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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: morije
cipher variations:
npsjkf oqtklg prulmh qsvmni rtwnoj
suxopk tvypql uwzqrm vxarsn wybsto
xzctup yaduvq zbevwr acfwxs bdgxyt
cehyzu dfizav egjabw fhkbcx gilcdy
hjmdez iknefa jlofgb kmpghc lnqhid

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: morije
Cipher: nlirqv

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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: morije

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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: morije
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: morije
Cipher: zbevwr

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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: morije
Cipher: 234324424251

Extended Methods:
Method #1

Plaintext: morije
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
m o r i j e 
2 4 2 4 4 5 
3 3 4 2 2 1 
They are then read out in rows:
Then divided up into pairs again, and the pairs turned back into letters using the square:
Plain: morije
Cipher: rrynib

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Method #3

Plaintext: morije
method variations:
shtrwf htrwfs trwfsh
rwfsht wfshtr fshtrw

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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: morije

all 720 cipher variations:
morije moriej morjie morjei moreji moreij moirje moirej moijre moijer moiejr
moierj mojire mojier mojrie mojrei mojeri mojeir moeijr moeirj moejir moejri
moerji moerij mroije mroiej mrojie mrojei mroeji mroeij mrioje mrioej mrijoe
mrijeo mriejo mrieoj mrjioe mrjieo mrjoie mrjoei mrjeoi mrjeio mreijo mreioj
mrejio mrejoi mreoji mreoij miroje miroej mirjoe mirjeo mirejo mireoj miorje
miorej miojre miojer mioejr mioerj mijore mijoer mijroe mijreo mijero mijeor
mieojr mieorj miejor miejro mierjo mieroj mjrioe mjrieo mjroie mjroei mjreoi
mjreio mjiroe mjireo mjiore mjioer mjieor mjiero mjoire mjoier mjorie mjorei
mjoeri mjoeir mjeior mjeiro mjeoir mjeori mjeroi mjerio merijo merioj merjio
merjoi meroji meroij meirjo meiroj meijro meijor meiojr meiorj mejiro mejior
mejrio mejroi mejori mejoir meoijr meoirj meojir meojri meorji meorij omrije
omriej omrjie omrjei omreji omreij omirje omirej omijre omijer omiejr omierj
omjire omjier omjrie omjrei omjeri omjeir omeijr omeirj omejir omejri omerji
omerij ormije ormiej ormjie ormjei ormeji ormeij orimje orimej orijme orijem
oriejm oriemj orjime orjiem orjmie orjmei orjemi orjeim oreijm oreimj orejim
orejmi oremji oremij oirmje oirmej oirjme oirjem oirejm oiremj oimrje oimrej
oimjre oimjer oimejr oimerj oijmre oijmer oijrme oijrem oijerm oijemr oiemjr
oiemrj oiejmr oiejrm oierjm oiermj ojrime ojriem ojrmie ojrmei ojremi ojreim
ojirme ojirem ojimre ojimer ojiemr ojierm ojmire ojmier ojmrie ojmrei ojmeri
ojmeir ojeimr ojeirm ojemir ojemri ojermi ojerim oerijm oerimj oerjim oerjmi
oermji oermij oeirjm oeirmj oeijrm oeijmr oeimjr oeimrj oejirm oejimr oejrim
oejrmi oejmri oejmir oemijr oemirj oemjir oemjri oemrji oemrij romije romiej
romjie romjei romeji romeij roimje roimej roijme roijem roiejm roiemj rojime
rojiem rojmie rojmei rojemi rojeim roeijm roeimj roejim roejmi roemji roemij
rmoije rmoiej rmojie rmojei rmoeji rmoeij rmioje rmioej rmijoe rmijeo rmiejo
rmieoj rmjioe rmjieo rmjoie rmjoei rmjeoi rmjeio rmeijo rmeioj rmejio rmejoi
rmeoji rmeoij rimoje rimoej rimjoe rimjeo rimejo rimeoj riomje riomej riojme
riojem rioejm rioemj rijome rijoem rijmoe rijmeo rijemo rijeom rieojm rieomj
riejom riejmo riemjo riemoj rjmioe rjmieo rjmoie rjmoei rjmeoi rjmeio rjimoe
rjimeo rjiome rjioem rjieom rjiemo rjoime rjoiem rjomie rjomei rjoemi rjoeim
rjeiom rjeimo rjeoim rjeomi rjemoi rjemio remijo remioj remjio remjoi remoji
remoij reimjo reimoj reijmo reijom reiojm reiomj rejimo rejiom rejmio rejmoi
rejomi rejoim reoijm reoimj reojim reojmi reomji reomij iormje iormej iorjme
iorjem iorejm ioremj iomrje iomrej iomjre iomjer iomejr iomerj iojmre iojmer
iojrme iojrem iojerm iojemr ioemjr ioemrj ioejmr ioejrm ioerjm ioermj iromje
iromej irojme irojem iroejm iroemj irmoje irmoej irmjoe irmjeo irmejo irmeoj
irjmoe irjmeo irjome irjoem irjeom irjemo iremjo iremoj irejmo irejom ireojm
ireomj imroje imroej imrjoe imrjeo imrejo imreoj imorje imorej imojre imojer
imoejr imoerj imjore imjoer imjroe imjreo imjero imjeor imeojr imeorj imejor
imejro imerjo imeroj ijrmoe ijrmeo ijrome ijroem ijreom ijremo ijmroe ijmreo
ijmore ijmoer ijmeor ijmero ijomre ijomer ijorme ijorem ijoerm ijoemr ijemor
ijemro ijeomr ijeorm ijerom ijermo iermjo iermoj ierjmo ierjom ierojm ieromj
iemrjo iemroj iemjro iemjor iemojr iemorj iejmro iejmor iejrmo iejrom iejorm
iejomr ieomjr ieomrj ieojmr ieojrm ieorjm ieormj jorime joriem jormie jormei
joremi joreim joirme joirem joimre joimer joiemr joierm jomire jomier jomrie
jomrei jomeri jomeir joeimr joeirm joemir joemri joermi joerim jroime jroiem
jromie jromei jroemi jroeim jriome jrioem jrimoe jrimeo jriemo jrieom jrmioe
jrmieo jrmoie jrmoei jrmeoi jrmeio jreimo jreiom jremio jremoi jreomi jreoim
jirome jiroem jirmoe jirmeo jiremo jireom jiorme jiorem jiomre jiomer jioemr
jioerm jimore jimoer jimroe jimreo jimero jimeor jieomr jieorm jiemor jiemro
jiermo jierom jmrioe jmrieo jmroie jmroei jmreoi jmreio jmiroe jmireo jmiore
jmioer jmieor jmiero jmoire jmoier jmorie jmorei jmoeri jmoeir jmeior jmeiro
jmeoir jmeori jmeroi jmerio jerimo jeriom jermio jermoi jeromi jeroim jeirmo
jeirom jeimro jeimor jeiomr jeiorm jemiro jemior jemrio jemroi jemori jemoir
jeoimr jeoirm jeomir jeomri jeormi jeorim eorijm eorimj eorjim eorjmi eormji
eormij eoirjm eoirmj eoijrm eoijmr eoimjr eoimrj eojirm eojimr eojrim eojrmi
eojmri eojmir eomijr eomirj eomjir eomjri eomrji eomrij eroijm eroimj erojim
erojmi eromji eromij eriojm eriomj erijom erijmo erimjo erimoj erjiom erjimo
erjoim erjomi erjmoi erjmio ermijo ermioj ermjio ermjoi ermoji ermoij eirojm
eiromj eirjom eirjmo eirmjo eirmoj eiorjm eiormj eiojrm eiojmr eiomjr eiomrj
eijorm eijomr eijrom eijrmo eijmro eijmor eimojr eimorj eimjor eimjro eimrjo
eimroj ejriom ejrimo ejroim ejromi ejrmoi ejrmio ejirom ejirmo ejiorm ejiomr
ejimor ejimro ejoirm ejoimr ejorim ejormi ejomri ejomir ejmior ejmiro ejmoir
ejmori ejmroi ejmrio emrijo emrioj emrjio emrjoi emroji emroij emirjo emiroj
emijro emijor emiojr emiorj emjiro emjior emjrio emjroi emjori emjoir emoijr
emoirj emojir emojri emorji emorij

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