (one sign into another sign), not necessarily of the same type. In some systems, however, multiple layers of encryption In cryptography, encryption is the process of transforming information using an algorithm (called cipher) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information (in cryptography, referred to as ciphertext). In many contexts, the word encryption are used, in which case the output of one encryption algorithm becomes plaintext input for the next.
Secure handling of plaintext
In a cryptosystem In this meaning, the term cryptosystem is used as shorthand for "cryptographic system". A cryptographic system is any computer system that involves cryptography. Such systems include for instance, a system for secure electronic mail which might include methods for digital signatures, cryptographic hash functions, key management, weaknesses can be introduced through insecure handling of plaintext, allowing an attacker to bypass the cryptography altogether. Plaintext is vulnerable in use and in storage, whether in electronic or paper format. Physical security Physical security describes both measures that prevent or deter attackers from accessing a facility, resource, or information stored on physical media and guidance on how to design structures to resist various hostile acts. It can be as simple as a locked door or as elaborate as multiple layers of armed Security guards and Guardhouse placement deals with methods of securing information and its storage media from local, physical, attacks. For instance, an attacker might enter a poorly secured building and attempt to open locked desk drawers or safes A safe is a secure lockable box used for securing valuable objects against theft or damage. A safe is usually a hollow cuboid or cylinder, with one face removable or hinged to form a door. The body and door may be cast from metal (such as steel) or formed out of plastic through blow molding. An attacker can also engage in dumpster diving Dumpster diving is the practice of sifting through commercial or residential trash to find items that have been discarded by their owners, but which may be useful to the dumpster diver. The practice of Dumpster diving is also known variously as bin diving, curb shopping,[citation needed] binning, bin diving[citation needed] (mostly British), alley, and may be able to reconstruct shredded information if it is sufficiently valuable to be worth the effort. One countermeasure is to burn or thoroughly crosscut shred A paper shredder is a mechanical device used to cut paper into chad, typically either strips or fine particles. Government organizations, businesses, and private individuals use shredders to destroy private, confidential, or otherwise sensitive documents. Privacy experts often recommend that individuals shred bills, tax documents, credit card and discarded printed plaintexts or storage media; NSA The National Security Agency/Central Security Service is a cryptologic intelligence agency of the United States government, administered as part of the United States Department of Defense. Created on November 4, 1952 by President Harry S. Truman, it is responsible for the collection and analysis of foreign communications and foreign signals is infamous for its disposal security precautions.
If plaintext is stored in a computer file A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished. Computer files can be considered as the modern (and the situation of automatically made backup files generated during program execution must be included here, even if invisible to the user), the storage media along with the entire computer and its components must be secure. Sensitive data is sometimes processed on computers whose mass storage is removable, in which case physical security of the removed disk is separately vital. In the case of securing a computer, useful (as opposed to handwaving) security must be physical (e.g., against burglary Burglary is a crime, the essence of which is entry into a building for the purposes of committing an offence. Usually that offence will be theft, but most jurisdictions specify others which fall within the ambit of burglary. To commit a burglary is to burgle (in British English) or burglarize (in American English), brazen removal under cover of supposed repair, installation of covert monitoring devices, etc.), as well as virtual (e.g., operating system An operating system is the software on a computer that manages the way different programs use its hardware, and regulates the ways that a user controls the computer. Operating systems are found on almost any device that contains a computer with multiple programs—from cellular phones and video game consoles to supercomputers and web servers. Some modification, illicit network access, Trojan A Trojan, sometimes referred to as a Trojan horse, is non-self-replicating malware that appears to perform a desirable function for the user but instead facilitates unauthorized access to the user's computer system. The term is derived from the Trojan Horse story in Greek mythology programs, ...). The wide availability of keydrives, which can plug into most modern computers and store large quantities of data, poses another severe security headache. A spy (perhaps posing as a cleaning person) could easily conceal one and even swallow it, if necessary.
Discarded computers, disk drives and media are also a potential source of plaintexts. Most operating systems do not actually erase anything — they simply mark the disk space occupied by a deleted file as 'available for use', and remove its entry from the file system directory Folder, directory, catalog, or drawer, in computing, is a virtual container within a digital file system, in which groups of computer files and other folders can be kept and organized. The information in a file deleted in this way remains fully present until overwritten at some later time when the operating system reuses the disk space. With even low-end computers commonly sold with many gigabytes of disk space and rising monthly, this 'later time' may be months later, or never. Even overwriting the portion of a disk surface occupied by a deleted file is insufficient in many cases. Peter Gutmann of the University of Auckland The University of Auckland is New Zealand's largest university and the top-ranked New Zealand university in the THES - QS World University Rankings. Established in 1883 as a constituent college of the University of New Zealand, the university is now made up of eight faculties over six campuses, and has more than 39,000 students at April 2006. Over wrote a celebrated 1996 paper on the recovery of overwritten information from magnetic disks; areal storage densities have gotten much higher since then, so this sort of recovery is likely to be more difficult than it was when Gutmann wrote.
Also, independently, modern hard drives automatically remap sectors that are starting to fail; those sectors no longer in use will contain information that is entirely invisible to the file system (and all software which uses it for access to disk data), but is nonetheless still present on the physical drive platter. It may, of course, be sensitive plaintext. Some government agencies (e.g., NSA The National Security Agency/Central Security Service is a cryptologic intelligence agency of the United States government, administered as part of the United States Department of Defense. Created on November 4, 1952 by President Harry S. Truman, it is responsible for the collection and analysis of foreign communications and foreign signals) require that all disk drives be physically pulverized when they are discarded, and in some cases, chemically treated with corrosives before or after. This practice is not widespread outside of the government, however. For example, Garfinkel and Shelat (2003) analyzed 158 second-hand hard drives acquired at garage sales and the like and found that less than 10% had been sufficiently sanitized. A wide variety of personal and confidential information was found readable from the others. See data remanence Data remanence is the residual representation of data that have been in some way nominally erased or removed. This residue may be due to data being left intact by a nominal delete operation, or through physical properties of the storage medium. Data remanence may make inadvertent disclosure of sensitive information possible, should the storage.
Laptop computers are a special problem. The US State Department, the British Secret Service, and the US Department of Defense have all had laptops containing secret information,some perhaps in plaintext form, 'vanish' in recent years. Announcements of similar losses are becoming a common item in news reports. Disk encryption techniques can provide protection against such loss or theft -- if properly chosen and used.
On occasion, even when the data on the host systems is itself encrypted, the media used to transfer data between such systems is nevertheless plaintext due to poorly designed data policy. An incident in October 2007 in which HM Revenue and Customs lost CDs containing no less than the records of 25 million child benefit recipients in the United Kingdom — the data apparently being entirely unencrypted — is a case in point.
Modern cryptographic systems are designed to resist known plaintext or even chosen plaintext attacks and so may not be entirely compromised when plaintext is lost or stolen. Older systems used techniques such as padding and Russian copulation to obscure information in plaintext that could be easily guessed, and to resist the effects of loss of plaintext on the security of the cryptosystem.
See also
References
- S. Garfinkel and A Shelat, "Remembrance of Data Passed: A Study of Disk Sanitization Practices", IEEE Security and Privacy, January/February 2003 (PDF).
- UK HM Revenue and Customs loses 25m records of child benefit recipients BBC
Categories: Cryptography Cryptography is, traditionally, the study of ways to convert information from its normal, comprehensible form into an obscured guise, unreadable without special knowledge — the practice of encryption. In the past, cryptography helped ensure secrecy in important communications, such as those of spies, military leaders, and diplomats. In recent
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