Beginning with Crypto 84, IACR conference and workshop proceedings have been published by Springer-Verlag, in the Lecture Notes in Computer Science Series. The 1982 and 1983 proceedings were published by Plenum, and the 1981 Proceedings was published as a tech report by UCSB.
On-line access for IACR members is available via the IACR Reading Room at Springer. On-line access for others is available via the SpringerLink service. Some volumes are also available below from the IACR Archive.
See also the comprehensive list of LNCS volumes on cryptography, containing also non-IACR volumes (courtesy of James Muir).
Bibliographic data for the Lecture Notes in Computer Science series is available from the DBLP server.
A CD-ROM containing all Crypto and Eurocrypt proceedings up to 1997 has been available from Springer-Verlag, but is out of print as of April 2004.
A second CD-ROM, containing the IACR conference proceedings 1998-2003 (Asiacrypt, Crypto and Eurocrypt) the FSE and PKC workshops in 1998-2003 has been made available to the attendees of Eurocrypt 2004, Crypto 2004, and Asiacrypt 2004.
The errata from the proceedings of Eurocrypt '96 is available in postscript or in HTML.