Most symmetric-key algorithms in common use are designed to have security equal to their key length.

The remainder of the conversation uses a (typically faster) symmetric-key algorithm for encryption.

Symmetric-key algorithms can be divided into stream ciphers and block ciphers.

One disadvantage of symmetric-key algorithms is the requirement of a shared secret key, with both parties holding the same copy at each end.

Symmetric-key algorithms are generally much less computationally intensive than asymmetric key algorithms.

Symmetric-key algorithms use a single shared key; keeping data secret requires keeping this key secret.

In the case of symmetric-key algorithm cryptosystems, an adversary must not be able to compute any information about a plaintext from its ciphertext.

By using one of these "asymmetric" algorithms to distribute an encrypted secret key for another, faster, symmetric-key algorithm, it's possible to improve overall performance considerably.

In cryptography, a S-Box (Substitution-box) is a basic component of symmetric-key algorithms.

Two algorithms are programmed into the chip: A key-exchange algorithm for the key agreement protocol and a symmetric-key algorithm for voice encryption.

The algorithm described by AES is a symmetric-key algorithm, meaning the same key is used for both encrypting and decrypting the data.

This first version included a symmetric-key algorithm that Zimmermann had designed himself, named BassOmatic after a Saturday Night Live sketch.

Symmetric-key algorithms are a class of algorithms for cryptography that use trivially related, often identical, cryptographic keys for both decryption and encryption.

Once a symmetric key is known to all parties of the session, faster symmetric-key algorithms using that key can be used to encrypt the remainder of the session.

OTR uses a combination of the AES symmetric-key algorithm, the Diffie-Hellman key exchange, and the SHA-1 hash function.

For this reason, the term "cryptosystem" is commonly used to refer to public key cryptography techniques; however both "cipher" and "cryptosystem" are used for Symmetric-key algorithm techniques.

At the receiving end, an identically configured machine produced the same key stream which was combined with the ciphertext to produce the plaintext, i. e. the system implemented a symmetric-key algorithm.

The original content M is encrypted under Symmetric-key algorithm with the key K. Resulting with the encryption E(M,K).

Modern cryptographic systems include symmetric-key algorithms (such as DES and AES) and public-key algorithms (such as RSA).

The cube attack is a method of cryptanalysis applicable to a wide variety of symmetric-key algorithms, published by Itai Dinur and Adi Shamir in a September 2008 preprint.

Vernam's cipher is a Symmetric-key algorithm, i.e. the same key is used both to encipher plaintext to produce the ciphertext and to decipher ciphertext to yield the original plaintext:

In contrast, symmetric-key algorithms - variations of which have been used for thousands of years - use a single secret key, which must be shared and kept private by both the sender and the receiver, for both encryption and decryption.

Since public-key algorithms tend to be much slower than symmetric-key algorithms, modern systems such as TLS and its predecessor SSL as well as the SSH use a combination of the two in which: