Underwriting Agreement

                                                                     Exhibit 8.1

                 [CADWALADER, WICKERSHAM & TAFT LLP LETTERHEAD]




                                 April 18, 2008




Credit Suisse First Boston Mortgage Securities Corp.
Eleven Madison Avenue
New York, New York 10010-3629

      Re:    Issuance of Credit Suisse First Boston Mortgage Securities Corp.,
            Commercial Mortgage Pass-Through Certificates, Series 2008-C1
            -----------------------------------------------------------------

Ladies and Gentlemen:

            We have acted as special counsel to Credit Suisse First Boston
Mortgage Securities Corp. (the "Depositor") in connection with the proposed sale
by the Depositor and purchase by Credit Suisse Securities (USA) LLC ("Credit
Suisse"), Morgan Stanley & Co. Incorporated ("Morgan Stanley") and Deutsche Bank
Securities Inc. ("Deutsche Bank" and together with Credit Suisse and Morgan
Stanley, the "Underwriters"; provided, that Deutsche Bank is not acting as an
Underwriter of the Class A-2 Certificates), of the Depositor's Commercial
Mortgage Pass-Through Certificates, Series 2008-C1, Class A-1, Class A-2, Class
A-AB, Class A-3 and Class A-1-A Certificates (the "Public Certificates" or
"Certificates") pursuant to the terms of an Underwriting Agreement, dated March
28, 2008 (the "Underwriting Agreement"), between the Depositor and the
Underwriters. The Public Certificates are being issued pursuant to a Pooling and
Servicing Agreement, dated as of April 1, 2008 (the "Pooling and Servicing
Agreement" and together with the Underwriting Agreement, the "Agreements"), by
and among the Depositor, as depositor, KeyCorp Real Estate Capital Markets,
Inc., as master servicer (the "Master Servicer"), Midland Loan Services, Inc.,
as special servicer (the "Special Servicer"), and Wells Fargo Bank, N.A., as
trustee (the "Trustee"). Capitalized terms used herein but not defined herein
have the respective meanings given to them in the Underwriting Agreement or, if
not defined therein, in the Pooling and Servicing Agreement.

            In rendering the opinions set forth below, we have examined and
relied upon the originals, copies or specimens, certified or otherwise
identified to our satisfaction, of the Transaction Documents (as defined below)
and such certificates, corporate and public records, agreements and instruments
and other documents, including, among other things, the documents delivered on
the date hereof, as we have deemed appropriate as a basis for the opinions
expressed below. In such examination we have assumed the genuineness of all
signatures, the authenticity of all documents, agreements and instruments
submitted to us as originals, the conformity to original documents, agreements
and instruments of all documents, agreements and instruments submitted to us as
copies or specimens, the authenticity of the originals of such documents,
agreements and instruments submitted to us as copies or specimens, the
conformity of the text of each document filed with the Securities and Exchange
Commission (the "Commission") through the Commission's Electronic Data
Gathering, Analysis and Retrieval System to the printed document reviewed by us,
and the accuracy of the matters set forth in the documents, agreements and
instruments we reviewed. As