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Letters and Their Frequencies

Letter Occurence Rates

Useful for determining if cyphertext is simple transposition (instead of substitution).

Vowels, with or without Y about 40% (with variation between 35% and 45%)
Consonants: L N R S T about 30% (with variation between 25% and 35%)
Consonants: J K Q X Z about 2% (may be influenced by nulls)

Single Letter Frequency

Useful for determining if cyphertext is simple 1:1 substitution

E 1231
T 959
A 805
O 794
N 719
I 718
S 659
R 603
H 514
L 403
D 365
C 320
U 310
P 229
F 228
M 225
W 203
Y 188
B 162
G 161
V 93
K 52
Q 20
X 20
J 10
Z 9

Letter Contacts

1981 F(4) L(4) C(5) D(5) M(5) N(6) S(6) W(7) T(8) R(8) E(11) H(14) A N(21) T(17) S(12) R(10) L(8) D(5) C(4) M(4) 694
5545 Y(4) B(4) N(5) T(5) U(8) D(9)O(9) S(10) A(16) E(16) B E(34) L(17) U(11) O(9) A(7) Y(5) B(4) R(4) 7030
6139 U(4) O(5) S(8) N(13) A(13) I(18) E(20) C H(19) O(19) E(17) A(13) I(7) T(6) R(4) L(4) K(4) 5941
5248 R(4) I(5) L(6) A(10) N(29) E(39) D E(16) I(14) T(14) A(10) O(8) S(6) U(5) 5446
892 C(4) B(4) E(5) M(5) V(5) D(5) S(5) L(5) N(6) T(6) R(11) H(24) E R(15) D(10) S(9) N(8)A(7) T(6) M(5) E(4) C(4) O(4) W(4) 2179
6931 S(4) N(5) F(5) D(5) A(6) I(7) E(12) O(41) F T(22) O(21) E(10) I(9) A(7) R(5) F(5) U(4) 5248
3664 O(4) D(4) U(5) R(5) I(9) E(9) A(10) N(48) G E(14) H(14) O(12) E(10) A(8) T(6) F(5) W(4) I(4) S(4) 4258
793 O(4) E(5) W(5) S(7) C(9) T(62) H E(50) A(23) I(12) I(7) 9010
1387 F(4) M(4) W(5) E(6) N(6) L(8) D(8) S(8) R(9) H(11) T(14) I N(25) T(13) S(10) O(8) C(7) R(4) E(4) M(4) A(4) L(4) 1783
2872 Y(7) W(7) T(7) S(7) N(7) E(7) C(7) B(7) A(14) M(29 J U(35) O(29) A(12) E(12)M(6) W(6) 8812
5347 Y(5) U(5) I(5) N(7) A(11) R(13) E(13) O(15) C(18) K E(34) I(21) N(10) A(9) T(7) S(6) 6832
5248 N(4) P(4) T(6) I(7) B(7) U(7) O(10) E(11) L(11) A(17) L E(19) I(15) Y(12) L(12) O(9) A(8) D(7) U(4) 6535
3931 S(4) D(4) M(5) R(5) I(12) A(13) O(16) E(24) M E(26) A(17) O(12) I(11) P(5) M(5) 7129
8911 U(7) E(14) O(22) A(23) I(24) N D(16) T(14) G(12) E(10) A(7) S(7) O(7) I(6) C(5) 3268
2179 M(4) O(4) D(4) L(4) P(4) H(5) N(6) E(6) C(7) F(7) S(8) I(8) R(9) T(11) O N(20) F(14) R(11) U(10) T(6) M(5) L(5) S(4) W(4) O(4) 1882
4753 R(4) L(4) T(4) N(4) I(4) P(6) M(6) A(7) O(8) U(10) E(16) S(17) P O(17) E(16) A(15) R(15) L(8) U(6) P(6) T(5) I(5) S(4) 5941
2080 O(10) N(10) L(10) E(10) D(10) R(20) S(30) Q U(100) 100--
7030 P(5) I(5) U(5) T(7) A(13) O(16) E(30) R E(23) O(12) A(11) T(11) I(10) S(7) Y(4) 6139
4852 D(4) T(4) O(6) U(6) R(7) N(8) S(9) I(11) A(16) E(18) S T(19) E(11) O(10) I(9) S(9) A(8) H(6) P(5) U(4) 4149
4357 U(4) O(5) D(6) T(6) F(7) R(7) E(8) I(10) N(10) S(13) A(14) T H(39) I(10) O(10) E(8) A(7) T(6) R(4) 3862
3565 P(5) F(5) T(5) L(5) B(6) D(8) S(9) O(30) U N(18) S(13) T(13) R(12) L(10) P(7) B(4) C(4) 892
8812 R(6) U(10) O(16) A(16) I(16) E(30) V E(65) I(14) O(9) A(8) 991
4852 G(4) D(4) Y(5) N(9) S(10) T(11) O(16) E(23) W A(27) H(16) I(16) E(15) O(11) N(4) 8020
955 U(5) N(5) I(16) E(74) X P(29) T(19) I(14) A(14) U(10) C(5) K(5) O(5) 3862
2476 B(4) N(8) A(8) T(13) E(14) R(15) L(25) Y A(15) O(12) S(12) T(9) W(7) H(5) I(5) E(5) D(4) M(4) B(4) 3862
8812 O(12) N(12) A(25) I(50) Z E(43) I(43) W(14) 8614

All figures indicate percentages. - Taking any one letter, as A: On the left, it is contacted 14% of the time by H, 11% by E, etc., and 81% of its total contacts on that side were consonants. On the right, it was contacted 21% of the time by N, and 94% of the time by consonants.

Taken from Cryptanalysis: A Study of Cyphers and their Solutions by Helen Fouche Gainess