Cipher rules and reference guides
Valid Affine Cipher Keys and Modular Inverses
Find a valid Affine key, look up its inverse, and understand why other values fail.
Open Valid Affine Cipher Keys and Modular InversesCipherSteps
Cipher rules and reference guides
Look up alphabet rules, valid keys, Morse timing, and the information each method can recover.
Cipher rules and reference guides
Text Normalization for Ciphers
Understand which text changes happen before a cipher runs and what decoding can recover.
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Cipher vs. Code: What Is the Difference?
Compare letter shifts, alphabet numbers, and Morse to see what each method changes.
Open Cipher vs. Code: What Is the Difference?Cipher rules and reference guides
Columnar Transposition with Repeated Key Letters
Use BALLOON to see how repeated key letters and a short final row affect column order.
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Letter Frequency Analysis: Counts and Percentages
Count letters, read the chart, and avoid drawing too much from a short message.
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Modulo 26: How Cipher Letters Wrap Around
See how letter positions wrap around the alphabet, including negative shifts.
Open Modulo 26: How Cipher Letters Wrap AroundCipher rules and reference guides
Morse Code Timing: Dots, Dashes, Gaps, and WPM
Use the timing table and SOS diagram to connect dots, dashes, silence, and speed.
Open Morse Code Timing: Dots, Dashes, Gaps, and WPMCipher rules and reference guides
Substitution vs. Transposition Ciphers
Does a cipher change the letters or just move them? Compare the two approaches.
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