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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: pignet
cipher variations:
qjhofu rkipgv sljqhw tmkrix unlsjy
vomtkz wpnula xqovmb yrpwnc zsqxod
atrype buszqf cvtarg dwubsh exvcti
fywduj gzxevk hayfwl ibzgxm jcahyn
kdbizo lecjap mfdkbq ngelcr ohfmds

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: pignet
Cipher: krtmvg

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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: pignet

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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: pignet
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: pignet
Cipher: cvtarg

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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: pignet
Cipher: 534222335144

Extended Methods:
Method #1

Plaintext: pignet
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
p i g n e t 
5 4 2 3 5 4 
3 2 2 3 1 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: pignet
Cipher: umuhmq

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Method #3

Plaintext: pignet
method variations:
sgmxqy gmxqys mxqysg
xqysgm qysgmx ysgmxq

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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: pignet

all 720 cipher variations:
pignet pignte pigent pigetn pigten pigtne pinget pingte pinegt pinetg pinteg
pintge piengt pientg piegnt piegtn pietgn pietng pitneg pitnge piteng pitegn
pitgen pitgne pginet pginte pgient pgietn pgiten pgitne pgniet pgnite pgneit
pgneti pgntei pgntie pgenit pgenti pgeint pgeitn pgetin pgetni pgtnei pgtnie
pgteni pgtein pgtien pgtine pngiet pngite pngeit pngeti pngtei pngtie pniget
pnigte pniegt pnietg pniteg pnitge pneigt pneitg pnegit pnegti pnetgi pnetig
pntieg pntige pnteig pntegi pntgei pntgie pegnit pegnti pegint pegitn pegtin
pegtni pengit pengti penigt penitg pentig pentgi peingt peintg peignt peigtn
peitgn peitng petnig petngi peting petign petgin petgni ptgnei ptgnie ptgeni
ptgein ptgien ptgine ptngei ptngie ptnegi ptneig ptnieg ptnige ptengi ptenig
ptegni ptegin pteign pteing ptineg ptinge ptieng ptiegn ptigen ptigne ipgnet
ipgnte ipgent ipgetn ipgten ipgtne ipnget ipngte ipnegt ipnetg ipnteg ipntge
ipengt ipentg ipegnt ipegtn ipetgn ipetng iptneg iptnge ipteng iptegn iptgen
iptgne igpnet igpnte igpent igpetn igpten igptne ignpet ignpte ignept ignetp
igntep igntpe igenpt igentp igepnt igeptn igetpn igetnp igtnep igtnpe igtenp
igtepn igtpen igtpne ingpet ingpte ingept ingetp ingtep ingtpe inpget inpgte
inpegt inpetg inpteg inptge inepgt ineptg inegpt inegtp inetgp inetpg intpeg
intpge intepg integp intgep intgpe iegnpt iegntp iegpnt iegptn iegtpn iegtnp
iengpt iengtp ienpgt ienptg ientpg ientgp iepngt iepntg iepgnt iepgtn ieptgn
ieptng ietnpg ietngp ietpng ietpgn ietgpn ietgnp itgnep itgnpe itgenp itgepn
itgpen itgpne itngep itngpe itnegp itnepg itnpeg itnpge itengp itenpg itegnp
itegpn itepgn itepng itpneg itpnge itpeng itpegn itpgen itpgne gipnet gipnte
gipent gipetn gipten giptne ginpet ginpte ginept ginetp gintep gintpe gienpt
gientp giepnt gieptn gietpn gietnp gitnep gitnpe gitenp gitepn gitpen gitpne
gpinet gpinte gpient gpietn gpiten gpitne gpniet gpnite gpneit gpneti gpntei
gpntie gpenit gpenti gpeint gpeitn gpetin gpetni gptnei gptnie gpteni gptein
gptien gptine gnpiet gnpite gnpeit gnpeti gnptei gnptie gnipet gnipte gniept
gnietp gnitep gnitpe gneipt gneitp gnepit gnepti gnetpi gnetip gntiep gntipe
gnteip gntepi gntpei gntpie gepnit gepnti gepint gepitn geptin geptni genpit
genpti genipt genitp gentip gentpi geinpt geintp geipnt geiptn geitpn geitnp
getnip getnpi getinp getipn getpin getpni gtpnei gtpnie gtpeni gtpein gtpien
gtpine gtnpei gtnpie gtnepi gtneip gtniep gtnipe gtenpi gtenip gtepni gtepin
gteipn gteinp gtinep gtinpe gtienp gtiepn gtipen gtipne nigpet nigpte nigept
nigetp nigtep nigtpe nipget nipgte nipegt nipetg nipteg niptge niepgt nieptg
niegpt niegtp nietgp nietpg nitpeg nitpge nitepg nitegp nitgep nitgpe ngipet
ngipte ngiept ngietp ngitep ngitpe ngpiet ngpite ngpeit ngpeti ngptei ngptie
ngepit ngepti ngeipt ngeitp ngetip ngetpi ngtpei ngtpie ngtepi ngteip ngtiep
ngtipe npgiet npgite npgeit npgeti npgtei npgtie npiget npigte npiegt npietg
npiteg npitge npeigt npeitg npegit npegti npetgi npetig nptieg nptige npteig
nptegi nptgei nptgie negpit negpti negipt negitp negtip negtpi nepgit nepgti
nepigt nepitg neptig neptgi neipgt neiptg neigpt neigtp neitgp neitpg netpig
netpgi netipg netigp netgip netgpi ntgpei ntgpie ntgepi ntgeip ntgiep ntgipe
ntpgei ntpgie ntpegi ntpeig ntpieg ntpige ntepgi ntepig ntegpi ntegip nteigp
nteipg ntipeg ntipge ntiepg ntiegp ntigep ntigpe eignpt eigntp eigpnt eigptn
eigtpn eigtnp eingpt eingtp einpgt einptg eintpg eintgp eipngt eipntg eipgnt
eipgtn eiptgn eiptng eitnpg eitngp eitpng eitpgn eitgpn eitgnp eginpt egintp
egipnt egiptn egitpn egitnp egnipt egnitp egnpit egnpti egntpi egntip egpnit
egpnti egpint egpitn egptin egptni egtnpi egtnip egtpni egtpin egtipn egtinp
engipt engitp engpit engpti engtpi engtip enigpt enigtp enipgt eniptg enitpg
enitgp enpigt enpitg enpgit enpgti enptgi enptig entipg entigp entpig entpgi
entgpi entgip epgnit epgnti epgint epgitn epgtin epgtni epngit epngti epnigt
epnitg epntig epntgi epingt epintg epignt epigtn epitgn epitng eptnig eptngi
epting eptign eptgin eptgni etgnpi etgnip etgpni etgpin etgipn etginp etngpi
etngip etnpgi etnpig etnipg etnigp etpngi etpnig etpgni etpgin etpign etping
etinpg etingp etipng etipgn etigpn etignp tignep tignpe tigenp tigepn tigpen
tigpne tingep tingpe tinegp tinepg tinpeg tinpge tiengp tienpg tiegnp tiegpn
tiepgn tiepng tipneg tipnge tipeng tipegn tipgen tipgne tginep tginpe tgienp
tgiepn tgipen tgipne tgniep tgnipe tgneip tgnepi tgnpei tgnpie tgenip tgenpi
tgeinp tgeipn tgepin tgepni tgpnei tgpnie tgpeni tgpein tgpien tgpine tngiep
tngipe tngeip tngepi tngpei tngpie tnigep tnigpe tniegp tniepg tnipeg tnipge
tneigp tneipg tnegip tnegpi tnepgi tnepig tnpieg tnpige tnpeig tnpegi tnpgei
tnpgie tegnip tegnpi teginp tegipn tegpin tegpni tengip tengpi tenigp tenipg
tenpig tenpgi teingp teinpg teignp teigpn teipgn teipng tepnig tepngi teping
tepign tepgin tepgni tpgnei tpgnie tpgeni tpgein tpgien tpgine tpngei tpngie
tpnegi tpneig tpnieg tpnige tpengi tpenig tpegni tpegin tpeign tpeing tpineg
tpinge tpieng tpiegn tpigen tpigne

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History of cryptography
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