To protect the data, either the signature alone or the signature plus the message are mapped into printable ASCII characters using a scheme known as or base64mapping.

Base64 encoding

Explanation:

Base64 encoding is a binary to text encoding scheme. Binary data is represented in a printable ASCII string format by translation into radix-64 representation.

Base64 mapping works with a 64-character subset of US ASCII charset. The 64 characters are mapped to an equivalent 64-bit binary sequence. An extra 65th character is used for padding.

An alphabet is assigned to each of the 6-bit binary sequences from 0 to 63. The 6-bit binary to alphabet mapping is used in the encoding process.