Strong authentication, also called two-factor authentication, is defined as two out of the following three proofs:
• something known, like a password,
• something possessed, like your ATM card, and
• something unique about your appearance or person, like a fingerprint.
Using strong authentication provides more protection for sensitive information than a simple username and password can provide. Strong authentication, especially when combined with other practices like mutual authentication and non-repudiation offers a strong assurance that financial transactions are conducted by two known and trusted parties.