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Vigenère cipher

Calculator encrypts entered text by using Vigenère cipher. Non-alphabetic symbols (digits, whitespaces, etc.) are not transformed.

Since we already have Caesar cipher, it seems logical to add Vigenère cipher as well. Here is the calculator, which transforms entered text (encrypt or decrypt) using Vigenere cipher.

The algorithm is quite simple. Vigenère cipher is the sequence of Caesar ciphers with different transformations (ROTX, see Caesar cipher). For example, first letter of text is transformed using ROT5, second - using ROT17, et cetera. The sequence is defined by keyword, where each letter defines needed shift. Phrase LEMON, for example, defines the sequence of ROT11-ROT4-ROT12-ROT14-ROT13, which is repeated until all block of text is encrypted.

As wikipedia tells us, it is a simple form of polyalphabetic substitution. The idea behind the Vigenère cipher, like all polyalphabetic ciphers, is to disguise plaintext letter frequencies, which interferes with a straightforward application of frequency analysis. For instance, if P is the most frequent letter in a ciphertext whose plaintext is in English, one might suspect that P corresponds to E, because E is the most frequently used letter in English. However, using the Vigenère cipher, E can be enciphered as different ciphertext letters at different points in the message, thus defeating simple frequency analysis.
The primary weakness of the Vigenère cipher is the repeating nature of its key. If a cryptanalyst correctly guesses the key's length, then the cipher text can be treated as interwoven Caesar ciphers, which individually are easily broken.

The running key variant of the Vigenère cipher was also considered unbreakable at one time. This version uses as the key a block of text as long as the plaintext. The problem with the running key Vigenère cipher is that the cryptanalyst has statistical information about the key (assuming that the block of text is in a known language) and that information will be reflected in the ciphertext.
If using a key which is truly random, is at least as long as the encrypted message and is used only once, the Vigenère cipher is theoretically unbreakable. However, in this case it is the key, not the cipher, which provides cryptographic strength and such systems are properly referred to collectively as one-time pad systems, irrespective of which ciphers are employed.

Created on PLANETCALC

Vigenère cipher

Transformed text
cpnf
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Comments

NOAH21 day ago

BORINGGGGGGGGG

Aviel1 month ago

ne'ie eo jtiaegvrj tf lfvv

Key: RA
yfu bnfw khv rllvs rnu sf df i
r fllc cfmdikmvnk's nhrt z'm khznbieg ff
pol wfucde't xek tyij fiod aey ftyei gly
z jlsk wrnea kecl pol hfw z'm wevlznx
gftka dabe pol uedvrjtrnu
nvvvr xoenr gzvv yfu lp
eemei gfnea cek yfu uonn
eemei gfnea iue aiolnu aed uejeit pol
nvvvr xoenr mrkv yfu trp
nvvvr xoenr sry xofdsyv
nvvvr xoenr tvlc a civ aed yuit pol
wv'vv keonn vath ftyei ffr jo coeg
polr yerrk's sevn rcyieg suk yfu'ie kof syy ko jap ik
ieszdv wv bfty keon wyak's sevn xoznx oe
wv keon tye xade rnu wv'rv gfnea glry zt
rnu iw yfu rsb mv hfw z'm wevlznx
dfn'k tvlc mv yfu'ie kof bcied ko jev
nvvvr xoenr gzvv yfu lp
eemei gfnea cek yfu uonn
eemei gfnea iue aiolnu aed uejeit pol
nvvvr xoenr mrkv yfu trp
nvvvr xoenr sry xofdsyv
nvvvr xoenr tvlc a civ aed yuit pol
nvvvr xoenr gzvv yfu lp
eemei gfnea cek yfu uonn
eemei gfnea iue aiolnu aed uejeit pol
nvvvr xoenr mrkv yfu trp
nvvvr xoenr sry xofdsyv
nvvvr xoenr tvlc a civ aed yuit pol
nvvvr xoenr gzvv, nvvvr xoenr gzvv
(gzvv yfu lp)
(foy) nvvvr xoenr gzvv, nvvvr xoenr gzvv
(gzvv yfu lp)
ne'me bnfwe ercy okhvr woi sf lfnx
yfui hvait'j bvee athznx blt pol'rv tfo jhp tf sry zt
znjiue ne sokh bnfw nhrt'j bvee gfieg fn
ne bnfw khv grmv aed ne'ie xoenr pcap ik
i aujt naenr tvlc yfu yon i'd fvecieg
xoktr mrkv yfu lnueiskaed
eemei gfnea xime pol ug
nvvvr xoenr lvt pol dfwe
nvvvr xoenr rln rrfued rnu dvsvrk yfu
eemei gfnea dabe pol ciy
eemei gfnea jap gfoubpe
eemei gfnea kecl r lze rnu hlrk yfu
eemei gfnea xime pol ug
nvvvr xoenr lvt pol dfwe
nvvvr xoenr rln rrfued rnu dvsvrk yfu
eemei gfnea dabe pol ciy
eemei gfnea jap gfoubpe
eemei gfnea kecl r lze rnu hlrk yfu
eemei gfnea xime pol ug
nvvvr xoenr lvt pol dfwe
nvvvr xoenr rln rrfued rnu dvsvrk yfu
eemei gfnea dabe pol ciy

Meridith2 months ago

How much is a tabula recta worth

Bekka2 months ago

EAEMA QAAYI IQEA

Charles Bol’shevikov4 months ago

cvvn: [srsvau ykl cifuwai a "ucfgsfu" bhhgbb] ugy, v knahrf tb dhfv gje oiggca, niyzvnb!
ykl: lch joav tus ohhgqn, cvvyzvr? ybi pnb'g jaaryr hug bhhgbb!
npgrzvpo: lqu ooovsf crr of qizd hrfr ng lqu nfr nh uqmr.
rvy: [osvee krghvpg uwzfsyh] wrs, jrs!
npgrzvpo: 'pgpg vvz. vr'u scsnxwai fesapv nnrroql.

Key: NONCANON

inscrito cineloucura show7 months ago

qyem veio pelo cineloucura show

Patrick Murphy10 months ago

bmkypwvhqr
mizc: uwpmpmf ayappwr saos
tjmilvrlcew: lzrvr bkb u
wcamaie: iifgll frocqs
shick eixh: avdbe n
cmev: h/s
zij: izvtp rqtnl t
zwar: lxs koevzq kil
hwtqqoym: kpbfhu ofe
vsj iculy: tapvkq hvp q
ivrvwlrr: wjpvkg hvmqu riczhr (kitklefprz)
vcypuupigb: aif mq
vvcoswa

Apophis10 months ago

Vi Attende

Apophis10 months ago

La

Apophis10 months ago

Morte

nameless10 months ago

ocdx wu fzvszcjvi... uz xxruc.

tam rcimi pscee eir isovvsdm qfffmhkx ehjzgxa oxem mzcxefw.
jhra qfesdc tai bfvvipceh i esxnszc ch dqff.
gi bckxzu jvwids, thvfw zgxqfv, lyu qrftu fflwa grgkgs.
v gi bifb zqrvki, ysix gadzx, zuqzgs mzc'bqbcexrfs vepugjx.

ioqf... bp ssebs.
occnm ovv gsz csuipwjvi mucb sdrzgm.
occhva qyx rq hihzmbf wm zifom.

INSPT11 months ago

lgri uzxvkg lg nsdtuyjsisrmuz

Enois12 months ago

rechirrcw evs ceo qlihran

Challenge 1 letter key1 year ago

znoy oy gt kyyge. ghuaz zxasv. euax cutjkxlar vxkyojktz. zngz cgy ygxigyzoi. nk qotjg yaiqy. haz zngz payz se uvotout. uq?

Chancellor Palpetine1 year ago

sah dgn ntyq anyg llj lkjeycr xd ssvyz iuyatxrq izi baln? g nghdewl rtl. bc’q hnm j qigvd lan hycb fmjdh yweu wit. bc’q p kmyz eneymw. mygll udtpsyhl fyh s hfjd umlc ho rww wnla, bm jnpnpump ffw bm qhln ft uszdw dqy san ddjgj lh rlzknnlrw xmw frbcbaumgaesk mx aldtcc aajj… zx qyx rnlf p crtoenbad ho rww hfjd bgxd mqyi zi hgnub yuxw itwt yzx xlyr an apjii suxsn ekxk sqmsy. mqc xzkt qxvi tx mqc znklc xk e usmquux mx kpfc ftbugnhxb qdei hggbgxdk cm qw ysftcslze. qc qwgfex bm jnpnpump… yzx xlfx mqgcy lj otb yzqtrb dx afk exqcmz qgh hsbwk, ffcba nttfxzseuw, ie vxsgki, mw wrb. omyxpimrflxuw, bd mjsvzx mal jnjqxwrxui jnxawngbwe ww oswp, cfym arq phtwwgcgwd drjawh maf rl bhl bjtwt. njhwgw. gx lmjdh xson mngxaq ujsr vxjrb, anc ldl lnelnjz.

Matrixbyte Cyberhacker1 year ago

jg v dbo efdjqifs uijt ufyu v bsf hpjoh up lopx xifo uif xpsme xjmm cffo eftuspzfe cz bmjfot:
bu uif ebz: 29
npoui: pdupcfs
zfbs: uxp,afsp,gjwf,pof
bu uijt ebz bmjfot xjmm dpnf up ljmm fwfszpof boe nvubuf uif xpsme, jg v xbou up tupq uifn, ifmq nf boe tfoe uif djqifs/fodszqufe ufyu up puifs qfpqmf, jg v bsf hpjoh up tfoe uif efdszqufe ufyu uif xpsme jt hpjoh up hfu eftuspzfe fbsmjfs

decrypt this text easy and u know when they earth will be destroyed, the key length is 1

Matrixbyte Cyberhacker1 year ago

decrypt kjsuecbh mc hr ckk.vkl.qrs obg rccn lcf ixss sufb!!! with key good

7771 year ago

key is key rykkr gc fcsre nsr msk

kieran1 year ago

hivx wt ft qpbq!

azamat1 year ago

vigenere "" must decrypt this messsage

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