16hexdigit

A 16-hexadecimal-digit (16hexdigit) string is a sequence of 16 characters, each representing a value between 0 and 15 in base-16 (hexadecimal) notation. Hexadecimal digits range from 0 to 9 for the first ten values and use letters A to F (case-insensitive) to represent values 10 through 15. This format is commonly used in computing and cryptography due to its compactness and ease of representation.

In many systems, a 16hexdigit string corresponds to 64 bits (8 bytes) of data, as each hexadecimal digit encodes exactly 4 bits. This makes it a standard representation for hashing algorithms, encryption keys, and unique identifiers such as UUIDs (Universally Unique Identifiers). For example, a UUID version 4 is typically expressed as a 36-character string containing hyphens, but its raw form is a 16hexdigit sequence.

The use of 16hexdigit strings is prevalent in cryptographic applications, including SHA-256 hashes, which produce a 64-character hexadecimal representation of a 256-bit hash value. Similarly, symmetric encryption keys, such as those used in AES (Advanced Encryption Standard), are often displayed in this format for readability.

When working with 16hexdigit strings, it is important to ensure proper formatting and case consistency, as some systems may treat uppercase and lowercase letters differently. Additionally, these strings are frequently used in APIs, configuration files, and data storage to ensure compatibility across different platforms and programming languages.