Base64 Encoding: How It Works

Many systems, including email, HTTP headers, and XML, were designed to handle text but not arbitrary binary data. A byte value of 0x00 (null) or 0x1A (control character) can cause parsing failures or data corruption.

Base64 encoding converts arbitrary binary data into a subset of ASCII characters that is safe for text-only systems, allowing binary content like images and certificates to be embedded in text-based protocols.

Base64 works by taking three 8-bit bytes (24 bits total) and splitting them into four 6-bit groups. Each 6-bit group represents a value from 0 to 63, which maps to one character in the Base64 alphabet.

This 3-to-4 ratio means every 3 bytes of input produce 4 characters of output, a 33% size increase. The math works out evenly because 3 bytes = 24 bits = 4 groups of 6 bits.