16byte

16byte is a term used to denote a quantity of data consisting of 16 bytes, equivalent to 128 bits. In computing, this unit appears in multiple contexts, including cryptography, networking, and data processing. The concept is fundamental because many standard algorithms and data formats operate on or reference 16-byte blocks or fields.

In cryptography, 16-byte blocks are most notably associated with the Advanced Encryption Standard (AES), which uses a block size of 16 bytes. When encrypting arbitrary-length data, padding is often employed to ensure that the final block also has 16 bytes. A 16-byte quantity can also refer to a 128-bit key in AES-128, and to common 16-byte digests produced by hash functions such as MD5, which yields a 16-byte (128-bit) output.

In memory, 16-byte alignment is a performance consideration on many architectures. Data aligned on 16-byte boundaries can be loaded more efficiently by modern processors using vector instructions. Vector and SIMD registers commonly hold 16 bytes of data at a time, enabling parallel operations on 128-bit chunks.

In networking and data formats, several 16-byte structures are common. IPv6 addresses are 16 bytes long, and many binary identifiers or GUIDs/UUIDs are 16 bytes in their binary representation. Some file and protocol formats also use 16-byte blocks or fields for specific data elements.

Endianness affects how a 16-byte sequence is interpreted or displayed, but not the total length itself. When represented textually, 16 bytes appear as a sequence of 32 hexadecimal digits, or as specific binary-to-text encodings such as Base16 or Base64.

See also: 128-bit, AES, MD5, IPv6, UUID, block cipher, padding, SIMD.