1469 PKCS #7 Cryptographic Message File Text (Structured) 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. 1 Digital Preservation Department / The National Archives 23 Sep 2014 11/2023 (v.116)- Priority over fmt/101 added. Internally researched. 16 Nov 2023 application/pkcs7-mime MIME application/pkcs7-signature MIME fmt/670 PUID p7m File extension p7b File extension p7s File extension 1003 PKCS #7 Cryptographic Message File The signature is seeking the first byte of 0x30, then the presence of the OID (Object Identifier) 1 2 840 113549 1 7 in ASN.1 (Abstract Syntax Notation) using BER (Basic encoding rules) encoding. 1 Absolute from BOF 0 0 30{1-5}06092A864886F7 Has lower priority than 2061 ZFO (Message) File Has lower priority than 2062 ZFO (Sent Message) File Has lower priority than 2063 ZFO (Proof of Delivery) File Has priority over 638 Extensible Markup Language