Equivoe-T: Transposition equivocation cryptography
View Patent ↗Equivoe-T complements its erosive cryptographic intractability with durable cryptographic equivocation. The captured ciphertext C generated through plaintext P using key K, may also be generated via a ‘fake plaintext’ P′≠P using a different key, K′≠K, presenting the cryptanalyst with a conclusive doubt as to the identity of the true plaintext. Prospectively there will be numerous plausible non-overlapping plaintext candidates, all guarding the identity of the true plaintext.
1. A method to transpose a plaintext list P n comprised of n elements to build a different permutation ciphertext C, to any of the possible n! permutations, using a secret key K comprised of a positive integer R greater than 1 and a positive integer g greater or equal to 1, the method comprising the steps of:
(i) constructing a list P n+g of (n+g) elements by placing g copies of ghost symbols within P n in a predetermined order, wherein the n elements in P n do not contain the ghost symbol, and n is greater or equal to 1; then
(ii) counting R elements from the first element in the list P n+g , wherein when the counting reaches the last element in the list P n+g , the counting continues at the first element of the list P n+g as the next element in the counting; then
(iii) identifying the element in the list P n+g where the counting of the R elements stopped, and removing that element to yield a new list P n+g-1 comprised of (n+g−1) elements; then
(iv) adding the removed element as a first element in a permutation ciphertext C; then
(v) starting another count of R elements in the list P n+g-1 from the next element of the removed element, wherein when the counting reaches the last element in the list P n+g-1 , the counting continues at the first element of the list P n+g-1 as the next element in the counting; then
(vi) identifying the element in the list P n+g-1 where the counting of the R elements stopped, and removing that element to yield a new list P n+g-2 comprised of (n+g−2) elements; then
(vii) adding the removed element from the list P n+g-1 as a new element in the permutation ciphertext C next to the first element; then
(viii) recursively repeating the counting-removing-and-adding sequence for the next n+g−2 times to yield the permutation ciphertext C with n+g elements (C n+g ); then
(ix) removing the g ghost symbol elements in the permutation ciphertext C n+g , resulting in a permutation ciphertext C n of n elements.
2. The method of claim 1 , further comprising the steps to reverse-transpose the permutation C n to the plaintext list P n by:
(x) creating a list of n elements, P # n as P # n =t 1# , t 2# , . . . , t n # , then
(xi) placing g copies of the ghost symbols within P # n , in the same way as in step (i) thereby creating a list of (n+g) elements, P # n+g , then
(xii) applying the process of steps (ii) through step (ix) to P # n+g , resulting in a permutation of C # n denoted as C t # n , where each element t i # for i=1, 2, . . . n will be in position j, and written as t ij , then
(xiii) constructing the reverse-transpose of C n by placing element t ij in position i, for j=1, 2, . . . n.
3. The method in claim 1 wherein the direction of counting is altered in some pre-agreed pattern.
4. The method in claim 1 applied over a list plaintext P n+m+1 comprised of n+m+1 elements constructed from a secret message P n comprised of n data elements, a subsequent marker symbol, followed by m data elements, which are regarded as decoy message, thereby constructing a permutation of P n+m+1 .