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lue this process does not alter the type or length of data which means it can be processed by legacy systems such as databases that may be sensitive to data length and type tokens require significantly less computational resources to process and less storage space in databases than traditionally encrypted data this is achieved by keeping specific data fully or partially visible for processing and analytics while sensitive information is kept hidden lower processing and storage requirements make tokenization an ideal method of securing data at rest in systems that manage large volumes of data a further method of preventing unwanted access to data at rest is the use of data federation 17 especially when data is distributed globally e g in offshore archives an example of this would be a european organisation which stores its archived data off site in the us under the terms of the usa patriot act 18 the american authorities can demand access to all data physically stored within its boundaries even if it includes personal information on european citizens with no connections to the us data encryption alone cannot be used to prevent this as the authorities have the right to demand decrypted information a data federation policy which retains personal citizen information with no foreign connections within its country of origin separate from information which is either not personal or is relevant to offshore authorities is one option to address this concern however data stored in foreign countries can be accessed using legislation in the cloud act data in use edit data in use is an information technology term referring to active data which is stored in a non persistent digital state or volatile memory typically in computer random access memory ram cpu caches or cpu registers 19 data in use has also been taken to mean active data in the context of being in a database or being manipulated by an application for example some enterprise encryption gateway solutions for the cloud claim to encrypt data at rest data in transit and data in use 20 some cloud software as a service saas providers refer to data in use as any data currently being processed by applications as the cpu and memory are utilized 21 security edit because of its nature data in use is of increasing concern to businesses government agencies and other institutions data in use or memory can contain sensitive data including digital certificates encryption keys intellectual property software algorithms design data and personally identifiable information compromising data in use enables access to encrypted data at rest and data in motion for example someone with access to random access memory can parse that memory to locate the encryption key for data at rest once they have obtained that encryption key they can decrypt encrypted data at rest threats to data in use can come in the form of cold boot attacks malicious hardware devices rootkits and bootkits encryption which prevents data visibility in the event of its unauthorized access or theft is commonly used to protect data in motion and data at rest and increasingly recognized as an optimal method for protecting data in use there have been multiple projects to encrypt memory microsoft xbox systems are designed to provide memory encryption and the company privatecore presently has a commercial software product vcage to provide attestation along with full memory encryption for x86 servers 22 several papers have been published highlighting the availability of security enhanced x86 and arm commodity processors 19 23 in that work an arm cortex a8 processor is used as the substrate on which a full memory encryption solution is built process segments for example stack code or heap can be encrypted individually or in composition this work marks the first full memory encryption implementation on a mobile general purpose commodity processor the system provides both confidentiality and integrity protections of code and data which are encrypted everywhere outside the cpu boundary for x86 systems amd has a secure memory encryption sme feature introduced in 2017 with epyc 24 intel has promised to deliver its total memory encryption tme feature in an upcoming cpu 25 26 operating system kernel patches such as tresor and loop amnesia modify the operating system so that cpu registers can be used to store encryption keys and avoid holding encryption keys in ram while this approach is not general purpose and does not protect all data in use it does protect against cold boot attacks encryption keys are held inside the cpu rather than in ram so that data at rest encryption keys are protected against attacks that might compromise encryption keys in memory enclaves enable an enclave to be secured with encryption in ram so that enclave data is encrypted while in ram but available as clear text inside the cpu and cpu cache intel corporation has introduced the concept of enclaves as part of its software guard extensions intel revealed an architecture combining software and cpu hardware in technical papers published in 2013 27 several cryptographic tools including secure multi party computation and homomorphic encryption allow for the private computation of data on untrusted systems data in use could be operated upon while encrypted and never exposed to the system doing the processing data in transit edit data in transit also referred to as data in motion 28 and data in flight 29 is data en route between source and destination typically on a computer network data in transit can be separated into two categories information that flows over the public or untrusted network such as the internet and data that flows in the confines of a private network such as a corporate or enterprise local area network lan 30 various types of data which can be visualized through a computer device in computing edit data within a computer in most cases moves as parallel data data moving to or from a computer in most cases moves as serial data data sourced from an analog device such as a temperature sensor may be converted to digital using an analog to digital converter data representing quantities characters or symbols on which operations are performed by a computer are stored and recorded on magnetic optical electronic or mechanical recording media and transmitted in the form of digital electrical or optical signals 31 data pass in and out of computers via peripheral devices physical computer memory elements consist of an address and a byte word of data storage digital data are often stored in relational databases like tables or sql databases and can generally be represented as abstract key value pairs data can be organized in many different types of data structures including arrays graphs and objects data structures can store data of many different types including numbers strings and even other data structures characteristics edit metadata helps translate data to information metadata is data about the data metadata may be implied specified or given data relating to physical events or processes will have a temporal component this temporal component may be implied this is the case when a device such as a temperature logger receives data from a temperature sensor when the temperature is received it is assumed that the data has a temporal reference of now so the device records the date time and temperature together when the data logger communicates temperatures it must also report the date and time as metadata for each temperature reading fundamentally computers follow a sequence of instructions they are given in the form of data a set of instructions to perform a given task or tasks is called a program a program is data in the form of coded instructions to control the operation of a computer or other machine 32 in the nominal case the program as executed by the computer will consist of machine code the elements of storage manipulated by the program but not actually executed by the central processing unit cpu are also data at its most essential a single datum is a value stored at a specific location therefore it is possible for computer programs to operate on other computer programs by manipulating their programmatic data to store data bytes in a file they have to be serialized in a file format typically programs are stored in special file types different from those used for other data executable files contain programs all other files are also data files however executable files may also contain data used by the program which is built into the program in particular some executable files have a data segment which nominally contains constants and initial values for variables both of which can be considered data the line between program and data can become blurry an interpreter for example is a program the input data to an interpreter is itself a program just not one expressed in native machine language in many cases the interpreted program will be a human readable text file which is manipulated with a text editor program metaprogramming similarly involves programs manipulating other programs as data programs like compilers linkers debuggers program updaters virus scanners and such use other programs as their data for example a user might first instruct the operating system to load a word processor program from one file and then use the running program to open and edit a document stored in another file in this example the document would be considered data if the word processor also features a spell checker then the dictionary word list for the spell checker would also be considered data the algorithms used by the spell checker to suggest corrections would be either machine code data or text in some interpretable programming language in an alternate usage binary files which are not human readable are sometimes called data as distinguished from human readable text 33 the total amount of digital data in 2007 was estimated to be 281 billion gigabytes 281 exabytes 34 35 data keys and values structures and persistence edit keys in data provide the context for values regardless of the structure of data there is always a key component present keys in data and data structures are essential for giving meaning to data values without a key that is directly or indirectly associated with a value or collection of values in a structure the values become meaningless and cease to be data that is to say there has to be a key component linked to a value component in order for it to be considered data 36 data can be represented in computers in multiple ways as per the following examples ram edit random access memory ram holds data that the cpu has direct access to a cpu may only manipulate data within its processor registers or memory this is as opposed to data storage where the cpu must direct the transfer of data between the storage device disk tape and memory ram is an array of linear contiguous locations that a processor may read or write by providing an address for the read or write operation the processor may operate on any location in memory at any time in any order in ram the smallest element of data is the binary bit the capabilities and limitations of accessing ram are processor specific in general main memory is arranged as an array of locations beginning at address 0 hexadecimal 0 each location can usually store 8 or 32 bits depending on the computer architecture keys edit data keys need not be a direct hardware address in memory indirect abstract and logical keys codes can be stored in association with values to form a data structure data structures have predetermined offsets or links or paths from the start of the structure in which data values are stored therefore the data key consists of the key to the structure plus the offset or links or paths into the structure when such a structure is repeated storing variations of the data values and the data keys within the same repeating structure the result can be considered to resemble a table in which each element of the repeating structure is considered to be a column and each repetition of the structure is considered as a row of the table in such an organization of data the data key is usually a value in one or a composite of the values in several of the columns organised recurring data structures edit the tabular view of repeating data structures is only one of many possibilities repeating data structures can be organised hierarchically such that nodes are linked to each other in a cascade of parent child relationships values and potentially more complex data structures are linked to the nodes thus the nodal hierarchy provides the key for addressing the data structures associated with the nodes this representation can be thought of as an inverted tree modern computer operating system file systems are a common example and xml is another sorted or ordered data edit data has some inherent features when it is sorted on a key all the values for subsets of the key appear together when passing sequentially through groups of the data with the same key or a subset of the key changes this is referred to in data processing circles as a break or a control break it particularly facilitates the aggregation of data values on subsets of a key peripheral storage edit until the advent of bulk non volatile memory like flash persistent data storage was traditionally achieved by writing the data to external block devices like magnetic tape and disk drives these devices typically seek to a location on the magnetic media and then read or write blocks of data of a predetermined size in this case the seek location on the media is the data key and the blocks are the data values early used raw disk data file systems or disc operating systems reserved contiguous blocks on the disc drive for data files in those systems the files could be filled up running out of data space before all the data had been written to them thus much unused data space was reserved unproductively to ensure adequate free space for each file later file systems introduced partitions they reserved blocks of disc data space for partitions and used the allocated blocks more economically by dynamically assigning blocks of a partition to a file as needed to achieve this the file system had to keep track of which blocks were used or unused by data files in a catalog or file allocation table though this made better use of the disc data space it resulted in fragmentation of files across the disc and a concomitant performance overhead due to additional seek time to read the data modern file systems reorganize fragmented files dynamically to optimize file access times further developments in file systems resulted in virtualization of disc drives i e where a logical drive can be defined as partitions from a number of physical drives indexed data edit retrieving a small subset of data from a much larger set may imply inefficiently searching through the data sequentially indexes are a way to copy ...
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