Sentinel Security Program v3.0

Encryption & Decryption

About Sentinel

Sentinel utilizes the PR1 stream cipher to, securely, encrypt and decrypt all of your sensitive files. The PR1 cipher is a, proprietary, strong and fast encryption algorithm that encrypts any file using the following methods.

 

3 unique Session Keys per file
a 16k transposition to rearrange the contents of the file
a 1k constant key per 16k file block
a 1k self-rearranging Password Key
a 1k self-rearranging sbox
a 256 Byte box for Byte rotation
Technical Info:

The PR1 algorithm utilizes an 8 step encryption procedure as follows.

 

  1. Right rotate Byte
  2. XOR Byte
  3. Left rotate Byte
  4. XOR Byte
  5. Transpose and XOR Byte
  6. Byte Addition
  7. XOR Byte
  8. Byte Subtraction

The decryption process reverses these procedures.

Sentinel utilizes a SYMMETRICAL KEY which means that the Passwords used to DECRYPT MUST be identical to the ones that were used to ENCRYPT the file originally.

The Password Key is 'USER DEPENDENT'. What that means is that this key gets hashed from the user's password. All other arrays are dependent on the Password Key; they cannot be re-established without the correct  Password Key.

The 3 unique Session Keys ensure that all encryption arrays are different each time. Even if you were to encrypt the same file, with the same password, numerous times the resulting cipher texts would be different each time. The Sentinel process is, essentially, a One Time Pad.

Upon encryption Sentinel will wipe the .zip file and upon decryption Sentinel will wipe the encrypted file and the .zip file. Wiping is accomplished in a 3 pass procedure in which the target files are filled, repeatedly, with junk before being erased.

What is new in v3.0 ?

Sentinel, now, utilizes CRC32 checksums in correlation with the password. Since CRC32 values are unique to the string(s) of characters the represent each of your password (pass phrase) will have a unique value that can be used as a seed for the pseudo random number generator. 

Also incorporated in this release is a 'Time difference' function. This function determines how many seconds, minutes or hours have passed since midnight Jan. 01, 1980 until the present moment.

These 'Timediff' values in conjunction with the system timer and the CRC32 checksums are used to provide the 3 unique Session Keys for each encryption session, making it extremely unlikely that the same 3 session keys will ever be repeated and therefore ensuring that each cipher text is unique.

The encryption algorithm has been, slightly, altered so that the last step of the encryption process is now a subtraction in place of the addition. This ensures less linearity of the cipher while maintaining the same speed as before.

Version 3.0 is not compatible with v2.x. If you have files that were encrypted with v2.x it is advisable to decrypt these with v2.x and then re-encrypt them with v3.0. 

Encryption

Sentinel offers you the following options:

 
Compression / No Compression
Single or multiple Files
Double Encryption

From the main menu select :

 
Encrypt a File

and...
check or uncheck...

 
Compress File

depending on whether, or not, you wish to compress the file(s) prior to encryption.

Compression can offer a slightly higher security than uncompressed files because the compression eliminates redundancy in the file. (The PR1 algorithm, by itself, has been tested on a file containing 1,000,000 "1"s without recurring key streams.) The second advantage is that the compressed file is smaller and, therefore, takes up less space on a disk or transmits faster over the Internet.

Once you are satisfied with your selection press the "Ok" button to continue.

The next screen will present you with the -Select File for Encryption- menu. Simply select the drive, directory and file you wish to encrypt and press "Ok"

If you have selected to -Compress- you may select multiple files by holding down the Mouse Button and dragging to highlight the, desired, files or to hold down the -Ctrl- Key and selecting the desired files.

Sentinel Password Validation

Enter your password on the first line and press -ENTER-, then re-enter the same password on the second line to validate your first entry. This ensures that no typing errors occurred.

Your Password must be at least 10 characters long to a maximum of 60 characters. Be sure that you select your password (pass phrase) wisely. If it is your pet's name, your kid's birthday or your mother's maiden name it will only present any attacker with a minimal headache. Instead use pass phrases such as

  My_Neighbour's_Car_Is_Not_As_Good_As_Mine

The password Is case sensitive(!), meaning that PLUTO is different from Pluto and different from pLuTo. Each of these examples would produce different encryption keys.

If you have chosen to compress you will now be prompted to NAME the Archive where the encrypted files will be stored. Enter the name of the archive and hit -ENTER-.

Check or uncheck...

 
Use PkZip Encryption

This option makes use of PkZip's built in ENCRYPTION capabilities. Even though PkZip's encryption is not strong encryption, it does offer a level of security upon which Sentinel will build. Use of this option will slow the encryption process slightly.

Once you are satisfied with your selection press "Ok".

If you have chosen NOT to compress you may only encrypt one file at a time.

Sentinel now has all the information, required, to process your file(s) and will display the 'Progress Meter' which will inform you of the progress of the compression and/or encryption process.

Once Sentinel has finished its assignment it will return you to the main menu where you may "Quit" or encrypt/decrypt additional files.

Decryption

Files encrypted by Sentinel will have the following file extensions...

 

  1. .sen - for uncompressed files
  2. .snn - for compressed files not PkZip encrypted.
  3. .szn - for compressed files with PkZip encryption.

From the main menu select :

 
Decrypt a File

and press "Ok"

The next screen will present you with the -Select File for Decryption- menu. Simply select the drive, directory and file you wish to decrypt and press "Ok"

Sentinel Password Validation

Enter your password on the first line and press -ENTER-, then re-enter the same password on the second line to validate your first entry. This ensures that no typing errors occurred.

Ensure that the Password used to decrypt the file is identical to the password used to encrypt the file, otherwise you will get Invalid Password and the program will stop. The file will not be decrypted!

Sentinel now has all the information, required, to process your file(s) and will display the 'Progress Meter' which will inform you of the progress of the decryption and/or decompression process.

Once Sentinel has finished its assignment it will return you to the main menu where you may "Quit" or encrypt/decrypt additional files.

Legal

This program offers the user secure encryption of sensitive files. Even though the PR1 algorithm and it's implementation in Sentinel have been tested extensively the author assumes no liability, stated or implied, for the safety of such files.

The use of this program may be in contravention with the laws in your country. 

Use of this program is on your own recognizance.

Support

This program has been designed to be user-friendly, but things can always be improved upon. Should you have any questions, or suggestions, please feel free to contact me, Peter Raddatz, via e-mail at: rabbit@bluecrow.com

Thank you.

Acknowledgements:

This program makes use of PkZip v2.5 for Windows. This program is Shareware but must be registered with continued use.

Surrey B.C., Canada - April 16, 2000