<PAGE>   1
                                                                  EXHIBIT 10.5


                              AMENDED AND RESTATED
                              EMPLOYMENT AGREEMENT


     THIS AMENDED AND RESTATED EMPLOYMENT AGREEMENT (the "Agreement") is made as
of the 1st day of November, 1997 (the "Agreement Date"), by and between Security
Dynamics Technologies, Inc., a Delaware corporation ("Employer"), and Charles R.
Stuckey, Jr. ("Employee").

     WHEREAS, Employer and Employee are parties to an Employment Agreement,
dated as of July 9, 1993 (the "1993 Agreement"); and

     WHEREAS, Employer and Employee are desirous of continuing Employee's
employment with Employer for the period, and on the terms and conditions, set
forth herein;

     NOW, THEREFORE, in consideration of the foregoing and of the mutual
covenants and conditions herein contained, the parties hereby agree that the
1993 Agreement is amended and restated in its entirety to read as follows:


Section 1. EMPLOYMENT.

     Employer hereby agrees to continue to employ Employee, and Employee accepts
such continued employment, according to the terms and conditions set forth in
this Agreement.

Section 2. TERM.

     The initial term of this Agreement (the "Initial Term") shall be for a
period commencing on November 1, 1997 and continuing through November 1, 1999.
Thereafter, this Agreement shall be automatically renewed for additional
one-year periods (the "Renewal Term") on the same terms and conditions (except
as may be otherwise mutually agreed to in writing by the parties) unless either
party gives the other written notice of non-renewal at least ninety (90) days
prior to the expiration of the then-current term. Notwithstanding the foregoing,
the Employment Period (as defined below) may be terminated at any time upon the
occurrence of any one of the following events: (i) Employee's decision to resign
pursuant to Section 9 of this Agreement, (ii) Employer's decision to terminate
Employee, either "for cause" or other than "for cause" pursuant to Section 9, or
(iii) the parties' agreement in writing to terminate the Agreement. The period
of time between the commencement and termination of Employee's employment shall
be referred to herein as the "Employment Period."


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Section 3. POSITION AND SERVICES.

     (a)  Employee will occupy the position of President and Chief Executive
          Officer of Employer. Employee will also be a member of the Employer's
          Board of Directors (the "Board of Directors"), subject to the terms of
          the Employer's Third Restated Certificate of Incorporation as amended
          from time to time. Any subsequent substantial diminution in the
          position, office or duties of Employee (other than any such diminution
          resulting from a Change in Control (as such term is defined in Section
          12 hereof)) or material breach by the Employer of its obligations
          under this Agreement shall be deemed a termination of this Agreement
          other than "for cause" as defined in Section 9 hereof. Employee will
          report directly to the Board of Directors and shall have such duties
          and responsibilities as are set forth in the Employer's Amended and
          Restated By-Laws, as amended from time to time, which duties and
          responsibilities shall include, but not be limited to, overall
          management responsibility for the operations and administration of
          Employer as well as such other duties and responsibilities, consistent
          with Employee's position as President and Chief Executive Officer, as
          shall be defined by the Board of Directors.

     (b)  Employee will be expected to be in the full-time employment of
          Employer, to devote substantially all of his business time and
          attention, and exert his best efforts, to the performance of his
          duties hereunder, and to serve Employer diligently and to the best of
          his ability. During the Employment Period, the Employee shall devote
          his full business time to the business and interests of the Employer;
          provided, that, except to the extent set forth in the Prior Agreements
          (as such term is defined in Section 8 hereof), nothing set forth
          herein shall prohibit the Employee from engaging in other activities
          to the extent that such activities do not impair the ability of the
          Employee to perform his duties and obligations under this Agreement.

Section 4. COMPENSATION.

     The Employer shall pay to the Employee an initial base salary (the "Base
Salary") at an annual rate of not less than $231,000, subject to deductions for
social security, state payroll and unemployment and all other legally required
or authorized deductions and withholding. Employee's salary shall be payable at
the same time and basis as Employer pays its payroll in general. The Board of
Directors shall review Employee's Base Salary during the Employment Period at
least on an annual basis. The Employee shall have the right, by written notice
to the Employer within thirty (30) days following any decrease in Employee's
Base Salary at any time during the Employment Period, to treat such reduction as
a termination of this Agreement other than "for cause" as defined in Section 9
hereof.


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<PAGE>   3


Section 5. INCENTIVE PAYMENTS.

     In addition to the Base Salary payable pursuant to Section 4 hereof,
Employee shall be entitled to annual bonuses if Employee satisfies agreed-upon
discrete goals/objectives to be contained in an annual incentive plan for the
Employee to be established by the Board of Directors at its sole and absolute
discretion in consultation with Employee on an annual basis. The incentive plan
for 1997 is attached as EXHIBIT A hereto.

Section 6. DEATH OR DISABILITY DURING EMPLOYMENT.

     If Employee is prevented from performing his duties hereunder by reason of
illness or injury for a period of (i) four or more consecutive months or (ii)
six months during any 12-month period as determined by a recognized physician
chosen by Employer and acceptable to Employee (the applicable date when either
of such disabling events shall occur being hereinafter referred to as the
"Effective Date of Disability"), or if Employee dies during the Employment
Period, Employer shall pay to the Employee, if the Employee is disabled, or to
Employee's spouse, the Executors under Employee's Last Will and Testament duly
admitted to probate within one year of his death or the Employee's heir at law,
if the Employee dies, in addition to such amounts (if any) as may be payable
pursuant to any short- or long-term disability or life insurance policies then
in effect and maintained by the Company with respect to the Employee
("Disability Policies"), the compensation which would otherwise be payable to
the Employee under this Agreement through the end of the month in which the
Employee's Effective Date of Disability or death occurs, or, in the case of
disability (and assuming any Disability Policies are currently in effect) such
later date as the Employee would, if eligible, be entitled to receive benefits
under such Disability Policies. In addition, the Employer shall pay, at the time
when such bonus would normally be paid, all bonus payments under Section 5
hereof which the Board of Directors, in good faith, believed that the Employee
was entitled to in respect of the year in which the Effective Date of Disability
or death occurred.

Section 7. BENEFITS; EXPENSES.

     (a)  The Employee shall be entitled to receive the same standard employment
          benefits as other executives of the Employer receive. The Employee
          shall be entitled to fully participate in all of the Employer's future
          employee benefit programs in accordance with their then-existing
          terms. The Employee shall be entitled to reimbursement for all
          approved reasonable travel and other business expenses incurred by the
          Employee in connection with his services to the Employer pursuant to
          the terms of this Agreement. All business expenses for which the
          Employee seeks reimbursement from the Employer shall be adequately
          documented by the Employee in accordance with the Employer's
          procedures covering expense


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<PAGE>   4



          reimbursement and in compliance with the regulations of the U.S.
          Internal Revenue Service.

     (b)  The Employee shall be entitled to five weeks of vacation during each
          year of the Employment Period. The Employee may accrue and carry
          forward vacation time to future years; provided, however, that in no
          event may the Employee carry forward into any year in excess of five
          weeks of accrued paid vacation time.

Section 8. CONFIDENTIALITY; NON-COMPETITION.

     The parties acknowledge that the Employee has previously entered into a
Non-Competition Agreement and a Nondisclosure and Developments Agreement, each
initially dated as of February 13, 1987 and amended and restated as of the
Agreement Date (together, as amended and restated, the "Prior Agreements"), in
connection with the Employee's employment by the Employer. The Prior Agreements
are each incorporated herein by this reference and made a part hereof as if set
forth herein in their entirety. The parties hereby agree that the Non-Disclosure
and Non-Competition Covenant, dated as of February 13, 1987, by and between the
Employer and the Employee be and hereby is terminated and shall be of no further
force and effect as of the Agreement Date.

Section 9. TERMINATION.

     This Agreement does not grant the Employee any right or entitlement to be
retained by the Employer, and shall not affect or prejudice the Employer's right
to discharge the Employee in accordance herewith. The Employee may terminate
this Agreement at any time during the Initial Term upon sixty (60) days' prior
written notice to the Employer. The Employer may terminate this Agreement "for
cause" (as defined below) at any time upon thirty (30) days' prior written
notice to the Employee. Employee shall, during such 30-day period, be given an
opportunity to defend the basis or facts giving rise to the notice. The Employer
may terminate this Agreement other than "for cause" at any time during the
Initial Term upon sixty (60) days' prior written notice to the Employee. Either
party may terminate this Agreement at any time during the Renewal Term upon
ninety (90) days' prior written notice to the other party. If Employee is
terminated either "for cause" or for reasons other than "for cause," Employee
shall be entitled to the following severance payments:

     (i)  If termination occurs by the Employer other than "for cause," then the
          following severance payments (less applicable deductions for social
          security, payroll and other applicable taxes) and related arrangements
          will be made:


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<PAGE>   5


          (a)  cash payments at the Employee's current monthly Base Salary at
               the time of termination (less applicable deductions) for a period
               of 24 months commencing with the month immediately succeeding the
               month during which the 30-day period after the giving of notice
               shall have ended (the "Effective Date of Termination");

          (b)  in addition to (a) above, normal employee medical and insurance
               benefits will be continued on an insured basis for the Employee
               and for the Employee's spouse at the Effective Date of
               Termination ("Spouse") until the latter to occur of (i)
               Employee's death or (ii) the Spouse's death, provided that
               medical benefits provided to the Employee and the Spouse pursuant
               to this subparagraph (b) may be reduced from time to time to the
               extent that medical benefits are provided through Medicare or
               through any other employer following the Effective Date of
               Termination;

          (c)  to the extent that all or any stock options granted to Employee
               shall not have vested as of the Effective Date of Termination,
               then all such stock options shall automatically vest;

          (d)  the Employer shall pay to the Employee, in a single lump sum
               payment within 30 days following the Effective Date of
               Termination, an amount equal to a pro rata portion of the
               Employee's current monthly Base Salary at the time of termination
               (less applicable deductions) with respect to the month in which
               the Effective Date of Termination occurs based upon the number of
               days elapsed in such month prior to the Effective Date of
               Termination;

          (e)  the Employer shall pay to the Employee, in a single lump sum
               payment within 30 days following the Effective Date of
               Termination, an amount equal to the greater of (i) a pro rata
               portion of the bonus payable to the Employee pursuant to Section
               5 of this Agreement with respect to the year in which such
               termination shall have occurred, calculated at 100% of the
               Employee's target bonus amount, and (ii) a pro rata portion of
               the actual bonus payable to the Employee pursuant to Section 5 of
               this Agreement with respect to the year in which such termination
               shall have occurred (assuming the Employee had been employed by
               the Employer the entire year);

          (f)  the Employer shall reimburse the Employee for any reasonable
               legal expenses incurred by the Employee in connection with the
               termination of the Agreement (excluding any expenses incurred in
               contesting any such termination, but including without limitation
               any reasonable legal expenses incurred by the Employee in


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<PAGE>   6



               connection with the negotiation, execution and delivery of the
               Consulting Agreement referred to in (g) below); and

          (g)  the Employer shall negotiate in good faith with the Employee
               regarding the retention of the Employee by the Employer as a
               consultant for the two-year period following the Effective Date
               of Termination pursuant to a Consulting Agreement to be entered
               into by the Employer and the Employee.

     (ii) If Employee is terminated by the Employer "for cause," the Employer
          shall (a) provide the Employee with normal employee medical and
          insurance benefits for a period of six months following the Effective
          Date of Termination, and (b) pay to the Employee an amount equal to a
          pro rata portion of any bonus payable to the Employee pursuant to
          Section 5 of this Agreement with respect to the year in which such
          termination shall have occurred based on the number of days elapsed in
          such year prior to the Effective Date of Termination. Except as set
          forth in the prior sentence, in the event of a termination for cause,
          the Employee shall not be entitled to any salary, severance or other
          payments or any benefits of any kind beyond the Effective Date of
          Termination. Termination "for cause" as used herein, and as determined
          by the Board of Directors, shall include only the following Employee
          behavior: (1) any act committed by Employee which shall represent (x)
          a breach in any material respect of any of the terms hereof or (y) a
          material breach of fiduciary duty to the Employer and/or all of its
          stockholders under the laws of the State of Delaware; (2) willful
          failure to carry out reasonable assigned duties; (3) gross negligence,
          consisting of wanton and reckless acts or omissions in the performance
          of Employee's duties to the material detriment of Employer; (4)
          addiction to drugs or chronic alcoholism which impairs the Employee's
          ability to carry out his obligations under this Agreement; or (5) any
          conviction of the Employee of a felony which is subject to a jail
          sentence of at least three months; provided, that in the case of a
          termination for cause pursuant to clause (1), (2) or (3) of this
          paragraph (ii), the Employee shall be provided with not less than 30
          days' written notice thereof from the Board of Directors or the
          Compensation Committee of the Board of Directors and an opportunity to
          cure such event to the reasonable satisfaction of the Board of
          Directors.

     (iii) If Employee voluntarily resigns then the following severance payments
          (less applicable deductions for social security, payroll and other
          applicable taxes) and related arrangements will be made:



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<PAGE>   7



          (a)  normal employee medical and insurance benefits will be continued
               on an insured basis for the Employee and for the Spouse until the
               latter to occur of (i) Employee's death or (ii) the Spouse's
               death, provided that medical benefits provided to the Employee
               and the Spouse pursuant to this subparagraph (a) may be reduced
               from time to time to the extent that medical benefits are
               provided through Medicare or through any other employer following
               the Effective Date of Termination;

               (b)  the Employer shall pay to the Employee, in a single lump sum
                    payment within 30 days following the Effective Date of
                    Termination, an amount equal to a pro rata portion of the
                    Employee's current monthly Base Salary at the time of
                    termination (less applicable deductions) with respect to the
                    month in which the Effective Date of Termination occurs
                    based upon the number of days elapsed in such month prior to
                    the Effective Date of Termination; and

               (c)  the Employer shall pay to the Employee, in a single lump sum
                    payment within 30 days following the Effective Date of
                    Termination, an amount equal to a pro rata portion of the
                    actual bonus payable to the Employee pursuant to Section 5
                    of this Agreement with respect to the year in which such
                    termination shall have occurred (assuming the Employee had
                    been employed by the Employer the entire year).

Section 10. BREACH OR VIOLATION OF AGREEMENT.

     Any controversy or claim arising out of, or relating to, this Agreement, or
the breach thereof, shall be settled by arbitration in accordance with the
Commercial Arbitration Rules of the American Arbitration Association, and
judgment upon the award rendered may be entered in any court having jurisdiction
thereof. Notwithstanding the foregoing, the parties agree that a breach or
violation of this Agreement will result in immediate and irreparable injury and
harm to the other party, who shall have the right of an injunction, specific
performance or other equitable relief to prevent the violation of the
obligations hereunder. In addition, the prevailing party in any arbitration or
litigation relating to the interpretation or enforcement of this Agreement shall
be entitled to reimbursement of all reasonable costs and expenses (including
without limitation fees and expenses of counsel) incurred in connection
therewith.


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<PAGE>   8



Section 11. NOTICES.

     Any notice required to be given pursuant to the provisions of this
Agreement shall be in writing and, if mailed, sent by registered or certified
mail, postage prepaid, with a copy delivered by an overnight courier service of
recognized standing, to the party named at the address set forth below, or at
such other address as each party may hereafter designate in writing to the other
party:

                  Employer:         Security Dynamics Technologies, Inc.
                                    20 Crosby Drive
                                    Bedford, MA  01730
                                    Attn:  Secretary

                  cc:               Hale and Dorr LLP
                                    60 State Street
                                    Boston, MA  02109
                                    Attn:  Hal J. Leibowitz, Esq.

                  Employee:         Charles R. Stuckey, Jr.
                                    121 Woodbine Road
                                    Carlisle, MA  01741

     Any such notices shall be deemed to have been delivered when served
personally, or 28 hours after being mailed in the manner specified above.

Section 12. CHANGE IN CONTROL EVENT.

     If a Change in Control (as such term is defined below) shall have occurred,
Employee shall be entitled, at his election, to receive, if he chooses to leave
Employer's management at any time during the first 18 months after the effective
date of the Change in Control, (a) a lump sum payment in an amount equal to two
times his then-current monthly Base Salary (less applicable deductions) provided
for in Section 4 hereof for a 12-month period, and (b) a pro rata portion of any
bonus otherwise payable to the Employee pursuant to Section 5 of this Agreement
with respect to the year in which such Change in Control shall have occurred,
calculated at 100% of the Employee's target bonus amount, based on the number of
days elapsed in such year prior to the Employee's last day of full time
employment with the Employer. In addition, all of the stock options granted to
Employee which shall not have vested or which shall still remain exercisable as
of the effective date of the Change in Control shall thereupon automatically
vest and be free from repurchase if Employee is terminated other than "for
cause" within one year after the effective date of the Change in Control.


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<PAGE>   9


     For purposes of this Agreement, a "Change in Control" shall be deemed to
have taken place if:

     (i)  there shall be consummated any consolidation or merger of Employer in
          which Employer is not the continuing or surviving corporation or
          pursuant to which shares of the Employer's capital stock are converted
          into cash, securities or other property, other than a consolidation or
          merger of Employer in which each holder of the Employer's capital
          stock immediately prior to the consolidation or merger has upon
          consummation of the consolidation or merger the same proportionate
          ownership of each class or series of capital stock of the surviving
          corporation as such holder had of each class or series of the
          Employer's capital stock immediately prior to the consolidation or
          merger, or any sale, lease, exchange or other transfer (in one
          transaction or a series of transactions contemplated or arranged by
          any party as a single plan) of all or substantially all of the assets
          of Employer; or

     (ii) any person (as such term is used in Sections 13(d) and 14(d)(2) of the
          Securities Exchange Act of 1934, as amended (the "Exchange Act"),
          shall after the Agreement Date become the beneficial owner (as defined
          in Rules 13(d)(3) and 13(d)(5) under the Exchange Act), directly or
          indirectly, of securities of Employer representing more than 50% of
          the voting power of all then outstanding securities of Employer having
          the right under ordinary circumstances to vote in an election of the
          Board of Directors (for purposes of this clause (ii), any securities
          of Employer that any such person has the right to acquire pursuant to
          any agreement, or upon exercise of conversion rights, warrants or
          options, or otherwise, shall be deemed beneficially owned by such
          person).

Section 13. EXERCISE OF STOCK OPTIONS.

     (a)  Subject to the provisions of Section 12 hereof, upon the termination
          of the Employment Period, Employee shall have the following periods
          during which to exercise all then vested stock options having a grant
          date on or before the Agreement Date:

          (i)  if Employee voluntarily resigns, Employee shall have 60 days from
               the date of resignation during which to exercise such vested
               options; and

          (ii) if there is a termination other than "for cause" and other than
               due to the occurrence of any of the events referred to in Section
               6 hereof, then Employee shall have six months from such date
               during which to exercise such vested options.


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<PAGE>   10



     (b)  Subject to the provisions of Section 12 hereof, upon the termination
          of the Employment Period, Employee shall have the following periods
          during which to exercise all then vested stock options having a grant
          date after the Agreement Date:

          (i)  if Employee voluntarily resigns, Employee shall have 12 months
               from the date of resignation during which to exercise such vested
               options; and

          (ii) if there is a termination other than "for cause" and other than
               due to the occurrence of any of the events referred to in Section
               6 hereof, then Employee shall have twelve months from the date of
               such termination during which to exercise such vested options.

     (c)  Upon a termination of the Employment Period "for cause," all stock
          options held by the Employee shall terminate automatically upon the
          Effective Date of Termination.

     (d)  Upon a termination of the Employment Period as a result of any of the
          events referred to in Section 6 hereof, the period of exercise of all
          or any portion of the Employee's then vested stock options shall be 12
          months from the Effective Date of Disability or death.

Section 14. LIMITATIONS ON PARACHUTE PAYMENTS.

     (a)  In the event that the Company undergoes a "Change in Ownership or
          Control" (as defined below), a portion of any "Contingent Compensation
          Payments" (as defined below) that the Employee would otherwise be
          entitled to receive shall be eliminated to the extent necessary to
          eliminate any "excess parachute payments" (as defined in Section
          280G(b)(1) of the Internal Revenue Code of 1986, as amended (the
          "Code")) for the Employee. For purposes of this Section 14, the
          Contingent Compensation Payments so eliminated shall be referred to as
          the "Eliminated Payments" and the aggregate amount (determined in
          accordance with Proposed Treasury Regulation Section 1.280G-1, Q/A-30
          or successor provision) of the Contingent Compensation Payments so
          eliminated shall be referred to as the "Eliminated Amount."
          Notwithstanding the foregoing, no such reduction in payments shall
          occur if the excess of (A) 110% of the Eliminated Amount (computed
          without regard to this sentence) over (B) the aggregate present value
          (determined in accordance with Proposed Treasury Regulation Section
          1.280G-1, Q/A-31, and Q/A-32 or successor provisions) of the amount of
          any additional taxes that would be incurred by the Employee if the
          Eliminated Payments (determined without regard to this sentence) were
          paid to him (including, state and federal income


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<PAGE>   11


          taxes on the Eliminated Payments, the excise tax imposed by Section
          4999 of the Code payable with respect to all of the Contingent
          Compensation Payments, and any withholding taxes) is greater than
          zero. For purpose of the preceding sentence, any federal or state
          income tax that would be attributable to the receipt of the Eliminated
          Payments shall be computed by multiplying the amount of the Eliminated
          Payment by the maximum combined federal and state income tax rate
          provided by law; provided, however, that if the Employee so notifies
          the Company within 90 days following the timely filing of all relevant
          tax returns for the Employee for the year or other taxable period in
          which the Eliminated Payments would have been made, the Eliminated
          Payments shall be recomputed based upon all of the Employee's actual
          tax circumstances. If, as a result of such recomputation, there are no
          Eliminated Payments, the Employee shall become entitled to receive
          Contingent Compensation Payments previously treated as Eliminated
          Payments within 10 days of the delivery of the aforementioned notice
          together with interest thereon computed at the prime rate announced
          from time to time by the Wall Street Journal compounded monthly from
          the date that such payments originally would have been made.


     (b)  For purposes of this Section 14, the following terms shall have the
          meaning given them in this subsection (b):

          (i)  "Change in Ownership or Control" shall mean a change in the
               ownership or effective control of the Company or in the ownership
               of a substantial portion of the assets of the Company determined
               in accordance with Section 280G(b)(2) of the Code.

          (ii) "Contingent Compensation Payment" shall mean any payment (or
               benefit) in the nature of compensation that is made or supplied
               to a "disqualified individual" (as defined in Section 280G(c) of
               the Code) and that is contingent (within the meaning of Section
               280G(b)(2)(A)(i) of the Code) on a Change in Ownership or Control
               of the Company.

     (c)  The amount of any payments or other benefits otherwise due to the
          Employee following a Change in Ownership or Control that could
          reasonably be characterized as Contingent Compensation Payments (as
          determined by the Company) shall not be made until 30 days after the
          date on which they would otherwise have been due (the "Extended Due
          Date"). Within 15 days of the date on which such payments or benefits
          would have originally been due, the Company shall determine and notify
          the Employee (with reasonable detail regarding the basis for its
          conclusions)


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<PAGE>   12


          (i)  whether some or all of such payments and benefits constitute
               Contingent Compensation Payments and (ii) the amount of any
               Eliminated Amount. On or prior to the Extended Due Date, the
               Employee shall notify the Company either (A) that he agrees with
               the Company's determination pursuant to the preceding sentence,
               in which case he shall indicate, if applicable, the Contingent
               Compensation Payments that will be treated as Eliminated Payments
               or (B) that he disagrees with such determination, in which case
               he shall indicate those payments that should be characterized as
               Contingent Compensation Payments, the amount of any Eliminated
               Amount and, if applicable, the Contingent Compensation Payments
               that will be treated as Eliminated Payments. The amount and
               characterization of any item in the notice from the Employee
               shall be final; provided, however, that in the event that the
               Employee fails to notify the Company pursuant to the preceding
               sentence on or before the Extended Due Date, the Company's
               initial determination shall be final and the Contingent
               Compensation Payments that will be treated as Eliminated Payments
               shall be determined by the Company in its absolute discretion. In
               no event shall the Company be liable to the Employee as a result
               of any factual or legal determination made by it pursuant to this
               subsection (c) or for any information supplied by it to the
               Employee or his advisors.

     (d)  The provisions of this Section 14 are intended to apply to any and all
          payments or benefits available to the Employee under this Agreement.

Section 15. LEGAL EXPENSES.

     The Employer shall reimburse the Employee for any reasonable legal expenses
incurred by the Employee in connection with the preparation and negotiation of
this Agreement and any amendments hereto.

Section 16. ENTIRE AGREEMENT.

     (a)  CHANGE, MODIFICATION, WAIVER. No change or modification of this
          Agreement shall be valid unless it is in writing and signed by each of
          the parties hereto. No waiver of any provision of this Agreement shall
          be valid unless it is in writing and signed by the party against whom
          the waiver is sought to be enforced. The failure of a party to insist
          upon strict performance of any provision of this Agreement in any one
          or more instances shall not be construed as a waiver or relinquishment
          of the right to insist upon strict compliance with such provision in
          the future.

     (b)  INTEGRATION OF ALL AGREEMENTS. This Agreement, together with the Prior
          Agreements, constitutes the entire Agreement between the parties and
          is intended to be an integration of all agreements between the parties
          with


                                      -12-


<PAGE>   13



          respect to Employee's service with Employer. Any and all prior
          agreements between Employee and Employer with respect to the subject
          matter hereof (other than the Prior Agreements) are hereby revoked.

     (c)  SEVERABILITY OF PROVISIONS. If for any reason any provision of this
          Agreement should be declared void or invalid, such declaration shall
          not affect the validity of the rest of this Agreement, which shall
          remain in force as if executed with the void or invalid provision
          eliminated. Each of the Prior Agreements shall survive any termination
          of this Agreement in accordance with its terms.

Section 17. BINDING EFFECT.

     This Agreement shall be binding upon all parties hereto and their heirs,
successors and assigns. This Agreement shall be binding upon any successor
entity to Employer, including without limitation any successor by merger,
consolidation or sale of assets, and shall be assignable by the Employer to any
entity controlled by or under common control with the Employer.

Section 18. GOVERNING LAW.

     This Agreement shall be governed by and construed in accordance with the
internal laws of The Commonwealth of Massachusetts, without regard to conflicts
of laws principles.

Section 19. MISCELLANEOUS.

     (a)  FORM. As employed in this Agreement, the singular form shall include,
          if appropriate, the plural.

     (b)  HEADINGS. The headings employed in this Agreement are solely for the
          convenience and reference of the parties and are not intended to be
          descriptive of the entire contents of any paragraph and shall not
          limit or otherwise affect any of terms, provisions or construction
          thereof.

     (c)  COUNTERPARTS. This Agreement may be executed in counterparts, each of
          which shall be deemed an original, but all of which together shall
          constitute one and the same instrument.



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<PAGE>   14


     IN WITNESS WHEREOF, this Agreement is executed as of the date first above
written.

                                                EMPLOYER:

                                                SECURITY DYNAMICS
                                                 TECHNOLOGIES, INC.



                                                  /s/ Joseph B. Lassiter, III
                                                ------------------------------
                                                Joseph B. Lassiter, III
                                                Director and Chairman of the
                                                Compensation Committee of the
                                                Board of Directors


                                                EMPLOYEE:



                                                  /s/ Charles R. Stuckey, Jr.
                                                ------------------------------
                                                Charles R. Stuckey, Jr.