Securing Your Data

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Securing Your Data

Protecting Data with Constraints

Controlling Access to Data

DES3 Encrypting Your Data

the ability to encrypt the data held in Recital database tables. Once a database table has been encrypted, the data cannot be accessed unless the correct three-part encryption key is specified, providing additional security for sensitive data.

The ENCRYPT command is used to encrypt the data in the specified table or tables matching a skeleton. If the skeleton syntax is used, then all matching tables will be given the same encryption key. The encryption key is a three part comma-separated key and may optionally be enclosed in angled brackets. Each part of the key can be a maximum of 8 characters. The key is DES3 encrypted and stored in a .dkf file with the same basename as the table. After encryption, the three parts of the key must be specified correctly before the table can be accessed.

// Encrypt individual tables
encrypt customers key "key_1,key_2,key_3"
encrypt employees key "<key_1,key_2,key_3>"
 
// Encrypt all .dbf files in the directory
encrypt *.dbf key "key_1,key_2,key_3"

If a database table is encrypted, the correct three-part encryption key must be specified before the table's data or structure can be accessed. The SET ENCRYPTION TO set command can be used to specify a default encryption key to be used whenever an encrypted table is accessed without the key being specified. The encryption key is a three part comma-separated key.

If the command to access the table includes the key, either by appending it to the table filename specification or using an explicit clause, this will take precedence over the key defined by SET ENCRYPTION TO. Issuing SET ENCRYPTION TO without a key causes any previous setting to be cleared. The key must then be specified for each individual encrypted table. The default key defined by SET ENCRYPTION is only active when SET ENCRYPTION is ON. SET ENCRYPTION OFF can be used to temporarily disable the default key. The SET ENCRYPTION ON | OFF setting does not change the default key itself. SET ENCRYPTION is ON by default.

// Encrypt individual tables
encrypt customers key "key_1,key_2,key_3";
encrypt shippers key "key_2,key_3,key_4"
// Specify a default encryption key
set encryption to "key_1,key_2,key_3"
// Open customers table using the default encryption key
 
use customers
// Specify shippers table's encryption key
use shippers<key_2,key_3,key_4>
// Disable the default encryption key
set encryption to
// Specify the individual encryption keys
use customers encryption "key_1,key_2,key_3"
use shippers<key_2,key_3,key_4>

The DECRYPT command is used to decrypt the data in the specified table or tables matching a skeleton. The specified key must contain the three part comma-separated key used to previously encrypt the table and may optionally be enclosed in angled brackets. The skeleton syntax can only be used if all tables matching the skeletonhave the same key. The DECRYPT command decrypts the data and removes the table's .dkf file. After decryption, the key need no longer be specified to gain access to the table.

// Decrypt individual tables
decrypt customers key "key_1,key_2,key_3"
decrypt employees key "<key_1,key_2,key_3>"
 
// Decrypt all .dbf files in the directory
decrypt *.dbf key "key_1,key_2,key_3"

All of the following commands are affected when a table is encrypted:

APPEND FROM Used to append records to the active table from another table.

// The key must be specified for an encrypted source table
use mycustomers
append from customers encryption "key_1,key_2,key_3";
for country = "UK"

COPY FILE Used to copy a file.

// The key file must also be copied for an encrypted source table
// as the target table will be encrypted
encrypt customers key "key_1,key_2,key_3"
copy file customers.dbf to newcustomers.dbf
copy file customers.dkf to newcustomers.dkf
use newcustomers encryption "key_1,key_2,key_3"

COPY STRUCTURE Used to copy a table's structure to a new table.

// The key file is automatically copied for an encrypted source table
// and the target table encrypted
encrypt customers key "key_1,key_2,key_3"
use customers encryption "key_1,key_2,key_3"
copy structure to blankcust
use blankcust encryption "key_1,key_2,key_3"

COPY Used to copy a table.

// By default, the key file is automatically copied for an encrypted
// source table and the target table encrypted with the same key
encrypt customers key "key_1,key_2,key_3"
 
use customers encryption "key_1,key_2,key_3"
copy to newcustomers
use newcustomers encryption "key_1,key_2,key_3"
 
// You can also create a copy with a different key
encrypt customers key "key_1,key_2,key_3"
use customers encryption "key_1,key_2,key_3"
copy to newcustomers encrypt "newkey_1,newkey_2,newkey_3"
 
use newcustomers encryption "newkey_1,newkey_2,newkey_3"
 
// Or create a decrypted copy
encrypt customers key "key_1,key_2,key_3";
use customers encryption "key_1,key_2,key_3"
copy to newcustomers decrypt
use newcustomers
 
// You can also create an encrypted copy of a non-encrypted source table
use orders
copy to encorders encrypt "newkey_1,newkey_2,newkey_3"
use encorders encryption "newkey_1,newkey_2,newkey_3"

DIR Used to display a directory listing of tables.

// Encrypted tables are flagged as such with (DES3)
open database southwind
dir
Current database: southwind
Tables            # Records    Last Update   Size  Dictionary Triggers Security
categories.dbf            8    01/10/06     24576  None       None     None
cisamdemo.dbf       ---> CISAM/Bridge        [cisamdemo]
customers.dbf (DES3)     91    05/12/04     49600  None       None     None
employees.dbf             9    05/12/04     25520  None       None     None
example.dbf   (DES3)    100    12/24/05     38080  Yes        Yes      None
order_details.dbf      2155    05/12/04    296320  None       None     None
orders.dbf              829    05/12/04    232704  None       None     None
products.dbf             77    05/12/04     37112  None       None     None
productsbyname.dbf       77    05/12/04     29104  None       None     None
shippers.dbf  (DES3)      3    05/12/04     20864  None       None     None
suppliers.dbf            29    12/08/05     29992  Yes        None     None

   0.765 MB in 11 files.
   1.093 GB remaining on drive.

USE Used to open a table.

// The three part key must be specified to open an
// encrypted table.  All of the following are valid.
// 1. Specifying a default encryption key before opening the table
set encryption to "key_1,key_2,key_3"
use customers
// 2. Appending the key to the filename
use customers<key_1,key_2,key_3>
// 3. Using the ENCRYPTION clause, optionally specifying angled brackets
use customers encryption "key_1,key_2,key_3"
use customers encryption "<key_1,key_2,key_3>"

SQL INSERT Used to add a row to a table via SQL.

// The three part key can be specified using a
// default encryption key before opening the table
exec sql
  OPEN DATABASE southwind;
exec sql
  SET ENCRYPTION TO "key_1,key_2,key_3"
exec sql
  INSERT INTO customers
  (customerid, companyname)
  VALUES
  ('RECIT','Recital Corporation');
 
// Or by appending the key to the filename
 
exec sql
  OPEN DATABASE southwind;
exec sql
  INSERT INTO customers<key_1,key_2,key_3>
  (customerid, companyname)
  VALUES
  ('RECIT','Recital Corporation');

SQL SELECT Used to return data from a table via SQL.

// The three part key can be specified using a
// default encryption key before opening the table
exec sql
  OPEN DATABASE southwind;
exec sql
  SET ENCRYPTION TO "key_1,key_2,key_3";
exec sql
  SELECT * FROM customers;
// Or by appending the key to the filename
 
exec sql
  OPEN DATABASE southwind;
exec sql
  SELECT * FROM customers<key_1,key_2,key_3>;
 
SQL UPDATE
Used to update data in a table via SQL.
 
<code lang="recital">
// The three part key can be specified using a
// default encryption key before opening the table
exec sql
  OPEN DATABASE southwind;
exec sql
  SET ENCRYPTION TO "key_1,key_2,key_3";
exec sql
  UPDATE customers
  SET companyname='Recital Corporation Inc.'
  WHERE customerid='RECIT';
// Or by appending the key to the filename
exec sql
  OPEN DATABASE southwind;
exec sql
  UPDATE customers<key_1,key_2,key_3>
 
  SET companyname='Recital Corporation Inc.'
  WHERE customerid='RECIT';