Security is a major issue for electronic commerce. Crytography is the foundation of security and oblivious transfer (OT) protocols are one primitive of modern cryptography. The main goal of this dissertation is to develop new and more efficient OT protocols and explore their applications in electronic commerce. A new m out of n OT scheme is proposed, its implementation, security and efficiency are discussed, and it is compared with a previous OT scheme. The analysis shows that the previous OT protocol can be regarded as a special case of the new proposed OT scheme. The new OT scheme's applicability in blind signatures is explored. A new non-interactive m out of n OT scheme is proposed that includes a newly developed public keys generation algorithm based on the discrete log problem and an OT protocol based on the Diffie-Hellman problem. The security of this scheme is discussed. A new buying digital goods scheme is proposed using the new m out of n priced OT which is based on the priced OT protocol developed by Bill Aiello, Yuval Isahai, and Omer Reingold. Tools used in this scheme are discussed and its security is analyzed. A concrete homomorphic protocol is given / Master of Science (Hons)