EXHIBIT
12.1

CERTIFICATIONS

I, Jacob (Yanki) Margalit, certify that:

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|(a) | I have reviewed this annual report on Form 20-F of
  Aladdin Knowledge Systems Ltd.;                                                                                                                                                                                                                              
|    |                                                                                                                                                                                                                                                                                                                   
|(b) | Based on my knowledge, this report does not contain
  any untrue statement of a material fact or omit to state a material fact
  necessary to make the statements made, in light of the circumstances under
  which such statements were made, not misleading with respect to the period
  covered by this report;
|    |                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                      
|(c) | Based on my knowledge, the financial statements, and
  other financial information included in his report, fairly present in all
  material respects the financial condition, results of operations and cash
  flows of the company as of, and for, the periods presented in this report;                         
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|(d) | The companys other certifying officer(s) and I are
  responsible for establishing and maintaining disclosure controls and
  procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the
  company and have:                                                                                    
|    |                                                                                                                                                                                                                                                                                                                   
|    | (i)                                                                                                                                                                                                                                                                                                                | Designed such disclosure controls and procedures, or
  caused such disclosure controls and procedures to be designed under our
  supervision, to ensure that material information relating to the company,
  including its consolidated subsidiaries, is made known to us by others within
  those entities, particularly during the period in which this report is being
  prepared;
|    |                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                      
|    | (ii)                                                                                                                                                                                                                                                                                                               | Evaluated the effectiveness of the companys
  disclosure controls and procedures and presented in this report our
  conclusions about the effectiveness of the disclosure controls and
  procedures, as of the end of the period covered by this report based on such
  evaluation; and                                                                                             
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|    | (iii)                                                                                                                                                                                                                                                                                                              | Disclosed in this report any change in the companys
  internal control over financial reporting that occurred during the period
  covered by the annual report that has materially affected, or is reasonably
  likely to materially affect, the companys internal control over financial
  reporting; and                                                                         
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|(e) | The companys other certifying officer(s) and I have
  disclosed, based on our most recent evaluation of internal control over
  financial reporting, to the companys auditors and the audit committee of the
  companys board of directors (or persons performing the equivalent
  functions):                 
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|    | (iv)                                                                                                                                                                                                                                                                                                               | All significant deficiencies and material weaknesses
  in the design or operation of internal control over financial reporting which
  are reasonably likely to adversely affect the companys ability to record,
  process, summarize and report financial information; and                                                                                                         
|    |                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                      
|    | (v)                                                                                                                                                                                                                                                                                                                | Any fraud, whether or not material, that involves
  management or other employees who have significant role in the companys
  internal control over financial reporting.                                                                                                                                                                                                            

Dated: June 27, 2006

| |                               |                           
| | ----------------------------- | --------------------------
| | By:                           | /s/ Jacob (Yanki) Margalit
| |                               |                           
| | Jacob (Yanki) Margalit       
| | Chief Executive Officer      
| | (Principal Executive Officer)

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