Definition(en): PKCS #7 Cryptographic Message File is a form of electronic signature used to secure messages that can only be read by the intended recipient. PKCS #7 describes a general syntax for data that may have cryptography applied to it, such as digital signatures and digital envelopes. PKCS #7 is one of the family of standards called Public-Key Cryptography Standards (PKCS) devised and published by RSA Security Inc, starting in the early 1990s; storing signed and/or encrypted data, usually attached to an email message that includes an S/MIME (Secure/Multipurpose Internet Mail Extensions) digital signature. The extension .p7s usually refers to PKCS #7 Signature Files; .p7m usually refers to PKCS #7 MIME Files; and .p7b usually refers to PKCS #7 Certificate Files. The research of this format is still ongoing, please contact the PRONOM team if you how any more information regarding this format.