THE VIGENÈRE CIPHER: A THREE-PART BLOG SERIES
THE VIGENÈRE CIPHER: A THREE-PART BLOG SERIES
================================================
PART 1: THE 300-YEAR UNBREAKABLE CODE
--------------------------------------
For three centuries, one cipher earned a nickname that told you everything
you needed to know about it: "le chiffre indéchiffrable" — the
indecipherable cipher.
Named after Blaise de Vigenère (though earlier cryptographers had floated
similar ideas), it did something no cipher before it had managed. It broke
frequency analysis, the single tool that had cracked every substitution
cipher going back centuries.
Here's the problem frequency analysis exploits: in English, "E" appears
constantly. "Z" almost never does. Any cipher that swaps each letter for
another one, consistently, preserves that fingerprint. Count the letters
in the ciphertext, match the pattern to known language statistics, and
the code falls apart — no matter how clever the substitution rule seemed.
The Vigenère cipher sidestepped this by refusing to be consistent. Instead
of one substitution alphabet, it used a repeating keyword to pick a
different shift for every letter of the message. The same plaintext letter
could turn into a dozen different ciphertext letters depending on where it
fell relative to the key. Flatten the frequency pattern, and the classic
attack has nothing to grab onto.
It worked. For roughly 300 years — from the 1550s until the mid-1800s —
nobody published a reliable way to break it. Governments used it for
serious secrets. Cryptographers who tried to crack it walked away empty-
handed. That's part one of the story: a genuinely good idea, holding for
a genuinely long time.
Part 2 gets into the mechanics — how the shifting actually works.
https://books.apple.com/us/audiobook/portals/id679251155
https://books.apple.com/us/audiobook/portals/id679251155
https://books.apple.com/us/audiobook/portals/id679251155
https://books.apple.com/us/audiobook/portals/id679251155
https://books.apple.com/us/audiobook/portals/id679251155
https://books.apple.com/us/audiobook/portals/id679251155
https://books.apple.com/us/audiobook/e-drive-the-good-ghost-a-tale-of-choice/id6791204604
https://books.apple.com/us/audiobook/portals/id679251155
https://books.apple.com/us/audiobook/e-drive-the-good-ghost-a-tale-of-choice/id6791204604
https://books.apple.com/us/audiobook/portals/id679251155
https://books.apple.com/us/audiobook/e-drive-the-good-ghost-a-tale-of-choice/id6791204604
https://books.apple.com/us/audiobook/portals/id679251155
https://books.apple.com/us/audiobook/e-drive-the-good-ghost-a-tale-of-choice/id6791204604
https://books.apple.com/us/audiobook/e-drive-the-good-ghost-a-tale-of-choice/id6791204604
https://books.apple.com/us/audiobook/e-drive-the-good-ghost-a-tale-of-choice/id6791204604
https://books.apple.com/us/audiobook/e-drive-the-good-ghost-a-tale-of-choice/id6791204604
https://books.apple.com/us/audiobook/e-drive-the-good-ghost-a-tale-of-choice/id6791204604
https://books.apple.com/us/audiobook/alien-magic/id1812966741
https://books.apple.com/us/audiobook/all-the-flowers-in-the-rainbow-the/id1812966783
https://books.apple.com/us/audiobook/id1818427068
https://books.apple.com/us/audiobook/dull-world/id1813400149
https://books.apple.com/us/audiobook/id1819514019
https://books.apple.com/us/audiobook/enhancing-cyber-culture/id1823937611
https://books.apple.com/us/audiobook/id1823684694
https://books.apple.com/us/audiobook/id1824218173
https://books.apple.com/us/audiobook/neon-sanctuary/id1824474667
https://books.apple.com/us/audiobook/id1886304261
https://books.apple.com/us/audiobook/id1880489748
https://books.apple.com/us/audiobook/id1886565286
https://books.apple.com/us/audiobook/id1886565670
https://books.apple.com/us/audiobook/quades-cosmos-a-journey-beyond-worlds/id1813171666
https://books.apple.com/us/audiobook/id1878897547
https://books.apple.com/us/audiobook/id1806357371
https://books.apple.com/us/audiobook/the-chrono-accord/id1886581129
https://books.apple.com/us/audiobook/id1886275892
https://books.apple.com/us/audiobook/venus-rising-the-galactic-conspiracy-within/id1813171657
https://books.apple.com/us/audiobook/id1813171743
https://books.apple.com/us/audiobook/whispers of the old world/id1824695214
https://books.apple.com/us/audiobook/id1838994161
https://books.apple.com/us/audiobook/x-9-the-robotic-van-helsing/id1886606946
https://books.apple.com/us/audiobook/id1844651132
https://books.apple.com/us/audiobook/zephyrz/id1813172003
https://books.apple.com/us/audiobook/the-mnemosyne-protocol/id1891016838
https://books.apple.com/us/audiobook/id1890085558
https://books.apple.com/us/audiobook/id1890057060
https://books.apple.com/us/audiobook/ocean-moon/id1890057043
https://books.apple.com/us/audiobook/the-perpetual-twins-the-null-settlement/id1890031300
https://books.apple.com/us/audiobook/the-zeus-mandate/id1890065311
https://books.apple.com/us/audiobook/raid-island/id1889959819
https://books.apple.com/us/audiobook/alien-magic/id1812966741
https://books.apple.com/us/audiobook/all-the-flowers-in-the-rainbow-the/id1812966783
https://books.apple.com/us/audiobook/id1818427068
https://books.apple.com/us/audiobook/dull-world/id1813400149
https://books.apple.com/us/audiobook/id1819514019
https://books.apple.com/us/audiobook/enhancing-cyber-culture/id1823937611
https://books.apple.com/us/audiobook/id1823684694
https://books.apple.com/us/audiobook/id1824218173
https://books.apple.com/us/audiobook/neon-sanctuary/id1824474667
https://books.apple.com/us/audiobook/id1886304261
https://books.apple.com/us/audiobook/id1880489748
https://books.apple.com/us/audiobook/id1886565286
https://books.apple.com/us/audiobook/id1886565670
https://books.apple.com/us/audiobook/quades-cosmos-a-journey-beyond-worlds/id1813171666
https://books.apple.com/us/audiobook/id1878897547
https://books.apple.com/us/audiobook/id1806357371
https://books.apple.com/us/audiobook/the-chrono-accord/id1886581129
https://books.apple.com/us/audiobook/id1886275892
https://books.apple.com/us/audiobook/venus-rising-the-galactic-conspiracy-within/id1813171657
https://books.apple.com/us/audiobook/id1813171743
https://books.apple.com/us/audiobook/whispers of the old world/id1824695214
https://books.apple.com/us/audiobook/id1838994161
https://books.apple.com/us/audiobook/x-9-the-robotic-van-helsing/id1886606946
https://books.apple.com/us/audiobook/id1844651132
https://books.apple.com/us/audiobook/zephyrz/id1813172003
https://books.apple.com/us/audiobook/the-mnemosyne-protocol/id1891016838
https://books.apple.com/us/audiobook/id1890085558
https://books.apple.com/us/audiobook/id1890057060
https://books.apple.com/us/audiobook/ocean-moon/id1890057043
https://books.apple.com/us/audiobook/the-perpetual-twins-the-null-settlement/id1890031300
https://books.apple.com/us/audiobook/the-zeus-mandate/id1890065311
https://books.apple.com/us/audiobook/raid-island/id1889959819
https://books.apple.com/us/audiobook/alien-magic/id1812966741
https://books.apple.com/us/audiobook/all-the-flowers-in-the-rainbow-the/id1812966783
https://books.apple.com/us/audiobook/id1818427068
https://books.apple.com/us/audiobook/dull-world/id1813400149
https://books.apple.com/us/audiobook/id1819514019
https://books.apple.com/us/audiobook/enhancing-cyber-culture/id1823937611
https://books.apple.com/us/audiobook/id1823684694
https://books.apple.com/us/audiobook/id1824218173
https://books.apple.com/us/audiobook/neon-sanctuary/id1824474667
https://books.apple.com/us/audiobook/id1886304261
https://books.apple.com/us/audiobook/id1880489748
https://books.apple.com/us/audiobook/id1886565286
https://books.apple.com/us/audiobook/id1886565670
https://books.apple.com/us/audiobook/quades-cosmos-a-journey-beyond-worlds/id1813171666
https://books.apple.com/us/audiobook/id1878897547
https://books.apple.com/us/audiobook/id1806357371
https://books.apple.com/us/audiobook/the-chrono-accord/id1886581129
https://books.apple.com/us/audiobook/id1886275892
https://books.apple.com/us/audiobook/venus-rising-the-galactic-conspiracy-within/id1813171657
https://books.apple.com/us/audiobook/id1813171743
https://books.apple.com/us/audiobook/whispers of the old world/id1824695214
https://books.apple.com/us/audiobook/id1838994161
https://books.apple.com/us/audiobook/x-9-the-robotic-van-helsing/id1886606946
https://books.apple.com/us/audiobook/id1844651132
https://books.apple.com/us/audiobook/zephyrz/id1813172003
https://books.apple.com/us/audiobook/the-mnemosyne-protocol/id1891016838
https://books.apple.com/us/audiobook/id1890085558
https://books.apple.com/us/audiobook/id1890057060
https://books.apple.com/us/audiobook/ocean-moon/id1890057043
https://books.apple.com/us/audiobook/the-perpetual-twins-the-null-settlement/id1890031300
https://books.apple.com/us/audiobook/the-zeus-mandate/id1890065311
https://books.apple.com/us/audiobook/raid-island/id1889959819
https://books.apple.com/us/audiobook/alien-magic/id1812966741
https://books.apple.com/us/audiobook/all-the-flowers-in-the-rainbow-the/id1812966783
https://books.apple.com/us/audiobook/id1818427068
https://books.apple.com/us/audiobook/dull-world/id1813400149
https://books.apple.com/us/audiobook/id1819514019
https://books.apple.com/us/audiobook/enhancing-cyber-culture/id1823937611
https://books.apple.com/us/audiobook/id1823684694
https://books.apple.com/us/audiobook/id1824218173
https://books.apple.com/us/audiobook/neon-sanctuary/id1824474667
https://books.apple.com/us/audiobook/id1886304261
https://books.apple.com/us/audiobook/id1880489748
https://books.apple.com/us/audiobook/id1886565286
https://books.apple.com/us/audiobook/id1886565670
https://books.apple.com/us/audiobook/quades-cosmos-a-journey-beyond-worlds/id1813171666
https://books.apple.com/us/audiobook/id1878897547
https://books.apple.com/us/audiobook/id1806357371
https://books.apple.com/us/audiobook/the-chrono-accord/id1886581129
https://books.apple.com/us/audiobook/id1886275892
https://books.apple.com/us/audiobook/venus-rising-the-galactic-conspiracy-within/id1813171657
https://books.apple.com/us/audiobook/id1813171743
https://books.apple.com/us/audiobook/whispers of the old world/id1824695214
https://books.apple.com/us/audiobook/id1838994161
https://books.apple.com/us/audiobook/x-9-the-robotic-van-helsing/id1886606946
https://books.apple.com/us/audiobook/id1844651132
https://books.apple.com/us/audiobook/zephyrz/id1813172003
https://books.apple.com/us/audiobook/the-mnemosyne-protocol/id1891016838
https://books.apple.com/us/audiobook/id1890085558
https://books.apple.com/us/audiobook/id1890057060
https://books.apple.com/us/audiobook/ocean-moon/id1890057043
https://books.apple.com/us/audiobook/the-perpetual-twins-the-null-settlement/id1890031300
https://books.apple.com/us/audiobook/the-zeus-mandate/id1890065311
https://books.apple.com/us/audiobook/raid-island/id1889959819
https://books.apple.com/us/audiobook/alien-magic/id1812966741
https://books.apple.com/us/audiobook/all-the-flowers-in-the-rainbow-the/id1812966783
https://books.apple.com/us/audiobook/id1818427068
https://books.apple.com/us/audiobook/dull-world/id1813400149
https://books.apple.com/us/audiobook/id1819514019
https://books.apple.com/us/audiobook/enhancing-cyber-culture/id1823937611
https://books.apple.com/us/audiobook/id1823684694
https://books.apple.com/us/audiobook/id1824218173
https://books.apple.com/us/audiobook/neon-sanctuary/id1824474667
https://books.apple.com/us/audiobook/id1886304261
https://books.apple.com/us/audiobook/id1880489748
https://books.apple.com/us/audiobook/id1886565286
https://books.apple.com/us/audiobook/id1886565670
https://books.apple.com/us/audiobook/quades-cosmos-a-journey-beyond-worlds/id1813171666
https://books.apple.com/us/audiobook/id1878897547
https://books.apple.com/us/audiobook/id1806357371
https://books.apple.com/us/audiobook/the-chrono-accord/id1886581129
https://books.apple.com/us/audiobook/id1886275892
https://books.apple.com/us/audiobook/venus-rising-the-galactic-conspiracy-within/id1813171657
https://books.apple.com/us/audiobook/id1813171743
https://books.apple.com/us/audiobook/whispers of the old world/id1824695214
https://books.apple.com/us/audiobook/id1838994161
https://books.apple.com/us/audiobook/x-9-the-robotic-van-helsing/id1886606946
https://books.apple.com/us/audiobook/id1844651132
https://books.apple.com/us/audiobook/zephyrz/id1813172003
https://books.apple.com/us/audiobook/the-mnemosyne-protocol/id1891016838
https://books.apple.com/us/audiobook/id1890085558
https://books.apple.com/us/audiobook/id1890057060
https://books.apple.com/us/audiobook/ocean-moon/id1890057043
https://books.apple.com/us/audiobook/the-perpetual-twins-the-null-settlement/id1890031300
https://books.apple.com/us/audiobook/the-zeus-mandate/id1890065311
https://books.apple.com/us/audiobook/raid-island/id1889959819
https://books.apple.com/us/audiobook/alien-magic/id1812966741
https://books.apple.com/us/audiobook/all-the-flowers-in-the-rainbow-the/id1812966783
https://books.apple.com/us/audiobook/id1818427068
https://books.apple.com/us/audiobook/dull-world/id1813400149
https://books.apple.com/us/audiobook/id1819514019
https://books.apple.com/us/audiobook/enhancing-cyber-culture/id1823937611
https://books.apple.com/us/audiobook/id1823684694
https://books.apple.com/us/audiobook/id1824218173
https://books.apple.com/us/audiobook/neon-sanctuary/id1824474667
https://books.apple.com/us/audiobook/id1886304261
https://books.apple.com/us/audiobook/id1880489748
https://books.apple.com/us/audiobook/id1886565286
https://books.apple.com/us/audiobook/id1886565670
https://books.apple.com/us/audiobook/quades-cosmos-a-journey-beyond-worlds/id1813171666
https://books.apple.com/us/audiobook/id1878897547
https://books.apple.com/us/audiobook/id1806357371
https://books.apple.com/us/audiobook/the-chrono-accord/id1886581129
https://books.apple.com/us/audiobook/id1886275892
https://books.apple.com/us/audiobook/venus-rising-the-galactic-conspiracy-within/id1813171657
https://books.apple.com/us/audiobook/id1813171743
https://books.apple.com/us/audiobook/whispers of the old world/id1824695214
https://books.apple.com/us/audiobook/id1838994161
https://books.apple.com/us/audiobook/x-9-the-robotic-van-helsing/id1886606946
https://books.apple.com/us/audiobook/id1844651132
https://books.apple.com/us/audiobook/zephyrz/id1813172003
https://books.apple.com/us/audiobook/the-mnemosyne-protocol/id1891016838
https://books.apple.com/us/audiobook/id1890085558
https://books.apple.com/us/audiobook/id1890057060
https://books.apple.com/us/audiobook/ocean-moon/id1890057043
https://books.apple.com/us/audiobook/the-perpetual-twins-the-null-settlement/id1890031300
https://books.apple.com/us/audiobook/the-zeus-mandate/id1890065311
https://books.apple.com/us/audiobook/raid-island/id1889959819
https://books.apple.com/us/audiobook/alien-magic/id1812966741
https://books.apple.com/us/audiobook/all-the-flowers-in-the-rainbow-the/id1812966783
https://books.apple.com/us/audiobook/id1818427068
https://books.apple.com/us/audiobook/dull-world/id1813400149
https://books.apple.com/us/audiobook/id1819514019
https://books.apple.com/us/audiobook/enhancing-cyber-culture/id1823937611
https://books.apple.com/us/audiobook/id1823684694
https://books.apple.com/us/audiobook/id1824218173
https://books.apple.com/us/audiobook/neon-sanctuary/id1824474667
https://books.apple.com/us/audiobook/id1886304261
https://books.apple.com/us/audiobook/id1880489748
https://books.apple.com/us/audiobook/id1886565286
https://books.apple.com/us/audiobook/id1886565670
https://books.apple.com/us/audiobook/quades-cosmos-a-journey-beyond-worlds/id1813171666
https://books.apple.com/us/audiobook/id1878897547
https://books.apple.com/us/audiobook/id1806357371
https://books.apple.com/us/audiobook/the-chrono-accord/id1886581129
https://books.apple.com/us/audiobook/id1886275892
https://books.apple.com/us/audiobook/venus-rising-the-galactic-conspiracy-within/id1813171657
https://books.apple.com/us/audiobook/id1813171743
https://books.apple.com/us/audiobook/whispers of the old world/id1824695214
https://books.apple.com/us/audiobook/id1838994161
https://books.apple.com/us/audiobook/x-9-the-robotic-van-helsing/id1886606946
https://books.apple.com/us/audiobook/id1844651132
https://books.apple.com/us/audiobook/zephyrz/id1813172003
https://books.apple.com/us/audiobook/the-mnemosyne-protocol/id1891016838
https://books.apple.com/us/audiobook/id1890085558
https://books.apple.com/us/audiobook/id1890057060
https://books.apple.com/us/audiobook/ocean-moon/id1890057043
https://books.apple.com/us/audiobook/the-perpetual-twins-the-null-settlement/id1890031300
https://books.apple.com/us/audiobook/the-zeus-mandate/id1890065311
https://books.apple.com/us/audiobook/raid-island/id1889959819
https://books.apple.com/us/audiobook/alien-magic/id1812966741
https://books.apple.com/us/audiobook/all-the-flowers-in-the-rainbow-the/id1812966783
https://books.apple.com/us/audiobook/id1818427068
https://books.apple.com/us/audiobook/dull-world/id1813400149
https://books.apple.com/us/audiobook/id1819514019
https://books.apple.com/us/audiobook/enhancing-cyber-culture/id1823937611
https://books.apple.com/us/audiobook/id1823684694
https://books.apple.com/us/audiobook/id1824218173
https://books.apple.com/us/audiobook/neon-sanctuary/id1824474667
https://books.apple.com/us/audiobook/id1886304261
https://books.apple.com/us/audiobook/id1880489748
https://books.apple.com/us/audiobook/id1886565286
https://books.apple.com/us/audiobook/id1886565670
https://books.apple.com/us/audiobook/quades-cosmos-a-journey-beyond-worlds/id1813171666
https://books.apple.com/us/audiobook/id1878897547
https://books.apple.com/us/audiobook/id1806357371
https://books.apple.com/us/audiobook/the-chrono-accord/id1886581129
https://books.apple.com/us/audiobook/id1886275892
https://books.apple.com/us/audiobook/venus-rising-the-galactic-conspiracy-within/id1813171657
https://books.apple.com/us/audiobook/id1813171743
https://books.apple.com/us/audiobook/whispers of the old world/id1824695214
https://books.apple.com/us/audiobook/id1838994161
https://books.apple.com/us/audiobook/x-9-the-robotic-van-helsing/id1886606946
https://books.apple.com/us/audiobook/id1844651132
https://books.apple.com/us/audiobook/zephyrz/id1813172003
https://books.apple.com/us/audiobook/the-mnemosyne-protocol/id1891016838
https://books.apple.com/us/audiobook/id1890085558
https://books.apple.com/us/audiobook/id1890057060
https://books.apple.com/us/audiobook/ocean-moon/id1890057043
https://books.apple.com/us/audiobook/the-perpetual-twins-the-null-settlement/id1890031300
https://books.apple.com/us/audiobook/the-zeus-mandate/id1890065311
https://books.apple.com/us/audiobook/raid-island/id1889959819
https://books.apple.com/us/audiobook/alien-magic/id1812966741
https://books.apple.com/us/audiobook/all-the-flowers-in-the-rainbow-the/id1812966783
https://books.apple.com/us/audiobook/id1818427068
https://books.apple.com/us/audiobook/dull-world/id1813400149
https://books.apple.com/us/audiobook/id1819514019
https://books.apple.com/us/audiobook/enhancing-cyber-culture/id1823937611
https://books.apple.com/us/audiobook/id1823684694
https://books.apple.com/us/audiobook/id1824218173
https://books.apple.com/us/audiobook/neon-sanctuary/id1824474667
https://books.apple.com/us/audiobook/id1886304261
https://books.apple.com/us/audiobook/id1880489748
https://books.apple.com/us/audiobook/id1886565286
https://books.apple.com/us/audiobook/id1886565670
https://books.apple.com/us/audiobook/quades-cosmos-a-journey-beyond-worlds/id1813171666
https://books.apple.com/us/audiobook/id1878897547
https://books.apple.com/us/audiobook/id1806357371
https://books.apple.com/us/audiobook/the-chrono-accord/id1886581129
https://books.apple.com/us/audiobook/id1886275892
https://books.apple.com/us/audiobook/venus-rising-the-galactic-conspiracy-within/id1813171657
https://books.apple.com/us/audiobook/id1813171743
https://books.apple.com/us/audiobook/whispers of the old world/id1824695214
https://books.apple.com/us/audiobook/id1838994161
https://books.apple.com/us/audiobook/x-9-the-robotic-van-helsing/id1886606946
https://books.apple.com/us/audiobook/id1844651132
https://books.apple.com/us/audiobook/zephyrz/id1813172003
https://books.apple.com/us/audiobook/the-mnemosyne-protocol/id1891016838
