S/mime — I wikipedia

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A wikipedia article, free l’encyclopéi.

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S/MIME ( Secure/Multipurpose Internet Mail Extensions ) is a standard of cryptography and digital signature of email encapsulated in mime format. It provides integrity, authentication, non-repudiation and data confidentiality.

Mime is an internet standard that offers no notion of security, which is why developers at RSA Security have created S/Mime. Like Mime, S/Mime has the task of checking the contents of the headers inserted at the start of each email. On the other hand, instead of determining what type of application use to open such file, s/mime inspects the headers and determines how digital encryption and signatures should be processed [ first ] .

Norms [ modifier | Modifier and code ]

S/MIME is a standard based on X.509 digital certificates to sign and encrypt emails. X.509 is the standard used to define what a digital certificate is as part of a public key infrastructure (PKI). In this infrastructure, the certification authorities (CA) guarantee that certificates describe the right entity. The certification authority may issue a digital certificate for several reasons, but it must assign the certificate a precise use. The rules that indicate the exact way to use a certificate are called certification policy.

The messages themselves are encrypted using symmetrical cryptography and a public key is used for key exchange and digital signatures. S/mime can be used with different symmetrical algorithms:

  • OF THE ( Data Encryption Standard );
  • 3des ( Triple of );
  • RC2 ( Ron’s Code 2 );
  • AES ( Advanced Encryption Standard ).

Example of signature s/mime [ modifier | Modifier and code ] 

MIME-Version: 1.0
Content-Type: multipart/signed; protocol="application/x-pkcs7-signature"; micalg=sha1;
boundary="----D7B623C746311F5D683A038DC482F307"

This is an S/MIME signed message

------D7B623C746311F5D683A038DC482F307
Content-Type: text/plain

Ceci est le texte d'origine qui est signé.
------D7B623C746311F5D683A038DC482F307
Content-Type: application/x-pkcs7-signature;
name="smime.p7s"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
filename="smime.p7s"

MIIGgQYJKoZIhvcNAQcCoIIGcjCCBm4CAQExCzAJBgUrDgMCGgUAMAsGCSqGSIb3
DQEHAaCCA7wwggO4MIICoKADAgECAgEMMA0GCSqGSIb3DQEBBAUAMIGrMQswCQYD
VQQGEwJGUjEPMA0GA1UECBMGRlJBTkNFMQ4wDAYDVQQHEwVQQVJJUzEZMBcGA1UE
ChMQVEhFIFNJR05BVFVSRSBDQTEaMBgGA1UECxMRU2lnbmF0dXJlIFNlcnZpY2Ux
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------D7B623C746311F5D683A038DC482F307--
  • (in) RFC 5750 : S/MIME Version 3.2 – Certificate Handling
  • (in) RFC 5751 : S/MIME Version 3.2 – Message Specification
  • (in) RFC 2634 : Enhanced Security Services for S/MIME
  1. ↑ (in) How to Cheat at Securing Your Network , Dubrawski, Ido – Burlington, MA : Elsevier, 2007. – p. 83 (ISBN  978-1-59749-231-7 ) .

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