Key size facts for kids
In cryptography, key size or key length is the size (measured in bits or bytes) of the key used in a cryptographic algorithm (such as a cipher). Typical key sizes in modern symmetric ciphers are 128, 192, and 256 bits. Older symmetric ciphers used only 40, 56, or 64 bits, which can be broken by brute force.
Key size Facts for Kids. Kiddle Encyclopedia.