Document:

<PAGE>   1
                                                                   Exhibit 10.49

                          COMMON STOCK PURCHASE WARRANT

Void after July 20, 2004

THE SECURITIES EVIDENCED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), OR ANY STATE OR OTHER SECURITIES
LAWS, AND MAY NOT BE OFFERED, REOFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED,
ENCUMBERED OR OTHERWISE DISPOSED OF OR DISTRIBUTED, DIRECTLY OR INDIRECTLY,
WITHIN THE UNITED STATES OR TO OR FOR THE ACCOUNT OF U.S. PERSONS UNLESS THE
TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF
THE SECURITIES ACT OR PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
SECURITIES ACT. THE HOLDER OF THIS SECURITY BY ITS ACCEPTANCE HEREOF, AGREES
THAT IT WILL NOT OFFER, REOFFER, SELL, ASSIGN, TRANSFER, PLEDGE, ENCUMBER OR
OTHERWISE DISPOSE OF OR DISTRIBUTE DIRECTLY OR INDIRECTLY THESE SECURITIES IN
THE UNITED STATES, ITS TERRITORIES, POSSESSIONS, OR AREAS SUBJECT TO ITS
JURISDICTION, OR TO OR FOR THE ACCOUNT OR BENEFIT OF A U.S. PERSON, AT ANY TIME
PRIOR TO TWO YEARS AFTER THE ORIGINAL ISSUANCE OF THESE SECURITIES, EXCEPT (A)
TO THE COMPANY OR A SUBSIDIARY OF THE COMPANY, (B) IN CONJUNCTION WITH AN
EFFECTIVE REGISTRATION STATEMENT FOR THE SECURITIES UNDER THE SECURITIES ACT,
(C) IN COMPLIANCE WITH AN EXEMPTION FROM REGISTRATION UNDER SUCH ACT, OR (D) IN
ACCORDANCE WITH THE PROVISIONS OF REGULATION S OF SUCH ACT, INCLUDING RULE 903,
RULE 904 AND RULE 905 THEREUNDER, AND AGREES THAT ANY HEDGING TRANSACTIONS
INVOLVING THE SECURITIES WILL BE CONDUCTED IN COMPLIANCE WITH REGULATION S UNDER
SUCH ACT AND AGREES THAT IT WILL GIVEN TO EACH PERSON TO WHOM THIS SECURITY IS
TRANSFERRED A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND; PROVIDED THAT
THE COMPANY, THE TRANSFER AGENT, AND THE REGISTRAR SHALL HAVE THE RIGHT PRIOR TO
ANY SUCH OFFER, SALE OR TRANSFER, IN EACH OF THE FOREGOING CASES, TO REQUIRE
DELIVERY OF A CERTIFICATION OF TRANSFER IN FORM SATISFACTORY TO THEM. AS USED
HEREIN, THE TERMS "UNITED STATES" AND "U.S. PERSON" HAVE THE MEANINGS GIVEN TO
THEM BY REGULATION S UNDER THE SECURITIES ACT.

                            ------------------------

                          COMMON STOCK PURCHASE WARRANT

VASCO DATA SECURITY INTERNATIONAL, INC., a Delaware corporation (the "COMPANY"),
having its principal office at 1901 South Meyers Road, Suite 210, Oakbrook
Terrace, Illinois 60181 hereby certifies that, for value received, UBIZEN N.V.,
or transferees or assigns (the "HOLDER") is entitled, subject to the terms set
forth below, to purchase from the Company at any time on or from time to time
after July 20, 2000 and before 5:00 p.m., New York City time, on July 20, 2004,
seven hundred eighty nine thousand four hundred and seventy four (789,474) fully
paid and non-assessable shares of Common Stock of the Company, par value $0.001
per share, at the price per share of Fifteen Dollars (U.S.$15.00) (the "PURCHASE
PRICE"), subject to the terms, conditions, adjustments and limitations set forth
herein.

                                      -1-
<PAGE>   2

As used herein the following terms, unless the context otherwise requires, have
the following respective meanings:

       (a)    The term "COMPANY" includes the Company and any corporation which
              shall succeed to or assume the obligations of the Company
              hereunder.

       (b)    The term "COMMON STOCK" includes all stock of any class or classes
              (however designated) of the Company, authorized upon the Original
              Issue Date or thereafter, the holders of which shall have the
              right, without limitation as to amount, either to all or to a
              share of the balance of current dividends and liquidating
              dividends after the payment of dividends and distributions on any
              shares entitled to preference, and the holders of which shall
              ordinarily, in the absence of contingencies, be entitled to vote
              for the election of a majority of directors of the Company (even
              though the right so to vote has been suspended by the happening of
              such a contingency).

       (c)    The "ORIGINAL ISSUE DATE" is July 20, 2000.

       (d)    The term "OTHER SECURITIES" refers to any stock (other than Common
              Stock) and other securities of the Company or any other person
              (corporate or otherwise) which the holder of this Warrant at any
              time shall be entitled to receive, or shall have received, upon
              the exercise of this Warrant, in lieu of or in addition to Common
              Stock, or which at any time shall be issuable or shall have been
              issued in exchange for or in replacement of Common Stock or Other
              Securities pursuant to section 6 or otherwise.

       (e)    The term "PURCHASE PRICE" shall be the then applicable exercise
              price for one share of Common Stock.

       (f)    The terms "REGISTERED" and "REGISTRATION" refer to a registration
              effected by filing a registration statement in accordance with the
              Securities Act, to permit the resale of Common Stock (or Other
              Securities) issued or issuable upon the exercise of this Warrant,
              and any post-effective amendments and supplements filed or
              required to be filed to permit any such disposition.

       (g)    The term "SECURITIES ACT" means the Securities Act of 1933 as the
              same shall be in effect at the time.

1      REGISTRATION, ETC.

       This Warrant, the shares of Common Stock issuable upon exercise thereof
       and the Other Securities shall have such registration rights as provided
       in Section 8 and Section 9 of the Securities Purchase Agreement dated
       July 18, 2000 between the Company and Ubizen, N.V..

2      SALE OR EXERCISE WITHOUT REGISTRATION

       If, at the time of any exercise, transfer or surrender for exchange of
       this Warrant or of Common Stock (or Other Securities) previously issued
       upon the exercise of this Warrant, this Warrant or Common Stock (or Other
       Securities) shall not be registered under the Securities Act, the Company
       may require, as a condition of allowing such exercise, transfer or
       exchange, that the record owner or transferee of this Warrant or Common
       Stock (or Other Securities), as the case may be, furnish to the Company a
       satisfactory opinion of counsel to the effect that such

                                      -2-
<PAGE>   3

       exercise, transfer or exchange may be made without registration under the
       Securities Act, provided that the disposition thereof shall at all times
       be within the control of such record owner or transferee, as the case may
       be, and provided further that nothing contained in this section 2 shall
       relieve the Company from complying with any request for registration
       pursuant to section 1 hereof. The first holder of this Warrant represents
       to the Company that it is acquiring this Warrant for investment and not
       with a view to the distribution thereof.

3      EXERCISE OF WARRANT; PARTIAL EXERCISE; EXERCISE BY SURRENDER

       3.1    EXERCISE IN FULL Subject to the provisions hereof, this Warrant
              may be exercised in full by the record owner hereof by surrender
              of this Warrant, with the form of subscription at the end hereof
              duly executed by such record owner, to the Company at its
              principal office accompanied by payment in the amount obtained by
              multiplying the number of shares of Common Stock called for on the
              face of this Warrant by the Purchase Price. Payment of the
              Purchase Price for the shares of Common Stock purchased pursuant
              to exercise of this Warrant shall be made (a) in cash or cash
              equivalents, (b) through the tender to the Company of shares of
              Common Stock, which shares shall be valued for purposes of
              determining the extent to which the Purchase Price has been paid,
              at their Market Price (determined by the Board of Directors of the
              Company in accordance with section 3.3 hereof) on the date of
              exercise, (c) by delivering a written direction to the Secretary
              of the Company that this Warrant is to be exercised pursuant to a
              "cashless" exercise/sale procedure (pursuant to which funds to pay
              for exercise of the Warrant are delivered to the Company by a
              broker upon receipt of stock certificates from the Company) or a
              "cashless" exercise/loan procedure (pursuant to which the holders
              would obtain a margin loan from a broker to fund the certificates
              for the shares of Common Stock for which the Warrant is exercised,
              such certificates will be delivered to the broker who will deliver
              to the Company the cash (or cash equivalents acceptable to the
              Company) equal to the Purchase Price for the shares of Common
              Stock purchased pursuant to the exercise of the Warrant plus the
              amount (if any) of federal and other taxes that the Company may,
              in its judgment after consultation with the record owner hereof,
              be required to withhold with respect to the exercise of the
              Warrant, or (d) a combination of the methods described in (a), (b)
              and (c) above.

       3.2    PARTIAL EXERCISE Subject to the provisions hereof, this Warrant
              may be exercised in part by surrender of this Warrant in the
              manner and at the place provided in section 3.1 except that the
              amount payable by the record owner upon any partial exercise shall
              be the amount obtained by multiplying (a) the number of shares of
              Common Stock designated by the record owner in the subscription at
              the end hereof by (b) the Purchase Price. Upon any such partial
              exercise, the Company at its expense will forthwith issue and
              deliver to or upon the order of the record owner hereof a new
              Warrant or Warrants of like tenor, in the name of the record owner
              hereof or as such record owner (upon payment by such record owner
              of any applicable transfer taxes) may request, calling in the
              aggregate on the face or faces thereof for the number of shares of
              Common Stock equal to the number of such shares called for on the
              face of this Warrant minus the number of such shares designated by
              the record owner in the subscription at the end hereof.

                                      -3-
<PAGE>   4

       3.3    DEFINITION OF MARKET PRICE As used herein, the phrase "Market
              Price" at any date shall be deemed to be (i) if the principal
              trading market for such securities is an exchange, the last
              reported sale price, or, in case no such reported sale takes place
              on such date, the average of the last reported sale prices for the
              preceeding three (3) trading days, in either case as officially
              reported on any consolidated tape, (ii) if the principal market
              for such securities is the over-the-counter market, the high bid
              price on such date as set forth by NASDAQ or, if the security is
              not quoted on NASDAQ, the high bid price as set forth in the
              National Quotation Bureau sheet listing such securities for such
              day. Notwithstanding the foregoing, if there is no reported
              closing price or high bid price, as the case may be, on the date
              next preceding the event requiring an adjustment hereunder, then
              the Market Price shall be determined as of the latest date prior
              to such day for which such closing price or high bid price is
              available, or if the securities are not quoted on NASDAQ, as
              determined in good faith by resolution of the Board of Directors
              of the Company, based on the best information available to it.

       3.4    COMPANY TO REAFFIRM OBLIGATIONS The Company will, at the time of
              any exercise of this Warrant, upon the request of the record owner
              hereof, acknowledge in writing its continuing obligation to afford
              to such record owner any rights (including, without limitation,
              any right to registration of the shares of Common Stock or Other
              Securities issued upon such exercise) to which such record owner
              shall continue to be entitled after such exercise in accordance
              with the provisions of this Warrant, provided that if the record
              owner of this Warrant shall fail to make any such request, such
              failure shall not affect the continuing obligation of the Company
              to afford such record owner any such rights.

4      DELIVERY OF STOCK CERTIFICATES, ETC., ON EXERCISE

       As soon as practicable after the exercise of this Warrant in full or in
       part, and in any event within ten (10) days thereafter, the Company at
       its expense (including the payment by it of any applicable issue taxes)
       will cause to be issued in the name of and delivered to the record owner
       hereof, or as such record owner (upon payment by such record owner of any
       applicable transfer taxes) may direct, a certificate or certificates for
       the number of fully paid and non-assessable shares of Common Stock (or
       Other Securities) to which such record owner shall be entitled upon such
       exercise, plus, in lieu of any fractional share to which such record
       owner would otherwise be entitled, cash equal to such fraction multiplied
       by the then current Market Price of one full share, together with any
       other stock or other securities and property (including cash, where
       applicable) to which such record owner is entitled upon such exercise
       pursuant to section 5 or otherwise.

5      ADJUSTMENT FOR DIVIDENDS IN OTHER STOCK, PROPERTY, ETC.;
       RECLASSIFICATION, ETC.

       In case at any time or from time to time after the Original Issue Date
       the holders of Common Stock (or Other Securities) shall have received or
       (on or after the record date fixed for the determination of stockholders
       eligible to receive) shall have become entitled to receive without
       payment therefor

       (a)    other or additional stock or other securities or, property (other
              than cash) by way of dividend, or

                                      -4-
<PAGE>   5

       (b)    any cash paid or payable (including, without limitation, by way of
              dividend other than a dividend payable out of earned surplus of
              the Company), or

       (c)    other or additional (or less) stock or other securities or
              property (including cash) by way of spin-off, split-up,
              recapitalization, combination of shares or similar corporate
              rearrangement,

       then, and in each such case the record owner of this Warrant, upon the
       exercise hereof as provided in section 3, shall be entitled to receive
       the amount of stock and other securities and property (including cash in
       the cases referred to in subdivisions (b) and (c) of this section 5)
       which such record owner would hold on the date of such exercise if on the
       Original Issue Date such person had been the holder of record of the
       number of shares of Common Stock called for on the face of this Warrant
       and had thereafter, during the period from the Original Issue Date to and
       including the date of such exercise, retained such shares and all such
       other additional (or less) stock and other securities and property
       (including cash in the cases referred to in subdivisions (b) and (c) of
       this section 5) receivable by such person as aforesaid during such
       period, giving effect to all adjustments called for during such period by
       sections 6 and 7 hereof.

6      REORGANIZATION, CONSOLIDATION, MERGER, ETC.

       In case the Company after the Original Issue Date shall (a) effect a
       reorganization, (b) consolidate or merge with any other person, or (c)
       transfer all or substantially all of its properties or assets to any
       other person under any plan or arrangement contemplating the dissolution
       of the Company, then, in each such case, the record owner of this
       Warrant, upon the exercise hereof as provided in section 3 at any time
       after the consummation of such reorganization, consolidation or merger or
       the effective date of such dissolution, as the case may be, shall be
       entitled to receive (and the Company shall be obligated to deliver), in
       lieu of the Common Stock (or Other Securities) issuable upon such
       exercise prior to such consummation or such effective date, the stock and
       other securities and property (including cash) to which such record owner
       would have been entitled upon such consummation or in connection with
       such dissolution, as the case may be, if such record owner had so
       exercised this Warrant immediately prior thereto, all subject to further
       adjustment thereafter as provided in sections 5 and 7 hereof.

7      OTHER ADJUSTMENTS

       7.1    GENERAL In any case to which sections 5 and 6 hereof are not
              applicable, where the Company shall issue or sell any (i) shares
              of its Common Stock, (ii) securities convertible into Common Stock
              ("CONVERTIBLE SECURITIES") or (iii) rights or options to subscribe
              for, purchase or otherwise acquire Common Stock after the Original
              Issue Date and prior to the expiration of this Warrant at a per
              share price less than the Purchase Price, the Purchase Price per
              share shall be reduced, concurrently with such issue price
              (calculated to the nearest cent) as determined in accordance with
              the following: multiplying the Purchase Price by a fraction, (a)
              the numerator of which shall be (1) the number of shares of Common
              Stock outstanding immediately prior to such issue plus (2) the
              number of shares of Common Stock which the aggregate consideration
              received by the Company for the total number of additional shares
              of Common Stock so issued or issuable would purchase at such
              Purchase Price; and (b) the denominator of which shall be (1) the
              number of shares of Common Stock

                                      -5-
<PAGE>   6

              outstanding immediately prior to such issue plus (2) the number of
              shares of Common Stock so issued or issuable. Such adjustments
              shall account for the number of shares of Common Stock received by
              the record owner of this Warrant as a result of any partial
              exercise hereof. Notwithstanding anything herein to the contrary,
              no adjustment shall be made for any shares of Common Stock or
              rights or options to subscribe for or purchase or otherwise
              acquire Common Stock after the Original Issue Date and prior to
              the expiration of this Warrant at a per share price less than the
              Purchase Price if such Common Stock or rights or options to
              subscribe for, purchase or otherwise acquire Common Stock are
              sold, issued or subscribed for (a) in connection with the granting
              of any employee stock options by the Company, or upon the exercise
              of such options, pursuant to the terms of a plan in effect on the
              date hereof or a successor to such a plan, (b) in connection with
              any merger or acquisition in which the shares of Common Stock or
              rights or options to subscribe for, purchase or otherwise acquire
              Common Stock are sold, issued or subscribed for value equal to or
              greater than the then current Market Price or (c) in connection
              with an investment by a Strategic Partner of the Company in which
              the shares of Common Stock or rights or options to subscribe for,
              purchase or otherwise acquire Common Stock are sold, issued or
              subscribed for value equal to or greater than the then current
              Market Price; provided that, with respect to any transaction
              described in (b) and (c), the Company shall provide the Purchaser
              with a copy of a resolution of its Board of Directors, duly
              certified by an executive officer of the Company, to the effect
              that (i) the value of the aggregate consideration received from
              such Strategic Partner with respect to such securities divided by
              (ii) the aggregate number of shares of Common Stock so issued or
              issuable is greater than or equal to the Market Price of the
              Common Stock on the closing date with respect to such merger,
              acquisition or investment. As used in the preceding sentence a
              "STRATEGIC PARTNER" shall mean an investor which, simultaneously
              with its investment in securities of the Company, is entering into
              one or more bona fide agreements with the Company relating to the
              provision of products or services which are central to the
              Company's business.

       7.2    MINIMUM ADJUSTMENT No adjustment shall be made under this section
              7 if the amount of any such adjustment would be an amount less
              than one percent (1%) of the Purchase Price then in effect, but
              any such amount shall be carried forward and an adjustment in
              respect thereof shall be made at the time of and together with any
              subsequent adjustment which, together with such amount and any
              other amount or amounts so carried forward, shall aggregate an
              increase or decrease of one percent (1%) or more.

8      FURTHER ASSURANCES

       The Company will take all such action as may be necessary or appropriate
       in order that the Company may validly and legally issue fully paid and
       non-assessable shares of Common Stock upon the exercise of all Warrants
       from time to time outstanding.

9      CERTIFICATE OF CHIEF FINANCIAL OFFICER AS TO ADJUSTMENTS

       In each case of any adjustment or readjustment in the shares of Common
       Stock (or Other Securities) issuable upon the exercise of this Warrant,
       the Company at its expense will promptly cause the Company's Chief
       Financial Officer to compute such adjustment or readjustment in

                                      -6-
<PAGE>   7

       accordance with the terms of this Warrant and prepare a certificate
       setting forth such adjustment or readjustment and showing in detail the
       facts upon which such adjustment or readjustment is based, and the number
       of shares of Common Stock outstanding or deemed to be outstanding;
       provided that if any similar certificate is provided by the Company's
       regularly retained auditor to the holder of any other warrant of the
       Company, the Company's regularly retained auditor shall provide this
       certificate to the record owner of this Warrant. The Company will
       forthwith mail a copy of each such certificate to the record owner of
       this Warrant.

10     NOTICES OF RECORD DATE, ETC.

       In the event of

       (a)    any taking by the Company of a record of the holders of any class
              of securities for the purpose of determining the holders thereof
              who are entitled to receive any dividend (other than a cash
              dividend payable out of earned surplus of the Company) or other
              distribution, or any right to subscribe for, purchase or otherwise
              acquire any shares of stock of any class or any other securities
              or property, or to receive any other right, or

       (b)    any capital reorganization of the Company, any reclassification or
              recapitalization of the capital stock of the Company or any
              transfer of all or substantially all the assets of the Company to
              or consolidation or merger of the Company with or into any other
              person, or

       (c)    any voluntary or involuntary dissolution, liquidation or
              winding-up of the Company,

       then and in each such event the Company will mail or cause to be mailed
       to the record owner of this Warrant a notice specifying (i) the date on
       which any such record is to be taken for the purpose of such dividend,
       distribution or right, and stating the amount and character of such
       dividend, distribution or right and (ii) the date on which any such
       reorganization, reclassification, recapitalization, transfer,
       consolidation, merger, dissolution, liquidation or winding-up is to take
       place, and the time, if any, as of which the holders of record of Common
       Stock (or Other Securities) shall be entitled to exchange their shares of
       Common Stock (or Other Securities) for securities or other property
       deliverable upon such reorganization, reclassification, recapitalization,
       transfer, consolidation, merger, dissolution, liquidation or winding-up.
       Such notice shall be mailed at least twenty (20) days prior to the date
       therein specified.

11     RESERVATION OF STOCK, ETC., ISSUABLE ON EXERCISE OF WARRANTS

       The Company will at all times reserve and keep available, solely for
       issuance and delivery upon the exercise of this Warrant, all shares of
       Common Stock (or Other Securities) from time to time issuable upon the
       exercise of this Warrant.

12     LISTING ON SECURITIES EXCHANGES

       The Company will, at its expense, to the extent permitted by the rules of
       any national securities exchange or automated inter-dealer quotation
       system on which the Common Stock is listed, simultaneously list on such
       exchange or system, upon official notice of issuance upon the exercise of
       this Warrant, all shares of Common Stock from time to time issuable upon
       the exercise of this Warrant, and maintain such listing of all shares of
       Common Stock from time to time issuable upon the exercise of this
       Warrant, and the Company will so list on any national

                                      -7-
<PAGE>   8

       securities exchange, will so register and will maintain such listing of,
       any Other Securities if and at the time that any securities of like class
       or similar type shall be listed on such national securities exchange or
       automated inter-dealer quotation system by the Company.

13     EXCHANGE OF WARRANTS

       Subject to the provisions of section 2 hereof, upon surrender for
       exchange of this Warrant, properly endorsed, to the Company, the Company
       at its own expense will issue and deliver to or upon the order of the
       record owner thereof a new Warrant of like tenor, in the name of such
       record owner or as such record owner (upon payment by such record owner
       of any applicable transfer taxes) may direct, calling in the aggregate on
       the face or faces thereof for the number of shares of Common Stock called
       for on the face of this Warrant.

14     REPLACEMENT OF WARRANTS

       Upon receipt of evidence reasonably satisfactory to the Company of the
       loss, theft, destruction or mutilation of this Warrant and, in the case
       of any such loss, theft or destruction, upon delivery of an indemnity
       agreement reasonably satisfactory in form and amount to the Company or,
       in the case of any such mutilation, upon surrender and cancellation of
       this Warrant, the Company at its expense will execute and deliver, in
       lieu thereof, a new Warrant of like tenor.

15     WARRANT AGENT

       The Company may, by written notice to each record owner of this Warrant,
       appoint an agent, for the purpose of issuing Common Stock (or Other
       Securities) upon the exercise of this Warrant pursuant to section 3,
       exchanging this Warrant pursuant to section 13, and replacing this
       Warrant pursuant to section 14, or any of the foregoing, and thereafter
       any such issuance, exchange or replacement, as the case may be, shall be
       made at such office by such agent.

16     NEGOTIABILITY, ETC.

       Subject to the provisions of section 2 hereof, this Warrant is issued
       upon the following terms, to all of which each holder or owner hereof by
       the taking hereof consents and agrees:

       (a)    subject to the provisions hereof, title to this Warrant may be
              transferred, in whole but not in part, by endorsement (by the
              holder hereof executing the form of assignment at the end hereof)
              and delivery in the same manner as in the case of a negotiable
              instrument transferable by endorsement and delivery;

       (b)    subject to the foregoing, any person in possession of this Warrant
              properly endorsed is authorized to represent himself as absolute
              owner hereof and is empowered to transfer absolute title hereto by
              endorsement and delivery hereof to a bona fide purchaser hereof
              for value; each prior taker or owner waives and renounces all of
              his equities or rights in this Warrant in favor of each such bona
              fide purchaser and each such bona fide purchaser shall acquire
              absolute title hereto and to all rights represented hereby; and

       (c)    until this Warrant is transferred on the books of the Company, the
              Company may treat the record owner hereof as the absolute owner
              hereof for all purposes, notwithstanding any notice to the
              Company.

                                      -8-
<PAGE>   9

17     NOTICES, ETC.

       All notices and other communications from the Company to the record owner
       of this Warrant shall be mailed by first class registered or certified
       mail, postage prepaid, at such address as may have been furnished to the
       Company in writing by such record owner, or, until an address is so
       furnished, to and at the address of the last record owner of this Warrant
       who has so furnished an address to the Company.

18     MISCELLANEOUS

       This Warrant and any term thereof may be changed, waived, discharged or
       terminated only by an instrument in writing signed by the party against
       which enforcement of such change, waiver, discharge or termination is
       sought. This Warrant is being delivered in the State of New York and
       shall be construed and enforced in accordance with and governed by the
       internal laws of such state. The headings in this Warrant are for
       purposes of reference only, and shall not limit or otherwise affect any
       of the terms hereof.

19     EXECUTED EXPIRATION

       The right to exercise this Warrant shall expire at 5:00 P.M., New York
       City time, on July 20, 2004.

20     ASSIGNABILITY

       This Warrant is fully assignable, in whole but not in part, at any time,
       subject to applicable securities laws and section 2 hereof.

                                      -9-
<PAGE>   10

IN WITNESS WHEREOF, the said Corporation has caused this Certificate to be
signed by its authorized officers, and its Corporate Seal, to be hereunto
affixed this 20th day of July, 2000.

By:
   --------------------------------------
   Name:
   Title:  Secretary/President

(Apply Corporate Seal)

                                      -10-
<PAGE>   11

                                    EXHIBIT A

                              FORM OF SUBSCRIPTION
                  (TO BE SIGNED ONLY UPON EXERCISE OF WARRANT)

To:    VASCO  DATA SECURITY INTERNATIONAL, INC.
       [         ]
       [         ]
       Attention: Corporate Secretary

The undersigned, the record owner of the within Warrant, hereby irrevocably
elects to exercise the purchase right represented by such Warrant for, and to
purchase thereunder,* shares of the Common Stock of VASCO DATA SECURITY
INTERNATIONAL, INC., and herewith make payment of $[    ] therefor, and requests
that the certificates for such shares be issued in the name of, and delivered
to, [     ], whose address is [     ].

Dated: [       ]

------------------------

(Signature must conform in all respects to
name of record owner as specified on the
face of the Warrant)

------------------------------------------

(Address)

--------
*  Insert here the number of shares called for on the face of the Warrant [or,
   in the case of a partial exercise, the portion thereof as to which the
   Warrant is being exercised], in either case without making any adjustment for
   additional Common Stock or any other stock or other securities or property or
   case which, pursuant to the adjustment provisions of the Warrant, may be
   deliverable upon exercise.

                                      -11-
<PAGE>   12

                               FORM OF ASSIGNMENT

                  (To be signed only upon transfer of Warrant)

For value received, the undersigned hereby sells, assigns and transfers unto [ ]
[ ] the right represented by the within Warrant to purchase shares of the Common
Stock of VASCO DATA SECURITY INTERNATIONAL, INC. to which the within Warrant
relates, and appoints [ ] as Attorney-in-Fact to transfer such right on the
books of [ ] with full power of substitution in the premises. The Warrant being
transferred hereby is the Common Stock Purchase Warrant initially issued by
VASCO DATA SECURITY INTERNATIONAL, INC. as of July [ ], 2000.

Dated:
      ----------------------

                                     -------------------------------------------
                                     (Signature  must conform in all respects to
                                     name of record  owner as  specified  on the
                                     face of the Warrant)

                                     -------------------------------------------
                                                     (Address)

Signature guaranteed by a Bank or Trust
Company having its principal office in
New York City or by a Member Firm of
the New York or American Stock Exchange

                                      -12-<PAGE>   1
                                                                   Exhibit 10.50

                          COMMON STOCK PURCHASE WARRANT

Void after July 20, 2004

THE SECURITIES EVIDENCED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), OR ANY STATE OR OTHER SECURITIES
LAWS, AND MAY NOT BE OFFERED, REOFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED,
ENCUMBERED OR OTHERWISE DISPOSED OF OR DISTRIBUTED, DIRECTLY OR INDIRECTLY,
WITHIN THE UNITED STATES OR TO OR FOR THE ACCOUNT OF U.S. PERSONS UNLESS THE
TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF
THE SECURITIES ACT OR PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE
SECURITIES ACT. THE HOLDER OF THIS SECURITY BY ITS ACCEPTANCE HEREOF, AGREES
THAT IT WILL NOT OFFER, REOFFER, SELL, ASSIGN, TRANSFER, PLEDGE, ENCUMBER OR
OTHERWISE DISPOSE OF OR DISTRIBUTE DIRECTLY OR INDIRECTLY THESE SECURITIES IN
THE UNITED STATES, ITS TERRITORIES, POSSESSIONS, OR AREAS SUBJECT TO ITS
JURISDICTION, OR TO OR FOR THE ACCOUNT OR BENEFIT OF A U.S. PERSON, AT ANY TIME
PRIOR TO TWO YEARS AFTER THE ORIGINAL ISSUANCE OF THESE SECURITIES, EXCEPT (A)
TO THE COMPANY OR A SUBSIDIARY OF THE COMPANY, (B) IN CONJUNCTION WITH AN
EFFECTIVE REGISTRATION STATEMENT FOR THE SECURITIES UNDER THE SECURITIES ACT,
(C) IN COMPLIANCE WITH AN EXEMPTION FROM REGISTRATION UNDER SUCH ACT, OR (D) IN
ACCORDANCE WITH THE PROVISIONS OF REGULATION S OF SUCH ACT, INCLUDING RULE 903,
RULE 904 AND RULE 905 THEREUNDER, AND AGREES THAT ANY HEDGING TRANSACTIONS
INVOLVING THE SECURITIES WILL BE CONDUCTED IN COMPLIANCE WITH REGULATION S UNDER
SUCH ACT AND AGREES THAT IT WILL GIVEN TO EACH PERSON TO WHOM THIS SECURITY IS
TRANSFERRED A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND; PROVIDED THAT
THE COMPANY, THE TRANSFER AGENT, AND THE REGISTRAR SHALL HAVE THE RIGHT PRIOR TO
ANY SUCH OFFER, SALE OR TRANSFER, IN EACH OF THE FOREGOING CASES, TO REQUIRE
DELIVERY OF A CERTIFICATION OF TRANSFER IN FORM SATISFACTORY TO THEM. AS USED
HEREIN, THE TERMS "UNITED STATES" AND "U.S. PERSON" HAVE THE MEANINGS GIVEN TO
THEM BY REGULATION S UNDER THE SECURITIES ACT.

                          COMMON STOCK PURCHASE WARRANT

VASCO DATA SECURITY INTERNATIONAL, INC., a Delaware corporation (the "Company")
having its principal office at 1901 South Meyers Road, Suite 210, Oakbrook

                                      -1-
<PAGE>   2

Terrace, Illinois 60181, hereby certifies that, for value received, UBIZEN,
N.V., or transferees or assigns (the "Holder") is entitled, subject to the
vesting schedule (attached as Exhibit B hereto) and the terms and conditions set
forth below, to purchase from the Company at any time and from time to time on
or after July 20, 2000 and before 5:00 p.m. New York City time, on July 20,
2004, four hundred eighty thousand (480,000) fully paid and non-assessable
shares of the Common Stock of the Company, par value $0.001 per share, (the
"Shares") at the price per share of Four Dollars and Twenty Five Cents (US
$4.25) (the "Purchase Price"), subject to the terms and conditions, adjustments
and limitations set forth herein.

     As used herein the following terms, unless the context otherwise requires,
have the following respective meanings:

(a)      The term "COMPANY" has the meaning set forth in the introductory
paragraph above, and include any corporation which shall succeed to or assume
the obligations of the Company hereunder.

(b)      The term "COMMON STOCK" includes all stock of any class or classes
(however designated) of the Company, authorized upon the Original Issue Date or
thereafter, the holders of which shall have the right, without limitation as to
amount, either to all or to a share of the balance of current dividends and
liquidating dividends after the payment of dividends and distributions on any
shares entitled to preference, and the holders of which shall ordinarily, in the
absence of contingencies, be entitled to vote for the election of a majority of
directors of the Company (even though the right so to vote has been suspended by
the happening of such a contingency

(c)      The "ORIGINAL ISSUE DATE" is July 20, 2000.

(d)      The term "OTHER SECURITIES" refers to any capital stock (other than
Common Stock) and other securities of the Company or any other person (corporate
or otherwise) which the holder of this Warrant at any time shall be entitled to
receive, or shall have received, upon the exercise of this Warrant, in lieu of
or in addition to Common Stock, or which at any time shall be issuable or shall
have been issued in exchange for or in replacement of Common Stock or Other
Securities pursuant to section 6 or otherwise.

(e)      The term "PURCHASE PRICE" shall have the meaning set forth in the
introductory paragraph above, as such price may be adjusted pursuant to the
terms hereof.

(f)      The term "SECURITIES ACT" means the Securities Act of 1933 as the same
shall be in effect at the time.

(g)      The term "SERIES C SHARES" means the shares of the Company's Series C
Preferred Stock being sold to Holder pursuant to the Purchase Agreement (as
defined in Section 1 below).

                                      -2-
<PAGE>   3

         1. Term, Vesting. This Warrant is being issued in connection with that
certain Securities Purchase Agreement, dated as of July 18, 2000, by and among
the Company and Ubizen, N.V. (the "Purchase Agreement"), and is subject to the
terms and conditions thereof. In the event of any conflict between the terms
hereof and the terms of the Purchase Agreement, the terms of the Purchase
Agreement shall control. Commencing with the calendar quarter ended September
30, 2000, for so long as all of the Series C Shares remain outstanding, the
Shares shall vest, and become exercisable, in sixteen (16) quarterly
installments of 30,000 shares, subject to adjustment as provided below. In the
event that any shares of the Series C Shares have been converted or redeemed
prior to the expiration of this Warrant, all unvested Shares shall vest from the
date of such conversion, or redemption, as the case may be, in quarterly
installments in an amount equal to the product of (a) 30,000 multiplied by (b) a
fraction, (i) the numerator of which shall be the remainder of (A) the number of
Series C Shares held by the Holder immediately prior to such conversion minus
(B) the number of Series C Shares so converted or redeemed, and (ii) the
denominator of which shall be 150,000, and the Warrant will automatically cease
to vest with respect to any additional Shares as of the date of such conversion
or redemption.

         2. Registration, etc. This Warrant, the shares of Common Stock issuable
upon exercise thereof and the Other Securities shall have such registration
rights as provided in Section 8 and Section 9 of the Purchase Agreement.

         3. Sale or Exercise Without Registration. If, at the time of any
exercise, transfer or surrender for exchange of this Warrant or of Common Stock
(or Other Securities) previously issued upon the exercise of this Warrant, this
Warrant or Common Stock (or Other Securities) shall not be registered under the
Securities Act, the Company may require, as a condition of allowing such
exercise, transfer or exchange, that the record owner or transferee of this
Warrant or Common Stock (or Other Securities), as the case may be, furnish to
the Company a satisfactory opinion of counsel to the effect that such exercise,
transfer or exchange may be made without registration under the Securities Act,
provided that the disposition of thereof shall at all times be within the
control of such record owner or transferee, as the case may be, provided further
that nothing contained in this section 3 shall relieve the Company from
complying with any request for registration pursuant to section 2 hereof. The
first Holder of this Warrant represents to the Company that it is acquiring this
Warrant for investment and not with a view to the distribution thereof.

4.       Method of Exercise; Payment.

(a)      Subject to the provisions hereof, this Warrant may be exercised, with
respect to vested Shares only, in whole or in part, by the record owner hereof
by surrender of this Warrant, with the form of subscription attached hereto as
Exhibit A duly executed by such record owner, to the Company at its principal
office accompanied by payment in an amount equal to the Purchase Price per share
multiplied by the number of Shares then

                                      -3-
<PAGE>   4

being purchased. Payment of the Purchase Price for the shares of Common Stock
purchased pursuant to exercise of this Warrant shall be made (a) in cash or cash
equivalents, (b) through the tender to the Company of shares of Common Stock,
which shares shall be valued for purposes of determining the extent to which the
Purchase Price has been paid, at their Market Price (determined by the Board of
Directors of the Company in accordance with section 3.3 hereof) on the date of
exercise, (c) by delivering a written direction to the Secretary of the Company
that this Warrant is to be exercised pursuant to a "cashless" exercise/sale
procedure (pursuant to which funds to pay for exercise of the Warrant are
delivered to the Company by a broker upon receipt of stock certificates from the
Company) or a "cashless" exercise/loan procedure (pursuant to which the holders
would obtain a margin loan from a broker to fund the certificates for the shares
of Common Stock for which the Warrant is exercised, such certificates will be
delivered to the broker who will deliver to the Company the cash (or cash
equivalents acceptable to the Company) equal to the Purchase Price for the
shares of Common Stock purchased pursuant to the exercise of the Warrant plus
the amount (if any) of federal and other taxes that the Company may, in its
judgment, be required to withhold with respect to the exercise of the Warrant,
or (d) a combination of the methods described in (a), (b) and (c) above.

(b)      As used herein, the phrase "Market Price" at any date shall be deemed
to be (i) if the principal trading market for such securities is an exchange,
the last reported sale price, or, in case no such reported sale takes place on
such date, the average of the last reported sale prices for the preceding three
(3) trading days, in either case as officially reported on any consolidated
tape, (ii) if the principal market for such securities is the over-the-counter
market, the high bid price on such date as set forth by NASDAQ or, if the
security is not quoted on NASDAQ, the high bid price as set forth in the
National Quotation Bureau sheet listing such securities for such day.
Notwithstanding the foregoing, if there is no reported closing price or high bid
price, as the case may be, on the date next preceding the event requiring an
adjustment hereunder, then the Market Price shall be determined as of the latest
date prior to such day for which such closing price or high bid price is
available, or if the securities are not quoted on NASDAQ, as determined in good
faith by resolution of the Board of Directors of the Company, based on the best
information available to it.

(c)      The Company will, at the time of any exercise of this Warrant, upon the
request of the record owner hereof, acknowledge in writing its continuing
obligation to afford to such record owner any rights (including, without
limitation, any right to registration of the shares of Common Stock or Other
Securities issued upon such exercise) to which such record owner shall continue
to be entitled after such exercise in accordance with the provisions of this
Warrant, provided that if the record owner of this Warrant shall fail to make
any such request, such failure shall not affect the continuing obligation of the
Company to afford such record owner any such rights.

         5. Delivery of Stock Certificates; etc. on Exercise.  As soon as
practicable after the exercise of this Warrant in full or in part, the Company
at its expense (including

                                      -4-
<PAGE>   5

the payment by it of any applicable issue taxes) will cause to be issued in the
name of and delivered to the record owner hereof, or as such record owner (upon
payment by such record owner of any applicable transfer taxes) may direct, a
certificate or certificates for the number of fully paid and non-assessable
shares of Common Stock (or Other Securities) to which such record owner shall be
entitled upon such exercise, plus, in lieu of any fractional share to which such
record owner would otherwise be entitled, cash equal to such fraction multiplied
by the then current Market Price of one full share, together with any other
stock or other securities and property (including cash, where applicable) to
which such record owner is entitled upon such exercise pursuant to section 1,
section 6 or otherwise.

         6. Adjustment for Dividends in Other Stock, Property, etc.;
Reclassification, etc. In case at any time or from time to time after the
Original Issue Date the holders of Common Stock (or Other Securities) shall have
received or (on or after the record date fixed for the determination of
stockholders eligible to receive) shall have become entitled to receive without
payment therefor

(a)  other or additional stock or other securities or, property (other than
cash) by way of dividend, or

(b)  any cash paid or payable (including, without limitation, by way of dividend
other than dividend payable out of earned surplus of the Company), or

(c)  other or additional (or less) stock or other securities or property
(including cash) by way of spin-off, split-up, recapitalization, combination of
shares or similar corporate rearrangement,

then, and in each such case the record owner of this Warrant, upon the exercise
hereof as provided in section 4 hereof, shall be entitled to receive the amount
of stock and other securities and property (including cash in the cases referred
to in subdivisions (b) and (c) of this section 6) which such record owner would
hold on the date of such exercise if on the Original Issue Date such person had
been the holder of record of the number of shares of Common Stock called for on
the face of this Warrant and had thereafter, during the period from the Original
Issue Date to and including the date of such exercise, retained such shares and
all such other additional (or less) stock and other securities and property
(including cash in the cases referred to in subdivisions (b) and (c) of this
section 6) receivable by such person as aforesaid during such period, giving
effect to all adjustments called for during such period by sections 1, 6 and 7
hereof.

         7. Reorganization, Consolidation, Merger, etc. In case the Company
after the Original Issue Date shall (a) effect a reorganization, (b) consolidate
or merge with any other person, or (c) transfer all or substantially all of its
properties or assets to any other person under any plan or arrangement
contemplating the dissolution of the Company, then, in each such case, the
record owner of this Warrant, upon the exercise hereof as provided in section 4
at any time after the consummation of such reorganization,

                                      -5-
<PAGE>   6

consolidation or merger or the effective date of such dissolution, as the case
may be, shall be entitled to receive (and the Company shall be obligated to
deliver), in lieu of the Common Stock (or Other Securities) issuable upon such
exercise prior to such consummation or such effective date, the stock and other
securities and property (including cash) to which such record owner would have
been entitled upon such consummation or in connection with such dissolution, as
the case may be, if such record owner had so exercised this Warrant immediately
prior thereto, all subject to further adjustment thereafter as provided in
sections 6 and 8 hereof.

         8. Further Assurances.  The Company will take all such action as may be
necessary or appropriate in order that the Company may validly and legally issue
fully paid and non-assessable shares of Common Stock upon the exercise of all
Warrants from time to time outstanding.

         9. Certificate of Chief Financial Officer as to Adjustments In each
case of any adjustment or readjustment in the shares of Common Stock (or Other
Securities) issuable upon the exercise of this Warrant, the Company at its
expense will promptly cause the Company's Chief Financial Officer to compute
such adjustment or readjustment in accordance with the terms of this Warrant and
prepare a certificate setting forth such adjustment or readjustment and showing
in detail the facts upon which such adjustment or readjustment is based, and the
number of shares of Common Stock outstanding or deemed to be outstanding;
provided that if any similar certificate is provided by the Company's regularly
retained auditor to the holder of any other warrant of the Company, the
Company's regularly retained auditor shall provide this certificate to the
record owner of this Warrant. The Company will forthwith mail a copy of each
such certificate to the record owner of this Warrant.

         10. Notices of Record Date, etc.  In the event of:

(a)      any taking by the Company of a record of the holders of any class of
securities for the purpose of determining the holders thereof who are entitled
to receive any dividend (other than a cash dividend payable out of earned
surplus of the Company) or other distribution, or any right to subscribe for,
purchase or otherwise acquire any shares of stock of any class or any other
securities or property, or to receive any other right, or

(b)      any capital reorganization of the Company, any reclassification or
recapitalization of the capital stock of the Company or any transfer of all or
substantially all the assets of the Company to or consolidation or merger of the
Company with or into any other person, or

(c)      any voluntary or involuntary dissolution, liquidation or winding-up of
the Company,

then and in each such event the Company will mail or cause to be mailed to the
record owner of this Warrant a notice specifying (i) the date on which any such
record is to be

                                      -6-
<PAGE>   7

taken for the purpose of such dividend, distribution or right, and stating the
amount and character of such dividend, distribution or right and (ii) the date
on which any such reorganization, reclassification, recapitalization, transfer,
consolidation, merger, dissolution, liquidation or winding-up is to take place,
and the time, if any, as of which the holders of record of Common Stock (or
Other Securities) shall be entitled to exchange their shares of Common Stock (or
Other Securities) for securities or other property deliverable upon such
reorganization, reclassification, recapitalization, transfer, consolidation,
merger, dissolution, liquidation or winding-up. Such notice shall be mailed at
least twenty (20) days prior to the date therein specified.

         11. Reservation of Stock, etc., Issuable on Exercise of Warrants The
Company will at all times reserve and keep available, solely for issuance and
delivery upon the exercise of this Warrant, all shares of Common Stock (or Other
Securities) from time to time issuable upon the exercise of this Warrant.

         12. Listing on Securities Exchanges The Company will, at its expense,
to the extent permitted by the rules of any national securities exchange or
automated inter-dealer quotation system on which the Common Stock is listed,
simultaneously list on such exchange or system, upon official notice of issuance
upon the exercise of this Warrant, all shares of Common Stock from time to time
issuable upon the exercise of this Warrant

         13. Replacement of Warrants Upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of any such loss, theft or destruction, upon
delivery of an indemnity agreement reasonably satisfactory in form and amount to
the Company or, in the case of any such mutilation, upon surrender and
cancellation of this Warrant, the Company at its expense will execute and
deliver, in lieu thereof, a new Warrant of like tenor.

         14. Warrant Agent The Company may, by written notice to each record
owner of this Warrant, appoint an agent, for the purpose of issuing Common Stock
(or Other Securities) upon the exercise of this Warrant pursuant to Section 4
and replacing this Warrant pursuant to Section 13, or any of the foregoing, and
thereafter any such issuance, exchange or replacement, as the case may be, shall
be made at such office by such agent.

         15. Notices, etc. All notices and other communications from the Company
to the record owner of this Warrant shall be mailed by first class registered or
certified mail, postage prepaid, at such address as may have been furnished to
the Company in writing by such record owner, or, until an address is so
furnished, to and at the address of the last record owner of this Warrant who
has so furnished an address to the Company.

         16. Miscellaneous This Warrant and any term thereof may be changed,
waived, discharged or terminated only by an instrument in writing signed by the
party against which enforcement of such change, waiver, discharge or termination
is sought. This Warrant is being delivered in the State of New York and shall be
construed and enforced in accordance with and governed by the internal laws of
such state. The

                                      -7-
<PAGE>   8

headings in this Warrant are for purposes of reference only, and shall not limit
or otherwise affect any of the terms hereof.

         17. Executed Expiration  The right to exercise this Warrant shall
expire at 5:00 p.m. New York City time, on July 20, 2000.

         18. Assignability This Warrant is not transferrable or assignable (a)
except pursuant to the terms and conditions of the Purchase Agreement, and (b)
in connection with, and only in connection with, a transfer of Series C
Preferred Stock, in any event subject to applicable securities laws and section
3 hereof.

                                      -8-
<PAGE>   9

IN WITNESS WHEREOF, the said Corporation has caused this Certificate to be
signed by its authorized officers, and its Corporate Seal, to be hereunto
affixed this 20th day of July, 2000.

By:
   ----------------------------------------
Name:   Mario Houthooft
Title:  President and Chief Executive Officer

(Apply Corporate Seal)

                                      -9-
<PAGE>   10
                                    EXHIBIT A
                              FORM OF SUBSCRIPTION
                  (To be signed only upon exercise of Warrant)

To:______VASCO  DATA SECURITY INTERNATIONAL, INC.
[          ]
[          ]
Attention: Corporate Secretary

The undersigned, the record owner of the within Warrant, hereby irrevocably
elects to exercise the purchase right represented by such Warrant for, and to
purchase thereunder,* shares of the Common Stock of VASCO DATA SECURITY
INTERNATIONAL, INC., and herewith make payment of $[    ] therefor, and requests
that the certificates for such shares be issued in the name of, and delivered
to, [       ], whose address is [          ].

Dated: [             ]

------------------------
(Signature must conform in all respects to
name of record owner as specified on the
face of the Warrant)

---------------------------------

(Address)

--------------------------
*  Insert here the number of shares called for on the face of the Warrant [or,
   in the case of a partial exercise, the portion thereof as to which the
   Warrant is being exercised], in either case without making any adjustment for
   additional Common Stock or any other stock or other securities or property or
   case which, pursuant to the adjustment provisions of the Warrant, may be
   deliverable upon exercise.

                                      -10-
<PAGE>   11
                                    EXHIBIT B
                                VESTING SCHEDULE

_________Set forth below is the date of vesting and the number of shares of
Common Stock to vest on such date (such schedule shall automatically be modified
in accordance with any adjustment(s) pursuant to the terms of the Warrant):

         DATE                 NUMBER OF SHARES
         ----                 ----------------

1.       9/30/00                    30,000
2.       12/31/00                   30,000
3.       3/31/01                    30,000
4.       6/30/01                    30,000
5.       9/30/01                    30,000
6.       12/31/01                   30,000
7.       3/31/02                    30,000
8.       6/30/02                    30,000
9.       9/30/02                    30,000
10.      12/31/02                   30,000
11.      3/31/03                    30,000
12.      6/30/03                    30,000
13.      9/30/03                    30,000
14.      12/31/03                   30,000
15.      3/31/04                    30,000
16.      6/30/04                    30,000

                                      -11-
<PAGE>   12
                                    EXHIBIT C
                               FORM OF ASSIGNMENT
                  (To be signed only upon transfer of Warrant)

For value received, the undersigned hereby sells, assigns and transfers unto
[       ][      ] the right represented by the within Warrant to purchase shares
of the Common Stock of VASCO DATA SECURITY INTERNATIONAL, INC. to which the
within Warrant relates, and appoints [       ] as Attorney-in-Fact to transfer
such right on the books of [        ] with full power of substitution in the
premises. The Warrant being transferred hereby is the Common Stock Purchase
Warrant initially issued by VASCO DATA SECURITY INTERNATIONAL, INC. as of July
[  ], 2000.

Dated:
      ----------------------

------------------------------
(Signature must conform in all respects to name of record owner as specified on
the face of the Warrant)

------------------------------
          (Address)

Signature guaranteed by a Bank or Trust Company having its principal office in
New York City or by a Member Firm of the New York or American Stock Exchange

                                      -12-

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00013-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00013-of-00352.parquet"}]]