Decrypting Text

Frequency analysis

Encrypted text is sometimes achieved by replacing one letter by another. To start deciphering the encryption it is useful to get a frequency count of all the letters. The most frequent letter may represent the most common letter in English E followed by T, A, O and I whereas the least frequent are Q, Z and X. Common percentages in standard English are:

a	b	c	d	e	f	g	h	i	j	k	l	m
8.2	1.5	2.8	4.3	12.7	2.2	2.0	6.1	7.0	0.2	0.8	4.0	2.4
n	o	p	q	r	s	t	u	v	w	x	y	z
6.7	7.5	1.9	0.1	6.0	6.3	9.1	2.8	1.0	2.4	0.2	2.0	0.1

and ranked in order:

e	t	a	o	i	n	s	h	r	d	l	u	c
12.7	9.1	8.2	7.5	7.0	6.7	6.3	6.1	6.0	4.3	4.0	2.8	2.8
m	w	f	y	g	p	b	v	k	x	j	q	z
2.4	2.4	2.2	2.0	2.0	1.9	1.5	1.0	0.8	0.2	0.2	0.1	0.1

Common pairs are consonants TH and vowels EA. Others are OF, TO, IN, IT, IS, BE, AS, AT, SO, WE, HE, BY, OR, ON, DO, IF, ME, MY, UP. Common pairs of repeated letters are SS, EE, TT, FF, LL, MM and OO. Common triplets of text are THE, EST, FOR, AND, HIS, ENT or THA.

If the results show that E followed by T are the most common letters then the ciphertext may be a transposition cipher rather than a substitution. If one of the characters has a 20% frequency then the language could be German since it has a high percentage of E. Italian has 3 letters with a frequency greater than 10% and 9 characters are less than 1%.

The box below contains example ciphertext. You can paste any text that you want to decipher over this example text. Press the button. Useful statistics will appear.

Enter your ciphertext below:

usklp lfxyn mqmsn xisgl tysnq ywwyv zsfkk qnwks wrvqh vswiy rvqps wwsyv olool hswyv wswmq xsyvw lifpp svsnu ssxln lkcws vsusm msnxn qxvsl hsnxk qulkl fnxsv usrxs kluqv vswrq nilnu suqis ssnxv soloo lhssx wswis ybuqm rkfus wksrv qpsww syvae slxwx qnssx kluqm xswws kqzsk lussn wsmok suswq nxxvq fwisw swrvf xwksw rkywq vfhfn lybis ksyvh snsvl xfqnf kwsmo kstyf kwwsv lfsnx fmrkf tyswi lnwks iszsk qrrsm snxiy nsmlu efnsr qyvkl uqifp fulxf qnlyx qmlxf tysis wmsww lhswu styfw svlfx ynsms nlusx svvfo ksrqy vkswf nxsvs xwisk loskk spvln usnqy wsxyi fqnwk lrqww fofkf xsisp lfvsi swuqr fswws uvsxs wisus wrkln wsnyx fkfwl nxksw cwxsm sfnhs nfsyb ismil hysvv szsyf kksdv srvsn ivsuq nxlux wfkzq ywrkl fxlzs ukszq ksyvt yfswx wqyru qnnsw sxvqy zsvlw qyxel mrxqn fknsp lfxly uyniq yxsty susxv lfxvs iswus ksvlx zlues vuesv lfmrq wsvwq nrvfb usufv skszs isklr kywel yxsfm rqvxl nusnl xfqnl ksplf wlnxk qogsx isklw lnuxf qnisk qyfwr efkfr rskyf msmss xrqyv vlfxm snlus vklkk flnus tyliv yrksw fuskl xqmol fxsnx vsism lyzlf wswml fnwxq yxsuq vvswr qniln uspyx yvsuq nusvn lnxus rvqrq wiszv llzqf vynuq iszfh snsvs ryfwt yfksw xfmrq wwfok slisu qisv

Display more than  occurrences of repeated small substrings

 Click here to show percentages of single letters