Electronic digital signatures are used for identity authentication when using electronic mail, contracts, or other web based applications. Transmissions with electronic digital signatures offer an extra layer of protection and validation, giving assurance to the recipients that the sender is authentic and that the content has not been altered or changed. Electronic digital signatures are often encrypted and require a specific key in order to protect them from tampering. Businesses, attorneys, or those engaging in online contracts often use electronic digital signatures in oder to add validation and protection to the contract. electronic digital signatures are generally legal and valid in the United States, though the legal definition of digital signatures is often debated, leaving the matter open to interpretation. The United States E-Sign Act defines an electronic signature as an "electronic sound, symbol, or process, attached to or logically associated with a contract or other record and executed or adopted by a person with the intent to sign the record."