Key Length

Updated 25 Jul 2026

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def
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  the size (in bits) of a cryptographic key
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rule of thumb
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  "length is strength" — the longer the key, the stronger it is; larger keys resist brute-force attacks better (an attacker has more possible combinations to try), and typical minimum lengths grow larger over time
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typical sizes
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  symmetric encryption — 128-bit keys or larger are common
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  asymmetric encryption — involves complex prime-number calculations, so keys are much larger than symmetric ones; 3,072 bits or larger is common
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example
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  AES 256 (256-bit key) is stronger than AES 128 (128-bit key)
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related

Linked references 4