1


                                                                     EXHIBIT 3.1


                                 THIRD RESTATED

                          CERTIFICATE OF INCORPORATION

                                       OF

                      SECURITY DYNAMICS TECHNOLOGIES, INC.


         Security Dynamics Technologies, Inc., a corporation organized and
existing under and by virtue of the General Corporation Law of the State of
Delaware, does hereby certify as follows:

         1. The Corporation filed its original Certificate of Incorporation with
the Secretary of State of Delaware on May 23, 1986. A Second Restated
Certificate of Incorporation was filed with the Secretary of State of the State
of Delaware on September 7, 1988, which Second Restated Certificate of
Incorporation was amended by a Certificate of Amendment of Second Restated
Certificate of Incorporation filed on April 27, 1990, a Second Certificate of
Amendment of Second Restated Certificate of Incorporation filed on September 21,
1990, a Third Certificate of Amendment of Second Restated Certificate of
Incorporation filed on March 19, 1991, a Fourth Certificate of Amendment of
Second Restated Certificate of Incorporation filed on July 13, 1993, a Fifth
Certificate of Amendment of Second Restated Certificate of Incorporation filed
on October 28, 1993, a Sixth Certificate of Amendment of Second Restated
Certificate of Incorporation filed on October 24, 1994, and a Certificate of
Retirement of Stock filed on even date herewith.

         2. At a meeting of the Board of Directors of the Corporation, a
resolution was duly adopted, pursuant to Sections 141(f) and 245 of the General
Corporation Law of the State of Delaware, setting forth a Third Restated
Certificate of


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Incorporation of the Corporation and declaring said Third Restated Certificate
of Incorporation advisable. The stockholders of the Corporation duly approved
said proposed Third Restated Certificate of Incorporation by written consent in
accordance with Sections 228, 242 and 245 of the General Corporation Law of the
State of Delaware, and written notice of such consent has been given to all
stockholders who have not consented in writing to said restatement. The
resolution setting forth the Third Restated Certificate of Incorporation is as
follows:


RESOLVED:    That the Second Restated Certificate of Incorporation of the
             Corporation, as amended, be and hereby is amended and restated in
             its entirety so that the same shall read as follows:


         FIRST.   The name of the Corporation is:

                      Security Dynamics Technologies, Inc.

         SECOND.  The address of its registered office in the State of Delaware
is Corporation Trust Center, 1209 Orange Street, in the City of Wilmington,
County of New Castle. The name of its registered agent at such address is The
Corporation Trust Company.

         THIRD.   The nature of the business or purposes to be conducted or
promoted by the Corporation is as follows:

                  To engage in any lawful act or activity for which corporations
         may be organized under the General Corporation Law of Delaware.

         FOURTH.  The total number of shares of all classes of stock which the
Corporation shall have authority to issue is Thirty Million (30,000,000) shares
of Common Stock, $.10 par value per share ("Common Stock").

         The following is a statement of the designations and the powers,
privileges and rights, and the qualifications, limitations or restrictions
thereof in respect of the Common Stock.

         1.       VOTING.  The holders of the Common Stock are entitled to one
vote for each share held at all meetings of stockholders. There shall be no
cumulative voting.


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         The number of authorized shares of Common Stock may be increased or
decreased (but not below the number of shares thereof then outstanding) by the
affirmative vote of the holders of a majority of the stock of the Corporation
entitled to vote, irrespective of the provisions of Section 242(b)(2) of the
General Corporation Law of Delaware.

         2.       DIVIDENDS.  Dividends may be declared and paid on the Common
Stock from funds lawfully available therefor as and when determined by the Board
of Directors.

         3.       LIQUIDATION. Upon the dissolution or liquidation of the
Corporation, whether voluntary or involuntary, holders of Common Stock will be
entitled to receive all assets of the Corporation available for distribution to
its stockholders.

         FIFTH.   The Corporation shall have a perpetual existence.

         SIXTH.   In furtherance of and not in limitation of powers conferred by
statute, it is further provided that the Board of Directors is expressly
authorized to adopt, amend or repeal the By-Laws of the Corporation.

         SEVENTH. Whenever a compromise or arrangement is proposed between this
corporation and its creditors or any class of them and/or between this
corporation and its stockholders or any class of them, any court of equitable
jurisdiction within the State of Delaware may, on the application in a summary
way of this corporation or of any creditor or stockholder thereof, or on the
application of any receiver or receivers appointed for this corporation under
the provisions of section 291 of Title 8 of the Delaware Code or on the
application of trustees in dissolution or of any receiver or receivers appointed
for this corporation under the provisions of section 279 of Title 8 of the
Delaware Code order a meeting of the creditors or class of creditors, and/or of
the stockholders or class of stockholders of this corporation, as the case may
be, to be summoned in such manner as the said court directs. If a majority in
number representing three-fourths in value of the creditors or class of
creditors, and/or of the stockholders or class of stockholders of this
corporation, as the case may be, agree to any compromise or arrangement and to
any promise or arrangement, the said compromise or arrangement and the said
reorganization shall, if sanctioned by the court to which the said application
has been made, be binding on all the creditors or class of creditors, and/or on
all the stockholders or class of stockholders, of this corporation, as the case
may be, and also on this corporation.

         EIGHTH.  Except to the extent that the General Corporation Law of the
State of Delaware prohibits the elimination or limitation of liability of
directors for breaches of fiduciary duty, no director of the Corporation shall
be personally liable to the Corporation or its stockholders for monetary damages
for any breach of fiduciary

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duty as a director, notwithstanding any provision of law imposing such
liability. No amendment to or repeal of this provision shall apply to or have
any effect on the liability or alleged liability of any director of the
Corporation for or with respect to any acts or omissions of such director
occurring prior to such amendment.

         NINTH.   1. ACTION, SUITS AND PROCEEDINGS OTHER THAN BY OR IN THE RIGHT
OF THE CORPORATION. The Corporation shall indemnify each person who was or is a
party or is threatened to be made a party to any threatened, pending or
completed action, suit or proceeding, whether civil, criminal, administrative or
investigative (other than an action by or in the right of the Corporation), by
reason of the fact that he is or was, or has agreed to become, a director or
officer of the Corporation, or is or was serving, or has agreed to serve, at the
request of the Corporation, as a director, officer or trustee of, or in a
similar capacity with, another corporation, partnership, joint venture, trust or
other enterprise (including any employee benefit plan) (all such persons being
referred to hereinafter as an "Indemnitee"), or by reason of any action alleged
to have been taken or omitted in such capacity, against all expenses (including
attorneys' fees) judgment, fines and amounts paid in settlement actually and
reasonably incurred by him or on his behalf in connection with such action, suit
or proceeding and any appeal therefrom, if he acted in good faith and in a
manner he reasonably believed to be in, or not opposed to, the best interests of
the Corporation, and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his conduct was unlawful. The termination of any
action, suit or proceeding by judgment, order, settlement, conviction or upon a
plea of NOLO CONTENDERE or its equivalent, shall not, of itself, create a
presumption that the person did not act in good faith and in a manner which he
reasonably believed to be in, or not opposed to, the best interests of the
Corporation, and, with respect to any criminal action or proceeding, had
reasonable cause to believe that his conduct was unlawful. Notwithstanding
anything to the contrary in this Article, except as set forth in Section 6
below, the Corporation shall not indemnify an Indemnitee seeking indemnification
in connection with a proceeding (or part thereof) initiated by the Indemnitee
unless the initiation thereof was approved by the Board of Directors of the
Corporation.

         2. ACTIONS OR SUITS BY OR IN THE RIGHT OF THE CORPORATION. The
Corporation shall indemnify any Indemnitee who was or is a party or is
threatened to be made a party to any threatened, pending or completed action or
suit by or in the right of the Corporation to procure a judgment in its favor by
reason of the fact that he is or was, or has agreed to become, a director or
officer of the Corporation, or is or was serving, or has agreed to serve, at the
request of the Corporation, as a director, officer or trustee of, or in a
similar capacity with, another corporation, partnership, joint venture, trust or
other enterprise (including any employee benefit plan), or by reason of any
action alleged to have been taken or omitted in such capacity, against all
expenses (including attorneys' fees) and amounts paid in settlement actually and
reasonably incurred by him or on his behalf in connection with such action, suit
or

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proceeding and any appeal therefrom, if he acted in good faith and in a manner
he reasonably believed to be in, or not opposed to, the best interests of the
Corporation, except that no indemnification shall be made in respect of any
claim, issue or matter as to which such person shall have been adjudged to be
liable to the Corporation unless and only to the extent that the Court of
Chancery of Delaware shall determine upon application that, despite the
adjudication of such liability but in view of all the circumstances of the case,
such person is fairly and reasonably entitled to indemnity for such expenses
(including attorneys' fees) which the Court of Chancery of Delaware shall deem
proper.

         3. INDEMNIFICATION FOR EXPENSES OF SUCCESSFUL PARTY. Notwithstanding
the other provisions of this Article, to the extent that an Indemnitee has been
successful, on the merits or otherwise, in defense of any action, suit or
proceeding referred to in Sections 1 and 2 of this Article, or in defense of any
claim, issue or matter therein, or on appeal from any such action, suit or
proceeding, he shall be indemnified against all expenses (including attorneys'
fees) actually and reasonably incurred by him or on his behalf in connection
therewith. Without limiting the foregoing, if any action, suit or proceeding is
disposed of, on the merits or otherwise (including a disposition without
prejudice), without (i) the disposition being adverse to the Indemnitee, (ii) an
adjudication that the Indemnitee was liable to the Corporation, (iii) a plea of
guilty or NOLO CONTENDERE by the Indemnitee, (iv) an adjudication that the
Indemnitee did not act in good faith and in a manner he reasonably believed to
be in or not opposed to the best interests of the Corporation, and (v) with
respect to any criminal proceeding, an adjudication that the Indemnitee had
reasonable cause to believe his conduct was unlawful, the Indemnitee shall be
considered for the purposes hereof to have been wholly successful with respect
thereto.

         4. NOTIFICATION AND DEFENSE OF CLAIM. As a condition precedent to his
right to be indemnified, the Indemnitee must notify the Corporation in writing
as soon as practicable of any action, suit, proceeding or investigation
involving him for which indemnity will or could be sought. With respect to any
action, suit, proceeding or investigation of which the Corporation is so
notified, the Corporation will be entitled to participate therein at its own
expense and/or to assume the defense thereof at its own expense, with legal
counsel reasonably acceptable to the Indemnitee. After notice from the
Corporation to the Indemnitee of its election so to assume such defense, the
Corporation shall not be liable to the Indemnitee for any legal or other
expenses subsequently incurred by the Indemnitee in connection with such claim,
other than as provided below in this Section 4. The Indemnitee shall have the
right to employ his own counsel in connection with such claim, but the fees and
expenses of such counsel incurred after notice from the Corporation of its
assumption of the defense thereof shall be at the expense of the Indemnitee
unless (i) the employment of counsel by the Indemnitee has been authorized by
the Corporation, (ii) counsel to the Indemnitee shall have reasonably concluded
that there may be a conflict of interest or position on any significant issue
between the Corporation and the

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Indemnitee in the conduct of the defense of such action or (iii) the Corporation
shall not in fact have employed counsel to assume the defense of such action, in
each of which cases the fees and expenses of counsel for the Indemnitee shall be
at the expense of the Corporation, except as otherwise expressly provided by
this Article. The Corporation shall not be entitled, without the consent of the
Indemnitee, to assume the defense of any claim brought by or in the right of the
Corporation or as to which counsel for the Indemnitee shall have reasonably made
the conclusion provided for in clause (ii) above.

         5. ADVANCE OF EXPENSES. Subject to the provisions of Section 6 below,
in the event that the Corporation does not assume the defense pursuant to
Section 4 of this Article of any action, suit, proceeding or investigation of
which the Corporation receives notice under this Article, any expenses
(including attorneys' fees) incurred by an Indemnitee in defending a civil or
criminal action, suit, proceeding or investigation or any appeal therefrom shall
be paid by the Corporation in advance of the final disposition of such matter;
PROVIDED, HOWEVER, that the payment of such expense incurred by an Indemnitee in
advance of the final disposition of such matter shall be made only upon receipt
of an undertaking by or on behalf of the Indemnitee to repay all amounts so
advanced in the event that it shall ultimately be determined that the Indemnitee
is not entitled to be indemnified by the Corporation as authorized in this
Article. Such undertaking shall be accepted without reference to the financial
ability of the Indemnitee to make such repayment.

         6. PROCEDURE FOR INDEMNIFICATION. In order to obtain indemnification or
advancement of expenses pursuant to Section 1, 2, 3 or 5 of this Article, the
Indemnitee shall submit to the Corporation a written request, including in such
request such documentation and information as is reasonably available to the
Indemnitee and is reasonably necessary to determine whether and to what extent
the Indemnitee is entitled to indemnification or advancement of expenses. Any
such indemnification or advancement of expenses shall be made promptly, and in
any event within 60 days after receipt by the Corporation of the written request
of the Indemnitee, unless with respect to requests under Section 1, 2 or 5 the
Corporation determines, by clear and convincing evidence, within such 60-day
period that the Indemnitee did not meet the applicable standard of conduct set
forth in Section 1 or 2, as the case may be. Such determination shall be made in
each instance by (a) a majority vote of the directors of the Corporation
consisting of persons who are not at that time parties to the action, suit or
proceeding in question ("disinterested directors"), even though less than
quorum, (b) a majority vote of a quorum of the outstanding shares of stock of
all classes entitled to vote for directors, voting as a single class, which
quorum shall consist of stockholders who are not at that time parties to the
action, suit or proceeding in question, (c) independent legal counsel (who may
be regular legal counsel to the Corporation), or (d) a court of competent
jurisdiction.


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         7. REMEDIES. The right to indemnification or advances as granted by
this Article shall be enforceable by the Indemnitee in any court of competent
jurisdiction if the Corporation denies such request, in whole or in part, or if
no disposition thereof is made within the 60-day period referred to above in
Section 6. Unless otherwise provided by law, the burden of proving that the
Indemnitee is not entitled to indemnification or advanced of expenses under this
Article shall be on the Corporation. Neither the failure of the Corporation to
have made a determination prior to the commencement of such action that
indemnification is proper in the circumstances because the Indemnitee has met
the applicable standard of conduct, nor an actual determination by the
Corporation pursuant to Section 6 that the Indemnitee has not met such
applicable standard of conduct, shall be a defense to the action or create a
presumption that the Indemnitee has not met the applicable standard of conduct.
The Indemnitee's expenses (including attorneys' fees) incurred in connection
with successfully establishing his right to indemnification, in whole or in
part, in any such proceeding shall also be indemnified by the Corporation.

         8. SUBSEQUENT AMENDMENT. No amendment, termination or repeal of this
Article or of the relevant provisions of the General Corporation Law of Delaware
or any other applicable laws shall affect or diminish in any way the rights of
any Indemnitee to indemnification under the provisions hereof with respect to
any action, suit, proceeding or investigation arising out of or relating to any
actions, transactions or facts occurring prior to the final adoption of such
amendment, termination or repeal.

         9. OTHER RIGHTS. The indemnification and advancement of expenses
provided by this Article shall not be deemed exclusive of any other rights to
which an Indemnitee seeking indemnification or advancement of expenses may be
entitled under any law (common or statutory), agreement or vote of stockholders
or disinterested directors or otherwise, both as to action in his official
capacity and as to action in any other capacity while holding office for the
Corporation, and shall continue as to an Indemnitee who has ceased to be a
director or officer, and shall inure to the benefit of the estate, heirs,
executors and administrators of the Indemnitee. Nothing contained in this
Article shall be deemed to prohibit, and the Corporation is specifically
authorized to enter into, agreements with officers and directors providing
indemnification rights and procedures different from those set forth in this
Article. In addition, the Corporation may, to the extent authorized from time to
time by its Board of Directors, grant indemnification rights to other employees
or agents of the Corporation or other persons serving the Corporation and such
rights may be equivalent to, or greater or less than, those set forth in this
Article.

         10. PARTIAL INDEMNIFICATION. If an Indemnitee is entitled under any
provision of this Article to indemnification by the Corporation for some or a
portion of the expenses (including attorneys' fees), judgments, fines or amounts
paid in

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settlement actually and reasonably incurred by him or on his behalf in
connection with any action, suit, proceeding or investigation and any appeal,
therefrom but not, however, for the total amount thereof, the Corporation shall
nevertheless indemnify the Indemnitee for the portion of such expenses
(including attorneys' fees), judgments, fines or amounts paid in settlement to
which the Indemnitee is entitled.

         11. INSURANCE. The Corporation may purchase and maintain insurance, at
its expense, to protect itself and any director, officer, employee or agent of
the Corporation or another corporation, partnership, joint venture, trust or
other enterprise (including any employee benefit plan) against any expense,
liability or loss incurred by him in any such capacity, or arising out of his
status as such, whether or not the Corporation would have the power to indemnify
such person against such expense, liability or loss under the General
Corporation law of Delaware.

         12. MERGER OR CONSOLIDATION. If the Corporation is merged into or
consolidated with another corporation and the Corporation is not the surviving
corporation, the surviving corporation shall assume the obligations of the
Corporation under this Article with respect to any action, suit, proceeding or
investigation arising out of or relating to any actions, transactions or facts
occurring prior to the date of such merger or consolidation.

         13. SAVINGS CLAUSE. If this Article or any portion hereof shall be
invalidated on any ground by any court of competent jurisdiction, then the
Corporation shall nevertheless indemnify each Indemnitee as to any expenses
(including attorneys' fees) judgments, fines and amounts paid in settlement in
connection with any action, suit, proceeding or investigation, whether civil,
criminal or administrative, including an action by or in the right of the
Corporation, to the fullest extent permitted by any applicable portion of this
Article that shall not have been invalidated and to the fullest extent permitted
by applicable law.

         14. DEFINITIONS. Terms used herein and defined in Section 145(h) and
Section 145(i) of the General Corporation Law of Delaware shall have the
respective meanings assigned to such terms in such Section 145(h) and Section
145(i).

         15. SUBSEQUENT LEGISLATION. If the General Corporation Law of Delaware
is amended after adoption of this Article to expand further the indemnification
permitted to Indemnitees, then the Corporation shall indemnify such persons to
the fullest extent permitted by the General Corporation Law of Delaware, as so
amended.

         TENTH.   The Corporation reserves the right to amend, alter, change or
repeal any provision contained in this Third Restated Certificate of
Incorporation, in the manner now or hereafter prescribed by statute and this
Third Restated Certificate of Incorporation, and all rights conferred upon
stockholders herein are granted subject to this reservation.

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         ELEVENTH.  This Article is inserted for the management of the business
and for the conduct of the affairs of the Corporation.

         1. NUMBER OF DIRECTORS. The number of directors of the Corporation
shall not be less than three. The exact number of directors within the
limitations specified in the preceding sentence shall be fixed from time to time
by, or in the manner provided in, the Corporation's By-Laws.

         2. CLASSES OF DIRECTORS. The Board of Directors shall be and is divided
into three classes: Class I, Class II and Class III. No one class shall have
more than one director more than any other class. If a fraction is contained in
the quotient arrived at by dividing the designated number of directors by three,
then, if such fraction is one-third, the extra director shall be a member of
Class I, and if such fraction is two-thirds, one of the extra directors shall be
a member of Class I and one of the extra directors shall be a member of Class
II, unless otherwise provided from time to time by resolution adopted by the
Board of Directors.

         3. ELECTION OF DIRECTORS. Elections of directors need not be by written
ballot except as and to the extent provided in the By-Laws of the Corporation.

         4. TERMS OF OFFICE. Each director shall serve for a term ending on the
date of the third annual meeting following the annual meeting at which such
director was elected; PROVIDED, that each initial director in Class I shall
serve for a term ending on the date of the annual meeting in 1995; each initial
director in Class II shall serve for a term ending on the date of the annual
meeting in 1996; and each initial director in Class III shall serve for a term
ending on the date of the annual meeting in 1997; and PROVIDED FURTHER, that the
term of each director shall be subject to the election and qualification of his
successor and to his earlier death, resignation or removal.

         5. ALLOCATION OF DIRECTORS AMONG CLASSES IN THE EVENT OF INCREASES OR
DECREASES IN THE NUMBER OF DIRECTORS. In the event of any increase or decrease
in the authorized number of directors, (i) each director then serving as such
shall nevertheless continue as a director of the class of which he is a member
and (ii) the newly created or eliminated directorships resulting from such
increase or decrease shall be apportioned by the Board of Directors among the
three classes of directors so as to ensure that no one class has more than one
director more than any other class. To the extent possible, consistent with the
foregoing rule, any newly created directorships shall be added to those classes
whose terms of office are to expire at the latest dates following such
allocation, and any newly eliminated directorships shall be subtracted from
those classes whose terms of offices are to expire at the earliest dates
following such allocation, unless otherwise provided from time to time by
resolution adopted by the Board of Directors.


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         6. QUORUM; ACTION AT MEETING. A majority of the directors at any time
in office shall constitute a quorum for the transaction of business. In the
event one or more of the directors shall be disqualified to vote at any meeting,
then the required quorum shall be reduced by one for each director so
disqualified, provided that in no case shall less than one-third of the number
of directors fixed pursuant to Section 1 above constitute a quorum. If at any
meeting of the Board of Directors there shall be less than such a quorum, a
majority of those present may adjourn the meeting from time to time. Every act
or decision done or made by a majority of the directors present at a meeting
duly held at which a quorum is present shall be regarded as the act of the Board
of Directors unless a greater number is required by law, by the By-Laws of the
Corporation or by this Third Restated Certificate of Incorporation.

         7. REMOVAL. Directors of the Corporation may be removed only for cause
by the affirmative vote of the holders of at least two-thirds of the shares of
the capital stock of the Corporation issued and outstanding and entitled to
vote.

         8. VACANCIES. Any vacancy in the Board of Directors, however occurring,
including a vacancy resulting from an enlargement of the board, shall be filled
only by a vote of a majority of the directors then in office, although less than
a quorum, or by a sole remaining director. A director elected to fill a vacancy
shall be elected to hold office until the next election of the class for which
such director shall have been chosen, subject to the election and qualification
of his successor and to his earlier death, resignation or removal.

         9. STOCKHOLDER NOMINATIONS AND INTRODUCTION OF BUSINESS, ETC. Advance
notice of stockholder nominations for election of directors and other business
to be brought by stockholders before a meeting of stockholders shall be given in
the manner provided by the By-Laws of the Corporation.

         10. AMENDMENTS TO ARTICLE. Notwithstanding any other provisions of law,
this Third Restated Certificate of Incorporation or the By-Laws of the
Corporation, each as amended, and notwithstanding the fact that a lesser
percentage may be specified by law, the affirmative vote of the holders of at
least seventy-five percent (75%) of the shares of capital stock of the
Corporation issued and outstanding and entitled to vote shall be required to
amend or repeal, or to adopt any provision inconsistent with, this Article
ELEVENTH.

         TWELFTH. Stockholders of the Corporation may not take any action by
written consent in lieu of a meeting. Notwithstanding any other provisions of
law, the Third Restated Certificate of Incorporation or the By-Laws of the
Corporation, each as amended, and notwithstanding the fact that a lesser
percentage may be specified by law, the affirmative vote of the holders of at
least seventy-five percent (75%) of the shares of capital stock of the
Corporation issued and outstanding and

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entitled to vote shall be required to amend or repeal, or to adopt any provision
inconsistent with, this Article TWELFTH.

         THIRTEENTH. Special meetings of stockholders may be called at any time
by only the Chairman of the Board of Directors, the Chief Executive Officer (or
if there is no Chief Executive Officer, the President) or the Board of
Directors. Business transacted at any special meeting of stockholders shall be
limited to matters relating to the purpose or purposes stated in the notice of
meeting. Notwithstanding any other provision of law, this Third Restated
Certificate of Incorporation or the By-Laws of the Corporation, each as amended,
and notwithstanding the fact that a lesser percentage may be specified by law,
the affirmative vote of the holders of at least seventy-five percent (75%) of
the shares of capital stock of the Corporation issued and outstanding and
entitled to vote shall be required to amend or repeal, or to adopt any provision
inconsistent with, this Article THIRTEENTH.

         IN WITNESS WHEREOF, the Corporation has caused its corporate seal to be
affixed hereto and this Third Restated Certificate of Incorporation to be signed
by its President this 21st day of December, 1994.

                                            SECURITY DYNAMICS TECHNOLOGIES, INC.



                                            By: /s/ Charles R. Stuckey, Jr.
                                                --------------------------------
                                                President






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                            CERTIFICATE OF AMENDMENT
                                       OF
                   THIRD RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                      SECURITY DYNAMICS TECHNOLOGIES, INC.


         Pursuant to Section 242 of the General Corporation Law of the State of
Delaware, Security Dynamics Technologies, Inc., a corporation organized and
existing under the General Corporation Law of the State of Delaware (the
"Corporation"), does hereby certify:

         FIRST:   That the Board of Directors of the Corporation, at a meeting
of the Board of Directors held on April 24, 1996, duly adopted resolutions
proposing and declaring advisable the following amendment to the Third Restated
Certificate of Incorporation of the Corporation:


RESOLVED:       That the Third Restated Certificate of Incorporation of the
                Corporation be amended by deleting the first paragraph of
                Article FOURTH in its entirety and inserting the following in
                lieu thereof:

                         "FOURTH.  The total number of shares of all classes of
                stock which the Corporation shall have authority to issue is
                Eighty Million (80,000,000) shares of Common Stock, $.01 par
                value per share ("Common Stock")."

         SECOND:  That the stockholders of the Corporation, at a Special Meeting
of Stockholders held on July 26, 1996, duly approved said proposed Certificate
of Amendment of Third Restated Certificate of Incorporation in accordance with
Section 242 of the General Corporation Law of the State of Delaware.




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         IN WITNESS WHEREOF, the Corporation has caused this Certificate of
Amendment to be signed by its President this 31st day of July, 1996.

                                            SECURITY DYNAMICS TECHNOLOGIES, INC.


                                            By: /s/ Charles R. Stuckey, Jr.
                                                --------------------------------
                                                President




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                            CERTIFICATE OF AMENDMENT
                                       OF
                   THIRD RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                      SECURITY DYNAMICS TECHNOLOGIES, INC.


         Pursuant to Section 242 of the General Corporation Law of the State of
Delaware, Security Dynamics Technologies, Inc., a corporation organized and
existing under the General Corporation Law of the State of Delaware (the
"Corporation"), does hereby certify:

         FIRST:   That the Board of Directors of the Corporation, by written
action in lieu of a meeting dated March 12, 1999 pursuant to Sections 141(f) and
242 of the General Corporation Law of the State of Delaware, duly adopted
resolutions proposing and declaring advisable the following amendment to the
Third Restated Certificate of Incorporation, as amended, of the Corporation:

RESOLVED:       That the Third Restated Certificate of Incorporation, as
                amended, of the Corporation be amended by deleting the first
                paragraph of Article FOURTH in its entirety and inserting the
                following in lieu thereof:

                         "FOURTH.   The total number of shares of all classes of
                stock which the Corporation shall have authority to issue is One
                Hundred Fifty Million (150,000,000) shares of Common Stock, $.01
                par value per share ("Common Stock")."

         SECOND:  That the stockholders of the Corporation, at the Annual
Meeting of Stockholders held on May 5, 1999, duly approved said proposed
Certificate of Amendment of Third Restated Certificate of Incorporation in
accordance with Section 242 of the General Corporation Law of the State of
Delaware.


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         IN WITNESS WHEREOF, the Corporation has caused this Certificate of
Amendment to be signed by its Chairman of the Board and Chief Executive Officer
this 5th day of May, 1999.

                                 SECURITY DYNAMICS TECHNOLOGIES, INC.



                                 By: /s/ Marian G. O'Leary
                                     ----------------------------------
                                     Marian G. O'Leary
                                     Senior Vice President and
                                     Chief Financial Officer