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Caesar cipher

Caesar cipher, is one of the simplest and most widely known encryption techniques. The transformation can be represented by aligning two alphabets, the cipher alphabet is the plain alphabet rotated left or right by some number of positions.

When encrypting, a person looks up each letter of the message in the 'plain' line and writes down the corresponding letter in the 'cipher' line. Deciphering is done in reverse.
The encryption can also be represented using modular arithmetic by first transforming the letters into numbers, according to the scheme, A = 0, B = 1,..., Z = 25. Encryption of a letter x by a shift n can be described mathematically as

Plaintext: xadwin
cipher variations:
ybexjo zcfykp adgzlq behamr cfibns
dgjcot ehkdpu fileqv gjmfrw hkngsx
ilohty jmpiuz knqjva lorkwb mpslxc
nqtmyd orunze psvoaf qtwpbg ruxqch
svyrdi twzsej uxatfk vybugl wzcvhm

Decryption is performed similarly,

(There are different definitions for the modulo operation. In the above, the result is in the range 0...25. I.e., if x+n or x-n are not in the range 0...25, we have to subtract or add 26.)
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Atbash Cipher

Atbash is an ancient encryption system created in the Middle East. It was originally used in the Hebrew language.
The Atbash cipher is a simple substitution cipher that relies on transposing all the letters in the alphabet such that the resulting alphabet is backwards.
The first letter is replaced with the last letter, the second with the second-last, and so on.
An example plaintext to ciphertext using Atbash:
Plain: xadwin
Cipher: czwdrm

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Baconian Cipher

To encode a message, each letter of the plaintext is replaced by a group of five of the letters 'A' or 'B'. This replacement is done according to the alphabet of the Baconian cipher, shown below.
a   AAAAA   g    AABBA     m    ABABB   s    BAAAB     y    BABBA
b   AAAAB   h    AABBB     n    ABBAA   t    BAABA     z    BABBB
c   AAABA   i    ABAAA     o    ABBAB   u    BAABB 
d   AAABB   j    BBBAA     p    ABBBA   v    BBBAB
e   AABAA   k    ABAAB     q    ABBBB   w    BABAA
f   AABAB   l    ABABA     r    BAAAA   x    BABAB

Plain: xadwin

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Affine Cipher
In the affine cipher the letters of an alphabet of size m are first mapped to the integers in the range 0..m - 1. It then uses modular arithmetic to transform the integer that each plaintext letter corresponds to into another integer that correspond to a ciphertext letter. The encryption function for a single letter is

where modulus m is the size of the alphabet and a and b are the key of the cipher. The value a must be chosen such that a and m are coprime.
Considering the specific case of encrypting messages in English (i.e. m = 26), there are a total of 286 non-trivial affine ciphers, not counting the 26 trivial Caesar ciphers. This number comes from the fact there are 12 numbers that are coprime with 26 that are less than 26 (these are the possible values of a). Each value of a can have 26 different addition shifts (the b value) ; therefore, there are 12*26 or 312 possible keys.
Plaintext: xadwin
cipher variations:

The decryption function is

where a - 1 is the modular multiplicative inverse of a modulo m. I.e., it satisfies the equation

The multiplicative inverse of a only exists if a and m are coprime. Hence without the restriction on a decryption might not be possible. It can be shown as follows that decryption function is the inverse of the encryption function,

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ROT13 Cipher
Applying ROT13 to a piece of text merely requires examining its alphabetic characters and replacing each one by the letter 13 places further along in the alphabet, wrapping back to the beginning if necessary. A becomes N, B becomes O, and so on up to M, which becomes Z, then the sequence continues at the beginning of the alphabet: N becomes A, O becomes B, and so on to Z, which becomes M. Only those letters which occur in the English alphabet are affected; numbers, symbols, whitespace, and all other characters are left unchanged. Because there are 26 letters in the English alphabet and 26 = 2 * 13, the ROT13 function is its own inverse:

ROT13(ROT13(x)) = x for any basic Latin-alphabet text x

An example plaintext to ciphertext using ROT13:

Plain: xadwin
Cipher: knqjva

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Polybius Square

A Polybius Square is a table that allows someone to translate letters into numbers. To give a small level of encryption, this table can be randomized and shared with the recipient. In order to fit the 26 letters of the alphabet into the 25 spots created by the table, the letters i and j are usually combined.
1 2 3 4 5
1 A B C D E
2 F G H I/J K
3 L M N O P
4 Q R S T U
5 V W X Y Z

Basic Form:
Plain: xadwin
Cipher: 351141254233

Extended Methods:
Method #1

Plaintext: xadwin
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
x a d w i n 
3 1 4 2 4 3 
5 1 1 5 2 3 
They are then read out in rows:
Then divided up into pairs again, and the pairs turned back into letters using the square:
Plain: xadwin
Cipher: cioevm

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Method #3

Plaintext: xadwin
method variations:
eqfumn qfumne fumneq
umneqf mneqfu neqfum

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Permutation Cipher
In classical cryptography, a permutation cipher is a transposition cipher in which the key is a permutation. To apply a cipher, a random permutation of size E is generated (the larger the value of E the more secure the cipher). The plaintext is then broken into segments of size E and the letters within that segment are permuted according to this key.
In theory, any transposition cipher can be viewed as a permutation cipher where E is equal to the length of the plaintext; this is too cumbersome a generalisation to use in actual practice, however.
The idea behind a permutation cipher is to keep the plaintext characters unchanged, butalter their positions by rearrangement using a permutation
This cipher is defined as:
Let m be a positive integer, and K consist of all permutations of {1,...,m}
For a key (permutation) , define:
The encryption function
The decryption function
A small example, assuming m = 6, and the key is the permutation :

The first row is the value of i, and the second row is the corresponding value of (i)
The inverse permutation, is constructed by interchanging the two rows, andrearranging the columns so that the first row is in increasing order, Therefore, is:

Total variation formula:

e = 2,718281828 , n - plaintext length

Plaintext: xadwin

all 720 cipher variations:
xadwin xadwni xadiwn xadinw xadniw xadnwi xawdin xawdni xawidn xawind xawnid
xawndi xaiwdn xaiwnd xaidwn xaidnw xaindw xainwd xanwid xanwdi xaniwd xanidw
xandiw xandwi xdawin xdawni xdaiwn xdainw xdaniw xdanwi xdwain xdwani xdwian
xdwina xdwnia xdwnai xdiwan xdiwna xdiawn xdianw xdinaw xdinwa xdnwia xdnwai
xdniwa xdniaw xdnaiw xdnawi xwdain xwdani xwdian xwdina xwdnia xwdnai xwadin
xwadni xwaidn xwaind xwanid xwandi xwiadn xwiand xwidan xwidna xwinda xwinad
xwnaid xwnadi xwniad xwnida xwndia xwndai xidwan xidwna xidawn xidanw xidnaw
xidnwa xiwdan xiwdna xiwadn xiwand xiwnad xiwnda xiawdn xiawnd xiadwn xiadnw
xiandw xianwd xinwad xinwda xinawd xinadw xindaw xindwa xndwia xndwai xndiwa
xndiaw xndaiw xndawi xnwdia xnwdai xnwida xnwiad xnwaid xnwadi xniwda xniwad
xnidwa xnidaw xniadw xniawd xnawid xnawdi xnaiwd xnaidw xnadiw xnadwi axdwin
axdwni axdiwn axdinw axdniw axdnwi axwdin axwdni axwidn axwind axwnid axwndi
axiwdn axiwnd axidwn axidnw axindw axinwd axnwid axnwdi axniwd axnidw axndiw
axndwi adxwin adxwni adxiwn adxinw adxniw adxnwi adwxin adwxni adwixn adwinx
adwnix adwnxi adiwxn adiwnx adixwn adixnw adinxw adinwx adnwix adnwxi adniwx
adnixw adnxiw adnxwi awdxin awdxni awdixn awdinx awdnix awdnxi awxdin awxdni
awxidn awxind awxnid awxndi awixdn awixnd awidxn awidnx awindx awinxd awnxid
awnxdi awnixd awnidx awndix awndxi aidwxn aidwnx aidxwn aidxnw aidnxw aidnwx
aiwdxn aiwdnx aiwxdn aiwxnd aiwnxd aiwndx aixwdn aixwnd aixdwn aixdnw aixndw
aixnwd ainwxd ainwdx ainxwd ainxdw aindxw aindwx andwix andwxi andiwx andixw
andxiw andxwi anwdix anwdxi anwidx anwixd anwxid anwxdi aniwdx aniwxd anidwx
anidxw anixdw anixwd anxwid anxwdi anxiwd anxidw anxdiw anxdwi daxwin daxwni
daxiwn daxinw daxniw daxnwi dawxin dawxni dawixn dawinx dawnix dawnxi daiwxn
daiwnx daixwn daixnw dainxw dainwx danwix danwxi daniwx danixw danxiw danxwi
dxawin dxawni dxaiwn dxainw dxaniw dxanwi dxwain dxwani dxwian dxwina dxwnia
dxwnai dxiwan dxiwna dxiawn dxianw dxinaw dxinwa dxnwia dxnwai dxniwa dxniaw
dxnaiw dxnawi dwxain dwxani dwxian dwxina dwxnia dwxnai dwaxin dwaxni dwaixn
dwainx dwanix dwanxi dwiaxn dwianx dwixan dwixna dwinxa dwinax dwnaix dwnaxi
dwniax dwnixa dwnxia dwnxai dixwan dixwna dixawn dixanw dixnaw dixnwa diwxan
diwxna diwaxn diwanx diwnax diwnxa diawxn diawnx diaxwn diaxnw dianxw dianwx
dinwax dinwxa dinawx dinaxw dinxaw dinxwa dnxwia dnxwai dnxiwa dnxiaw dnxaiw
dnxawi dnwxia dnwxai dnwixa dnwiax dnwaix dnwaxi dniwxa dniwax dnixwa dnixaw
dniaxw dniawx dnawix dnawxi dnaiwx dnaixw dnaxiw dnaxwi wadxin wadxni wadixn
wadinx wadnix wadnxi waxdin waxdni waxidn waxind waxnid waxndi waixdn waixnd
waidxn waidnx waindx wainxd wanxid wanxdi wanixd wanidx wandix wandxi wdaxin
wdaxni wdaixn wdainx wdanix wdanxi wdxain wdxani wdxian wdxina wdxnia wdxnai
wdixan wdixna wdiaxn wdianx wdinax wdinxa wdnxia wdnxai wdnixa wdniax wdnaix
wdnaxi wxdain wxdani wxdian wxdina wxdnia wxdnai wxadin wxadni wxaidn wxaind
wxanid wxandi wxiadn wxiand wxidan wxidna wxinda wxinad wxnaid wxnadi wxniad
wxnida wxndia wxndai widxan widxna widaxn widanx widnax widnxa wixdan wixdna
wixadn wixand wixnad wixnda wiaxdn wiaxnd wiadxn wiadnx wiandx wianxd winxad
winxda winaxd winadx windax windxa wndxia wndxai wndixa wndiax wndaix wndaxi
wnxdia wnxdai wnxida wnxiad wnxaid wnxadi wnixda wnixad wnidxa wnidax wniadx
wniaxd wnaxid wnaxdi wnaixd wnaidx wnadix wnadxi iadwxn iadwnx iadxwn iadxnw
iadnxw iadnwx iawdxn iawdnx iawxdn iawxnd iawnxd iawndx iaxwdn iaxwnd iaxdwn
iaxdnw iaxndw iaxnwd ianwxd ianwdx ianxwd ianxdw iandxw iandwx idawxn idawnx
idaxwn idaxnw idanxw idanwx idwaxn idwanx idwxan idwxna idwnxa idwnax idxwan
idxwna idxawn idxanw idxnaw idxnwa idnwxa idnwax idnxwa idnxaw idnaxw idnawx
iwdaxn iwdanx iwdxan iwdxna iwdnxa iwdnax iwadxn iwadnx iwaxdn iwaxnd iwanxd
iwandx iwxadn iwxand iwxdan iwxdna iwxnda iwxnad iwnaxd iwnadx iwnxad iwnxda
iwndxa iwndax ixdwan ixdwna ixdawn ixdanw ixdnaw ixdnwa ixwdan ixwdna ixwadn
ixwand ixwnad ixwnda ixawdn ixawnd ixadwn ixadnw ixandw ixanwd ixnwad ixnwda
ixnawd ixnadw ixndaw ixndwa indwxa indwax indxwa indxaw indaxw indawx inwdxa
inwdax inwxda inwxad inwaxd inwadx inxwda inxwad inxdwa inxdaw inxadw inxawd
inawxd inawdx inaxwd inaxdw inadxw inadwx nadwix nadwxi nadiwx nadixw nadxiw
nadxwi nawdix nawdxi nawidx nawixd nawxid nawxdi naiwdx naiwxd naidwx naidxw
naixdw naixwd naxwid naxwdi naxiwd naxidw naxdiw naxdwi ndawix ndawxi ndaiwx
ndaixw ndaxiw ndaxwi ndwaix ndwaxi ndwiax ndwixa ndwxia ndwxai ndiwax ndiwxa
ndiawx ndiaxw ndixaw ndixwa ndxwia ndxwai ndxiwa ndxiaw ndxaiw ndxawi nwdaix
nwdaxi nwdiax nwdixa nwdxia nwdxai nwadix nwadxi nwaidx nwaixd nwaxid nwaxdi
nwiadx nwiaxd nwidax nwidxa nwixda nwixad nwxaid nwxadi nwxiad nwxida nwxdia
nwxdai nidwax nidwxa nidawx nidaxw nidxaw nidxwa niwdax niwdxa niwadx niwaxd
niwxad niwxda niawdx niawxd niadwx niadxw niaxdw niaxwd nixwad nixwda nixawd
nixadw nixdaw nixdwa nxdwia nxdwai nxdiwa nxdiaw nxdaiw nxdawi nxwdia nxwdai
nxwida nxwiad nxwaid nxwadi nxiwda nxiwad nxidwa nxidaw nxiadw nxiawd nxawid
nxawdi nxaiwd nxaidw nxadiw nxadwi

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History of cryptography
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