Update enc(1) examples to more recent ciphers and key derivation algorithms

The B<enc> program does not support authenticated encryption modes

like CCM and GCM, and will not support such modes in the future.

The B<enc> interface by necessity must begin streaming output (e.g.,

to standard output when B<-out> is not used before the authentication

to standard output when B<-out> is not used) before the authentication

tag could be validated, leading to the usage of B<enc> in pipelines

that begin processing untrusted data and are not capable of rolling

back upon authentication failure.  The AEAD modes currently in common

 openssl base64 -d -in file.b64 -out file.bin

Encrypt a file using triple DES in CBC mode using a prompted password:

Encrypt a file using AES-128 using a prompted password

and PBKDF2 key derivation:

 openssl des3 -salt -in file.txt -out file.des3

 openssl enc -aes128 -pbkdf2 -in file.txt -out file.aes128

Decrypt a file using a supplied password:

 openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword

 openssl enc -aes128 -pbkdf2 -d -in file.aes128 -out file.txt \

    -pass pass:<password>

Encrypt a file then base64 encode it (so it can be sent via mail for example)

using Blowfish in CBC mode:

using AES-256 in CTR mode and PBKDF2 key derivation:

 openssl bf -a -salt -in file.txt -out file.bf

 openssl enc -aes-256-ctr -pbkdf2 -a -in file.txt -out file.aes256

Base64 decode a file then decrypt it:

Base64 decode a file then decrypt it using a password supplied in a file:

 openssl bf -d -salt -a -in file.bf -out file.txt

Decrypt some data using a supplied 40 bit RC4 key:

 openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405

 openssl enc -aes-256-ctr -pbkdf2 -d -a -in file.aes256 -out file.txt \

    -pass file:<passfile>

=head1 BUGS