This paper presents randomized protocols for signing contracts, certified mail, and flipping a coin. The protocols use a 1-out-of-2 oblivious transfer subprotocol, which allows one party to transfer exactly one secret out of two recognizable secrets to the other party. The first (second) secret is received with probability one half, while the sender is ignorant of which secret has been received. The paper proposes protocols for contract signing, certified mail, and coin flipping, all of which use the 1-out-of-2 oblivious transfer subprotocol. The contract signing protocol ensures that each party can instantly present their counterpart's signature to the contract, and that with very high probability, each party can compute their counterpart's signature using approximately the same amount of work. The certified mail protocol ensures that the receiver gets the mail if and only if the sender gets a receipt that certifies the contents of the mail. The coin flipping protocol ensures that the outcome of the coin flip is random and unforgeable, and that one party knows the outcome if and only if their counterpart knows it. The paper also discusses the assumptions and implementation of the 1-out-of-2 oblivious transfer subprotocol, which is based on public key cryptography. The implementation of the 1-out-of-2 oblivious transfer is presented, and the paper concludes with a discussion of the properties and advantages of the proposed protocols.This paper presents randomized protocols for signing contracts, certified mail, and flipping a coin. The protocols use a 1-out-of-2 oblivious transfer subprotocol, which allows one party to transfer exactly one secret out of two recognizable secrets to the other party. The first (second) secret is received with probability one half, while the sender is ignorant of which secret has been received. The paper proposes protocols for contract signing, certified mail, and coin flipping, all of which use the 1-out-of-2 oblivious transfer subprotocol. The contract signing protocol ensures that each party can instantly present their counterpart's signature to the contract, and that with very high probability, each party can compute their counterpart's signature using approximately the same amount of work. The certified mail protocol ensures that the receiver gets the mail if and only if the sender gets a receipt that certifies the contents of the mail. The coin flipping protocol ensures that the outcome of the coin flip is random and unforgeable, and that one party knows the outcome if and only if their counterpart knows it. The paper also discusses the assumptions and implementation of the 1-out-of-2 oblivious transfer subprotocol, which is based on public key cryptography. The implementation of the 1-out-of-2 oblivious transfer is presented, and the paper concludes with a discussion of the properties and advantages of the proposed protocols.