Sorry, "encryption" was not what I meant, but "encoded". Here's example code:

use Net::LDAP::LDIF;
our $old_ldif = Net::LDAP::LDIF->new( "dump.ldif", "r", onerror => 'un
+def' );
our $new_ldif = Net::LDAP::LDIF->new( "dump_new.ldif", "w", onerror =>
+ 'undef', wrap => 76, encode => 'base64' );
while (not $old_ldif->eof()) {
    my $entry = $old_ldif->read_entry();
    if ($old_ldif->error()) {
        warn "Error msg: ", $old_ldif->error(), "\n";
        warn "Error lines:\n", $old_ldif->error_lines(), "\n";
    } else {
        # delete attributes no longer needed
        foreach my $a ($entry->attributes()) {
            if ($a =~ /^attrMatch/) {
                $entry->delete($a);
            }
        }
        $new_ldif->write_entry($entry);
    }
}
$old_ldif->done();
$new_ldif->done();
[download]

Assuming userPassword is not the attribute to remove, I would expect a diff between dump.ldap and dump_new.ldap to only show the attribute(s) that were deleted. But in dump.ldif (from an OpenLDAP slapcat command) the userPassword field is base64 encoded. In the dump_new.ldif file, it's not base64 encoded. Makes the diff harder to read... nothing incorrect with either version though.

At the moment, I don't see anything in the documentation that mentions how to encode individual attributes and not others. Could you also provide a sample LDIF file (anonymized but representative of the original) so that we have something to play with?

So here's a test entry. See that the userPassword is base64 encoded (noted with the two '::'). As an example, let's say my code is just interested in deleting the rutgersEduStatus attribute.

dn: uid=testing,ou=People,dc=rutgers,dc=edu
objectClass: top
objectClass: person
objectClass: organizationalPerson
objectClass: inetorgperson
objectClass: rutgersEduPerson
objectClass: eduPerson
uid: testing
givenName: Record
sn: Testing
cn: Record Testing
eduPersonAffiliation: alum
eduPersonAffiliation: member
eduPersonAffiliation: student
eduPersonPrimaryAffiliation: student
eduPersonPrincipalName: testing@rutgers.edu
employeeType: ALUMNI
employeeType: STUDENT
homePostalAddress: 433 W County Dr$Somerville, NJ 088763470
postalAddress: R U C S
rutgersEduDateOfBirth: 1960-01-01
rutgersEduStatus: active
uidNumber: 120001
userPassword:: e1NBU0x9dGVzdGluZ0BSVVRHRVJTLkVEVQ==
[download]