In information security, message authentication or data origin authentication is a property that a message has not been modified while in transit (data integrity) and that the receiving party can verify the source of the message.^[1] Message authentication does not necessarily include the property of non-repudiation.
Message authentication is typically achieved by using message authentication codes (MACs), authenticated encryption (AE) or digital signatures.
Some cryptographers distinguish between "message authentication without secrecy" systems -- which allow the intended receiver to verify the source of the message, but don't bother hiding the plaintext contents of the message -- from authenticated encryption systems. A few cryptographers have researched subliminal channel systems that send messages that appear to use a "message authentication without secrecy" system, but in fact also transmit a secret message.

Deniable authentication

In cryptography, deniable authentication refers to message authentication between a set of participants where the participants themselves can be confident in the authenticity of the messages, but it cannot be proved to a third party after the event.
In practice, deniable authentication between two parties can be achieved through the use of message authentication codes (MACs) by making sure that if an attacker is able to decrypt the messages, they would also know the MAC key as part of the protocol, and would thus be able to forge authentic-looking messages. For example, in the Off-the-Record Messaging (OTR) protocol, MAC keys are derived from the asymmetric decryption key through a cryptographic hash function. In addition to that, the OTR protocol also reveals used MAC keys as part of the next message, when they have already been used to previously received messages and will not be re-used .

Deniable encryption

In cryptography and steganography, plausibly deniable encryption describes encryption techniques where the existence of an encrypted file or message is deniable in the sense that an adversary cannot prove that the plaintext data exists.
The users may convincingly deny that a given piece of data is encrypted, or that they are able to decrypt a given piece of encrypted data, or that some specific encrypted data exists. Such denials may or may not be genuine. For example, it may be impossible to prove that the data is encrypted without the cooperation of the users. If the data is encrypted, the users genuinely may not be able to decrypt it. Deniable encryption serves to undermine an attacker's confidence either that data is encrypted, or that the person in possession of it can decrypt it and provide the associated plaintext.

Function

Deniable encryption makes it impossible to prove the existence of the plaintext message without the proper encryption key. This may be done by allowing an encrypted message to be decrypted to different sensible plaintexts, depending on the key used. This allows the sender to have plausible deniability if compelled to give up his or her encryption key. The notion of "deniable encryption" was used by Julian Assange and Ralf Weinmann in the Rubberhose filesystem and explored in detail in a paper by Ran Canetti, Cynthia Dwork, Moni Naor, and Rafail Ostrovsky in 1996.

Scenario

Deniable encryption allows the sender of an encrypted message to deny sending that message. This requires a trusted third party. A possible scenario works like this:

Bob suspects his wife Alice is engaged in adultery. That being the case, Alice wants to communicate with her secret lover Carl. She creates two keys, one intended to be kept secret, the other intended to be sacrificed. She passes the secret key (or both) to Carl.
Alice constructs an innocuous message M1 for Carl (intended to be revealed to Bob in case of discovery) and an incriminating love letter M2 to Carl. She constructs a cipher-text C out of both messages M1, M2 and emails it to Carl.
Carl uses his key to decrypt M2 (and possibly M1, in order to read the fake message, too).
Bob finds out about the email to Carl, becomes suspicious and forces Alice to decrypt the message.
Alice uses the sacrificial key and reveals the innocuous message M1 to Bob. Since it is impossible for Bob to know for sure that there might be other messages contained in C, he might assume that there are no other messages.

Another possible scenario involves Alice sending the same ciphertext (some secret instructions) to Bob and Carl, to whom she has handed different keys. Bob and Carl are to receive different instructions and must not be able to read each other's instructions. Bob will receive the message first and then forward it to Carl.

Alice constructs the ciphertext out of both messages, M1 and M2, and emails it to Bob.
Bob uses his key to decrypt M1 and isn't able to read M2.
Bob forwards the ciphertext to Carl.
Carl uses his key to decrypt M2 and isn't able to read M1.

Forms of deniable encryption

Normally, ciphertexts decrypt to a single plaintext that is intended to be kept secret. However, one form of deniable encryption allows its users to decrypt the ciphertext to produce a different (innocuous but plausible) plaintext and plausibly claim that it is what they encrypted. The holder of the ciphertext will not be able to differentiate between the true plaintext, and the bogus-claim plaintext. In general, decrypting one ciphertext to multiple plaintexts is not possible unless the key is as large as the plaintext,^[4] so this is not practical for most purposes.^[5] However, some schemes allow decryption to decoy plaintexts that are close to the original in some metric (such as edit distance). ^[6]
Modern deniable encryption techniques exploit the fact that without the key, it is infeasible to distinguish between ciphertext from block ciphers and data generated by a cryptographically secure pseudorandom number generator (the cipher's pseudorandom permutation properties).^[7]
This is used in combination with some decoy data that the user would plausibly want to keep confidential that will be revealed to the attacker, claiming that this is all there is. This is a form of steganography.
If the user does not supply the correct key for the truly secret data, decrypting it will result in apparently random data, indistinguishable from not having stored any particular data there.
One example of deniable encryption is a cryptographic filesystem that employs a concept of abstract "layers", where each layer can be decrypted with a different encryption key. Additionally, special "chaff layers" are filled with random data in order to have plausible deniability of the existence of real layers and their encryption keys. The user can store decoy files on one or more layers while denying the existence of others, claiming that the rest of space is taken up by chaff layers. Physically, these types of filesystems are typically stored in a single directory consisting of equal-length files with filenames that are either randomized (in case they belong to chaff layers), or cryptographic hashes of strings identifying the blocks. The timestamps of these files are always randomized. Examples of this approach include Rubberhose filesystem and PhoneBookFS.
Another approach used by some conventional disk encryption software suites is creating a second encrypted volume within a container volume. The container volume is first formatted by filling it with encrypted random data,^[8] and then initializing a filesystem on it. The user then fills some of the filesystem with legitimate, but plausible-looking decoy files that the user would seem to have an incentive to hide. Next, a new encrypted volume (the hidden volume) is allocated within the free space of the container filesystem which will be used for data the user actually wants to hide. Since an adversary cannot differentiate between encrypted data and the random data used to initialize the outer volume, this inner volume is now undetectable. LibreCrypt^[9] and BestCrypt can have many hidden volumes in a container; TrueCrypt is limited to one hidden volume.

Detection

The existence of hidden encrypted data may be revealed by flaws in the implementation. It may also be revealed by a so-called 'watermarking attack' if an inappropriate cipher mode is used. The existence of the data may be revealed by it 'leaking' into non-encrypted disk space where it can be detected by forensic tools.^[
Doubts have been raised about the level of plausible deniability in 'hidden volumes' – the contents of the "outer" container filesystem have to be 'frozen' in its initial state to prevent the user from corrupting the hidden volume (this can be detected from the access and modification timestamps), which could raise suspicion. This problem can be eliminated by instructing the system not to protect the hidden volume, although this could result in lost data.

Drawbacks

Deniable encryption has been criticized because it does not defend users from revealing keys under coercion or torture. Possession of deniable encryption tools could lead attackers to continue torturing a user even after the user has revealed all his keys, because the attackers could not know whether the user had revealed his last key or not.

Deniable authentication

Some in-transit encrypted messaging suites, such as off-the-Record Messaging, offer deniable authentication which gives the participants plausible deniability of their conversations. While deniable authentication is not technically "deniable encryption" in that the encryption of the messages is not denied, its deniability refers to the inability of an adversary to prove that the participants had a conversation or said anything in particular.
This is achieved by the fact that all information necessary to forge messages is appended to the encrypted messages – if an adversary is able to create digitally authentic messages in a conversation (see hash-based message authentication code (HMAC)), he is also able to forge messages in the conversation. This is used in conjunction with perfect forward secrecy to assure that the compromise of encryption keys of individual messages does not compromise additional conversations or messages.

Software

OpenPuff, freeware semi-open-source steganography for MS Windows.
EDS, a mobile encryption app available on Android, includes plausible-deniability encryption.
Espionage, shareware for Mac OS X. Source code is available to security researchers.
Fuyoal, an open-source tool that provides plausible deniability based on indiscernibility between encrypted files which contain and do not contain hidden content.
LibreCrypt, opensource transparent disk encryption for MS Windows and PocketPC PDAs that provides both deniable encryption and plausible deniability. Offers an extensive range of encryption options, and doesn't need to be installed before use as long as the user has administrator rights.
Off-the-Record Messaging, a cryptographic technique providing true deniability for instant messaging.
PhoneBookFS, another cryptographic filesystem for Linux, providing plausible deniability through chaff and layers. A FUSE implementation. No longer maintained.
Rubberhose, defunct project (last release in 2000, not compatible with modern Linux distributions)
StegFS, the current successor to the ideas embodied by the Rubberhose and PhoneBookFS filesystems
TrueCrypt, which was (now discontinued) on-the-fly disk encryption software for Windows, Mac and Linux providing limited deniable encryption and to some extent (due to limitations on the number of hidden volumes which can be created) plausible deniability, without needing to be installed before use as long as the user had full administrator rights
VeraCrypt, a successor to TrueCrypt with similar features, including plausible-deniability encryption.
Vanish, a research prototype implementation of self-destructing data storage
ScramDisk 4 Linux, a free software suite of tools, for GNU/Linux systems, which can open and create scramdisk and truecrypt container.

XXX . V000000 Chaffing and winnowing

Chaffing and winnowing is a cryptographic technique to achieve confidentiality without using encryption when sending data over an insecure channel. The name is derived from agriculture: after grain has been harvested and threshed, it remains mixed together with inedible fibrous chaff. The chaff and grain are then separated by winnowing, and the chaff is discarded. The technique was conceived by Ron Rivest and published in an on-line article on 18 March 1998. Although it bears similarities to both traditional encryption and steganography, it cannot be classified under either category.
This technique allows the sender to deny responsibility for encrypting their message. When using chaffing and winnowing, the sender transmits the message unencrypted, in clear text. Although the sender and the receiver share a secret key, they use it only for authentication. However, a third party can make their communication confidential by simultaneously sending specially crafted messages through the same channel.

How it works

The sender (Alice) wants to send a message to the receiver (Bob). In the simplest setup, Alice enumerates the symbols (usually bits) in her message and sends out each in a separate packet. In general the method requires each symbol to arrive in-order and to be authenticated by the receiver. When implemented over networks that may change the order of packets, the sender places the symbol's serial number in the packet, the symbol itself (both unencrypted), and a message authentication code (MAC). Many MACs use a secret key Alice shares with Bob, but it is sufficient that the receiver has a method to authenticate the packets. Charles, who transmits Alice's packets to Bob, interleaves the packets with corresponding bogus packets (called "chaff") with corresponding serial numbers, arbitrary symbols, and a random number in place of the MAC. Charles does not need to know the key to do that (real MAC are large enough that it is extremely unlikely to generate a valid one by chance, unlike in the example). Bob uses the MAC to find the authentic messages and drops the "chaff" messages. This process is called "winnowing".
An eavesdropper located between Alice and Charles can easily read Alice's message. But an eavesdropper between Charles and Bob would have to tell which packets are bogus and which are real (i.e. to winnow, or "separate the wheat from the chaff"). That is infeasible if the MAC used is secure and Charles does not leak any information on packet authenticity (e.g. via timing).
If a fourth party, Dave, (anyone other than Alice, Charles, or Bob) requires Alice to disclose her secret key, she can defend with the argument that she used the key merely for authentication and did not intend to make the message confidential. If Dave cannot force Alice to disclose an authentication key (the knowledge of which would enable him to forge messages from Alice), then her messages will remain confidential. On the other hand, Charles does not even possess any secret keys that he could be ordered to disclose.

Variations

The simple variant of the chaffing and winnowing technique described above adds many bits of overhead per bit of original message. To make the transmission more efficient, Alice can process her message with an all-or-nothing transform and then send it out in much larger chunks. The chaff packets will have to be modified accordingly. Because the original message can be reconstructed only by knowing all of its chunks, Charles needs to send only enough chaff packets to make finding the correct combination of packets computationally infeasible.
Chaffing and winnowing lends itself especially well to use in packet-switched network environments such as the Internet, where each message (whose payload is typically small) is sent in a separate network packet. In another variant of the technique, Charles carefully interleaves packets coming from multiple senders. That eliminates the need for Charles to generate and inject bogus packets in the communication. However, the text of Alice's message cannot be well protected from other parties who are communicating via Charles at the same time. This variant also helps protect against information leakage and traffic analysis.

Implications for law enforcement

Ron Rivest suggests that laws related to cryptography, including export controls, would not apply to chaffing and winnowing because it does not employ any encryption at all.

The power to authenticate is in many cases the power to control, and handing all authentication power to the government is beyond all reason

— Ronald L. Rivest, 1998

The author of the paper proposes that the security implications of handing everyone's authentication keys to the government for law-enforcement purposes would be far too risky, since possession of the key would enable someone to masquerade and communicate as another entity, such as an airline controller. Furthermore, Ron Rivest contemplates the possibility of rogue law enforcement officials framing up innocent parties by introducing the chaff into their communications, concluding that drafting a law restricting chaffing and winnowing would be far too difficult.

Trivia

The term winnowing was suggested by Ronald Rivest's father. Before the publication of Rivest's paper in 1998 other people brought to his attention a 1965 novel, Rex Stout's The Doorbell Rang, which describes the same concept and was thus included in the paper's references.

Null cipher

A null cipher, also known as concealment cipher, is an ancient form of encryption where the plaintext is mixed with a large amount of non-cipher material. Today it is regarded as a simple form of steganography, which can be used to hide ciphertext. .

Classical cryptography

In classical cryptography, a null is intended to confuse the cryptanalyst. In a null cipher, the plaintext is included within the ciphertext and one needs to discard certain characters in order to decrypt the message. Most characters in such a cryptogram are nulls, only some are significant, and some others can be used as pointers to the significant ones.
Examples of messages containing null ciphers:

News Eight Weather: Tonight increasing snow. Unexpected precipitation smothers eastern towns. Be extremely cautious and use snowtires especially heading east. The [highway is not] knowingly slippery. Highway evacuation is suspected. Police report emergency situations in downtown ending near Tuesday.

Taking the first letter in each word successively yields the real message: "Newt is upset because he thinks he is President."
You can also choose to instead use the last letter of every word, or something like a pattern such as:

Susan sAys GaIl Lies. MAtt leTs Susan fEel joVial. Elated (or) aNgry?

Using the pattern (1,2,3,1,2,3 [each letter in each word]) gives the message: "Sail at seven."
Other options include positioning of the significant letters next to or at certain intervals from punctuation marks or particular characters. Historically, users of concealment ciphers often used substitution and transposition ciphers on the data prior to concealment. For example, Cardinal Richelieu is said to have used a grille to write secret messages, after which the blank spaces were filled out with extraneous matter to create the impression of a continuous text.

Usage

It is difficult and time-consuming to produce encapsulating messages that feel natural and wouldn't raise suspicions. The message may read clumsily, and suspected messages can be detected by mail filters. More importantly, the security of the message relies entirely on the secrecy of the concealment method. Null ciphers are no longer in serious use

Transposition cipher

In cryptography, a transposition cipher is a method of encryption by which the positions held by units of plaintext (which are commonly characters or groups of characters) are shifted according to a regular system, so that the ciphertext constitutes a permutation of the plaintext. That is, the order of the units is changed (the plaintext is reordered). Mathematically a bijective function is used on the characters' positions to encrypt and an inverse function to decrypt.
Following are some implementations.

Rail Fence cipher

The Rail Fence cipher is a form of transposition cipher that gets its name from the way in which it is encoded. In the rail fence cipher, the plaintext is written downwards on successive "rails" of an imaginary fence, then moving up when we get to the bottom. The message is then read off in rows. For example, using three "rails" and a message of 'WE ARE DISCOVERED. FLEE AT ONCE', the cipherer writes out:

W . . . E . . . C . . . R . . . L . . . T . . . E
. E . R . D . S . O . E . E . F . E . A . O . C .
. . A . . . I . . . V . . . D . . . E . . . N . .

Then reads off:

WECRL TEERD SOEEF EAOCA IVDEN

(The cipherer has broken this ciphertext up into blocks of five to help avoid errors. This is a common technique used to make the cipher more easily readable. The spacing is not related to spaces in the plaintext and so does not carry any information about the plaintext.)
The rail fence cipher was used by the ancient Greeks in the scytale, a mechanical system of producing a transposition cipher. The system consisted of a cylinder and a ribbon that was wrapped around the cylinder. The message to be encrypted was written on the coiled ribbon. The letters of the original message would be rearranged when the ribbon was uncoiled from the cylinder. However, the message was easily decrypted when the ribbon was recoiled on a cylinder of the same diameter as the encrypting cylinder.

Route cipher

In a route cipher, the plaintext is first written out in a grid of given dimensions, then read off in a pattern given in the key. For example, using the same plaintext that we used for rail fence:

W R I O R F E O E 
E E S V E L A N J 
A D C E D E T C X

The key might specify "spiral inwards, clockwise, starting from the top right". That would give a cipher text of:

EJXCTEDECDAEWRIORFEONALEVSE

Route ciphers have many more keys than a rail fence. In fact, for messages of reasonable length, the number of possible keys is potentially too great to be enumerated even by modern machinery. However, not all keys are equally good. Badly chosen routes will leave excessive chunks of plaintext, or text simply reversed, and this will give cryptanalysts a clue as to the routes.
A variation of the route cipher was the Union Route Cipher, used by Union forces during the American Civil War. This worked much like an ordinary route cipher, but transposed whole words instead of individual letters. Because this would leave certain highly sensitive words exposed, such words would first be concealed by code. The cipher clerk may also add entire null words, which were often chosen to make the ciphertext humorous .

Columnar transposition.

In a columnar transposition, the message is written out in rows of a fixed length, and then read out again column by column, and the columns are chosen in some scrambled order. Both the width of the rows and the permutation of the columns are usually defined by a keyword. For example, the keyword ZEBRAS is of length 6 (so the rows are of length 6), and the permutation is defined by the alphabetical order of the letters in the keyword. In this case, the order would be "6 3 2 4 1 5".
In a regular columnar transposition cipher, any spare spaces are filled with nulls; in an irregular columnar transposition cipher, the spaces are left blank. Finally, the message is read off in columns, in the order specified by the keyword. For example, suppose we use the keyword ZEBRAS and the message WE ARE DISCOVERED. FLEE AT ONCE. In a regular columnar transposition, we write this into the grid as follows:

6 3 2 4 1 5
W E A R E D
I S C O V E 
R E D F L E 
E A T O N C 
E Q K J E U

providing five nulls (QKJEU), these letters can be randomly selected as they just fill out the incomplete columns and are not part of the message. The ciphertext is then read off as:

EVLNE ACDTK ESEAQ ROFOJ DEECU WIREE

In the irregular case, the columns are not completed by nulls:

6 3 2 4 1 5
W E A R E D 
I S C O V E 
R E D F L E 
E A T O N C 
E

This results in the following ciphertext:

EVLNA CDTES EAROF ODEEC WIREE

To decipher it, the recipient has to work out the column lengths by dividing the message length by the key length. Then he can write the message out in columns again, then re-order the columns by reforming the key word.
In a variation, the message is blocked into segments that are the key length long and to each segment the same permutation (given by the key) is applied. This is equivalent to a columnar transposition where the read-out is by rows instead of columns.
Columnar transposition continued to be used for serious purposes as a component of more complex ciphers at least into the 1950s.

Double transposition

A single columnar transposition could be attacked by guessing possible column lengths, writing the message out in its columns (but in the wrong order, as the key is not yet known), and then looking for possible anagrams. Thus to make it stronger, a double transposition was often used. This is simply a columnar transposition applied twice. The same key can be used for both transpositions, or two different keys can be used.
As an example, we can take the result of the irregular columnar transposition in the previous section, and perform a second encryption with a different keyword, STRIPE, which gives the permutation "564231":

5 6 4 2 3 1 
E V L N A C
D T E S E A
R O F O D E
E C W I R E
E

As before, this is read off columnwise to give the ciphertext:

CAEEN SOIAE DRLEF WEDRE EVTOC

If multiple messages of exactly the same length are encrypted using the same keys, they can be anagrammed simultaneously. This can lead to both recovery of the messages, and to recovery of the keys (so that every other message sent with those keys can be read).
During World War I, the German military used a double columnar transposition cipher, changing the keys infrequently. The system was regularly solved by the French, naming it Übchi, who were typically able to quickly find the keys once they'd intercepted a number of messages of the same length, which generally took only a few days. However, the French success became widely known and, after a publication in Le Matin, the Germans changed to a new system on 18 November 1914.
During World War II, the double transposition cipher was used by Dutch Resistance groups, the French Maquis and the British Special Operations Executive (SOE), which was in charge of managing underground activities in Europe.^[3] It was also used by agents of the American Office of Strategic Services^[4] and as an emergency cipher for the German Army and Navy.
Until the invention of the VIC cipher, double transposition was generally regarded as the most complicated cipher that an agent could operate reliably under difficult field conditions.
In late 2013, the double transposition problem was solved by George Lasry.

Myszkowski transposition

A variant form of columnar transposition, proposed by Émile Victor Théodore Myszkowski in 1902, requires a keyword with recurrent letters. In usual practice, subsequent occurrences of a keyword letter are treated as if the next letter in alphabetical order, e.g., the keyword TOMATO yields a numeric keystring of "532164."
In Myszkowski transposition, recurrent keyword letters are numbered identically, TOMATO yielding a keystring of "432143."

4 3 2 1 4 3
W E A R E D
I S C O V E
R E D F L E
E A T O N C
E

Plaintext columns with unique numbers are transcribed downward; those with recurring numbers are transcribed left to right:

ROFOA CDTED SEEEA CWEIV RLENE

Disrupted transposition

In a disrupted transposition, certain positions in a grid are blanked out, and not used when filling in the plaintext. This breaks up regular patterns and makes the cryptanalyst's job more difficult.

Grilles

Another form of transposition cipher uses grilles, or physical masks with cut-outs. This can produce a highly irregular transposition over the period specified by the size of the grille, but requires the correspondents to keep a physical key secret. Grilles were first proposed in 1550, and were still in military use for the first few months of World War One.

Scytale

A cipher from ancient Greek times that was used to make encryptions. The device used to make these ciphers was a rod with a polygon base, which was wrapped in paper. People then, could write on the paper horizontally. When the paper was removed from the device, it would make a strip of letters that seemed randomized. The only way to read the message would be to have a Scytale machine of your own.

Detection and cryptanalysis

Since transposition does not affect the frequency of individual symbols, simple transposition can be easily detected by the cryptanalyst by doing a frequency count. If the ciphertext exhibits a frequency distribution very similar to plaintext, it is most likely a transposition. This can then often be attacked by anagramming—sliding pieces of ciphertext around, then looking for sections that look like anagrams of English words, and solving the anagrams. Once such anagrams have been found, they reveal information about the transposition pattern, and can consequently be extended.
Simpler transpositions also often suffer from the property that keys very close to the correct key will reveal long sections of legible plaintext interspersed by gibberish. Consequently, such ciphers may be vulnerable to optimum seeking algorithms such as genetic algorithms.
A detailed description of the cryptanalysis of a German transposition cipher can be found in chapter 7 of Herbert Yardley's "The American Black Chamber."

Combinations

Transposition is often combined with other techniques such as evaluation methods. For example, a simple substitution cipher combined with a columnar transposition avoids the weakness of both. Replacing high frequency ciphertext symbols with high frequency plaintext letters does not reveal chunks of plaintext because of the transposition. Anagramming the transposition does not work because of the substitution. The technique is particularly powerful if combined with fractionation (see below). A disadvantage is that such ciphers are considerably more laborious and error prone than simpler ciphers.

Fractionation

Transposition is particularly effective when employed with fractionation - that is, a preliminary stage that divides each plaintext symbol into several ciphertext symbols. For example, the plaintext alphabet could be written out in a grid, then every letter in the message replaced by its co-ordinates Another method of fractionation is to simply convert the message to Morse code, with a symbol for spaces as well as dots and dashes.
When such a fractionated message is transposed, the components of individual letters become widely separated in the message, thus achieving Claude E. Shannon's diffusion. Examples of ciphers that combine fractionation and transposition include the bifid cipher, the trifid cipher, the ADFGVX cipher and the VIC cipher.
Another choice would be to replace each letter with its binary representation, transpose that, and then convert the new binary string into the corresponding ASCII characters. Looping the scrambling process on the binary string multiple times before changing it into ASCII characters would likely make it harder to break. Many modern block ciphers use more complex forms of transposition related to this simple idea.

[1]

[4]

[5]

[6]

[7]

[8]

[9]

[

[3]

[4]

decibans	exact value	approx. value	approx. ratio	accurate ratio	probability
0	10^0/10	1	1:1		50%
1	10^1/10	1.26	5:4		56%
2	10^2/10	1.58	3:2	8:5	61%
3	10^3/10	2.00	2:1		67%
4	10^4/10	2.51	5:2		71.5%
5	10^5/10	3.16	3:1	19:6, 16:5	76%
6	10^6/10	3.98	4:1		80%
7	10^7/10	5.01	5:1		83%
8	10^8/10	6.31	6:1	19:3, 25:4	86%
9	10^9/10	7.94	8:1		89%
10	10^10/10	10	10:1		91%

×	1	2	10	11	12	20	21	22	100
1	1	2	10	11	12	20	21	22	100
2	2	11	20	22	101	110	112	121	200
10	10	20	100	110	120	200	210	220	1000
11	11	22	110	121	202	220	1001	1012	1100
12	12	101	120	202	221	1010	1022	1111	1200
20	20	110	200	220	1010	1100	1120	1210	2000
21	21	112	210	1001	1022	1120	1211	2002	2100
22	22	121	220	1012	1111	1210	2002	2101	2200
100	100	200	1000	1100	1200	2000	2100	2200	10000

Ternary	1	2	10	11	12	20	21	22	100
Binary	1	10	11	100	101	110	111	1000	1001
Decimal	1	2	3	4	5	6	7	8	9

Ternary	101	102	110	111	112	120	121	122	200
Binary	1010	1011	1100	1101	1110	1111	10000	10001	10010
Decimal	10	11	12	13	14	15	16	17	18

Ternary	201	202	210	211	212	220	221	222	1000
Binary	10011	10100	10101	10110	10111	11000	11001	11010	11011
Decimal	19	20	21	22	23	24	25	26	27

Ternary	1	10	100	1 000	10 000
Binary	1	11	1001	1 1011	101 0001
Decimal	1	3	9	27	81
Power	3⁰	3¹	3²	3³	3⁴

Ternary	100 000	1 000 000	10 000 000	100 000 000	1 000 000 000
Binary	1111 0011	10 1101 1001	1000 1000 1011	1 1001 1010 0001	100 1100 1110 0011
Decimal	243	729	2 187	6 561	19 683
Power	3⁵	3⁶	3⁷	3⁸	3⁹

Fraction	1/2	1/3	1/4	1/5	1/6	1/7	1/8	1/9	1/10	1/11	1/12	1/13
Ternary	0.1	0.1	0.02	0.0121	0.01	0.010212	0.01	0.01	0.0022	0.00211	0.002	0.002
Binary	0.1	0.01	0.01	0.0011	0.001	0.001	0.001	0.000111	0.00011	0.0001011101	0.0001	0.000100111011
Decimal	0.5	0.3	0.25	0.2	0.16	0.142857	0.125	0.1	0.1	0.09	0.083	0.076923

Minggu, 03 Desember 2017

electronic equipment usability in finance and business strategy AMNIMARJESLOW GOVERNMENT 91220017 LOR STATUE EL BUSINESS AT ELECTRONIC CITY STRATEGY 02096010014 LJBUSAF XAM$ YES AND NOT JES STATUE

Business model

Revenue model

E-commerce

Concerns

Security

Privacy and confidentiality

Authenticity

Data integrity

Non-repudiation

Access control

Availability

Cost

Security solutions

Access and data integrity

Encryption

Digital certificates

Digital signatures

Definition

Impact

Response

Name

Design principles

Meaning

Effects

Challenges

Role of big data and analytics

Impact of Industry 4.0

Technology Roadmap for Industry 4.0

Motivation

Technology

Development

OFFICE SYSTEMS

TYPES OF TECHNOLOGIES

Intranets and Internets

Web Pages

Web-Based E-Mail

Voice Mail

Electronic Calendars

Office Suites

Portable PCs

Groupware and Decision Support Systems

Teleconferencing

Voice Recognition and Videoconferencing

Multimedia System

Electronic Whiteboard

Smart Board

RECORDS MANAGEMENT

COMMUNICATION IN ORGANIZATIONS

Integrity types

Physical integrity

Logical integrity

Databases

Types of integrity constraints

Examples

File systems

Data storage

Message authentication

Deniable authentication

Deniable encryption

Function

Scenario

Forms of deniable encryption

Detection

Drawbacks

Deniable authentication

Software

How it works

Variations

Implications for law enforcement

Trivia

Classical cryptography

Usage

Rail Fence cipher

Route cipher

Columnar transposition.

Double transposition

Myszkowski transposition

Disrupted transposition