Document:

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                                                                    EXHIBIT 4.2

                                 PROMISSORY NOTE

$203,159.07                                                   February 14, 2002

     FOR VALUE RECEIVED, JOHN T. BOTTI, an individual with a place of business
at 2165 Technology Drive, Schenectady, New York, New York 10017, (the "Payor"),
hereby promises to pay to the order of Authentidate Holding Corp., (the "Payee"
or "Holder"), or registered assigns, the principal amount of TWO HUNDRED THREE
THOUSAND ONE HUNDRED FIFTY NINE DOLLARS AND SEVEN CENTS ($203,159.07) and
interest in bi-weekly installments of $5,000 each until the earlier of the date
that (i) all payments of principal and interest are satisfied or (ii) on which
there is an acceleration pursuant to the terms of this Note (the "Maturity
Date"). Interest shall accrue and be payable at the rate of 6% per annum (except
as provided in Section 1.4), calculated for the actual number of days the
Principal is outstanding and interest is accrued and unpaid based on a 360-day
year, in accordance with the terms hereof.

     1. Terms of Repayment

     1.1 All payments received on account of this Note shall be applied first to
the payment of accrued interest on this Note and then to the reduction of the
unpaid principal balance of this Note. Interest shall be computed on the basis
of a year of 365 days, for the actual number of days elapsed.

     1.2 If payment of the outstanding principal amount of this Note, together
with accrued unpaid interest thereon at the applicable rate of interest (as set
forth herein), is not made on the Maturity Date, then interest shall accrue on
the outstanding principal amount due under this Note and on any unpaid accrued
interest due on the Maturity Date, in full on such amounts (including from and
after the date of the entry of judgment in favor of the Holder in an action to
collect this Note) at an annual rate equal to the lesser of 15% or the maximum
rate of interest permitted by applicable law.

     1.3 Notwithstanding anything to the contrary contained in this Note, Payor
shall not be obligated to pay, and the Holder shall not be entitled to charge,
collect, or receive, interest in excess of the maximum rate allowed by
applicable law. During any period of time in which the interest rate specified
herein exceeds such maximum rate, any amounts of interest collected by the
Holder in excess of such maximum rate shall be deemed to apply to principal and
all payments of interest and principal shall be recalculated to allow for such
characterization.

     1.4 In the event that the date for the payment of any amount payable under
this Note falls due on a Saturday, Sunday or public holiday under the laws of
the State of Delaware, the time for payment of such amount shall be extended to
the next succeeding business day and interest shall continue to accrue on any
principal amount so effected until the payment thereof on such extended due
date.

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     2. Security. The obligations represented by this Note are secured by the
collateral described in that certain Amended and Restated Security and Pledge
Agreement between Payor and Holder, dated as of the 14th day of February, 2002.
The holder of this Note is entitled to all rights and benefits of a secured
creditor under the Pledge and Security Agreement. Payor specifically
acknowledges that, in the event of foreclosure under the above-referenced
security agreement, Holder shall be entitled to the entry of a deficiency
judgment against Payor to the extent of any deficiency.

     3. Prepayment. The principal of and accrued interest on this Note may be
prepaid in full at any time without premium or penalty.

     4. Holder Deemed Owner. The registered Holder hereof may be deemed the
absolute owner of this Note (whether or not this Note shall be overdue and
notwithstanding any notice of ownership or writing hereon made by anyone other
than Payor, for the purpose of receiving payment hereof or thereof or on account
hereof and for all other purposes) and Payor shall not be affected by notice to
the contrary.

     5. Default. If one or more of the following events (herein called "Events
of Default") shall occur for any reason whatsoever (and whether such occurrence
shall be voluntary or involuntary or come about or be effected by operation of
law or pursuant to or in compliance with any judgment, decree or order of any
court or any order, rule or regulation or any administrative or governmental
body):

     (i) default in the due and punctual payment of the principal of, and
interest on, the Note when and as the same shall become due and payable, whether
on the Maturity Date or otherwise and continuance of such default for a period
of 10 days; or

     (ii) the Payor makes an assignment for the benefit of creditors or admits
in writing its inability to pay his debts generally as they become due; or

     (iii) an order, judgment or decree is entered adjudicating Payor bankrupt
or insolvent; or

     (iv) the Payor commences any proceedings under any bankruptcy,
reorganization, arrangement, insolvency, readjustment of debt, dissolution or
liquidation law of any jurisdiction whether now or hereafter in effect; or

     (v) any such petition or application is filed, or any such proceedings are
commenced, against the Payor, and the Payor by any act indicates its approval
thereof, consent or acquiescence therein, or an order, judgment or decree is
entered approving the petition in any such proceedings, and such order, judgment
or decree remains unstayed and in effect for more than 60 days; or

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     (vi) the Payor shall take any action for the purpose of effecting any of
the actions set forth in clauses (ii) through (v) of this section 4; or

     (vii) a default in the due observance or performance of any covenant,
condition or agreement on the part of the Payor to be observed or performed
pursuant to the terms and provisions of this Note (other than the payment
provisions) and such default shall continue for 30 days after written notice
thereof shall have been given to the Payor by the holder hereof; or

then, and in each and every such case, so long as such Event of Default shall
not have been remedied, the holder of this Note, by notice in writing to the
Payor, may declare the principal of this Note then outstanding and the interest
accrued thereon if not already due and payable, to be due and payable
immediately, and upon any such declaration the same shall become and shall be
immediately due and payable, anything in this Note contained to the contrary
notwithstanding. Additionally, upon the occurrence of an Event of Default, Maker
shall cease to own, and shall surrender all interest in and to the securities
pledged to Holder as described above.

     5. Miscellaneous

     5.1 The obligations to make the payments provided for in this Note are
absolute and unconditional and not subject to any defense, set-off,
counterclaim, rescission, recoupment or adjustment whatsoever. No provision of
this Note shall alter or impair the obligations of the Payor hereby.

     5.2 Payment of principal shall be made to the registered owner of this Note
upon presentation of this Note on or after maturity. No interest shall be due on
this Note for such period of time that may elapse between the maturity of this
Note and its presentation for payment.

     5.3 The Payor hereby waives presentment, demand, protest, notice of
non-payment and dishonor of the debt and each and every notice of any kind
regarding this Note.

     5.4 No forbearance, indulgence, delay or failure to exercise any right or
remedy with respect to this Note shall operate as a waiver or as an acquiescence
in any Default, nor shall any single or partial exercise of any right or remedy
preclude any other or further exercise thereof or the exercise of any other
right or remedy.

     5.5 This Note may not be modified or discharged (other than by payment),
except by a writing duly executed by the Payor and Holder.

     5.6 The headings of various sections and subsections of this Note are for
convenience of reference only and shall in no way modify any of the terms or
provisions of this Note.

     5.7 All notices required to be given to any of the parties hereunder shall
be in writing and shall be deemed to have been sufficiently given for all
purposes when presented

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personally to such party, sent by telecopier (with the
original timely mailed), registered, certified or express mail, return receipt
requested, or sent by national overnight delivery service, to such party at its
address set forth below:

         If to the Holder, to:                    If to the Payor, to:

         Authentidate Holding Corp.               John T. Botti
         2165 Technology Drive                    2165 Technology Drive
         Schenectady, NY 12308                    Schenectady, NY 12308
         Attention: Dennis H. Bunt                Telecopier No.: (518) 346-3644
         Telecopier No.: (518) 346-3644

     5.8 The Payor may not delegate his obligations under this Note and such
attempted delegations shall be null and void. The Holder may assign, pledge or
otherwise transfer this Note without prior written consent of the Payor. This
Note inures to the benefit of Payees, their successors and their assignees of
this Note and binds the Payor, and his successors and assigns, and the terms
"Payee" whenever occurring herein shall be deemed and construed to include such
respective successors and assigns.

     5.9 This Note shall continue to be effective or be reinstated, as the case
may be, if at any time any payment made pursuant to it is rescinded or must
otherwise be returned by the Holder upon bankruptcy or reorganization or
otherwise of the Payor, all as though such payment had not been made.

     5.10 THE PAYOR AND THE HOLDER EACH (I) AGREES THAT ANY SUIT, ACTION OR
PROCEEDING ARISING OUT OF OR RELATING TO THIS NOTE SHALL BE INSTITUTED
EXCLUSIVELY IN THE SUPREME COURT OF THE STATE OF NEW YORK, (II) WAIVE ANY
OBJECTION WHICH THEY MAY HAVE NOW OR HEREAFTER BASED UPON FORUM NON CONVENIENS
OR TO THE VENUE OF ANY SUCH SUIT, ACTION OR PROCEEDING, AND (III) IRREVOCABLY
CONSENTS TO THE JURISDICTION OF THE SUPREME COURT, NEW YORK, COUNTY OF
SCHENECTADY IN ANY SUCH SUIT, ACTION OR PROCEEDING. THE PAYOR AND THE HOLDER
EACH FURTHER AGREES TO ACCEPT AND ACKNOWLEDGE SERVICE OF ANY AND ALL PROCESS
WHICH MAY BE SERVED IN ANY SUCH SUIT, ACTION OR PROCEEDING IN THE SUPREME COURT,
STATE OF NEW YORK AND AGREES THAT SERVICE OF PROCESS UPON THE PAYOR OR THE
HOLDER, MAILED BY CERTIFIED MAIL TO THEIR RESPECTIVE ADDRESSES, SUCH SERVICE TO
BECOME EFFECTIVE THREE BUSINESS DAYS AFTER SUCH MAILING, WILL BE DEEMED IN EVERY
RESPECT EFFECTIVE SERVICE OF PROCESS UPON THE COMPANY OR THE HOLDER, AS THE CASE
MAY BE, IN ANY SUIT, ACTION OR PROCEEDING.

     5.11 This Note is exchangeable, without expense, upon the surrender hereof
by the Holder to the Payor for two or more new Notes of like tenor and date
(except for the principal

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amounts thereof) representing in the aggregate the same principal amount as this
Note, in such denominations as shall be designated by the Holder thereof at the
time of such surrender, provided that such new Notes shall be issuable in
minimum denominations of $10,000 and integral multiples thereof.

     5.12 This Note shall be construed in accordance with and governed by the
laws of the State of New York without regard to principles of conflicts of law,
and cannot be changed, discharged or terminated orally but only by an instrument
in writing signed by the party against whom enforcement of any change, discharge
or termination is sought.

     5.13 Upon receipt by the Payor of evidence reasonably satisfactory to it of
the loss, theft, destruction or mutilation of this Note, and, in case of loss,
theft or destruction, of indemnity or security reasonably satisfactory to it,
and upon surrender and cancellation of this Note, if mutilated, the Payor will
make and deliver a new Note of like date and tenor, in lieu hereof.

     5.14 Interest Rate. If any interest rate specified herein is held to be
impermissible, then the rate charged on the indebtedness represented hereby
shall be reduced to the highest rate then permitted by law.

     IN WITNESS WHEREOF, JOHN T. BOTTI, has caused this Note to be signed in his
name and to be dated the date and year first above written.

                                                         PAYOR:

                                                         JOHN T. BOTTI
                                                         ----------------------

                                       5<PAGE>
                                                                   EXHIBIT 10.1

                              AMENDED AND RESTATED

                          SECURITY AND PLEDGE AGREEMENT

     AMENDED AND RESTATED SECURITY AND PLEDGE AGREEMENT, dated as of February
14, 2002, between John T. Botti on the one hand (referred to herein as
"Pledgor"), intending to be liable under this security and pledge agreement
(this "Agreement"), with an address as indicated below his signature, and
Authentidate Holding Corp., on the other hand, having its principal office at
2165 Technology Drive, Schenectady, New York 12308 (the "Pledgee").

                              W I T N E S S E T H :
                              --------------------

     WHEREAS, Pledgee has made a loan (the "2001 Loan") to Pledgor in the
principal amount of $317,000 as evidenced by that certain Promissory Note dated
January 5, 2001 (the "2001 Note"); and

     WHEREAS, in order to secure the obligations of Pledgor arising from the
2001 Loan by Pledgee, Pledgee and Pledgor executed a Security and Pledge
Agreement dated January 5, 2001; and

     WHEREAS, the Pledgor owns 409,341 shares of the Common Stock of
Authentidate Holding Corp., Inc., and has been granted options to purchase
1,065,000 shares of the Common Stock of Authentidate Holding Corp., all of which
are fully vested; and

     WHEREAS, the 409,341 shares of Common Stock of Authentidate Holding Corp.
owned by Pledgor are currently held in account no.   . (the "Account"); and

     WHEREAS, Authentidate Holding Corp. has purchased from First Union
Securities a prior lien on the Account in respect of a margin loan of
approximately $241,159.07 (the "2002"

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Loan and together with the 2001 Loan, the "Loans"), as evidenced by that certain
Promissory Note dated February 14, 2002 in the principal amount of $203,159.07
(the "2002 Note" and together with the 2001 Note, the "Notes") and in
consideration thereof, Pledgor has consented to the transfer of such lien; and

     WHEREAS, the Pledgor and Pledgee have agreed that the aforementioned shares
of Common Stock of Authentidate Holding Corp., the options to purchase the
shares of Common Stock of Authentidate Holding Corp., the proceeds of any sales
of the such securities and the Account will secure the obligations represented
by all of the Notes and therefore desire to amend and restate the January 5,
2001 Pledge and Security Agreement; and

     WHEREAS, in connection with and prior to the making of the 2002 Loan, the
Pledgee is requiring that the Pledgor shall have executed and delivered this
Agreement and granted to it the security interest contemplated hereby;

     NOW, THEREFORE, in consideration of the premises and the covenants
hereinafter contained, and to induce the Pledgee to make the Loans, it is agreed
as follows:

     1. Pledge.

     (a) In order to secure the payment or performance, as the case may be, in
full of the obligations of the Pledgor under the Notes, the Pledgor hereby
pledges, assigns, transfers, delivers, deposits, sets over and confirms as a
second priority pledge unto the Pledgee, and its successors and assigns, (i)
409,341 Shares of Common Stock of Authentidate Holding Corp. owned (beneficially
and of record) by the Pledgor (the "Pledged Shares"), (ii) options to purchase
1,065,000 shares of the Common Stock of Authentidate Holding Corp. (the "Pledged
Options") (the Pledged Shares and the Pledged Options may be collectively
referred to herein as the

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"Pledged Securities"), (iii) all proceeds of, including cash or other securities
delivered in exchange for, the Pledged Securities, and (iv) the Account.

     (b) All of the Pledged Securities collectively owned by the Pledgor are
free and clear of all liens, claims, encumbrances, rights of third parties, and
any and all lockup agreements. Further, all restrictions on the Pledged
Securities, and all restrictive legends on the share certificates and option
certificates representing the Pledged Securities, have been removed or may be
removed pursuant to the Securities Act of 1933, as amended.

     (c) Certificates representing the Pledged Securities are currently held in
the Account by First Union and may be delivered to the Pledgee upon its demand.

     (d) Certificates representing the Pledged Options, accompanied by proper
instruments of assignment duly executed in blank by the Pledgor are herewith
delivered to Pledgee.

     (e) The Pledgor agrees that he has delivered herewith to the Pledgee (i)
proper instruments of assignment duly executed in blank by the Pledgor together
with the certificates representing any additional shares of capital stock of
Pledgee hereafter acquired; and (ii) a duly executed financing statements
covering the Account.

     2. Pledgor and Pledgee's Rights. Unless an Event of Default under this
Agreement shall have occurred: (i) the Pledgor shall be entitled to receive and
retain non-cash dividends and other distributions with respect to the Pledged
Securities, other than any such distributions of securities of Pledgee which
shall be forthwith delivered by Pledgor to the Pledgee, upon the execution and
delivery of this Agreement; (ii) the Pledgor shall be entitled to receive all
cash dividends and distributions in respect of the Pledged Securities declared
and paid by Authentidate Holding Corp.; (iii) Pledgor shall have all voting
rights with respect to the

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Pledged Securities; (iv) Pledgee shall have, with respect to the Pledged
Securities, the rights and obligations of a secured party under Article 9 of the
Uniform Commercial Code; (v) the Pledgee may file Financing Statements and
continuations thereof relating to the Pledgor in various filing offices to
perfect the Pledgee's security interest in the Account, and Debtor agrees to
execute copies thereof; and (vi) Pledgee may contact First Union, at any time,
for the purpose of, among other things, to arrange for the delivery of the
Pledged Securities to Pledgee. If any distribution in respect of the Pledged
Securities is paid, in whole or in part, in voting securities or capital
interests of Authentidate Holding Corp., the certificates for such securities
shall be delivered by the Pledgor to the Pledgee and shall constitute a part of
the Pledged Securities.

     3. Representations and Warranties: Pledgor represents nd warrants that he
owns the Pledged Securities, that the shares are not subject to any lien,
pledge, charge, encumbrance, security interest, lockup agreement effecting the
Pledgor's ability to sell the shares, or a right or action on the part of any
third person to purchase or require such shares or any part of such share.
Further, the undersigned Pledgor executing this Agreement has been authorized to
execute and deliver to Pledgee this Agreement and any other documents required
to consummate the transactions contemplated by this Agreement.

     4. Authority. Pledgor has the power and authority to execute, deliver and
perform its obligations under this Agreement and this Agreement constitutes the
legal, valid and binding obligation of Pledgor, enforceable against Pledgor in
accordance with its terms, except as limited by equitable principles,
bankruptcy, insolvency, or other laws of general application relating to the
enforcement of creditor's rights.

     5. Covenants.

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     (a) The Pledgor covenants and agrees that, unless the prior written consent
of the Pledgee to the contrary is obtained, from and after the date hereof until
the payment and performance in full of all obligations of the Pledgor under the
Notes, Pledgor shall defend the title to the Pledged Securities and the lien of
Pledgee thereon against the claim of any third party claiming against or through
the Pledgor and shall maintain and preserve such lien so long as this Agreement
shall remain in effect.

     (b) The Pledgor further covenants and agrees that (i) First Union may
deliver the Pledged Shares to Pledgee without the requirement of any further
consent or writing on the part of Pledgor and (ii) Pledgor shall, concurrently
herewith, cause First Union to execute and deliver to Pledgee an Acknowledgment
and Consent or such similar instrument in order for Pledgee to protect its
interest in the Pledged Securities.

     (c) The Pledgor further acknowledges that Pledgee, through its extension of
the 2002 Loan, has purchased from First Union Securities the lien on the Account
held by First Union Securities and Pledgor shall therefore be entitled to all
rights as a holder of such lien that previously accrued to First Union
Securities.

     6. Defaults and Remedies.

     (a) Upon the occurrence of an Event of Default as herein defined, the
Pledgee is hereby authorized and empowered and shall have the right, at its
election, to transfer and register in its name the whole or any part of the
Pledged Securities, to exercise all voting rights with respect thereto, to
collect and receive all cash dividends and other distributions made thereon, to
sell in one or more sales after five (5) business days' notice (which notice the
Pledgor agrees is commercially reasonable) but without any previous notice or
advertisement, the whole or any

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part of the Pledged Securities and otherwise to act with respect to the Pledged
Securities as though the Pledgee were the outright owner thereof, the Pledgor
hereby irrevocably constituting the Pledgee in such regard as his proxy and
attorney-in-fact, with full power of substitution to do so; provided, however,
that the Pledgee shall not have any duty to exercise any such right or to
preserve the same and shall not be liable for any failure to do so or for any
delay in doing so. Any sale shall be made at a public or private sale at the
Pledgee's place of business, or at any public building in the State of New York
to be named in the notice of sale, either for cash or upon credit or for future
delivery at such price as the Pledgee may deem fair, and the Pledgee may be the
purchaser of the whole or any part of the Pledged Securities so sold and hold
the same thereafter in its own right free from any claim of the Pledgor or any
right of redemption, which right is hereby expressly waived. Each sale shall be
made to the highest bidder, but the Pledgee reserves the right to reject any and
all bids at such sale which, in its sole discretion, it shall deem inadequate.
Demands of performance, except as otherwise herein specifically provided for,
notices of sale, advertisements and the presence of property at sale are hereby
waived and any sale hereunder may be conducted by an auctioneer or any officer
or agent of the Pledgee.

     (b) If, at the original time or times appointed for the sale of the whole
or any part of the Pledged Securities, the highest bid, if there be but one bid,
shall be inadequate to discharge in full all of the obligations of the Pledgor
under the Notes, or if the Pledged Securities be offered for sale in lots, if at
any of such sales, the highest bid for the lot offered for sale would indicate
to the Pledgee, in its sole discretion, the unlikelihood of the proceeds of the
sales of the whole of the Pledged Securities being sufficient to discharge all
of such obligations, the Pledgee may, on one or more occasions, postpone any of
said sales by public announcement at the time of such

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sale. In the event of any such postponement, the Pledgee shall give the Pledgor
notice of such postponement or postponements of sale.

     (c) In the event of any sale(s) under this Section 6, the Pledgee shall,
after deducting all costs or expenses of every kind (including attorneys fees
and disbursements) for care, safekeeping, collection, sale, delivery or
otherwise, apply the residue of the proceeds of the sale(s) to the payment or
reduction, either in whole or in part, of the obligations of the Pledgor under
the Notes, whether or not then due, returning the surplus (including any Pledged
Securities not sold by the Pledgee), if any, to the Pledgor.

     (d) In view of the fact that federal and state securities laws may impose
certain restrictions on the method by which a sale of the Pledged Securities may
be affected, the Pledgor recognizes that the Pledgee may be unable to effect a
public sale of all or part of the Pledged Securities, and may be compelled to
resort to one or more private sales to a restricted group of purchasers who will
be obligated to agree, among other things, to acquire such securities for their
own account, for investment and not with a view to the distribution or resale
thereof. The Pledgor acknowledges that any such private sales may be at places
and on terms less favorable to the Pledgee than if sold at public sales. The
Pledgor agrees that any such private sales shall not be deemed to have been made
in other than a commercially reasonable manner because such Pledged Securities
shall not have been registered and that the Pledgee has no obligation to delay
sale of any such securities for the period of time necessary to permit the
issuer of such securities to register such securities for public sale.

     (e) The Pledgor agrees that he will not at any time plead, claim or take
the benefit of any appraisal, valuation, stay, extension, moratorium or
redemption law now or hereafter in force in order to prevent or delay the
enforcement of this Agreement, or the absolute sale of the

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whole or any part of the Pledged Securities or the possession thereof by any
purchaser at any sale hereunder, and the Pledgor waives the benefit of all such
laws to the extent he lawfully may do so. The Pledgor agrees that he will not
interfere with any right, power or remedy of the Pledgee provided for in this
Agreement or now or hereafter existing at law or in equity or by statute or
otherwise, or the exercise or beginning of the exercise by the Pledgee of any
one or more of such rights, powers or remedies. No failure or delay on the part
of the Pledgee to exercise any such right, power or remedy, and no notice or
demand which may be given to or made upon the Pledgor by the Pledgee with
respect to any such remedies shall operate as a waiver thereof, or limit or
impair the Pledgee's right to take any action or to exercise any power or remedy
hereunder without notice or demand, or prejudice its rights as against the
Pledgor in any respect.

     (f) Each and every right granted to the Pledgee hereunder or under any
other document delivered hereunder or in connection herewith, or allowed it by
law or equity, shall be cumulative and may be exercised from time to time.

     (g) In addition to all other rights and remedies granted to the Pledgee
hereunder, the Pledgee shall have all the rights granted to creditors generally
under the Uniform Commercial Code as in effect in the State of New York.

     (h) For purposes herein, Event of Default shall be defined to mean the
occurrence of any of the following:

          (i) an Event of Default under the Notes; and

          (ii) the failure to comply by Pledgor with any term or provision of
     this Agreement which failure to comply has not been cured by the Pledgor
     within five (5) days of such failure to comply or breach.

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     7. Waiver. No failure or delay on the Pledgee's part in exercising any
power of sale, lien, option or other right hereunder, and no notice or demand
which may be given to or made upon the Pledgor by the Pledgee with respect to
any power of sale, lien, option or other right hereunder, shall constitute a
waiver thereof, or limit or impair the Pledgee's right to take any action or to
exercise any power of sale, lien, option or any other right hereunder, without
notice or demand, or prejudice the Pledgee's rights as against the Pledgor in
any respect, nor shall any single or partial exercise of any right preclude any
other or future exercise thereof or the exercise of any other right.

     8. Termination. Upon the payment and performance in full of all of the
obligations of the Pledgor under the Notes, the Pledgee shall deliver to the
Pledgor the Pledged Securities which are subject to this Agreement at such time
and all instruments of assignment executed in connection therewith, free and
clear of the lien hereof and, except as otherwise provided herein, all of the
Pledgor's obligations hereunder shall, upon such payment and performance,
terminate.

     9. Renewal or Extensions: No renewal or extension of the Notes, and no
delay in the enforcement or exercise of the rights granted the Pledgee under
this Agreement shall constitute a waiver or affect the rights of the Pledgee
with respect to the shares of stock or any part of such stock.

     10. Additional Documents: Pledgor stipulates that he will execute and
deliver to Pledgee any and all additional documents that may be necessary to
perfect the security interest given to the Pledgee under this Agreement. These
documents, include, but are not limited to, stock and/or option certificates
representing the Pledged Securities, Rule 144 paperwork, attorney opinion
letters, signed and medallion guaranteed stock powers, duly executed waivers of

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any applicable lockup agreements, etc., signed by the Pledgor.

     11. Miscellaneous.

     (a) No Waiver. Neither the failure by Pledgee to, nor the delay on the part
of Pledgee in, the exercise of any power or right granted to it hereunder, or
with respect to any agreement or instrument executed and delivered pursuant to
this Agreement, shall constitute a waiver of such power or right or prevent
Pledgee's exercise or partial exercise of any other right, power or privilege,
it being understood that the rights and remedies of Pledgee under and in respect
of this Agreement and the other documents referred to herein are cumulative and
shall be in addition to any and all other rights and remedies now or hereafter
existing in law or in equity. No modification or waiver of any provision of this
Agreement nor consent to any departure herefrom by any party shall, in any
event, be effective unless such waiver or modification shall be in writing
signed by the party against whom enforcement of the waiver or modification is
sought and then shall be effective only for the period and on the conditions,
and for the specific instance and purpose, for which given. No notice to or
demand on Pledgor in any case shall entitle Pledgor to any other or further
notice or demand in similar or other circumstances. This Agreement may not be
changed or terminated orally.

     (b) Entire Agreement. This Agreement, together with the other documents
executed and delivered in connection herewith, contains the sole and entire
understanding and agreement of Pledgor and Pledgee with respect to the subject
matter hereof and all prior negotiations, discussions, commitments,
representations, agreements and understandings heretofore between Pledgor and
Pledgee with respect thereto are merged herein.

     (c) Amendment or Modification: This Agreement may not be amended or
modified except in writing, executed and signed by the parties.

     (d) Successors and Assigns. This Agreement shall be binding on and shall
inure to

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the benefit of the parties hereto and their respective permitted successors and
assigns. Pledgor may not assign this Agreement without Pledgee's written
consent, and any such attempted assignment without such consent shall be null
and void.

     (e) Binding Effect: This Agreement shall be binding on the parties and
their representatives, heirs, successors, and assigns.

     (f) Notices. All notices, requests, demands, consents or other
communications provided for herein shall be in writing and shall be deemed to
have been given or made when received or three days following deposit for
mailing by first-class registered or certified mail, return receipt requested,
to the address of the other party set forth below or to such other address as
may be specified by notice given in accordance with this Section 11:

         If to Pledgor, to:                 John T. Botti
                                            Authentidate Holding Corp.
                                            2165 Technology Drive
                                            Schenectady, NY 12308

         If to Pledgee, to:                 Authentidate Holding Corp.
                                            2165 Technology Drive
                                            Schenectady, NY 12308
                                            Attention: Dennis H. Bunt

     (g) APPLICABLE LAW: SERVICE OF PROCESS; APPOINTMENT OF PROCESS AGENT. THIS
AGREEMENT SHALL BE DEEMED TO BE MADE AND TO BE GOVERNED AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO THE
PROVISIONS OF CHOICE OF LAW THEREUNDER. PLEDGOR HEREBY IRREVOCABLY CONSENTS TO
THE NON-EXCLUSIVE JURISDICTION OF THE COURTS OF THE STATE OF NEW YORK OR OF ANY
FEDERAL COURT LOCATED WITHIN SCHENECTADY COUNTY, NEW YORK IN CONNECTION WITH ANY
ACTION OR PROCEEDING ARISING OUT OF OR RELATING TO THIS AGREEMENT. PLEDGOR
HEREBY EXPRESSLY AND IRREVOCABLY

                                       11
<PAGE>
WAIVES ANY CLAIM OR DEFENSE IN ANY SUCH ACTION OR PROCEEDING BASED ON ANY
ALLEGED LACK OF PERSONAL JURISDICTION, IMPROPER VENUE OR FORUM NON-CONVENIENS OR
ANY SIMILAR BASIS. PLEDGOR SHALL NOT BE ENTITLED IN ANY SUCH ACTION OR
PROCEEDING TO ASSERT ANY DEFENSE GIVEN OR ALLOWED UNDER THE LAWS OF ANY STATE
OTHER THAN THE STATE OF NEW YORK. NOTHING IN THIS SECTION SHALL AFFECT OR IMPAIR
IN ANY MANNER OR TO ANY EXTENT THE RIGHT OF PLEDGEE TO COMMENCE LEGAL
PROCEEDINGS OR OTHERWISE PROCEED AGAINST PLEDGOR IN ANY JURISDICTION OR TO SERVE
PROCESS IN ANY MANNER PERMITTED BY LAW.

     (h) Waiver of Jury Trial. To the fullest extent permitted by law, Pledgor
hereby waives trial by jury in any litigation in any court with respect to, in
connection with, or arising out of this Agreement, or any instrument, document
or guaranty delivered pursuant to this Agreement, or the validity, protection,
interpretation, collection or enforcement hereof, or any other claim or dispute
hereunder.

     (i) Partial Invalidity. If any provision of this Agreement is held to be
invalid or unenforceable, such invalidity or unenforceability shall not
invalidate this Agreement as a whole but this Agreement shall be construed and
enforced only to such extent as shall be permitted by law.

     (j) Captions. The captions of the various sections of this Agreement have
been inserted only for the purposes of convenience; such captions are not a part
of this Agreement and shall not be deemed, in any manner, to modify, explain,
enlarge or restrict any of the provisions of this Agreement.

     (k) Counterparts. This Agreement may be executed in two counterparts, each
of which shall be deemed an original and both of which shall constitute a single
instrument.

                                       12
<PAGE>
     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed as of the date first above written.

                           PLEDGOR:
                                       -------------------------------------
                                       John T. Botti

                           PLEDGEE:    AUTHENTIDATE HOLDING CORP.

                                       By:
                                       ------------------------------------
                                       Dennis H. Bunt,
                                       Chief Financial Officer

                                       13

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