Interactive learning lab

Block Cipher Modes Lab

Compare AES modes of operation side by side — ECB, CBC, CTR, CFB, and OFB — and watch how a single one-byte plaintext change propagates through each, plus the classic ECB penguin.

Plaintext (ASCII)

Flip one plaintext byte (position 4)key 2b7e1516… · iv 00010203…

The agic words are squeamish ossifrage.

The ECB Penguin

The same key encrypts the same image three ways. ECB encrypts each 16-byte block on its own, so the picture's flat regions produce repeating ciphertext blocks and the silhouette stays visible. A streaming mode like CTR masks every block differently, leaving nothing to see.

OriginalThe plaintext image.

AES-ECBStructure leaks — identical blocks encrypt identically.

AES-CTRPure noise — every block gets a fresh keystream.

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