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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: jduffy
cipher variations:
kevggz lfwhha mgxiib nhyjjc oizkkd
pjalle qkbmmf rlcnng smdooh tneppi
uofqqj vpgrrk wqhssl xrittm ysjuun
ztkvvo aulwwp bvmxxq cwnyyr dxozzs
eypaat fzqbbu garccv hbsddw icteex

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: jduffy
Cipher: qwfuub

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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: jduffy

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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: jduffy
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: jduffy
Cipher: wqhssl

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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: jduffy
Cipher: 424154121245

Extended Methods:
Method #1

Plaintext: jduffy
method variations:

Method #2
Bifid cipher
The message is converted to its coordinates in the usual manner, but they are written vertically beneath:
j d u f f y 
4 4 5 1 1 4 
2 1 4 2 2 5 
They are then read out in rows:
Then divided up into pairs again, and the pairs turned back into letters using the square:
Plain: jduffy
Cipher: teqbiw

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Method #3

Plaintext: jduffy
method variations:
rvdbru vdbrur dbrurv
brurvd rurvdb urvdbr

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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: jduffy

all 720 cipher variations:
jduffy jdufyf jduffy jdufyf jduyff jduyff jdfufy jdfuyf jdffuy jdffyu jdfyfu
jdfyuf jdffuy jdffyu jdfufy jdfuyf jdfyuf jdfyfu jdyffu jdyfuf jdyffu jdyfuf
jdyuff jdyuff judffy judfyf judffy judfyf judyff judyff jufdfy jufdyf juffdy
juffyd jufyfd jufydf juffdy juffyd jufdfy jufdyf jufydf jufyfd juyffd juyfdf
juyffd juyfdf juydff juydff jfudfy jfudyf jfufdy jfufyd jfuyfd jfuydf jfdufy
jfduyf jfdfuy jfdfyu jfdyfu jfdyuf jffduy jffdyu jffudy jffuyd jffyud jffydu
jfydfu jfyduf jfyfdu jfyfud jfyufd jfyudf jfufdy jfufyd jfudfy jfudyf jfuydf
jfuyfd jffudy jffuyd jffduy jffdyu jffydu jffyud jfdfuy jfdfyu jfdufy jfduyf
jfdyuf jfdyfu jfyfdu jfyfud jfydfu jfyduf jfyudf jfyufd jyuffd jyufdf jyuffd
jyufdf jyudff jyudff jyfufd jyfudf jyffud jyffdu jyfdfu jyfduf jyffud jyffdu
jyfufd jyfudf jyfduf jyfdfu jydffu jydfuf jydffu jydfuf jyduff jyduff djuffy
djufyf djuffy djufyf djuyff djuyff djfufy djfuyf djffuy djffyu djfyfu djfyuf
djffuy djffyu djfufy djfuyf djfyuf djfyfu djyffu djyfuf djyffu djyfuf djyuff
djyuff dujffy dujfyf dujffy dujfyf dujyff dujyff dufjfy dufjyf duffjy duffyj
dufyfj dufyjf duffjy duffyj dufjfy dufjyf dufyjf dufyfj duyffj duyfjf duyffj
duyfjf duyjff duyjff dfujfy dfujyf dfufjy dfufyj dfuyfj dfuyjf dfjufy dfjuyf
dfjfuy dfjfyu dfjyfu dfjyuf dffjuy dffjyu dffujy dffuyj dffyuj dffyju dfyjfu
dfyjuf dfyfju dfyfuj dfyufj dfyujf dfufjy dfufyj dfujfy dfujyf dfuyjf dfuyfj
dffujy dffuyj dffjuy dffjyu dffyju dffyuj dfjfuy dfjfyu dfjufy dfjuyf dfjyuf
dfjyfu dfyfju dfyfuj dfyjfu dfyjuf dfyujf dfyufj dyuffj dyufjf dyuffj dyufjf
dyujff dyujff dyfufj dyfujf dyffuj dyffju dyfjfu dyfjuf dyffuj dyffju dyfufj
dyfujf dyfjuf dyfjfu dyjffu dyjfuf dyjffu dyjfuf dyjuff dyjuff udjffy udjfyf
udjffy udjfyf udjyff udjyff udfjfy udfjyf udffjy udffyj udfyfj udfyjf udffjy
udffyj udfjfy udfjyf udfyjf udfyfj udyffj udyfjf udyffj udyfjf udyjff udyjff
ujdffy ujdfyf ujdffy ujdfyf ujdyff ujdyff ujfdfy ujfdyf ujffdy ujffyd ujfyfd
ujfydf ujffdy ujffyd ujfdfy ujfdyf ujfydf ujfyfd ujyffd ujyfdf ujyffd ujyfdf
ujydff ujydff ufjdfy ufjdyf ufjfdy ufjfyd ufjyfd ufjydf ufdjfy ufdjyf ufdfjy
ufdfyj ufdyfj ufdyjf uffdjy uffdyj uffjdy uffjyd uffyjd uffydj ufydfj ufydjf
ufyfdj ufyfjd ufyjfd ufyjdf ufjfdy ufjfyd ufjdfy ufjdyf ufjydf ufjyfd uffjdy
uffjyd uffdjy uffdyj uffydj uffyjd ufdfjy ufdfyj ufdjfy ufdjyf ufdyjf ufdyfj
ufyfdj ufyfjd ufydfj ufydjf ufyjdf ufyjfd uyjffd uyjfdf uyjffd uyjfdf uyjdff
uyjdff uyfjfd uyfjdf uyffjd uyffdj uyfdfj uyfdjf uyffjd uyffdj uyfjfd uyfjdf
uyfdjf uyfdfj uydffj uydfjf uydffj uydfjf uydjff uydjff fdujfy fdujyf fdufjy
fdufyj fduyfj fduyjf fdjufy fdjuyf fdjfuy fdjfyu fdjyfu fdjyuf fdfjuy fdfjyu
fdfujy fdfuyj fdfyuj fdfyju fdyjfu fdyjuf fdyfju fdyfuj fdyufj fdyujf fudjfy
fudjyf fudfjy fudfyj fudyfj fudyjf fujdfy fujdyf fujfdy fujfyd fujyfd fujydf
fufjdy fufjyd fufdjy fufdyj fufydj fufyjd fuyjfd fuyjdf fuyfjd fuyfdj fuydfj
fuydjf fjudfy fjudyf fjufdy fjufyd fjuyfd fjuydf fjdufy fjduyf fjdfuy fjdfyu
fjdyfu fjdyuf fjfduy fjfdyu fjfudy fjfuyd fjfyud fjfydu fjydfu fjyduf fjyfdu
fjyfud fjyufd fjyudf ffujdy ffujyd ffudjy ffudyj ffuydj ffuyjd ffjudy ffjuyd
ffjduy ffjdyu ffjydu ffjyud ffdjuy ffdjyu ffdujy ffduyj ffdyuj ffdyju ffyjdu
ffyjud ffydju ffyduj ffyudj ffyujd fyujfd fyujdf fyufjd fyufdj fyudfj fyudjf
fyjufd fyjudf fyjfud fyjfdu fyjdfu fyjduf fyfjud fyfjdu fyfujd fyfudj fyfduj
fyfdju fydjfu fydjuf fydfju fydfuj fydufj fydujf fdufjy fdufyj fdujfy fdujyf
fduyjf fduyfj fdfujy fdfuyj fdfjuy fdfjyu fdfyju fdfyuj fdjfuy fdjfyu fdjufy
fdjuyf fdjyuf fdjyfu fdyfju fdyfuj fdyjfu fdyjuf fdyujf fdyufj fudfjy fudfyj
fudjfy fudjyf fudyjf fudyfj fufdjy fufdyj fufjdy fufjyd fufyjd fufydj fujfdy
fujfyd fujdfy fujdyf fujydf fujyfd fuyfjd fuyfdj fuyjfd fuyjdf fuydjf fuydfj
ffudjy ffudyj ffujdy ffujyd ffuyjd ffuydj ffdujy ffduyj ffdjuy ffdjyu ffdyju
ffdyuj ffjduy ffjdyu ffjudy ffjuyd ffjyud ffjydu ffydju ffyduj ffyjdu ffyjud
ffyujd ffyudj fjufdy fjufyd fjudfy fjudyf fjuydf fjuyfd fjfudy fjfuyd fjfduy
fjfdyu fjfydu fjfyud fjdfuy fjdfyu fjdufy fjduyf fjdyuf fjdyfu fjyfdu fjyfud
fjydfu fjyduf fjyudf fjyufd fyufjd fyufdj fyujfd fyujdf fyudjf fyudfj fyfujd
fyfudj fyfjud fyfjdu fyfdju fyfduj fyjfud fyjfdu fyjufd fyjudf fyjduf fyjdfu
fydfju fydfuj fydjfu fydjuf fydujf fydufj yduffj ydufjf yduffj ydufjf ydujff
ydujff ydfufj ydfujf ydffuj ydffju ydfjfu ydfjuf ydffuj ydffju ydfufj ydfujf
ydfjuf ydfjfu ydjffu ydjfuf ydjffu ydjfuf ydjuff ydjuff yudffj yudfjf yudffj
yudfjf yudjff yudjff yufdfj yufdjf yuffdj yuffjd yufjfd yufjdf yuffdj yuffjd
yufdfj yufdjf yufjdf yufjfd yujffd yujfdf yujffd yujfdf yujdff yujdff yfudfj
yfudjf yfufdj yfufjd yfujfd yfujdf yfdufj yfdujf yfdfuj yfdfju yfdjfu yfdjuf
yffduj yffdju yffudj yffujd yffjud yffjdu yfjdfu yfjduf yfjfdu yfjfud yfjufd
yfjudf yfufdj yfufjd yfudfj yfudjf yfujdf yfujfd yffudj yffujd yffduj yffdju
yffjdu yffjud yfdfuj yfdfju yfdufj yfdujf yfdjuf yfdjfu yfjfdu yfjfud yfjdfu
yfjduf yfjudf yfjufd yjuffd yjufdf yjuffd yjufdf yjudff yjudff yjfufd yjfudf
yjffud yjffdu yjfdfu yjfduf yjffud yjffdu yjfufd yjfudf yjfduf yjfdfu yjdffu
yjdfuf yjdffu yjdfuf yjduff yjduff

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