+A **block cipher** is a core [cryptographic](/wiki/cryptography) algorithm that transforms fixed-size blocks of data. It takes a plaintext block and, guided by a secret [key](/wiki/key), produces a ciphertext block of the same size, acting as a fundamental digital lock.
+## See also
+- [Stream Cipher](/wiki/stream_cipher)
+- [Symmetric-key](/wiki/symmetric-key)
+- [Encryption](/wiki/encryption)
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