b64digest#

Finalise the context and return the digest as a 22-char base64 string.

Synopsis#

my $b64 = $ctx->b64digest;    # 22 chars, no padding

What you get back#

A 22-character string using the standard base64 alphabet A-Z a-z 0-9 + /. The result is not padded with =; the full base64 encoding of 16 bytes would be 24 characters, but the tail is fixed so the padding is redundant. Append "==" yourself if an interop partner strictly requires multiples of 4.

Base64 gives you a compact, one-line-friendly identifier that is roughly 30% shorter than hex while still printable. Common in cache keys, URL query parameters, and condensed log formats.

b64digest is destructive: the context is reset after use.

Examples#

Compact digest for a cache key:

my $key = Digest::MD5->new->add($url)->b64digest;

Pad to a multiple of 4 for strict base64 consumers:

my $padded = Digest::MD5->new->add($data)->b64digest . "==";

Peek without consuming:

my $snapshot = $ctx->clone->b64digest;

Edge cases#

Empty context → 1B2M2Y8AsgTpgAmY7PhCfg (the MD5 of the empty string in base64).
Contains / and +, so the result is not safe to drop into a URL path without further encoding — use URL-safe base64 for that (substitute - for + and _ for /).
Resets the context after returning.

Differences from upstream#

Fully compatible with upstream Digest::MD5 2.58.