Base64 is a binary-to-text encoding scheme that converts binary data into a sequence of printable ASCII characters. It uses a set of 64 unique characters—uppercase and lowercase letters (A–Z, a–z), digits (0–9), and two special characters (typically “+” and “/”)—to represent data. This encoding is called “Base64” because it uses 64 different symbols, which are used to encode each 6 bits of the original binary data.
Why is Base64 Used?
Base64 is primarily used to transmit binary data (such as images, files, or multimedia) over channels that only reliably support text, such as email (SMTP), HTTP, or other text-based protocols. Many of these protocols were originally designed to handle only 7-bit ASCII characters, making it difficult to transfer raw binary data without potential corruption. By encoding binary data as text, Base64 ensures the information remains intact during transmission.
How Does Base64 Work?
• The binary data is divided into 6-bit groups.
• Each 6-bit group is mapped to one of the 64 printable characters in the Base64 alphabet.
• If the original data does not divide evenly into 6-bit chunks, padding characters (”=”) are added to the end to complete the encoding.
Common Uses
• Sending email attachments (MIME encoding)
• Embedding images or other binary assets within HTML, CSS, or JSON files
• Storing or transmitting binary data in XML or other text-based formats
• Ensuring data integrity when transferring over systems that may not be “8-bit clean”
Limitations
• Base64 encoding increases the size of the data by about 33% compared to the original binary.
• It is not a form of encryption and does not provide security; it is simply a way to encode data for safe transport.