# Symmetric-key algorithm

## Algorithm / From Wikipedia, the free encyclopedia

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**Symmetric-key algorithms**^{[lower-alpha 1]} are algorithms for cryptography that use the same cryptographic keys for both the encryption of plaintext and the decryption of ciphertext. The keys may be identical, or there may be a simple transformation to go between the two keys.^{[1]} The keys, in practice, represent a shared secret between two or more parties that can be used to maintain a private information link.^{[2]} The requirement that both parties have access to the secret key is one of the main drawbacks of symmetric-key encryption, in comparison to public-key encryption (also known as asymmetric-key encryption).^{[3]}^{[4]} However, symmetric-key encryption algorithms are usually better for bulk encryption. With exception of the one-time pad they have a smaller key size, which means less storage space and faster transmission. Due to this, asymmetric-key encryption is often used to exchange the secret key for symmetric-key encryption.^{[5]}^{[6]}^{[7]}