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                                                                     EXHIBIT 4.8

THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF
1933, AS AMENDED ("SECURITIES ACT"), OR ANY STATE SECURITIES LAWS AND HAS BEEN
OFFERED AND SOLD ONLY TO PERSONS OUTSIDE THE UNITED STATES PURSUANT TO AN
EXEMPTION FROM REGISTRATION PROVIDED BY REGULATION S OF THE SECURITIES ACT. THE
HOLDER OF THIS WARRANT, DURING THE PERIOD OF TIME COMMENCING ON ____________ AND
EXPIRING ONE YEAR FROM SUCH DATE, MAY NEITHER OFFER, SELL, DELIVER, TRANSFER NOR
EXERCISE THIS WARRANT, DIRECTLY OR INDIRECTLY, IN THE UNITED STATES OR TO ANY
U.S. PERSON, OR ON BEHALF OF ANY U.S. PERSON (AS SUCH TERMS ARE DEFINED IN
REGULATION S), UNLESS SUCH ACTION IS PURSUANT TO (A) A REGISTRATION STATEMENT
WHICH HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT, (B) OFFERS AND SALES
TO NON-U.S. PERSONS THAT OCCUR OUTSIDE THE UNITED SATES, WITHIN THE MEANING OF
REGULATION S, IN A TRANSACTION MEETING THE REQUIREMENTS OF RULE 904 OF THE
SECURITIES ACT, OR (C) ANOTHER AVAILABLE EXEMPTION FROM THE REGISTRATION
REQUIREMENTS OF THE SECURITIES ACT, AND IN EACH CASE ONLY UPON THE DELIVERY OF
THE COMPANY OF SUCH OPINION OF COUNSEL, CERTIFICATES, AND/OR OTHER INFORMATION
REASONABLY REQUIRED BY THE COMPANY TO PROVE COMPLIANCE WITH THIS PARAGRAPH. THE
HOLDER OF THIS WARRANT FURTHER AGREES NOT TO ENGAGE IN HEDGING TRANSACTIONS
INVOLVING THESE SECURITIES, UNLESS IN COMPLIANCE WITH THE SECURITIES ACT.

WARRANT NO. AHC-G1            Warrant to Purchase _______ Shares of Common Stock

                        WARRANT TO PURCHASE COMMON STOCK
                                       OF
                           AUTHENTIDATE HOLDING CORP.

                           VOID AFTER _________, 2006

      This certifies that ______________________, for value received, is
entitled to purchase from Authentidate Holding Corp., a Delaware corporation
(the "Company"), having a place of business at 2165 Technology Drive,
Schenectady, New York 12308, _______ shares of Common Stock of the Company at
the Stock Purchase Price set forth in Section 1. The term "Common Stock" means
the common stock of the Company.

      This Warrant is subject to the following terms and conditions:

1. Determination of Stock Purchase Price. The exercise price per share of this
Warrant is $4.845 per share of Common Stock (the "Stock Purchase Price").
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2. Exercise; Issuance of Certificates; Payment for Shares. This Warrant shall be
exercisable at the option of the Holder, at any time or from time to time,
commencing on the earlier of one year from the Closing Date or on the effective
date of a registration statement covering the issuance and resale of the shares
of Common Stock issuable upon the exercise of this Warrant, before 5:00 p.m.
Eastern Standard Time on _____, 2006 (the "Expiration Date") upon surrender to
the Company, at its principal office or such other place as Company may
designate, of this Warrant, together with the Purchase Form (attached hereto)
fully completed and signed and accompanied by an opinion of counsel or other
information described in the Purchase Form, and payment in full, of the Stock
Purchase Price, by cashier's check or wire transfer. The Company agrees that the
shares of Common Stock purchased under this Warrant shall be and are deemed to
be issued to the Holder as the record owner of such shares as of the close of
business on the date on which this Warrant shall have been surrendered, together
with the completed, executed Purchase Form, opinion of counsel or other
information and payment in full. Certificates for the shares of Common Stock so
purchased, together with any other securities or property to which the Holder is
entitled upon such exercise, shall be delivered to the Holder by the Company at
the Company's expense within a reasonable time after the rights represented by
this Warrant have been so exercised. In case of a purchase of less than all the
shares which may be purchased under this Warrant, the Company shall cancel this
Warrant and execute and deliver to the Holder a new Warrant or Warrants of like
tenor for the balance of the shares purchasable under this Warrant within a
reasonable time.

3. Reservation of Shares. The Company covenants and agrees that all shares of
Common Stock which may be issued upon the exercise of the rights represented by
this Warrant will, upon issuance, be free of all taxes, liens and charges with
respect to the issuance thereof (other than income taxes and taxes in respect of
any transfer by Holder). The Company further covenants and agrees that during
the period within which the rights represented by this Warrant may be exercised,
the Company will at all times have authorized and reserved a sufficient number
of shares of authorized but unissued Common Stock, or other appropriate
securities and property, when and as required to provide for the exercise of the
rights represented by this Warrant.

4. Adjustment of Stock Purchase Price and Number of Shares. The Stock Purchase
Price and the number of shares purchasable upon the exercise of this Warrant
shall be subject to adjustment from time to time upon the occurrence of the
events described in this Section 5.

      4.1 Subdivision or Combination of Stock. If the Company at any time while
this Warrant or any portion of it remains outstanding and unexpired shall
subdivide its outstanding shares of Common Stock into a greater number of
shares, the Stock Purchase Price in effect immediately prior to such subdivision
shall be proportionately reduced, and conversely, in case the outstanding shares
of Common Stock of the Company shall be combined into a smaller number of
shares, the Stock Purchase Price in effect immediately prior to such combination
shall be proportionately increased.

      4.2 Notice of Adjustment. Upon any determination or adjustment of the
Stock Purchase Price or in the conversion ratio of the Common Stock or any
increase or decrease in the number of shares purchasable upon the exercise of
this Warrant, the Company shall give written notice thereof to the registered
Holder of this Warrant as provided in Section 10. The notice shall be signed by
the Company's chief financial officer and shall state the Stock Purchase Price
resulting from such adjustment and the increase or decrease, if any, in the
number of shares purchasable at such price

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upon the exercise of this Warrant, setting forth in reasonable detail the method
of calculation and the facts upon which such calculation is based.

      4.3 Other Notices. If at any time:

            (A) the Company shall declare any cash dividend upon its Common
Stock;

            (B) the Company shall declare any dividend upon its Common Stock
payable in stock or make any special dividend or other distribution to the
holders of its Common Stock;

            (C) the Company shall offer for subscription pro rata to the holders
of its Common Stock any additional shares of stock of any class or other rights;

            (D) there shall be any capital reorganization or reclassification of
the capital stock of the Company; or consolidation or merger of the Company
with, or sale of all or substantially all of its assets to another corporation

then, in any one or more of said cases, the Company shall give to the registered
Holder of this Warrant at least 15 days prior written notice of the date on
which the books of the Company shall close or a record shall be taken for such
dividend, distribution or subscription rights or for determining rights to vote
in respect of any such reorganization, reclassification, consolidation, merger
or sale, so that the Holder may make a best efforts attempt to respond to such
notice by exercising his Warrant for Common Stock entitling him to the rights of
a holder of Common Stock.

5. Representations of Holder. The holder is not a U.S. person and the Warrant is
not being exercised on behalf of a U.S. person. The holder has obtained and
given to the Company an opinion of counsel or other information reasonably
required by the Company to prove that the delivery of the Warrant has been
registered under the Securities Act or is exempt from registration.

6. Restriction on Transfer of Warrant and Shares Issuable upon Exercise.

      This Warrant and the Warrant Shares have not been registered under the
United States Securities Act of 1933, as amended (the "Securities Act"), or any
state securities laws and have been offered and sold only to persons outside the
United States pursuant to an exemption from registration provided by Regulation
S of the Securities Act. The holder of this certificate, during the period of
time commencing on the date certified by Banca del Gottardo that the
distribution of the Warrants is complete and expiring one year from such date,
may not offer, sell, deliver or transfer, directly or indirectly, in the United
States or to, or exercised by or on behalf of, any U.S. Person (as such terms
are defined in Regulation S under the Securities Act) unless such action is (A)
pursuant to a registration statement which has been declared effective under the
Securities Act, (B) pursuant to offers and sales to non-U.S. persons that occur
outside the United States within the meaning of Regulation S under the
Securities Act in a transaction meeting the requirements of Rule 904 under the
Securities Act, or (C) pursuant to another available exemption from the
registration requirements of the Securities Act, and in each case only upon
delivery of the company of such opinion of counsel, certificates, and/or other
information reasonably required by the company to prove compliance with this
paragraph. The holder of this security further agrees not to engage in any
hedging transactions

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involving these securities, unless such transactions meet the requirements of
and are in compliance with the Securities Act.

      6.1. Legend Requirement. The shares of common stock issuable upon exercise
of this Warrant shall bear a legend substantially similar to the following:

            The shares represented by this certificate have not been registered
            under the United States Securities Act of 1933, as amended (the
            "Securities Act"), or any state securities laws and have been
            offered and sold only to persons outside the United States pursuant
            to an exemption from registration provided by Regulation S of the
            Securities Act. The holder of this certificate, during the period of
            time commencing on _______, 2001 and expiring one year from such
            date, may not offer, sell, deliver or transfer, directly or
            indirectly, in the United States or to, or exercised by or on behalf
            of, any U.S. Person (as such terms are defined in Regulation S under
            the Securities Act) unless such action is (A) pursuant to a
            registration statement which has been declared effective under the
            Securities Act, (B) pursuant to offers and sales to non-U.S. persons
            that occur outside the United States within the meaning of
            Regulation S under the Securities Act in a transaction meeting the
            requirements of Rule 904 under the Securities Act, or (C) pursuant
            to another available exemption from the registration requirements of
            the Securities Act, and in each case only upon delivery of the
            company of such opinion of counsel, certificates, and/or other
            information reasonably required by the company to prove compliance
            with this paragraph. The holder of this security further agrees not
            to engage in any hedging transactions involving these securities,
            unless such transactions meet the requirements of and are in
            compliance with the Securities Act.

7. No Voting or Dividend Rights; Limitation of Liability. Nothing contained in
this Warrant shall be construed as conferring upon the Holder the right to vote
or to consent or to receive notice as a shareholder of the Company on any other
matters or any rights whatsoever as a shareholder of the Company. No dividends
or interest shall be payable or accrued in respect of this Warrant or the
interest represented hereby or the shares purchasable hereunder until, and only
to the extent that, this Warrant shall have been exercised. No provisions
hereof, in the absence of affirmative action by the Holder to purchase shares of
Common Stock, and no mere enumeration herein of the rights or privileges of the
Holder hereof, shall give rise to any liability of such Holder for the Stock
Purchase Price or as a shareholder of the Company, whether such liability is
asserted by the Company or by its creditors.

8. Modification and Waiver. This Warrant and any provision hereof may be
changed, waived, discharged or terminated only by an instrument in writing
signed by the party against which enforcement of the same is sought.

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9. Notices. All notices, demands and requests required or permitted by this
Agreement shall be in writing and, except as otherwise provided herein, shall be
deemed to have been given for all purposes (i) upon personal delivery, (ii) four
days after being sent, when sent by professional overnight courier service from
one country to another, (iii) eight days after having posting when sent by
international air mail, with postage prepaid, or (iv) on the date of
transmission when sent by confirmed facsimile; if directed to the person or
entity to which notice is to be given at his or its address set forth in this
Section or at any other address such person or entity has designated by notice.

10. Binding Effect on Successors. This Warrant shall be binding upon any
corporation succeeding the Company by merger, consolidation or acquisition of
all or substantially all of the Company's assets. All of the covenants and
agreements of the Company shall inure to the benefit of any successor or assign
of the Holder which holds or has warrants to purchase at least 1,000 shares of
Common Stock.

11. No Recourse. No recourse shall be had for any claim based hereon or
otherwise in any manner in respect hereof, against any incorporator,
stockholder, officer or director, past, present or future, of the Company or of
any predecessor corporation, whether by virtue of any constitutional provision
or statute or rule of law, or by the enforcement of any assessment or penalty or
in any other manner, all such liability being expressly waived and released by
the acceptance hereof and as part of the consideration for the issue hereof.

12. No Waiver. No course of dealing between the Company and the Holder hereof
shall operate as a waiver of any right of any Holder hereof, and no delay on the
part of the Holder in exercising any right hereunder shall so operate.

13. Descriptive Headings and Governing Law. The description headings of the
several sections and paragraphs of this Warrant are inserted for convenience
only and do not constitute a part of this Warrant. The provisions of this
Warrant shall in all respects be constructed according to, and the rights and
liabilities of the parties hereto shall in all respects be governed by, the laws
of the State of New York. This Warrant shall be deemed a contract made under the
laws of the State of New York and the validity of this Warrant and all rights
and liabilities hereunder shall be determined under the laws of said State.

14. Lost Warrants. The Company represents and warrants to the Holder that upon
receipt of evidence satisfactory to the Company of the loss, theft, destruction,
or mutilation of this Warrant and, in the case of any such loss, theft or
destruction, upon receipt of an indemnity reasonably satisfactory to the
Company, or in the case of any such mutilation upon surrender and cancellation
of such Warrant, the Company, at its expense, will make and deliver a new
Warrant, of like tenor, in lieu of the lost/stolen, destroyed or mutilated
Warrant.

15. Fractional Shares. No fractional shares shall be issued upon exercise of
this Warrant. The Company shall, in lieu of issuing any fractional share, pay to
the Holder entitled to such fraction a sum in cash equal to such fraction
multiplied by the then effective Stock Purchase Price.

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      IN WITNESS WHEREOF, the Company has caused this Warrant to be duly
executed, as of the __ day of __________, 2001.

HOLDER:                                   AUTHENTIDATE HOLDING CORP.

By:_________________________              By: _______________________________
Name:                                           John Botti, President
Title:

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                                  PURCHASE FORM

To Be Executed
Upon Exercise of Warrant

      The undersigned hereby exercises the right to purchase _____ shares of
Common Stock evidence by the attached Warrant, according to the terms and
conditions thereof, and herewith makes payment of the purchase price in full.
The undersigned requests that certificate(s) for such shares shall be issued in
the name set forth below.

      The undersigned is not a U.S. person and the Warrant is not being
exercised on behalf of a U.S. person.

      The undersigned has obtained and given to the Company an opinion of
counsel or other information reasonably required by the Company to prove that
the delivery of the Common Stock have been registered under the Securities Act
or is exempt from registration.

      The undersigned acknowledges the resale and transfer of the Common Stock
issued pursuant to the exercise of this Warrant must comply with Regulations S
or another exemption from registration under the Securities Act of 1933.

DATED:                                    [NAME OF HOLDER]

                                          By______________________________
                                                (Signature)

                                          Name: __________________________
                                                (Please print)

                                          Address:
                                                __________________________

                                                __________________________

                                                __________________________

                                          Employer Identification No., Social
                                          Security No. or other identifying
                                          number:

                                          ________________________________

                                       7<PAGE>   1
                                                                     Exhibit 4.9

              INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE

NUMBER                                                          SHARES
 C 0
                                                    SEE REVERSE SIDE FOR CERTAIN
                                                    CONDITIONS AND RESTRICTIONS

                           AUTHENTIDATE HOLDING CORP.

               9,000 SHARES SERIES C CONVERTIBLE PREFERRED STOCK
                                 PAR VALUE $.10
                   SEE REVERSE SIDE FOR CERTAIN RESTRICTIONS.

 THE CORPORATION WILL FURNISH WITHOUT CHARGE TO ANY SHAREHOLDER WHO SO REQUESTS
 THE POWERS, DESIGNATIONS, PREFERENCES AND RELATIVE, PARTICIPATING, OPTIONAL OR
     OTHER SPECIAL RIGHTS OF EACH CLASS OF STOCK OR SERIES THEREOF AND THE
 QUALIFICATIONS, LIMITATIONS OR RESTRICTIONS OF SUCH PREFERENCES AND/OR RIGHTS.

This is to Certify that ________________________________________ is the owner of

________________________________________________________________________________

                   FULLY PAID AND NON-ASSESSABLE SHARES OF THE
                    SERIES C CONVERTIBLE PREFERRED STOCK OF

                           AUTHENTIDATE HOLDING CORP.

transferable on the books of the Corporation by the holder hereof in person or
by duly authorized Attorney, upon surrender of this Certificate, properly
endorsed.

Witness, the seal of the Corporation and the signatures of its duly authorized
officers.

Dated:

_________________________                                _______________________
  SECRETARY/TREASURER                                            PRESIDENT
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     The following abbreviations, when used in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

<Table>
<S>       <C>                                <S>                 <C>
TEN COM   --as tenants in common             UNIF GIFT MIN ACT              Custodian
TEN ENT   --as tenants by the entireties                         -----------------------------
JT TEN    --as joint tenants with right of
            survivorship and not as tenants                       (Cust)              (Minor)
            in common                                            under Uniform Gifts to Minors
                                                                 Act
                                                                     -------------------------
                                                                               (State)
</Table>

    Additional abbreviations may also be used though not in the above list.

               CONVERSION INSTRUCTIONS

               To: Authentidate Holding Corp.
                   Office of President
                   2165 Technology Drive
   FOR             Schenectady, New York 12308

CONVERSION          The undersigned hereby irrevocably exercises the right to
               convert             shares of the Series C Convertible Preferred
   USE         Stock, represented by this Certificate into            shares of
               Common Stock of the Corporation in accordance with the provisions
  ONLY         of the Certificate of Incorporation of the Corporation
               Dated:
                                                  Signature
                                                           ---------------------

PLEASE INSERT SOCIAL SECURITY
OR OTHER IDENTIFYING NUMBER
                                   NOTICE:  The signature in these instructions
                                            must correspond with the name as
                                            written upon the face of the
                                            Certificate in every particular,
                                            without alteration or enlargement or
                                            any change whatever.

For Value Received,               hereby sell, assign and transfer unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
   IDENTIFYING NUMBER OF ASSIGNEE
/                                    /
/                                    /

-------------------------------------------------------------------------------
            (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS OF ASSIGNEE)

-------------------------------------------------------------------------------
                                                                         Shares
-----------------------------------------------------------------------
of the stock represented by the within Certificate, and do hereby irrevocably
constitute and appoint
                                                                       Attorney
-----------------------------------------------------------------------
to transfer the said stock on the books of the within named Corporation with
full power of substitution in the premises.

Dated
     ---------------------

                    -----------------------------------------------------------
                    THE SIGNATURE TO THE ASSIGNMENT MUST CORRESPOND WITH THE
          NOTICE:   NAME AS WRITTEN UPON THE FACE OF THE CERTIFICATE IN EVERY
                    PARTICULAR, WITHOUT ALTERATION OR ENLARGEMENT, OR ANY
                    CHANGE WHATEVER.

Signature(s) Guaranteed

By
  ----------------------
  THE SIGNATURES SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR
  INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND
  CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE
  MEDALLION PROGRAM) PURSUANT TO S.E.C. RULE 17A6-14.

The Shares represented by this certificate and the common stock issuable upon
conversion of this certificate have not been registered under the United States
Securities Act of 1933, as amended (the "Securities Act"), or any state
securities laws and have been offered and sold only to persons outside the
United States pursuant to an exemption from registration provided by Regulation
S of the Securities Act. The holder of this certificate (and the common stock
issuable upon conversion), during the period of time commencing on          ,
2001 and expiring one year from such date, may not offer, sell, deliver or
transfer such shares, directly or indirectly, in the United States or to, or
for the benefit of, any U.S. Person (as such terms are defined in Regulation S
under the Securities Act) unless such action is (A) pursuant to a registration
statement which has been declared effective under the Securities Act, (B)
pursuant to offers and sales to non-U.S. persons that occur outside the United
States within the meaning of Regulation S under the Securities Act in a
transaction meeting the requirements of Rule 904 under the Securities Act, or
(C) pursuant to another available exemption from the registration requirements
of Securities Act, and in each case only upon delivery of the company of such
opinion of counsel, certificates, and/or other information reasonably required
by the company to prove compliance with this paragraph. The holder of this
security further agrees not to engage in any hedging transactions involving
these securities, unless such transactions meet the requirements of and are in
compliance with the Securities Act.

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