Undetectable Encryption via N-gram Rotation

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Solution Overview

Problem

Existing encryption methods are detectable by malicious entities, leading to easy interception and decryption, especially in open communication channels, and lack sufficient capacity for secure data transmission without drawing attention.

Innovation Solution

The method involves creating a syntax graph from an information support, encrypting secret information using a rotation of n-grams, and transmitting the rotated information, which maintains the appearance of natural language, making it undetectable by automated encryption detection mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If classic encryption techniques are used, then sensitive data can be protected from reading, but the encrypted streams become easily detectable by malicious entities

Engineering Contradiction:
Improvedata protectionVSAvoidencryption detectability
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent uses a cover text as an intermediary medium to hide the encrypted message. The encrypted data is embedded within the cover text in such a way that the cover text itself becomes the carrier, making the encrypted content undetectable while still allowing reliable transmission of sensitive information

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent transforms the encrypted message by changing its parameters - specifically, it embeds the encrypted data within the statistical parameters of the cover text (such as n-gram frequencies). This parameter transformation makes the encrypted content indistinguishable from normal text variations, solving both protection and undetectability requirements

Inventive Principle:
Principle #35Parameter changes

2Difficulty of detecting and measuring

If steganography techniques are used to hide secret information in images, then the secret information can be concealed, but the capacity for secret information transmission is very limited

Engineering Contradiction:
Improvesecret information concealmentVSAvoidsecret information capacity
Core Design Contradiction:
Difficulty of detecting and measuringVSQuantity of substance

Solution Approach 1:

The patent changes from image-based steganography to text-based steganography, utilizing the vast parameter space of natural language text (n-gram frequencies, letter distributions). This parameter change enables much larger capacity for hidden messages while maintaining concealment, as text can be generated indefinitely without attracting attention

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent makes the cover text serve multiple functions simultaneously: it acts as both the visible message and the hidden carrier of secret information. The same text that appears to be ordinary communication also encodes the secret message through its statistical properties, dramatically increasing capacity without requiring separate hidden channels

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3001402B8Undetectable encryption based on N-gram rotations
Publication Date: 2018.05.16 ALCATEL LUCENT SA

AI summary

This invention relates to a method for transmitting secret information (I_S) over a communication channel between a transmitter and a receiver, comprising : - determining by said transmitter a syntax graph G(T_S) from an information support T_S, wherein the nodes of said syntax graph G(T_S) represents the n-grams of a given size in said information support T_S, - encrypting said secret information I_S in a secret number N , - determining by said transmitter a rotation from said secret number N, the number N relative to the secret information I_S being smaller than the maximum number of rotations B(T_S), and decomposing said secret number N into a sequence representative of the permutations on each of the n-grams' outgoing edges, - applying said sequence on each of the n-grams' outgoing edges of the syntax graph G(T_S) in order to produce a rotated information T'_S.