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Delphix

Algorithm: Tokenization in Masking (KBA1002)

 

Overview

The Tokenization algorithm is normally used in Tokenization/Re-Identification though it is frequently used to mask data. This article describes how to use the Tokenization algorithm in Masking

Note

Note:

The use of Tokenization algorithm in masking is an undocumented feature and support will be provided on a best-effort basis only.

Out of the box, there are three Tokenization Algorithms. These algorithms are designed to be used in Tokenization - Re-Identification jobs, but can be used when masking data. 

The out of the box algorithms are: 

  • NAME_TK
  • ACCOUNT_TK
  • SSN_TK

Additional algorithms can be created and there are no configurations for these algorithms and each definition has its own seed to scramble the data. 

At a Glance

Description: By default, this is an algorithm used with Tokenization - Re-Identification. 
This algorithm is frequently used as a Masking Algorithm. 

The algorithm has two modes - if the tokenized string is longer than the specified Data Type for the field, the algorithm will switch and use mode 2 (Caesar Cipher):

  1. BASE-64 Encoding
  2. Caesar Cipher
Characteristics:
 
Type
Referential
Integrity1

1:1 Mapping2

Strength
Base-64 Code based Yes  Yes Strong
Ceasar Code based Yes Yes Weak

1 Referential Integrity - The masked value will be the same between job executions as well as tables.
2 1:1 Mapping - The masked value will be mapped uniquely to the input value within masked column.

Character 
Encodings:

In: Depending on Mode
Out, mode 1: BASE-64

  • All characters and encodings.

Out, mode 2: Caesar Cipher

  • US-ASCII 7 bit alphabetic characters.
  • Special characters are retained. 
  • Case (upper/lower) is retained.  
Lookup Pool Size: None
Limitations:

The algorithm can change behavior depending on the masked data length.

Caesar Cipher does not work on extended characters encoding such as Japanese nor on binary data.  Caesar Cipher is reversible. 

The algorithm can only be selected on the Inventory page. 

Creating Algorithm  

To create this algorithm, there is only one field that needs to be specified - Algorithm Name.

Fields are:

  1. Properties
    • Algorithm Name
    • Description (optional & editable)
Note

Note:

The optional value (description) is editable.

User Interface 

When creating (and modifying) the algorithm, the following popup will display:

Tokenization Algorithm Popup.png

Considerations  

There are some considerations when using this algorithm:

  • Low Memory Requirements 
  • The algorithm having two modes
  • Caesar Cipher is not strong 

Low Memory Requirements  

The memory requirements are very small. If there is an error, it is usually related to too much memory allocated. 

Algorithm Having Two Modes  

The mode depends on the number of characters in the masked column. This can cause issues:

  • The masked result is dependent on the number of characters defined for the column. 
    • If the length of the Data Type can NOT hold the length of the BASE-64, then Caesar will be used. 
    • For varchar the thresholds for Caesar are:
      • String length 1-15  - Caesar if Data Type < 24 
      • String length 16-31 - Caesar if Data Type < 44
      • String length 32-47 - Caesar if Data Type < 64
      • String length 48-63 - Caesar if Data Type < 88
      • ...
  • When the Data Type is char and nchar
    • This will cause the algorithm to always use Caesar Cipher due to the trailing spaces stored with the algorithm. Data might need to be trimmed if this is causing an issue: Algorithms - Casting Values before Masking
  • When the Data Type is text
    • This will cause the algorithm to always use BASE 64 and no workaround is available. 

Caesar Cipher is Not Strong 

Caesar Cipher should only be used on insensitive data as the masking algorithm is very weak and easy to reverse engineer. 

Examples 

Database Example 

Below is an example of masked data. The example shows both the long and the short response. 

  • Masked Short:
    • Caesar Cipher
    • The output if the Tokenized data is not fitting the number of character in the column.
  • Masked Long:
    • BASE-64 Encoding
    • The output if the Tokenized data fits within the number of characters in the column. 
+-------------+--------------+--------------------------+
| Input       | Masked Short | Masked Long              |
+=============+==============+==========================+
| NULL        | NULL         | NULL                     |
+-------------+--------------+--------------------------+
|             |              |                          |
+-------------+--------------+--------------------------+
| 1           | 0            | JIEaxAUiS07BJ1b83VK67A== |
|  1          |  0           | RVpBr7jwkzBrsbylJ8RsqA== |  << Leading space
| 2           | 1            | DtEpeeQPGlUiWyTFtX/9Pc== |
| 3           | 2            | Tt0DD/xi8T7/oNQM4zngHe== |
+-------------+--------------+--------------------------+
| 1000        | 999          | Bx9Q08KjWJOjmLRxctjwjc== |
| 1000000     | 999999       | tzwwW7oCpWH4ugQ/0+JG3e== |
+-------------+--------------+--------------------------+
| Anders      | Ylnsfk       | QDWGg040FuM4x3wXI+LZYA== |
| Jack        | Ryiw         | 4rceRCHDfLrgykiUtF+IXc== |
| JACK        | RYIW         | zyXPE8U2j4vAVWuyjiAyNY== |  << Different case
| Mask Data   | Gykw Nypy    | lrKFSutznXgmSGMjfyjLEe== |  
| Mask (Data) | Gykw (Nypy)  | OOieiOzmVfmpjg7/a0iOpA== |  << Special characters
| 0A1b2C      | 9Y0d1I       | AtdPaY3mlys7hVXA/QFEMc== |
+-------------+--------------+--------------------------+
| άλφα        | hehg         | Nf9hicuZwzXlJJ+2agmW+Y== |  << Same result 
| βήτα        | hehg         | Nf9hicuZwzXlJJ+2agmW+Y== |  <<  "
| ovol        | hehg         | Nf9hicuZwzXlJJ+2agmW+Y== |  <<  "
| глаголь       | gurgjub      | Lh30YlrZItxBeDHASHn5tA== |
| quyến       | auoel        | bBVHAPX1slfcVz+IdqmtuY== |
+-------------+--------------+--------------------------+
| -           | -            | WrvOd+8a90lUniLNvjzKOY== |  << Caesar pass through
| !@#$%       | !@#$%        | RAEP34kIsLJMNzI8T0O3lY== |  <<  "
| こんばんは    | こんばんは    | 4RbopLsq2CVHll0cMhtxYA== |  <<  " 
+-------------+--------------+--------------------------+

Text File Example 

The examples below show the Tokenization algorithm on CSV delimited and Fixed Width text files. Note that with CSV we will always get BASE-64 Encoding.

Input

1234,1234
   4,   4
1  4,1  4
 2 4, 2 4
12 4,12 4
 234, 234

CSV delimited

1234,fLfQlqvzuWPdpH6POQVhDM==
   4,2noZSlGxak1rgQcOpN3Ywc==
1  4,RYZbPyVHtylBlPkyiHNyZM==
 2 4,JVZDzDeukSa7brDr6dCFik==
12 4,IpChIhAL4qSKxgN0gP/H8M==
 234,ze5VXnwxMHw6RbssrqIelU==

Fixed Width

1234,8901
   4,   1
1  4,8  1
 2 4, 9 1
12 4,89 1
 234, 901

Common Errors 

Caesar is not tokenizing (masking) characters outside the alphabetic characters 

The Caesar Cipher is not tokenizing characters not convertible to a US ASCII. As examples, special characters and Japanese characters will pass through un-tokenized (unmasked).

Algorithm is not unique for characters outside the US-ASCII set 

Tokenized words in Russian will be Re-Identified as US-ASCII characters. See example above. This is for characters that can be converted to an equivalent version in the US ASCII - i.e. Ü and U.

Example, these three strings will be masked using Caesar to the same result:

ovol >> hehg
άλφα >> hehg
βήτα >> hehg

Data Type CHAR causes the use of Caesar Cipher 

Data stored in a column of Data Type CHAR (or NCHAR) will be padded with spaces and cause Caesar to be used all the time.

Resolution: To resolve this - cast (trim) the masked value before. Algorithms - Casting Values before Masking

Related Articles

The following articles may provide more information or related information to this article.

Knowledge Base Article 

Documentation