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Format

PKCS #7 Cryptographic Message File

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Summary

Name
PKCS #7 Cryptographic Message File
Identifiers
  • MIME: application/pkcs7-signature
  • PUID: fmt/670
Format type
Text (Structured)
Description
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.
Note
https://en.wikipedia.org/wiki/PKCS_7 https://en.wikipedia.org/wiki/PKCS https://en.wikipedia.org/wiki/S/MIME https://www.cryptomathic.com/news-events/blog/introduction-to-digital-signatures-and-pkcs-7 https://comodosslstore.com/resources/what-is-an-smime-p7s-file-attachment-and-how-do-i-open-it/
File extensions
p7m, p7b, p7s
Source
Digital Preservation Department / The National Archives

Relationships

Has lower priority than
Has priority over

Internal signatures

PKCS #7 Cryptographic Message File

Note
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.

Byte sequences

Min Frag Length
Absolute from BOF
Offset
0
Max offset
0
Byte Sequence
30{1-5}06092A864886F7
Endianness
None

Changelog

  • Updated in V105

    Release date
    29 June 2022

    PKCS #7 Cryptographic Message File: Adjusted signature to include first BOF byte and changed signature name to PKCS #7 Cryptographic Message File from P7M. Updated description and reference links. Added extensions .p7s, .p7b, and MIME types. Submitted by Tatiana Canelhas.

  • Updated in V98

    Release date
    27 October 2021

    PKCS #7 Cryptographic Message File: File format title updated. Submitted by the National Library of the Netherlands.

  • Added in V78

    Release date
    23 September 2014

    PKCS #7 Crytographic message file: Signature developed through PRONOM Research.

    PKCS #7 Crytographic message file: Full entry added. Submitted by Antonio Dalvit.