Tool to extract letters from a message according to a pattern. It is possible to hide a text into another by adding parasites letters. Letters can follow a regular extraction pattern (eg: 1 letter of 2).
Letters Extraction - dCode
Tag(s) : Steganography, Data Processing
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Letters Extraction
Letters Extractor from a Text
Answers to Questions (FAQ)
What is a letter extraction? (Definition)
Extracting letters from text is the process of selecting and isolating individual letters from a text or string. This process can make it possible to reconstruct a subtext or a hidden word.
How to extract letters from a text?
Take the message ABCDEFGHIJKLMNOPQRSTUVWXYZ, dCode offers different modes for letters extraction:
Take 1 of N letters
Example: Taking 1 of 2 letters: A-C-E-G-I-K-M-O-O-O-U-W-Y-
Example: Taking 1 of 3 letters: A--D--G--J--M--P--S--V--Y-
Extract a pattern
Example: The pattern 2,3 means to take 1 letter each 2 and 1 letter each 3 steps: A-C--F-H--K-M--P-R--U-W--Z
Extract by mask (1 = preserved letter, 0 = letter ignored)
Example: Using the binary mask 101: A-CD-FG-IJ-LM-OP-RS-UV-XY
The patterns and masks are repeated until reaching the end of the message.
If needed, start using any letter rather than the first letter.
Example: Taking a letter of 2 (starting at position 1): A-C-E-G-I-K-M-O-O-O-U-W-Y-
Example: Taking a letter of 2 (starting at position 2): -B-D-F-H-J-L-N-P-R-T-V-X-Z
Punctuation may (or may not) be taken into account in characters count.
What are the most common patterns?
In addition to the 1 letter out of N (1 letter out of 2, 3 or 4), extracting the letters according to known sequences is possible:
— Sequence of even numbers: 2,4,6,8,10
— Sequence of prime numbers: 2,3,5,7,11
— Fibonacci sequence: 2,3,5,8,13
— Digits of Pi: 3,1,4,1,5,9
etc.
For all these sequences, it is possible to start at the letter 1 or at the letter N.
How to implement a function to extract 1 letter out of N?
To isolate 1 letter every N, here is an algorithm // Pseudo-code
function extractLetters1ofN(text, n) {
extracted = ""
textLength = length(text)
for (i = 0 ; i < textLength; i++) {
if (i % N == 0) extracted += text[i]
}
return extracted
}
How to extract letters in Excel?
Although this is not practical, Excel provides functions such as RIGHT() or LEFT() to extract N letters at the beginning or end of words. (dCode is better and recommended)
What is an acrostic?
An acrostic is a poem or message from which certain letters or words can be extracted to give a second meaning to the message.
Source code
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