How to encode string to Base64 with MIME::Base64 in Perl?

Encoding a string into Base64 is a common task when dealing with binary data, email attachments, or transmitting data over media that are designed to handle textual data. In Perl, the MIME::Base64 module from the core distribution provides easy-to-use functions to encode and decode Base64 strings.

Using MIME::Base64 to Encode a String

The MIME::Base64 module exports the encode_base64 function, which takes a plain string and returns its Base64-encoded equivalent. By default, it adds a newline every 76 characters (to conform with MIME standards), but you can suppress this behavior by passing an optional second argument.

Here's the basic approach:

• use MIME::Base64; to include the module.
• Call encode_base64($string) to get the encoded string.
• Optionally, suppress newlines with encode_base64($string, "").

Understanding Perl Concepts in This Context

• Sigil: The $ sigil denotes a scalar variable (a single value like a string).
• Context: encode_base64 returns a scalar in scalar context (the encoded string).
• TMTOWTDI: Perl's “There's more than one way to do it” philosophy means you could also use other modules or write your own encoding—but MIME::Base64 is simplest and standard.

Common Pitfalls

• For multiline safe Base64 strings (typical in emails), allow the default behavior (newlines every 76 characters).
• To get a clean single-line Base64 string (for APIs, URLs, etc.), pass an empty string as the second argument.
• Remember to use MIME::Base64; before calling the functions.
• encode_base64 expects a string, not a file handle or binary stream—read binary data into a scalar first if needed.

Example Code

use strict;
use warnings;
use MIME::Base64;

# Original string to encode
my $string = "Hello, Perl Base64 encoding!";

# Encode with default line breaks (MIME standard)
my $encoded = encode_base64($string);

print "Encoded with line breaks:\n$encoded\n";

# Encode without any line breaks (single line)
my $encoded_single_line = encode_base64($string, "");

print "Encoded without line breaks:\n$encoded_single_line\n";

When you run this script, you should see output similar to:

Encoded with line breaks:
SGVsbG8sIFBlcmwgQmFzZTY0IGVuY29kaW5nIQ==

Encoded without line breaks:
SGVsbG8sIFBlcmwgQmFzZTY0IGVuY29kaW5nIQ==

Because the encoded string is short, no line breaks appear by default in this example, but longer strings will show line breaks unless suppressed.

Version Notes

MIME::Base64 has been part of core Perl distributions since very early versions (at least Perl 5.6+), so no special installation is needed for most modern Perl interpreters (5.10+ and above).

In summary, just use MIME::Base64; and call encode_base64($string) to get a Base64 encoded string easily and reliably!