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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: magnus
cipher variations:
nbhovt ocipwu pdjqxv qekryw rflszx
sgmtay thnubz uiovca vjpwdb wkqxec
xlryfd ymszge zntahf aoubig bpvcjh
cqwdki drxelj esyfmk ftzgnl guahom
hvbipn iwcjqo jxdkrp kyelsq lzfmtr

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: magnus
Cipher: nztmfh

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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: magnus

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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: magnus
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: magnus
Cipher: zntahf

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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: magnus
Cipher: 231122335434

Extended Methods:
Method #1

Plaintext: magnus
method variations:

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

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Method #3

Plaintext: magnus
method variations:
cfmxoi fmxoic mxoicf
xoicfm oicfmx icfmxo

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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: magnus

all 720 cipher variations:
magnus magnsu maguns magusn magsun magsnu mangus mangsu manugs manusg mansug
mansgu maungs maunsg maugns maugsn mausgn mausng masnug masngu masung masugn
masgun masgnu mganus mgansu mgauns mgausn mgasun mgasnu mgnaus mgnasu mgnuas
mgnusa mgnsua mgnsau mgunas mgunsa mguans mguasn mgusan mgusna mgsnua mgsnau
mgsuna mgsuan mgsaun mgsanu mngaus mngasu mnguas mngusa mngsua mngsau mnagus
mnagsu mnaugs mnausg mnasug mnasgu mnuags mnuasg mnugas mnugsa mnusga mnusag
mnsaug mnsagu mnsuag mnsuga mnsgua mnsgau mugnas mugnsa mugans mugasn mugsan
mugsna mungas mungsa munags munasg munsag munsga muangs muansg muagns muagsn
muasgn muasng musnag musnga musang musagn musgan musgna msgnua msgnau msguna
msguan msgaun msganu msngua msngau msnuga msnuag msnaug msnagu msunga msunag
msugna msugan msuagn msuang msanug msangu msaung msaugn msagun msagnu amgnus
amgnsu amguns amgusn amgsun amgsnu amngus amngsu amnugs amnusg amnsug amnsgu
amungs amunsg amugns amugsn amusgn amusng amsnug amsngu amsung amsugn amsgun
amsgnu agmnus agmnsu agmuns agmusn agmsun agmsnu agnmus agnmsu agnums agnusm
agnsum agnsmu agunms agunsm agumns agumsn agusmn agusnm agsnum agsnmu agsunm
agsumn agsmun agsmnu angmus angmsu angums angusm angsum angsmu anmgus anmgsu
anmugs anmusg anmsug anmsgu anumgs anumsg anugms anugsm anusgm anusmg ansmug
ansmgu ansumg ansugm ansgum ansgmu augnms augnsm augmns augmsn augsmn augsnm
aungms aungsm aunmgs aunmsg aunsmg aunsgm aumngs aumnsg aumgns aumgsn aumsgn
aumsng ausnmg ausngm ausmng ausmgn ausgmn ausgnm asgnum asgnmu asgunm asgumn
asgmun asgmnu asngum asngmu asnugm asnumg asnmug asnmgu asungm asunmg asugnm
asugmn asumgn asumng asmnug asmngu asmung asmugn asmgun asmgnu gamnus gamnsu
gamuns gamusn gamsun gamsnu ganmus ganmsu ganums ganusm gansum gansmu gaunms
gaunsm gaumns gaumsn gausmn gausnm gasnum gasnmu gasunm gasumn gasmun gasmnu
gmanus gmansu gmauns gmausn gmasun gmasnu gmnaus gmnasu gmnuas gmnusa gmnsua
gmnsau gmunas gmunsa gmuans gmuasn gmusan gmusna gmsnua gmsnau gmsuna gmsuan
gmsaun gmsanu gnmaus gnmasu gnmuas gnmusa gnmsua gnmsau gnamus gnamsu gnaums
gnausm gnasum gnasmu gnuams gnuasm gnumas gnumsa gnusma gnusam gnsaum gnsamu
gnsuam gnsuma gnsmua gnsmau gumnas gumnsa gumans gumasn gumsan gumsna gunmas
gunmsa gunams gunasm gunsam gunsma guanms guansm guamns guamsn guasmn guasnm
gusnam gusnma gusanm gusamn gusman gusmna gsmnua gsmnau gsmuna gsmuan gsmaun
gsmanu gsnmua gsnmau gsnuma gsnuam gsnaum gsnamu gsunma gsunam gsumna gsuman
gsuamn gsuanm gsanum gsanmu gsaunm gsaumn gsamun gsamnu nagmus nagmsu nagums
nagusm nagsum nagsmu namgus namgsu namugs namusg namsug namsgu naumgs naumsg
naugms naugsm nausgm nausmg nasmug nasmgu nasumg nasugm nasgum nasgmu ngamus
ngamsu ngaums ngausm ngasum ngasmu ngmaus ngmasu ngmuas ngmusa ngmsua ngmsau
ngumas ngumsa nguams nguasm ngusam ngusma ngsmua ngsmau ngsuma ngsuam ngsaum
ngsamu nmgaus nmgasu nmguas nmgusa nmgsua nmgsau nmagus nmagsu nmaugs nmausg
nmasug nmasgu nmuags nmuasg nmugas nmugsa nmusga nmusag nmsaug nmsagu nmsuag
nmsuga nmsgua nmsgau nugmas nugmsa nugams nugasm nugsam nugsma numgas numgsa
numags numasg numsag numsga nuamgs nuamsg nuagms nuagsm nuasgm nuasmg nusmag
nusmga nusamg nusagm nusgam nusgma nsgmua nsgmau nsguma nsguam nsgaum nsgamu
nsmgua nsmgau nsmuga nsmuag nsmaug nsmagu nsumga nsumag nsugma nsugam nsuagm
nsuamg nsamug nsamgu nsaumg nsaugm nsagum nsagmu uagnms uagnsm uagmns uagmsn
uagsmn uagsnm uangms uangsm uanmgs uanmsg uansmg uansgm uamngs uamnsg uamgns
uamgsn uamsgn uamsng uasnmg uasngm uasmng uasmgn uasgmn uasgnm uganms ugansm
ugamns ugamsn ugasmn ugasnm ugnams ugnasm ugnmas ugnmsa ugnsma ugnsam ugmnas
ugmnsa ugmans ugmasn ugmsan ugmsna ugsnma ugsnam ugsmna ugsman ugsamn ugsanm
ungams ungasm ungmas ungmsa ungsma ungsam unagms unagsm unamgs unamsg unasmg
unasgm unmags unmasg unmgas unmgsa unmsga unmsag unsamg unsagm unsmag unsmga
unsgma unsgam umgnas umgnsa umgans umgasn umgsan umgsna umngas umngsa umnags
umnasg umnsag umnsga umangs umansg umagns umagsn umasgn umasng umsnag umsnga
umsang umsagn umsgan umsgna usgnma usgnam usgmna usgman usgamn usganm usngma
usngam usnmga usnmag usnamg usnagm usmnga usmnag usmgna usmgan usmagn usmang
usanmg usangm usamng usamgn usagmn usagnm sagnum sagnmu sagunm sagumn sagmun
sagmnu sangum sangmu sanugm sanumg sanmug sanmgu saungm saunmg saugnm saugmn
saumgn saumng samnug samngu samung samugn samgun samgnu sganum sganmu sgaunm
sgaumn sgamun sgamnu sgnaum sgnamu sgnuam sgnuma sgnmua sgnmau sgunam sgunma
sguanm sguamn sguman sgumna sgmnua sgmnau sgmuna sgmuan sgmaun sgmanu sngaum
sngamu snguam snguma sngmua sngmau snagum snagmu snaugm snaumg snamug snamgu
snuagm snuamg snugam snugma snumga snumag snmaug snmagu snmuag snmuga snmgua
snmgau sugnam sugnma suganm sugamn sugman sugmna sungam sungma sunagm sunamg
sunmag sunmga suangm suanmg suagnm suagmn suamgn suamng sumnag sumnga sumang
sumagn sumgan sumgna smgnua smgnau smguna smguan smgaun smganu smngua smngau
smnuga smnuag smnaug smnagu smunga smunag smugna smugan smuagn smuang smanug
smangu smaung smaugn smagun smagnu

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