A strong data security program with key management, for
use under Microsoft Windows and DOS.
Cloak2 takes a secret key phrase and one or more filenames, then
transforms or enciphers files into random binary data.
The original file contents can be recovered only by
deciphering with exactly the same key. Files thus
protected can be saved locally, archived off-site, or sent by
e-mail (using conventional binary protocols) without exposing
Cloak2 enciphered alias files hold secret keys and allow
them to be selected by public aliases, thus minimizing the
impact of secrecy on ordinary users. Keys can be updated while
users continue to use exactly the same alias in exactly the
same way. Dated alias allow access to old archived ciphertext
protected by outdated keys.
Now available in Advanced, Commercial Demo, Decipher-Only
and Corporate versions for DOS and Microsoft Windows. Not for
For greatest ease and security, the user should have an
alias file. An alias file is an enciphered file of
public aliases and related secret keys. The user can thus
select one of many secret keys by supplying the key to the
alias file plus the public alias for the desired key.
In normal operation, the user supplies the input filename,
output filename (if different), the alias, and selects encipher
or decipher. The program requests entry of the alias-file key,
once. The program then finds the "closest" alias file, deciphers
it in memory only, finds the indicated alias, then uses the secret
key associated with that alias to cipher data.
The "generate" function in the advanced version automatically
creates or adds to a local alias file, and will encipher the new
key in a different file for transport. The transport file can
be used as a beginning alias file, or added to an existing alias
file, without deciphering the alias file.
Examples of Commands
- Encipher Multiple .TXT Files Using Alias
cloak2 *.txt *.clo /e /a fred
- Decipher Multiple .CLO Files In-Place Using Alias
cloak2 *.clo /d /a fred
- Decipher Using Key Active on Dec. 15, 1993
cloak2 file1.clo file1.res /d /a fred /m 93-12-15
- Change Key to Alias File
cloak2 cloak2.mgt /d (Enter Old Key)
cloak2 cloak2.mgt /e (Enter New Key)
- Encipher Particular Files into Ciphertext Archive
cloak2 file1.txt+file2.txt+file3.txt arch1.clo /e
- Easy to use under Microsoft Windows or DOS.
- Fast: Up to 150K bytes/sec on large files
(on a 486DX2/50).
- Extremely Strong: Uses a 992-bit internal
key, with a random 992-bit message key in every file.
- Small: Under 50K including on-line help.
- Enciphers any file of any sort and recovers the
original data without loss. CRC error-detection checks
each deciphered file. CRC also detects the use of a wrong
- No "wrong" operating mode: produces only
- Optionally overwrites the original file,
thus (providing DOS cooperates) hiding the original data, even
from file-recovery programs.
- Ciphers one file, multiple files, or an entire disk
with a single command. Filenames being selected can be
simply displayed without ciphering.
- Supports enciphered batch files of commands.
- Ciphertext can be concatenated in secure
- Fixed 132-byte file expansion: Ideal for
local storage, off-site archives, or as a first-level cipher for
- A limited commercial demo can be
distributed for corporate evaluation or individual use.
- The straightforward secret key cipher is
much like using house keys or car keys.
- Uses patented Dynamic Substitution
technology. Does not infringe any known patents.
- Enciphered alias files for each user hold
and protect their secret keys.
- A public alias for each key selects that
key from among all others in the alias file.
- A user need only remember one key for their
alias file, instead of remembering every key they use.
- Aliases support the use of large random
keys for better security.
- Dated aliases support access to old
- Aliases can be kept on a floppy and
personally retained when not in use.
- A key-generation mode constructs a long
random key for a given alias. Groups can be given a single key
for all members to use with each other.
- Generated keys are automatically added to the local
- Generated keys are also placed in a separate
enciphered file for transport to the far end or for
distribution to other members of the group.
- New keys can be added to an alias file without
deciphering the file and thus exposing the keys inside.
- Key updates restore security periodically,
or when individuals leave a group.
- Painless key-update: The user continues to
use exactly the same alias to select a new key.
- Key-updates can be programmed in advance,
to support automatic company-wide shifts to new keys on a given
- Corporate version supports corporate key
Terry Ritter, his
current address, and his
Last updated: 1995-08-07