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(also S/MIME, Secure/Multipurpose Internet Mail Extensions)

SMIME definition

SMIME is a standard for digitally signing and encrypting email messages. Originally developed by RSA Data Security, SMIME functionality has been since incorporated into most popular email software.

SMIME helps authenticate messages, ensure their integrity, and provide proof of origin. SMIME is based on asymmetric cryptography and protects the content of email messages from surveillance or tampering. SMIME is also an effective anti-phishing measure because it lets senders verify their identity with an advanced digital signature.

Real SMIME uses

  • Authentication: SMIME lets users add a digital signature to the email to verify their identity to the recipient.
  • Nonrepudiation: Digital signatures added with the help of SMIME are unique to the person issuing them and can be made legally binding.
  • Data verification: Digital signatures confirm to the recipient that the message they received was the same one that was sent by the sender.
  • Confidentiality: Encryption prevents third parties from spying on the contents of email messages, letting users exchange sensitive information.
  • Data integrity: Encryption protects email messages from outside tampering.