my $binary_digest = ...;

my @digits = (0..9, 'A'..'V');
my $base32_digest = '';
for (0..3) { # 2^32^4 = 2^128
   $base32_digest = $digits[$binary_digest & 31]. $base32_digest;
   $binary_digest >>= 5;
}

print("$base32_digest\n");