base64urlkoodaukselle

Base64url encoding is a variation of the standard Base64 encoding scheme. It is designed for use in Uniform Resource Locators (URLs) and other contexts where the standard Base64 alphabet, which includes '+' and '/', can cause issues due to their special meaning in URLs. Base64url replaces these characters with '+' replaced by '-', and '/' replaced by '_'. It also omits the padding character '=' from the end of the encoded string.

The standard Base64 encoding represents binary data in an ASCII string format. It achieves this by taking groups of 3 bytes (24 bits) and dividing them into 4 groups of 6 bits each. Each 6-bit group is then mapped to a specific character from a 64-character alphabet. This alphabet typically consists of uppercase letters A-Z, lowercase letters a-z, digits 0-9, and the characters '+' and '/'.

The primary motivation for Base64url is to ensure that encoded data can be safely embedded in URLs without requiring further escaping. This makes it useful for transmitting data like session tokens, API keys, or other identifiers directly within a URL. The removal of the padding character simplifies parsing and reduces the length of the encoded string, which can be beneficial in systems with URL length limitations. The decoding process for Base64url is identical to standard Base64, except for the character mapping and the handling of the missing padding.