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                                                                    Exhibit 10.2


                                CERTICOM CORP.
                         2000 UNITED STATES STOCK PLAN
                      (AS AMENDED AS OF OCTOBER 19, 2000)


1.   Adoption and Purpose of the Plan

     This stock plan, to be known as the Certicom  Corp.  2000 United States
Stock Plan (but referred to herein as the "Plan"), has been adopted by the board
of directors (the "Board") of Certicom Corp., a corporation  incorporated in the
Yukon  Territory  (the  "Company"),  and  is  subject  to  the  approval  of its
shareholders  pursuant to Section  15. The  purpose of the Plan is to  encourage
Directors,  Officers,  Employees  and  Consultants  of the Company or any of its
Subsidiaries  who  are  residents  of the  United  States:  (a) to  promote  the
interests,  growth and  development  of the Company by  providing  them with the
opportunity  through options (the "Options") for Shares (the "Option Shares") to
acquire a proprietary interest in the Company; (b) to recognize the contribution
of such Directors,  Officers,  Employees and other persons; and (c) to encourage
such Directors,  Officers,  Employees and other persons to acquire Shares of the
Company through the grant of Options and Stock Purchase Rights.  Options granted
hereunder  may be either ISOs or  Nonstatutory  Stock  Options and Shares may be
sold to Employees or Consultants pursuant to Stock Purchase Rights hereunder, at
the discretion of the  Administrator  and as reflected in the terms of a written
Option Agreement or a Restricted  Stock Purchase  Agreement,  as applicable.

2.   Certain Definitions

     The  defined  terms  set  forth  in  Exhibit  A  attached   hereto  and
incorporated  herein (together with other capitalized terms defined elsewhere in
the Plan) will govern the interpretation of the Plan.

3.   Eligibility

     The Company may grant Options and Stock Purchase Rights under the Plan only
to (a) persons who, at the time of such grant, are Directors, Officers and
Employees of the Company and/or any of its Subsidiaries and (b) Consultants of
the Company (collectively, "Eligible Participants"); provided that, no grant of
Options or Stock Purchase Rights may be made to any person who is not a United
States resident on the date such Options or Stock Purchase Rights are approved
for grant by the Administrator. No person will be an Eligible Participant
following his or her Termination of Eligibility Status and no Option or Stock
Purchase Right may be granted to any person other than an Eligible Participant.
A person who has been granted an Option or Stock Purchase Right may, if he or
she is otherwise eligible, be granted additional Options or Stock Purchase
Rights.

4.   Shares Subject to the Plan

     (a)  Subject to the provisions of Section 16, the maximum aggregate number
          of Shares that may be optioned and/or sold under the Plan is
          3,000,000. If
<PAGE>

        any Option or Stock Purchase Right shall for any reason expire or
        otherwise terminate, in whole or in part, without having been exercised
        in full, the Shares not purchased under such Option or Stock Purchase
        Right shall revert to again become available for issuance under the
        Plan. The following restrictions shall also collectively apply to the
        Plan and to all other plans or stock option agreements, including the
        1997 Stock Option Plan, to which the Company may be a party:

        (i)  no Participant together with such Participant's Associates shall be
             issued, within any one-year period, a number of Option Shares under
             all such plans and agreements which exceeds 5% of the Outstanding
             Issue.

        (ii) the number of Option Shares under all such plans and agreements
             reserved for issuance pursuant to Options under all such plans and
             agreements to any one Participant shall not exceed 5% of the
             Outstanding Issue.

    (b) The Company, during the term of the Plan, will at all times reserve and
        keep available such number of Shares as shall be sufficient to satisfy
        the requirements of the Plan.

5.  Administration

    (a) The Plan will be administered and interpreted by the Board, or by a
        Committee appointed by the Board for such purpose in accordance with
        Section 5(c) (the Board, or such Committee, referred to herein as the
        "Administrator"). A majority of the members of the Board, or a Committee
        if so appointed, shall constitute a quorum and all actions of the Board
        or Committee shall be taken by a majority of the members present at any
        meeting. Any action of the Board, or a Committee, may be taken by an
        instrument or instruments in writing signed by all the members of the
        Board, or a Committee, and any actions so taken shall be as effective as
        if it had been passed by a majority of the votes cast by the members of
        the Board, or a Committee, present at a meeting of such members duly
        called and held.

    (b) Subject to the express terms and conditions hereof, the Administrator is
        authorized to prescribe, amend and rescind rules and regulations
        relating to the Plan, and to make all other determinations necessary or
        advisable for its administration and interpretation. Specifically, the
        Administrator will have full and final authority in its discretion,
        subject to the specific limitations on that discretion as are set forth
        herein and in the organic instruments of the Company, at any time:

        (i)  to select and approve the Eligible Participants to whom Options
             will be granted from time to time hereunder.
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        (ii)   to grant Stock Purchase Rights; to determine the price per share
               and the method of payment for any Shares to be sold pursuant to a
               Stock Purchase Right; to determine the Eligible Participants to
               whom and the time or times at which Shares may be sold under
               Stock Purchase Rights; and to determine the number of Shares to
               be sold and all additional terms of the Restricted Stock Purchase
               Agreement.

        (iii)  with respect to each Option it decides to grant, to determine the
               terms and conditions of that Option to be set forth in the Option
               Agreement evidencing that Option (the form of which also being
               subject to approval by the Administrator), which may vary from
               the "default" terms and conditions set forth in Section 9, except
               to the extent otherwise provided in the Plan, including, without
               limitation, as follows:

               (A)   the total number of Option Shares that may be acquired by
                     the Optionee pursuant to the Option;

               (B)   if the Option satisfies the conditions under Section 422(b)
                     of the Code, whether the Option will be treated as an ISO;

               (C)   the per share purchase price to be paid and the method of
                     payment to the Company by the Optionee to acquire the
                     Option Shares issuable upon exercise of the Option (the
                     "Option Price"), provided that the Option Price will not be
                     less than the Market Value of the Shares as of the Grant
                     Date, unless the Optionee is a 10% shareholder, in which
                     case the Option Price will not be less than 110% of such
                     Market Value;

               (D)   the maximum period or term during which the Option will be
                     exercisable (the "Option Term"), provided that in no event
                     may the Option Term be longer than 10 years from the Grant
                     Date;

               (E)   the maximum period following any Termination of Eligibility
                     Status, whether resulting from an Optionee's death,
                     disability or any other reason, during which period (the
                     "Grace Period") the Option will be exercisable, subject to
                     Vesting and to the expiration of the Option Term, provided
                     that in no event may the Administrator designate a Grace
                     Period that is shorter than six months after such
                     Termination of Eligibility Status by reason of the
                     Optionee's death or disability or 30 days after such
                     Termination of Eligibility for any other reason, except in
                     the event of a Termination for Cause, in which case no
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                     Grace Period will be required (i.e., the Option will
                     terminate immediately);

               (F)   the conditions (e.g., the passage of time or the occurrence
                     of events), if any, that must be satisfied prior to the
                     vesting of the right to exercise all or specified portions
                     of an Option (such portions being described as the number
                     of Option Shares or the percentage of the total number of
                     Option Shares that may be acquired by the Optionee pursuant
                     to the Option; the vested portion being referred to as a
                     "Vested Option" and the unvested portion being referred to
                     as an "Unvested Option"); and


               (G)   to prescribe the form of the instruments relating to the
                     grant, exercise and other terms of Option Shares and the
                     persons to receive Option Shares.


         (iv)  to delegate all or a portion of the Administrator's authority
               under this Section 5 to one or more members of the Board who also
               are executive officers of the Company, subject to such
               restrictions and limitations as the Administrator may decide to
               impose on such delegation.

         (v)   The Board may delegate administration of the Plan to a Committee
               or Committees of one or more members of the Board. In the
               discretion of the Board, a Committee may consist solely of two or
               more Outside Directors, in accordance with Code Section 162(m),
               or solely of two or more Non-Employee Directors, in accordance
               with Rule 16b-3. If administration is delegated to a Committee,
               the Committee shall have, in connection with the administration
               of the Plan, the powers theretofore possessed by the Board (and
               references in the Plan to the Board shall thereafter be to the
               Committee), subject, however, to such resolutions, not
               inconsistent with the provisions of the Plan, as may be adopted
               from time to time by the Board. The Board may abolish the
               Committee at any time and revest in the Board the administration
               of the Plan. Within the scope of this authority, the Board or the
               Committee may delegate to a committee of one or more members of
               the Board the authority to grant Options and Stock Purchase
               Rights to eligible persons who (i) are not then subject to
               Section 16 of the Exchange Act and/or (ii) are either (A) not
               then Covered Employees and are not expected to be Covered
               Employees at the time of recognition of income resulting from
               such Option or (B) not persons with respect to whom the Company
               wished to comply with Section 162(m) of the Code.

     6. Stock Purchase Rights
<PAGE>

        (a)   Stock Purchase Rights may be issued either alone, in addition to,
              or in tandem with other awards granted under the Plan. After the
              Administrator determines that it will offer Stock Purchase Rights
              under the Plan, it shall advise the offeree in writing, by means
              of a Notice of Grant, of the terms, conditions and restrictions
              related to the offer, including the number of Shares that the
              offeree shall be entitled to purchase, the price to be paid and
              the time within which the offeree must accept such offer. The
              offer shall be accepted by execution of a Restricted Stock
              Purchase Agreement in the form determined by the Administrator.

        (b)   Unless the Administrator determines otherwise, the Restricted
              Stock Purchase Agreement shall grant the Company a repurchase
              option exercisable upon the voluntary or involuntary termination
              of the purchaser's service with the Company for any reason
              (including death or disability). The purchase price for Shares
              repurchased pursuant to the Restricted Stock Purchase Agreement
              shall be the original price paid by the purchaser and may be paid
              by cancellation of any indebtedness of the purchaser to the
              Company. The repurchase option shall lapse at a rate determined by
              the Administrator.

        (c)   The Restricted Stock Purchase Agreement shall contain such other
              terms, provisions and conditions not inconsistent with the Plan as
              may be determined by the Administrator in its sole discretion.

        (d)   Once the Stock Purchase Right is exercised, the purchaser shall
              have the rights equivalent to those of a shareholder, and shall be
              a shareholder when his or her purchase is entered upon the records
              of the duly authorized transfer agent of the Company. No
              adjustment will be made for a dividend or other right for which
              the record date is prior to the date the Stock Purchase Right is
              exercised, except as provided in Section 16 of the Plan.

7.       Payment

         The Participant from time to time may elect to purchase all or a
portion of the Option Shares available for purchasing during the relevant Option
Period or the Shares which he or she is eligible to purchase pursuant to a Stock
Purchase Right by lump sum payment by delivering to the Company at its corporate
office in the United States, a notice in writing which shall specify the number
of Option Shares or Shares the Participant desires to purchase and shall be
accompanied by payment in full of the purchase price of such Option Shares or
Shares. Payment can be made by (a) cash, certified check, bank draft, money
order or the equivalent in U.S. dollars payable to the order of Certicom Corp;
(b) delivery of other Shares which (i) in the case of Shares acquired upon
exercise of an option, have been owned by the Optionee for more than six months
on the date of surrender and (ii) have a Market Value on the date of surrender
equal to the aggregate Option Price of the Shares as to which said Option shall
be exercised; or (c) such other consideration approved by the Administrator.
<PAGE>

8.   Buyout Provisions

     The Administrator may at any time offer to buy out for a payment in cash or
Shares an Option or Stock Purchase Right previously granted based on such terms
and conditions as the Administrator shall establish and communicate to the
Participant at the time that such offer is made.

9.   Default Terms and Conditions of Option Agreements

     Unless otherwise expressly provided in an Option Agreement based on the
Administrator's determination pursuant to Section 5, the following terms and
conditions will be deemed to apply to each Option as if expressly set forth in
the Option Agreement:

     9.1   ISO. If granted to an Eligible Participant who, as of the Grant Date,
is an Employee of the Company or any Subsidiary, and expressly designated as an
ISO, the Option will be an ISO, subject to the following additional terms and
conditions:

     (a)   The Market Value of Option Shares (determined as of the Grant Date)
           with respect to which all ISOs are exercisable for the first time by
           any individual during any calendar year (pursuant to the Plan and all
           other plans of the Company and/or its Subsidiaries) cannot exceed
           $100,000.

     (b)   The Option Price will not be less than 100% of the Market Value of
           the Shares as of the Grant Date, except that if the Optionee is a 10%
           shareholder the Option Price will not be less than 110% of the Market
           Value of the Shares as of the Grant Date, and the Option Term may not
           be more than 5 years.

     (c)   Notwithstanding any Grace Period selected by the Administrator
           pursuant to Section 5(b)(iii)(E) above, or the default provisions of
           Section 9.3 below, the tax treatment available pursuant to Section
           422 of the Code upon the exercise of the ISO will not be available to
           an Optionee who exercises the Option more than (i) three months
           following the Optionee's Termination of Eligibility Status other than
           by reason of his or her death or permanent and total disability
           (within the meaning of Section 22(e)(3) of the Code), or (ii) 12
           months following such Optionee's Termination of Eligibility Status by
           reason or his or her permanent and total disability.

     9.2   Option Term. The Option Term will be for a period of 5 years
beginning on the Grant Date. In the case of an ISO granted to a 10%
shareholder, the Option Term will not exceed a period of 5 years beginning on
the Grant Date.

     9.3   Grace Periods. Following a Termination of Eligibility Status, the
Vesting in respect of Options held by that Participant shall immediately cease
but:
<PAGE>

          (a)  the Grace Period will be ninety (90) days, unless the Termination
               of Eligibility Status is a result of a Termination for Cause or
               the death or disability of the Optionee;

          (b)  the Grace Period will be one hundred eighty (180) days if the
               Termination of Eligibility Status is a result of the death or
               disability of the Optionee;

          (c)  the Option will terminate, and there will be no Grace Period,
               effective immediately as of the date and time of a Termination
               for Cause of the Optionee, regardless of whether the Option is
               Vested or Unvested; and

          (d)  to the extent permitted by the Code at any time before or after
               the expiration of the Grace Period set forth in Sections 9.3(a),
               9.3(b) and 9.3(c), the Administrator may extend such period as it
               applies to any Participant to a date which is not later than the
               expiration of the term of such Options.

          9.4  Vesting. The Option initially will be deemed an entirely Unvested
Option, but portions of the Option will vest and become a Vested Option
("Vesting") on the following schedule: 25% of the Option Shares shall vest on
the first anniversary of the Grant Date of the Option and thereafter a further
2.083333% of the Shares covered by the Option following the expiration of each
one-month period following the expiration of the initial 12-month period from
the Grant Date; provided that the Optionee does not suffer a Termination of
Eligibility Status prior to each such vesting date and provided further that
additional vesting will be suspended during any period while the Optionee is on
a leave of absence from the Company or its Subsidiaries, as determined by the
Administrator.

          9.5  Exercise of the Option; Issuance of Shares.

          (a)  The portion of the Option that is an Unvested Option may not be
               exercised. The portion of the Option that is a Vested Option may
               be exercised by giving written notice thereof to the Company, on
               such form as may be specified by the Administrator, but in any
               event stating: the Optionee's intention to exercise the Option;
               the date of exercise; the number of full Option Shares to be
               purchased; the amount and form of payment of the Option Price;
               and such assurances of the Optionee's investment intent as the
               Company may require to ensure that the transaction complies in
               all respects with the requirements of the 1933 Act and other
               applicable securities laws. The notice of exercise will be signed
               by the person or persons exercising the Option. In the event that
               the Option is being exercised by the representative of the
               Optionee, the notice will be accompanied by proof satisfactory to
               the Company of the representative's right to exercise the Option.
               The notice of exercise will be accompanied by full payment of the
               Option Price for the number of Option Shares in the manner set
               forth in Section 7.
<PAGE>

     (b)  To the extent required by applicable United States federal, state,
          local or Canadian law, and as a condition to the Company's obligation
          to issue any Shares upon the exercise of the Option in full, the
          Optionee will make arrangements satisfactory to the Company for the
          payment of any applicable Tax Withholding Liability that may arise by
          reason of or in connection with the exercise, sale or repurchase of
          Options or Option Shares. Such arrangements may include, in the
          Company's sole discretion, that the Optionee tender to the Company the
          amount of such Tax Withholding Liability, in a manner set forth in
          Section 7 of the Plan.


     (c)  After receiving a proper notice of exercise and payment of the
          applicable Option Price and Tax Withholding Liability, the Company
          will cause to be issued the Option Shares as to which the Option has
          been exercised.

10.  Compliance with Law

     Notwithstanding any other provision of the Plan, Options and Stock Purchase
Rights may be granted pursuant to the Plan, and Option Shares and Shares may be
issued pursuant to the exercise thereof by an Optionee or grantee, only after
and on the condition that there has been compliance with all applicable United
States federal and state securities laws, applicable Canadian and provincial
laws and, to the extent applicable, all applicable rules and regulations of all
stock exchanges or quotation systems on which the Shares are listed or posted
for trading (together "Applicable Laws"). The Company's obligation to issue and
deliver Shares under any Option or Stock Purchase Right or to sell any Shares is
subject to:

     (a)  the satisfaction of all requirements under Applicable Laws in respect
          thereof and obtaining all regulatory approvals as the Company shall
          determine to be necessary or advisable in connection with the
          authorization, issuance and sale thereof;

     (b)  the admission of such Shares to listing on the Nasdaq National Market;
          and

     (c)  the registration of the Plan and the Shares to be issued pursuant to
          the Plan with the United States Securities and Exchange Commission on
          a Form S-8 Registration Statement under the 1933 Act, or any successor
          form thereto.

     In this connection, the Company shall take all reasonable steps to obtain
such approvals and registrations as may be necessary for the issuance of such
Shares in compliance with Applicable Laws and for the registration of such
Shares. As a condition to the exercise of an Option or the sale of any Shares,
the Company may impose various conditions, including a requirement that the
person exercising such Option or purchasing such Shares represents and warrants,
at the time of any such exercise or purchase, that the Shares are being
purchased only for investment and without any present intention to sell or
distribute such Shares and other restrictions on such Shares relating to
employment or
<PAGE>

other matters as may be determined by the Board. The Company may, upon advice of
counsel to the Company, place legends on share certificates issued under the
Plan as counsel to the Company deems necessary or advisable in order to comply
with applicable securities laws, including, but not limited to, legends
restricting the transfer of the Shares.

11.  Restrictions on Transfer

     An Option shall not be transferable except by will or the laws of descent
and distribution. During the lifetime of a natural person who is granted an
Option under the Plan, the Option will be exercisable only by him or her.
Notwithstanding anything else in the Plan to the contrary, no Option Agreement
will contain any provision which is contrary to, or which modifies, the
provisions of this Section 11.

12.  Corporate Reorganizations

     In the case of a proposed merger or amalgamation of the Company with one or
more other corporations or other entities, the making of a takeover bid (as
defined in the Securities Act (Ontario)) for any of the outstanding Shares, the
sale or distribution of all or substantially all of the Company's assets or a
proposed corporate arrangement or reorganization, the Board may, in its absolute
discretion, determine the manner in which all unexercised Options granted under
the Plan shall be treated including, notwithstanding Section 19 hereof, changing
the Option Period.

13.  Notices

     Any notice to be given to the Company under the terms of an Option
Agreement or a Restricted Stock Purchase Agreement will be addressed to the
Company at its corporate office in the United States: Attention: Secretary, or
at such other address as the Company may designate in writing. Any notice to be
given to an Optionee or grantee will be addressed to him or her at the address
provided to the Company by such person. Any such notice will be deemed to have
been duly given if and when enclosed in a properly sealed envelope, addressed as
aforesaid, deposited, postage prepaid, in a post office or branch post office
regularly maintained by the local postal authority.

14.  Other Provisions

     Each Option Agreement and Stock Purchase Right may contain such other terms
and provisions not inconsistent with the Plan and Applicable Law, as may be
determined by the Administrator in its sole discretion.

15.  Term of the Plan

     The Plan will become effective on the date of its adoption by the
Shareholders of the Company. The Plan will expire on the tenth (10th)
anniversary of the date of its adoption by the shareholders of the Company
unless it is terminated earlier pursuant to Section 19 of the Plan, after which
no more Options or Stock Purchase Rights may be granted under the Plan, although
all outstanding Options and Stock Purchase Rights granted prior to such
expiration or termination will remain subject to the provisions of the
<PAGE>

Plan, and no such expiration or termination of the Plan will result in the
expiration or termination of any such Option or Stock Purchase Right prior to
the expiration or early termination of the applicable Option Term or the term
set forth in the Stock Purchase Right, as applicable.

16.  Adjustments Upon Changes in Shares

     The number of Shares subject to the Plan, the number of Shares available
under Options and the Stock Purchase Rights granted and the Option Price and the
price payable for Shares under the Stock Purchase Right shall be adjusted
automatically from time to time to reflect adjustments in the number of Shares
arising as a result of subdivisions, stock dividends, consolidations or
reclassifications of the Shares or other relevant changes in the authorized or
issued capital of the Company. No such adjustments will be required by reason of
the issuance or sale by the Company for cash or other consideration of
additional Shares or securities convertible into or exchangeable for Shares. No
fractional Shares may be purchased or issued hereunder. If a Participant is
entitled to purchase a fraction of a Share pursuant to an Option or Stock
Purchase Right such entitlement shall be rounded down to the nearest whole
number.

17.  Modification, Extension and Renewal of Options

     Subject to the terms and conditions and within the limitations of the Plan,
the Administrator may modify, extend or renew outstanding Options granted under
the Plan, or accept the surrender of outstanding Options (to the extent not
theretofore exercised) and authorize the granting of new Options in substitution
therefor (to the extent not theretofore exercised). Notwithstanding the
foregoing, however, no modification of any Option will, without the consent of
the Optionee, alter or impair any rights or obligations under any outstanding
Option.

18.  Governing Law

     The internal laws of the Province of Ontario (irrespective of its choice of
law principles) will govern the validity of the Plan, the construction of its
terms and the interpretation of the rights and duties of the parties hereunder
and under any Option Agreement.

19.  Amendment and Discontinuance

     The Board may amend, suspend or discontinue the Plan at any time or from
time to time; provided that no action of the Board will, without the approval of
the shareholders of the Company, materially increase (other than by reason of an
adjustment pursuant to Section 16 hereof) the maximum aggregate number of Shares
subject to the Plan, materially increase the benefits accruing to Eligible
Participants, or materially modify the category of, or eligibility requirements
for persons who are Eligible Participants. However, no such action may alter or
impair any Option or Stock Purchase Right previously granted under the Plan
without the consent of the Optionee or grantee, nor may the number of Shares
subject to the Plan be reduced to a number that is less than
<PAGE>

the aggregate number of Option Shares and Shares (i) that may be issued pursuant
to the exercise of all outstanding and unexpired Options or Stock Purchase
Rights granted hereunder and (ii) that have been issued and are outstanding
pursuant to the exercise of Options or Stock Purchase Rights granted hereunder.
The Board may in its sole discretion submit any other amendment to the Plan for
shareholder approval, including, but not limited to, amendments to the Plan
intended to satisfy the requirements of Section 162(m) of the Code and the
regulations promulgated thereunder regarding the exclusion of performance-based
compensation from the limit on corporate deductibility of compensation paid to
certain executive officers.

20.  No Shareholder or Employment Rights; Corporate Action

     No rights or privileges of a shareholder in the Company are conferred by
reason of the granting of an Option or Stock Purchase Right. No Optionee will
become a shareholder in the Company with respect to any Option Shares unless and
until the Option has been properly exercised, the Option Price has been fully
paid as to the portion of the Option exercised and the name of the person
rightfully exercising the Option has been entered in the register of
shareholders of the Company. The granting of an Option or the sale of Shares to
a Participant pursuant to a Stock Purchase Right does not confer upon the
Participant any right to continue in the employment of the Company or any
Subsidiary of the Company or on the Board, as the case may be, nor does it
interfere in any way with the right of the Participant or the Company to
terminate the Participant's employment at any time or shareholders' right to
elect directors. Nothing contained in the Plan or in the Option Agreement or
Restricted Stock Purchase Agreement shall be construed so as to prevent the
Company or any Subsidiary from taking corporate action which is deemed by the
Company or the Subsidiary to be appropriate or in the Company's best interest,
whether or not such action would have an adverse effect on the Plan.

21.  Copies of Plan; Electronic Delivery

     A copy of the Plan will be delivered to each Optionee and grantee of a
Stock Purchase Right at or before the time he, she or it executes an Option
Agreement or Restricted Stock Purchase Agreement, as applicable. Notwithstanding
any other provision of the Plan, to the extent permitted by Applicable Law, the
Company may provide copies of the Plan and any other documentation or writing to
be delivered to any Participant or Eligible Participant (including Option
Agreements and Restricted Stock Purchase Agreements) electronically, and, as
determined by the Administrator and permitted by Applicable Law, all notices and
other documentation or writing required to be provided by a Participant or
Eligible Participant to the Company may be transmitted electronically.

Date Plan Adopted by Board of Directors:     March 26, 2000

Date Plan Approved by the Shareholders:      April 27, 2000
<PAGE>

                                CERTICOM CORP.
                         2000 UNITED STATES STOCK PLAN

                                   Exhibit A
                                  Definitions


1.   "10% shareholder" means a person who owns, either directly or indirectly by
virtue of the ownership attribution provisions set forth in Section 424(d) of
the Code at the time he or she is granted an Option, shares possessing more than
10% of the total combined voting power or value of all classes of equity of the
Company and/or of its Subsidiaries.

2.   "1997 Stock Option Plan" means the Company's 1997 Stock Option Plan, as may
be amended from time to time.

3.   "1933 Act" means the United States Securities Act of 1933, as amended.

4.   "Administrator" has the meaning set forth in Section 5(a) of the Plan.

5.   "Affiliate" means any parent corporation or subsidiary corporation of the
Company, whether now or hereafter existing, as those terms are defined in
Sections 424(e) and (f), respectively, of the Code.

6.   "Associate" has the meaning assigned by the Securities Act (Ontario), as
amended from time to time.

7.   "Board" has the meaning set forth in Section 1 of the Plan.

8.   "Code" means the United States Internal Revenue Code of 1986, as amended
(references herein to Sections of the Code are intended to refer to Sections of
the Code as enacted at the time of the Plan's adoption by the Board and as
subsequently amended, or to any substantially similar successor provisions of
the Code resulting from recodification, renumbering or otherwise).

9.   "Committee" means a committee appointed by the Board in accordance with
Section 5(c) of the Plan.

10.  "Company" has the meaning set forth in Section 1 of the Plan.

11.  "Consultant" is as an individual who is a Contractor or who:

(a)  provides ongoing consulting services to the Company or an Affiliate under a
     written contract;

(b)  possesses technical, business or management expertise of value to the
     Company or an Affiliate;

(c)  spends a significant amount of time and attention on the business and
     affairs of the Company or on an Affiliate; and
<PAGE>

(d)  has a relationship with the Company or an Affiliate that enables the
     individual to be knowledgeable concerning the business and affairs of the
     Company.

12.  "Contractor" means an individual who is not an Employee but works full-time
or part-time for the Company providing services normally provided by an
Employee.

13.  "Covered Employee" means the chief executive officer and the four other
highest compensated officers of the Company for whom total compensation is
required to be reported to shareholders under the Exchange Act, as determined
for purposes of Section 162(m) of the Code.

14.  "disability" means any physical or mental disability which results in a
Termination of Eligibility Status under applicable law, except that for purposes
of Section 9.3(a) of the Plan, the term "disability" means permanent and total
disability within the meaning of Section 22(e)(3) of the Code.

15.  "Director" means a member of the Board.

16.  "Eligible Participants" has the meaning set forth in Section 3 of the Plan.

17.  "Employee" means any person, including Officers and Directors, employed by
the Company or any Affiliate. Neither service as a Director nor payment of a
director's fee by the Company shall be sufficient to constitute "employment" by
the Company.

18.  "Exchange Act" means the United States Securities Exchange Act of 1934, as
amended.

19.  "Grace Period" has the meaning set forth in Section 5(b)(iii)(E) of the
Plan.

20.  "Grant Date" means, with respect to an Option, the date on which the Option
Agreement evidencing that Option is entered into between the Company and the
Optionee, or such other date as may be set forth in that Option Agreement as the
"Grant Date" which will be the effective date of that Option Agreement.

21.  "ISO" means an "incentive stock option" as defined in Section 422 of the
Code.

22.  Market Value" per Share at any date shall be the closing price of the
Shares on the Nasdaq National Market (the "NNM") (or if the Shares are not then
listed and posted for trading on the NNM, on such stock exchange on which such
Shares are then listed and posted for trading as may be selected for such
purpose by the Administrator) on the trading day immediately preceding the Grant
Date or, in the event of a measurement of Share price pursuant to Section 7(b),
the trading day immediately preceding the surrender of the Shares. In the event
that the Shares are not listed and posted for trading on the NNM or any stock
exchange, the Market Value shall be determined by the Administrator in its sole
discretion; provided that, such determination is consistent with the
requirements of Section 422 of the Code. Notwithstanding the preceding, in the
event that the Shares are listed in a currency other than U.S. dollars, the
Market Value shall be converted into U.S. dollars from such currency based on
the New York foreign exchange mid-range rates applying to trading among banks in
the amounts of $1 million and more
<PAGE>

as quoted at 4 p.m. New York time on the trading day preceding the Grant Date
(or, in the event of a measurement of Share price pursuant to Section 7(b), the
date prior to the surrender of the Shares) as reported by Reuters and other
sources or, if not available, such other exchange rate as determined by the
Administrator in its sole discretion.

23.  "Non-Employee Director" means a Director who either (i) is not a current
Employee or Officer of the Company or its parent or Subsidiary, does not receive
compensation (directly or indirectly) from the Company or its parent or
Subsidiary for services rendered as a Consultant or in any capacity other than
as a Director (except for an amount as to which disclosure would not be required
under Item 404(a) of Regulation S-K promulgated pursuant to the 1933 Act), does
not possess an interest in any other transaction as to which disclosure would be
required under Item 404(a) of Regulation S-K, and is not engaged in a business
relationship as to which disclosure would be required under Item 404(b) of
Regulation S-K or (ii) is otherwise considered a "non-employee director" for
purposed of Rule 16b-3.

24.  "Nonstatutory Stock Option" means an Option not intended to qualify as an
ISO.

25.  "Notice of Grant" means a written notice evidencing certain terms and
conditions of an individual Stock Purchase Right grant.

26.  "Officer" means a person who is an officer of the Company within the
meaning of Section 16 of the Exchange Act and the rules and regulations
promulgated thereunder.

27.  "Option Agreement" means an agreement pursuant to which an Optionee is
granted Options to purchase Option Shares pursuant to the Plan.

28.  "Option Price" has the meaning set forth in Section 5(b)(iii)(C) of the
Plan.

29.  "Option Shares" has the meaning set forth in Section 1 of the Plan,
provided that for purposes of Section 12 of the Plan, the term "Option Shares"
includes all Shares issued by the Company to a Participant (or his, her or its
predecessor) by reason of such holdings, including any securities which may be
acquired as a result of a stock split, stock dividend and other distributions of
Shares in the Company made upon, or in exchange for, other securities of the
Company.

30.  "Option Term" has the meaning set forth in Section 5(b)(iii)(D) of the
Plan.

31.  "Optionee" means a person who is granted an Option pursuant to the Plan.

32.  "Options" has the meaning set forth in Section 1 of the Plan.

33.  "Outside Director" means a Director who either (i) is not a current
Employee of the Company or an "affiliated corporation" (within the meaning of
the Treasury regulations promulgated under Section 162(m) of the Code), is not a
former Employee of the Company or an "affiliated corporation" receiving
compensation for prior services (other than benefits under a tax qualified
pension plan), was not an Officer of the Company or an "affiliated corporation"
at any time, and is not currently receiving direct
<PAGE>

or indirect remuneration from the Company or an "affiliated corporation" for
services in any capacity other than as a Director, or (ii) is otherwise
considered an "outside director" for purposes of Section 162(m) of the Code.

34.  "Outstanding Issue" means the number of Shares that are outstanding
immediately prior to any issuance of Options under the Plan or any issuance of
Option Shares, as the case may be, excluding Option Shares issued pursuant to
the Plan and all other plans or stock option agreements, including the 1997
Stock Option Plan, to which the Company may be a party during the preceding one-
year period.

35.  "Participant" means Eligible Participants to whom Options are granted
pursuant to the Plan which remain unexercised or to whom a Stock Purchase Right
has been granted which remains unexercised.

36.  "Plan" has the meaning set forth in Section 1 of the Plan.

37.  "Restricted Stock Purchase Agreement" means a written agreement between the
Company and the grantee of a Stock Purchase Right evidencing the terms and
restrictions applying to Shares to be purchased under a Stock Purchase Right.
The Restricted Stock Purchase Agreement is subject to the terms and conditions
of the Plan and the Notice of Grant.

38.  "Rule 16b-3" means Rules 16b-3 of the Exchange Act or any successor to Rule
16b-3, as in effect when discretion is being exercised with respect to the Plan.

39.  "Shares" means the Common Shares of the Company or, in the event of an
adjustment contemplated in Section 16 hereof, such other securities to which an
Eligible Participant may be entitled upon the exercise of an Option or a Stock
Purchase Right as a result of such adjustment.

40.  "Stock Purchase Right" means the right to purchase Shares pursuant to
Section 6 of the Plan, as evidenced in the Notice of Grant.

41.  "Subsidiary" for purposes of Section 3 of the Plan only, has the same
meaning as "subsidiary corporation" as defined in the Securities Act (Ontario);
for all other purposes under the Plan, "Subsidiary" means a corporation or other
entity that is both (i) a "subsidiary corporation" as defined in the Securities
Act (Ontario) and (ii) a "subsidiary corporation" as defined in Section 424(f)
of the Code.

42.  "Tax Withholding Liability" in connection with the exercise, sale or
repurchase of any Option or Option Shares means all Canadian or United States
federal, state or provincial income taxes, social security taxes, employment
taxes and any other taxes (together with any interest or penalties applicable
thereon) related to any compensation income arising from the transaction
required by applicable law to be withheld by the Company.

43.  "Termination of Eligibility Status" means (i) in the case of any Employee
of the Company and/or any of its Subsidiaries, a termination of his or her
employment, whether by the Employee or employer, and whether voluntary or
involuntary, including without
<PAGE>

limitation as a result of the death or disability of the Employee; (ii) in the
case of any Consultant of the Company and/or any of its Subsidiaries, the
termination of the services relationship pursuant to any contract between the
parties or otherwise under applicable law; and (iii) in the case of any director
of the Company and/or any of its Subsidiaries, the death of or resignation by
the director or his or her removal from the Board in the manner provided by the
organic instruments of the Company or Subsidiary or otherwise in accordance with
applicable law.

44.  "Termination  for  Cause"  means (i) in the case of an  Optionee  who is an
Employee of the Company  and/or any of its  Subsidiaries,  a termination  by the
employer of the Optionee's  employment for "cause" as defined by applicable law,
by any contract of employment or the Option  Agreement or the  Restricted  Stock
Purchase  Agreement,  or if not  defined  therein,  pursuant  to the "For  Cause
Standard" set forth below, (ii) in the case of an Optionee who is or which is an
Consultant to the Company and/or any of its  Subsidiaries,  a termination of the
services  relationship by the hiring party for "cause" or breach of contract, as
defined by  applicable  law, by any  contract  between the parties or the Option
Agreement or the Restricted Stock Purchase Agreement, or if not defined therein,
pursuant to the "For Cause  Standard" set forth below,  and (iii) in the case of
an Optionee  who is a Director of the  Company  and/or any of its  Subsidiaries,
removal  of him or her from the  Board by  action  of the  shareholders  or,  if
permitted  by  applicable  law  and  the  articles,   bylaws  or  other  organic
instruments of the Company or the Subsidiary, as the case may be, or pursuant to
applicable  law,  by the other  Directors,  in  connection  with the good  faith
determination of the Board (or of the Company's or Subsidiary's  shareholders if
so required,  but in either case excluding the vote of the subject individual if
he or she is a Director or a  shareholder)  that the Optionee has engaged in any
acts which breach any fiduciary duty to the Company,  any of its Subsidiaries or
their shareholders, or in any acts involving dishonesty or moral turpitude or in
any  acts  that  materially  and  adversely  affect  the  business,  affairs  or
reputation of the Company or any of its Subsidiaries (the "For Cause Standard").

45.  "Unvested Options" has the meaning set forth in Section 5(b)(iii)(F) of the
Plan.

46.  "Vested Option" has the meaning set forth in Section 5(b)(iii)(F) of the
Plan.

47.  "Vesting" has the meaning set forth in Section 9.4 of the Plan.