<PAGE>   1
                                                                  EXHIBIT 10.12

                              STANDARD SUBLEASE

                 American Industrial Real Estate Association

                                    [AIR LOGO]

1.  PARTIES.  This Sublease, dated, for reference purposes only, March 27,
1996, is made by and between Sega of America, Inc. (herein called
"Sublessor") and Cybercash, Inc. (herein called "Sublessee").

2.  PREMISES.  Sublessor hereby subleases to Sublessee and Sublessee hereby
subleases from Sublessor for the term, at the rental, and upon all of the
conditions set forth herein, that certain real property situated in the County
of San Mateo, State of California, commonly known as 303 Twin Dolphin Drive,
Suite 200, Redwood City, CA and described as approximately 22,414 Rentable
square feet.

Said real property, including the land and all improvements thereon, is
hereinafter called the "Premises".

3.  TERM.

    3.1  TERM. The term of this Sublease shall be for 24.5 months commencing on
May 1, 1996 and ending on May 14, 1998 unless sooner terminated pursuant to
any provision hereof.

    3.2  DELAY IN COMMENCEMENT.  Notwithstanding said commencement date, if for
any reason Sublessor cannot deliver possession of the Premises to Sublessee on
said date, Sublessor shall not be subject to any liability therefore nor shall
such failure affect the validity of this Lease or the obligations of Sublessee
hereunder or extend the term hereof, but in such case Sublessee shall not be
obligated to pay rent until possession of the Premises is tendered to
Sublessee, provided, however, that if Sublessor shall not have delivered
possession of the Premises within sixty (60) days from said commencement date,
Sublessee may, at Sublessee's option, by notice in writing to Sublessor within
ten (10) days thereafter, cancel this Sublease, in which event the parties
shall be discharged from all obligations thereunder.  If Sublessee occupies the
Premises prior to said commencement date, such occupancy shall be subject to
all provisions hereof, such occupancy shall not advance the termination date
and Sublessee shall pay rent for such period at the initial monthly rates set
forth below.

4.  RENT.  Sublessee shall pay to Sublessor as rent for the Premises equal
monthly payments of $52,672.90 in advance on the 1st day of each month of the
term hereof.  Sublessee shall pay Sublessor upon the execution hereof
$52,672.90 as rent for the first month.

Rent for any period during the term hereof which is for less than one month
shall be a prorata portion of the monthly installment.  Rent shall be payable
in lawful money of the United States to Sublessor at the address stated herein
or to such other persons or at such other places as Sublessor may designate in
writing.

5.  SECURITY DEPOSIT.  Sublessee shall deposit with Sublessor upon execution
hereof $52,672.90 as security for Sublessee's faithful performance of
Sublessee's obligations hereunder.  If Sublessee fails to pay rent or other
charges due hereunder or otherwise defaults with respect to any provision of
this Sublease, Sublessor may use, apply or retain all or any portion or said
deposit for the payment of any rent or other charge in default or for the
payment of any other sum to which Sublessor may become obligated by reason of
Sublessee's default or to compensate Sublessor for any loss or damage which
Sublessor may suffer thereby.  If Sublessor so uses or applies all or any
portion of said deposit, Sublessee shall within ten (10) days after written
demand therefore deposit cash with Sublessor in an amount sufficient to restore
said deposit to the full amount hereinabove stated and Sublessee's failure to
do so shall be a material breach of this Sublease.  Sublessor shall not be
required to keep said deposit separate from its general accounts.  If
Sublessee performs all of Sublessee's obligations hereunder, said deposit, or
so much thereof as has not theretofore been applied by Sublessor, shall be
returned, without payment of interest or other increment for its use to
Sublessee (or at Sublessor's option, to the last assignee, if any, of
Sublessee's interest hereunder) at the expiration of the term hereof, and after
Sublessee has vacated the Premises.  No trust relationship is created herein
between Sublessor and Sublessee with respect to said Security Deposit.

6.  USE.

    6.1  USE.  The Premises shall be used and occupied only for Software
development, storage, distribution, office, marketing and other related legal
uses, and for no other purpose.

    6.2  COMPLIANCE WITH LAW.

         (a)  Sublessor warrants to Sublessee that the Premises in its
existing state, but without regard to the use for which Sublessee will use the
Premises does not violate any applicable building code regulation or ordinance
at the time that this Sublease is executed.  In the event that it is determined
that this warranty has been violated, that it shall be the obligation of the
Sublessor, after written notice from Sublessee, to promptly, at Sublessor's
sole cost and expense, rectify any such violation in the event that Sublessee
does not give to Sublessor written notice of the violation of this warranty
within 1 year from the commencement of the term of this Sublease, it shall be
conclusively deemed that such violation did not exist and the correction of the
same shall be the obligation of the Sublessee.

         (b)  Except as provided in paragraph 6.2(a), Sublessee shall, at
Sublessee's expense, comply promptly with all applicable statutes, ordinances,
rules, regulations, orders, restrictions of record, and requirements in effect
during the term or any part of the term hereof regulating the use by Sublessee
of the Premises.  Sublessee shall not use or permit the use of the Premises in
any manner that will tend to created waste or a nuisance or if there shall be
more than one tenant of the building containing the Premises, which shall tend
to disturb such other tenants.

    6.3  CONDITION OF PREMISES.  Except as provided in paragraph 6.2(a)
Sublessee hereby accepts the Premises in their condition existing as of the
date of the execution hereof subject to all applicable zoning, municipal,
county and state laws, ordinances and regulations governing and regulating the
use of the Premises and accepts this Sublease subject thereto and to all matters
disclosed thereby and by any exhibits attached hereto.  Sublessee acknowledges
that neither Sublessor nor Sublessor's agents have made any representation or
warranty as to the suitability of the Premises for the conduct of Sublessee's
business.

7.  MASTER LEASE.

    7.1  Sublessor is the lessee of the Premises by virtue of a lease,
hereinafter referred to as the "Master Lease", a copy of which is attached
hereto marked Exhibit 1, dated April 23, 1993, wherein Provident Central Credit
Union, a California cooperative financial institution is the lessor,
hereinafter referred to as the "Master Lessor".

    7.2  This Sublease is and shall be at all times subject and subordinate to
the Master Lease.

    7.3  The terms, conditions and respective obligations of Sublessor and
Sublessee to each other under this Sublease shall be the terms and conditions
of the Master Lease except for those provisions of the Master Lease which are
directly contradicted by this Sublease in which event the terms of this Sublease
document shall control over the Master Lease. Therefore, for the purposes of
this Sublease, wherever in the Master Lease the word "Lessor" is used, it shall
be deemed to mean the Sublessor herein and wherever in the Master Lease the
word "Lessee" is used it shall be deemed to mean the Sublessee herein.

    7.4  During the term of this Sublease and for all periods subsequent for
obligations which have arisen prior to the termination of this Sublease
Sublessee does hereby expressly assume and agree to perform and comply with,
for the benefit of Sublessor and Master Lessor, each and every obligation of
Sublessor under the Master Lease except for the following paragraphs which are
excluded therefrom

    paragraphs: 1.2.1; 3.1; 3.1.1; 5.1; 5.9


<PAGE>   2

    7.5  The obligations that Sublessee has assumed under paragraph 7.4 hereof
are hereinafter referred to as the Sublessee's Assumed Obligations." The
obligations that the Sublessee has not assumed under paragraph 7.4 hereof are
hereinafter referred to as the "Sublessor's Remaining Obligations."

    7.6  Sublessee shall hold Sublessor free and harmless of and from all
liability, judgments, costs, damages, claims or demands, including reasonable
attorneys fees, arising out of Sublessee's failure to comply with or perform
Sublessee's Assumed Obligations.

    7.7  Sublessor agrees to maintain the Master lease during the entire term
of this Sublease, subject, however, to any earlier termination of the Master
Lease without the fault of the Sublessor, and to comply with or perform
Sublessor's Remaining Obligations and to hold Sublessee free and harmless of
and from all liability, judgments, costs, damages, claims or demands arising
out of Sublessor's failure to comply with or perform Sublessor's Remaining
Obligations.

    7.8  Sublessor represents to Sublessee that the Master Lease is in full
force and effect and that no default exists on the part of any party to the
Master Lease.


8.  ASSIGNMENT OF SUBLEASE AND DEFAULT.

    8.1  Sublessor hereby assigns and transfers to Master Lessor the
Sublessor's interest in this Sublease and all rentals and income arising
therefrom, subject, however, to terms of Paragraph 8.2 hereof.

    8.2  Master Lessor by executing this document, agrees that until a default
shall occur in the performance of Sublessor's Obligations under the Master
Lease, that Sublessor may receive, collect and enjoy the rents accruing under
this Sublease. However, if Sublessor shall default in the performance of its
obligations to Master Lessor then Master Lessor may, at its option, receive and
collect, directly from Sublessee, all rents owing and to be owed under this
Sublease. Master Lessor shall not, by reason of this assignment of the Sublease
nor by reason of the collection of the rents from the Sublessee, be deemed
liable to Sublessee for any failure of the Sublessor to perform and comply with
Sublessor's Remaining Obligations.

    8.3  Sublessor hereby irrevocably authorizes and directs Sublessee,
upon receipt of any written notice from the Master Lessor stating that a default
exists in the performance of Sublessor's obligations under the Master Lease, to
pay to Master Lessor the rents due and to become due under the Sublease.
Sublessor agrees that Sublessee shall have the right to rely upon any such
statement and request from Master Lessor, and that Sublessee shall pay such
rents to Master Lessor without any obligation or right to inquire as to whether
such default exists and notwithstanding any notice from or claim from Sublessor
to the contrary and Sublessor shall have no right or claim against Sublessee
for any such rents so paid by Sublessee.

    8.4  No changes or modifications shall be made to this Sublease without the
consent of Master Lessor.


9.  CONSENT OF MASTER LESSOR.

    9.1  In the event that the Master Lease requires that Sublessor obtain the
consent of Master Lessor to any subletting by Sublessor then this Sublease
shall not be effective unless, within 10 days of the date hereof, Master Lessor
signs this Sublease thereby giving its consent to this Subletting.

    9.2  In the event that the obligations of the Sublessor under the Master
Lease have been guaranteed by third parties then this Sublease, nor the Master
Lessor's consent, shall not be effective unless, within 10 days of the date
hereof, said guarantors sign this Sublease thereby giving guarantors consent to
this Sublease and the terms thereof.

    9.3  In the event that Master Lessor does give such consent then

         (a)  Such consent will not release Sublessor of its obligations or
after the primary liability of Sublessor to pay the rent and perform and comply
with all of the obligations of Sublessor to be performed under the Master
Lease.

         (b)  The acceptance of rent by Master Lessor from Sublessee or any one
else liable under the Master Lease shall not be deemed a waiver by Master
Lessor of any provisions of the Master Lease.

         (c)  The consent to this Sublease shall not constitute a consent to
any subsequent subletting or assignment.

         (d)  In the event of any default of Sublessor under the Master Lease,
Master Lessor may proceed directly against Sublessor, any guarantors or any one
else liable under the Master Lease or this Sublease without first exhausting
Master Lessor's remedies against any other person or entity liable thereon to
Master Lessor.

         (e)  Master Lessor may consent to subsequent sublettings and
assignments of the Master Lease or this Sublease or any amendments or
modifications thereto without notifying Sublessor nor any one else liable under
the Master Lease and without obtaining their consent and such action shall not
relieve such persons from liability.

         (f)  In the event that sublessor shall default in its obligations
under the Master Lease, then Master Lessor, at its option and without being
obligated to do so, may require Sublessee to attorn to Master Lessor in which
event Master Lessor shall undertake the obligations of Sublessor under this
Sublease from the time of the exercise of said option to termination of this
Sublease but Master Lessor shall not be liable for any prepaid rents nor any
security deposit paid by Sublessee, nor shall master Lessor be liable for any
other defaults of the Sublessor under the Sublease.

    9.4  The signatures of the Master Lessor and any Guarantors of Sublessor at
the end of this document shall constitute their consent to the terms of this
Sublease.

    9.5  Master Lessor acknowledges that, to the best of Master Lessor's
knowledge, no default presently exists under the Master Lease of obligations to
be performed by Sublessor and that the Master Lease is in full force and
effect.

    9.6  In the event that Sublessor defaults under its obligations to be
performed under the Master Lease by Sublessor, Master Lessor agrees to deliver
to Sublessee a copy of any such notice of default.  Sublessee shall have the
right to cure any default of Sublessor described in any notice of default
within ten days after service of such notice of default on Sublessee. If such
default is cured by Sublessee then Sublessee shall have the right of
reimbursement and offset from and against Sublessor.


10.  BROKERS FEE.

     10.1  Upon execution hereof by all parties, Sublessor shall pay to BT
COMMERCIAL, a licensed real estate broker, (herein called "Broker"), a fee as
set forth in a separate agreement between Sublessor and Broker.

     10.2  Sublessor agrees that if Sublessee exercises any option or right of
first refusal granted by Sublessor herein, or any option or right substantially
similar thereto, either to extend the term of this Sublease, to renew this
Sublease, to purchase the Premises, or to lease or purchase adjacent property
which Sublessor may own or in which Sublessor has an interest, or if Broker is
the procuring cause of any lease, sublease, or sale pertaining to the Premises
or any adjacent property which Sublessor may own or in which Sublessor has an
interest, then as to any of said transactions Sublessor shall pay to Broker a
fee, in cash, in accordance with the schedule of Broker in effect at the time
of the execution of this Sublease. Notwithstanding the foregoing, Sublessor's
obligation under this Paragraph 10.2 is limited to a transaction in which
Sublessor is acting as a sublessor, lessor or seller.

    10.3  Master Lessor agrees, by its consent to this Sublease, that if
Sublessee shall exercise any option or right of first refusal granted to
Sublessee by Master Lessor in connection with this Sublease, or any option or
right substantially similar thereto, either to extend the Master Lease, to
renew the Master Lease, to purchase the Premises or any part thereof, or to
lease or purchase adjacent property which Master Lessor may own or in which
Master Lessor has an interest, or if Broker is the procuring cause of any other
lease or sale entered into between Sublessee and Master Lessor pertaining to
the Premises, any part thereof, or any adjacent property which Master Lessor
owns or in which it has an interest, then as to any of said transactions Master
Lessor shall pay to Broker a fee, in cash, in accordance with the schedule of
Broker in effect at the time of its consent to this Sublease.

    10.4  Any fee due from Sublessor or Master Lessor hereunder shall be due and
payable upon the exercise of any option to extend or renew, as to any extension
or renewal, upon the execution of any new lease, as to a new lease transaction
or the exercise of a right of first refusal to lease, or at the close or
escrow, as to the exercise of any option to purchase or other sale transaction.

    10.5  Any transferee of Sublessor's interest in this Sublease, or of Master
Lessor's interest in the Master Lease, by accepting an assignment thereof,
shall be deemed to have assumed the respective obligations of Sublessor or
Master Lessor under this Paragraph 10. Broker shall be deemed to be a
third-party beneficiary of this paragraph 10.


11.  ATTORNEY'S FEES.  If any party or the Broker named herein brings an action
to enforce the terms hereof or to declare rights hereunder, the prevailing
party in any such action, on trial and appeal, shall be entitled to his
reasonable attorney's fees to be paid by the losing party as fixed by the
Court. The provision of this paragraph shall inure to the benefit of the Broker
named herein who seeks to enforce a right hereunder



<PAGE>   3

12.  ADDITIONAL PROVISIONS.  [If there are no additional provisions draw a
line from this point to the next printed word after the space left here. If
there are additional provisions place the same here.]

See attached addendum



        IF THIS SUBLEASE HAS BEEN FILLED IN IT HAS BEEN PREPARED FOR SUBMISSION
        TO YOUR ATTORNEY FOR HIS APPROVAL. NO REPRESENTATION OR RECOMMENDATION
        IS MADE BY THE REAL ESTATE BROKER OR ITS AGENTS OR EMPLOYEES AS TO THE
        LEGAL SUFFICIENCY, LEGAL EFFECT, OR TAX CONSEQUENCES OF THIS SUBLEASE
        OR THE TRANSACTION RELATING THERETO.

<TABLE>
<S>                                                 <C>
Executed at                                         Sega of America, Inc.
           ---------------------------------        ------------------------------------
on                                                  By  [SIG]                  4/12/96
  ------------------------------------------          ----------------------------------
address                                             By
       -------------------------------------          ----------------------------------

                                                       "Sublessor" (Corporate Seal)
--------------------------------------------


Executed at                                         Cybercash, Inc.
           ---------------------------------        ------------------------------------
on                                                  By   [SIG]
  ------------------------------------------          ----------------------------------
address                                             By
       -------------------------------------          ----------------------------------

                                                       "Sublessee" (Corporate Seal)


Executed at                                         Provident Central Credit Union
           ---------------------------------        ------------------------------------
on                                                  By
  ------------------------------------------          ----------------------------------
address                                             By
       -------------------------------------          ----------------------------------

                                                       "Master Lessor" (Corporate Seal)
--------------------------------------------

Executed at
           ---------------------------------        ------------------------------------
on
  ------------------------------------------        ------------------------------------
address
       -------------------------------------        ------------------------------------

                                                               "Guarantors"
--------------------------------------------
                                                                         Form  401 778
</TABLE>
NOTE:  These forms are often modified to meet changing requirements of law and
       needs of the industry.  Always write or call to make sure you are
       utilizing the most current form:  AMERICAN REAL ESTATE ASSOCIATION, 345
       So. Figueroa St., M-1, Los Angeles, CA 90071 (213) 687-8777



<PAGE>   4
                              ADDENDUM NUMBER ONE


This Addendum is made a part of the Sublease dated March 27,1996 between Sega
of America, Inc., as sublessor, and CyberCash, Inc., as Sublessee, for the
premises at 303 Twin Dolphin Drive, Suite 200, Redwood City, California.

13.              For purposes of this Sublease, Base Operating Expenses (para
                 2.31) shall be those Operating Expenses established by
                 Landlord for calendar year 1996.  Sublessee shall be
                 responsible for increases to Operating Expenses and Real
                 Estate Taxes in excess of Base Operating Expenses in
                 accordance with paragraph 2.3 of the Master Lease.

14.              Sublessor shall deliver the Premises, including the existing
                 furniture and office fixtures pursuant to paragraph 1.5 of the
                 Master Lease, in clean and orderly condition.  Otherwise,
                 Sublessee shall take the Premises in "as is" condition.

15.              A complete inventory of the furniture and fixtures in place in
                 the Premises which are subject to paragraph 1.5 of the Master
                 Lease is attached hereto as Schedule 1.

16.              Effective upon the full execution of and commencement of this
                 Sublease, Sublessor shall be deemed to have waived its rights
                 under the Extension Option (para. 1.2.2 of the Master Lease)
                 and Early Termination Right (para.1.2.1. of the Master Lease).

17.              Sublessor hereby acknowledges that Sublessee may, at
                 Sublessee's option, (1) install improvements to the Premises,
                 and/or (2) sub-sublease all or a portion of the Premises
                 during this Sublease term, subject to the terms of the Master
                 Lease, and Sublessor's consent to one or both shall not be
                 unreasonably withheld, conditioned, or delayed.

18.              Sublessee shall have the right to early access to the Premises
                 at any time after April 20, 1996 in order TO install its phone
                 and data lines within the Premises, subject to the terms of
                 this Sublease (other than the obligation to pay rent) and the
                 Master Lease, as applicable.

19.              In addition to those paragraphs of the Master Lease excluded
                 from the Sublease per Sublease paragraph 7.4, the following
                 paragraphs of the Master Lease shall also be excluded: 1.4,
                 2.2, 2.3.1, 2.3.2, 2.5, 2.7*, 11.4. Master Lease paragraphs
                 3.1.1,5.1 and 5.9, excluded per paragraph 7.4, shall remain a
                 part of this Sublease.

                 *Sublessee shall have no liability, under paragraph 2.7, to
                 Master Lessor for Sublessor's late payment or default.

20.              SUBLESSOR HEREBY ACKNOWLEDGES THAT SUBLESSEE'S OCCUPANCY OF
                 THE PREMISES ON OR BEFORE MAY 1, 1996 IS CRITICAL TO
                 SUBLESSEE'S BUSINESS.  THEREFORE, SUBLESSOR SHALL PAY TO
                 SUBLESSEE $1,800 PER DAY AS LIQUIDATED DAMAGES FOR EVERY DAY
                 SUBLESSEE IS DENIED POSSESSION OF THE PREMISES COMMENCING AS
                 OF MAY 1, 1996.  THE PARTIES AGREE THAT IT WOULD BE
                 IMPRACTICABLE AND EXTREMELY

<PAGE>   5
                 DIFFICULT TO ASCERTAIN THE ACTUAL DAMAGES SUFFERED BY
                 SUBLESSEE AS A RESULT OF SUBLESSOR'S FAILURE TO DELIVER
                 POSSESSION OF THE PREMISES TO SUBLESSEE ON OR BEFORE MAY 1,
                 1996, AND THAT UNDER THE CIRCUMSTANCES EXISTING AS OF THE DATE
                 OF THIS SUBLEASE, LIQUIDATED DAMAGES IN THE AMOUNT OF $1,800
                 PER DAY REPRESENTS A REASONABLE ESTIMATE OF THE DAMAGES WHICH
                 SUBLESSEE WILL INCUR AS A RESULT OF SUCH FAILURE.

21.              In the event of Sublessor's default under any of the
                 provisions of the Master Lease, the rent due from Sublessee
                 under the Sublease shall be deemed assigned to Master Lessor
                 and Master Lessor shall have the right, under such default, at
                 any time at its option, to give notice to Sublessee of such
                 assignment.  Master Lessor shall credit Sublessor with any
                 rent received by Master Lessor under such assignment, but the
                 acceptance of any payment on account of rent from Sublessee as
                 the result of any such default shall in no manner whatsoever
                 serve to release Sublessor from any liability under the terms,
                 covenants, conditions, provisions or agreements under the
                 Master Lease, except to the extent of the rent so credited.

                 Master Lessor covenants that if, and so long as, Sublessee
                 keeps and performs each and every covenant agreement term,
                 provision and condition contained in the Sublease and Master
                 Lease, and provideD that Sublessee attorns to Master Lessor,
                 Sublessee shall quietly enjoy the premises from and against
                 the claims of all persons.

Sublessor

SEGA OF AMERICA, INC.

By: [SIG]                                 Date: 4/12/96
   --------------------------             -----------------------------


Its:  VP Admin.
    -------------------------

Sublessee

CYBERCASH, INC.

By: [SIG]                                 Date:
   --------------------------             -----------------------------

Its: CFO
    -------------------------

Master Lessor

PROVIDENT CENTRAL CREDIT UNION

By:                                       Date:
   --------------------------             -----------------------------

Its:
    -------------------------