[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"extension:v3:en:p7s":3},{"resolvedFromAlias":4,"canonicalExt":5,"ext":5,"name":6,"category":7,"categoryName":8,"updatedAt":9,"popularity":10,"summary":11,"howToOs":12,"quickAnswer":18,"answerIntro":19,"whatIs":20,"description":21,"furtherReading":22,"openInstructions":38,"commonIssues":52,"securityNotes":73,"faq":77,"aliases":90,"mimeTypes":91,"relatedExtensions":93,"breadcrumbs":139,"categoryAnchor":149,"categoryFuturePath":150,"metaDescription":151,"availableHowToOs":152,"openOnDeviceLinks":153,"cannotOpenReasons":169,"cannotOpenFixes":170,"convertOptions":171,"securityAffiliateMessaging":172,"securityAffiliates":173},false,"p7s","PKCS #7 / S/MIME Digital Signature (detached signature)","certificates","Certificates","2026-06-12T09:20:59.265Z",35,".p7s files are PKCS #7 signature objects most commonly used as detached digital signatures for S/MIME-signed email. You typically open them by verifying the signature in an email client or by inspecting/verifying with OpenSSL.",[13,14,15,16,17],"windows","mac","linux","ios","android","To open .P7S files on Windows, if the .p7s came from an email, open the message in your email client and use its signature/verification UI (the .p7s is usually not meant to be “viewed” as a standalone document).","To open a .p7s file, use the email program that produced/received the signed message (common with S/MIME) or use OpenSSL tools to inspect and verify the PKCS #7 signature. A .p7s file usually does not contain the original content by itself—it’s a signature for something else.",".p7s is a common filename extension for a PKCS #7 Cryptographic Message Syntax signature object. In S/MIME, the media type application/pkcs7-signature is used for “signed-only” parts, and the file extension for that signature is defined as .p7s. The signature is typically “detached,” meaning you need the original signed data (for example, the email body/attachment) to verify it.","PKCS #7 defines a syntax for cryptographic messages such as signed data and encrypted data. In everyday use, .p7s most often appears as a detached digital signature, especially as part of S/MIME-signed email workflows.\n\nWhen you receive a signed email, your mail client may store or expose the signature as a .p7s attachment (sometimes shown alongside the message). The actual human-readable message and attachments are usually separate; the .p7s is the signature information that lets software validate integrity and the signer’s certificate chain.\n\nTechnically, .p7s corresponds to the S/MIME signature media type application/pkcs7-signature, and it is defined in the S/MIME message specification. For troubleshooting, inspection, or automation, OpenSSL includes tooling for working with PKCS #7 structures.",[23,26,29,32,35],{"title":24,"url":25},"IANA Media Types Registry (application/pkcs7-signature)","https://www.iana.org/assignments/media-types/",{"title":27,"url":28},"RFC 8551: S/MIME Version 4.0 Message Specification","https://www.rfc-editor.org/info/rfc8551/",{"title":30,"url":31},"OpenSSL Documentation: openssl-pkcs7","https://docs.openssl.org/master/man1/openssl-pkcs7/",{"title":33,"url":34},"PKCS 7 (Wikipedia overview)","https://en.wikipedia.org/wiki/PKCS_7",{"title":36,"url":37},"FileInfo: P7S File Extension (PKCS #7 Signature File)","https://fileinfo.com/extension/p7s",{"windows":39,"macos":42,"linux":45,"ios":48,"android":50},[40,41],"If the .p7s came from an email, open the message in your email client and use its signature/verification UI (the .p7s is usually not meant to be “viewed” as a standalone document).","For inspection on the command line, install OpenSSL and use the PKCS#7 tooling (for example, commands described in OpenSSL’s pkcs7 documentation) to parse the structure.",[43,44],"If the .p7s is attached to an S/MIME email, open the email in your mail client and look for a signature indicator; verification is typically shown as part of the message.","For technical inspection, use OpenSSL on the command line and follow the pkcs7 tool documentation to examine the PKCS #7 structure.",[46,47],"If the .p7s belongs to a signed email, open the message in an email client that supports S/MIME signing and verification.","Use OpenSSL’s pkcs7 command-line tooling to inspect the PKCS #7 signature object and (when you have the original data) verify it.",[49],"If the .p7s came from an S/MIME email, open the email in a mail app that supports showing S/MIME signature status; otherwise, transfer the file to a desktop for OpenSSL-based inspection.",[51],"If you can’t verify it in your email app, transfer the .p7s and the signed content to a desktop system and use an S/MIME-capable mail client or OpenSSL tools to inspect/verify it.",[53,60,67],{"title":54,"description":55,"steps":56},"“It won’t open” or looks like a meaningless attachment","A .p7s file is usually a detached signature, not the actual message or document. Double-clicking it may not display anything useful because it’s meant to be verified against the original signed data.",[57,58,59],"Find the original signed content (often the email body and/or the original attachment) that the .p7s corresponds to.","Open the email in an S/MIME-capable mail client so it can automatically associate the signature with the message and show verification status.","If you only have the .p7s file, use OpenSSL to inspect the PKCS #7 structure (you may not be able to verify without the original data).",{"title":61,"description":62,"steps":63},"Signature verification fails or shows as “untrusted”","Verification can fail if the signed content doesn’t exactly match what was signed, or if the signer’s certificate chain is missing/untrusted in your environment.",[64,65,66],"Confirm you are verifying the signature against the exact original content (even minor changes can break validation).","Check whether your software trusts the signer’s certificate chain (for S/MIME, the signer’s certificate and issuing chain typically must be available and trusted).","Use OpenSSL tools to examine the included certificates and signature details to help diagnose chain and trust issues.",{"title":68,"description":69,"steps":70},"Confusion with .p7m (encrypted) vs .p7s (signature)","PKCS #7 is used for multiple message types. In S/MIME, .p7s is specifically for signed-only signature objects, while other PKCS #7 files may represent encrypted data or combined structures.",[71,72],"Check the extension and context: .p7s commonly indicates a signature object for S/MIME signed-only parts.","If you expected encrypted content, look for a different S/MIME/PKCS #7 object (such as a file used for enveloped/encrypted data) rather than a detached signature.",[74,75,76],"A .p7s file is a signature container; it is usually safe to treat as data, but its purpose is to influence trust decisions (who signed what). Only treat a message as authentic after successful signature verification and certificate trust validation.","Detached signatures depend on the exact bytes of the signed content—if content was modified in transit (or you are verifying the wrong file/message), validation will fail. Be cautious when someone sends a .p7s without the original signed content or without clear context.","Tools that parse cryptographic message syntax (including PKCS #7) are complex; prefer well-maintained implementations (for example, OpenSSL) and keep them updated when handling untrusted inputs.",[78,81,84,87],{"question":79,"answer":80},"Is a .p7s file the actual document or email message?","Usually no. A .p7s is commonly a detached PKCS #7 signature used with S/MIME; it signs other content (often an email or attachment) rather than containing the readable content itself.",{"question":82,"answer":83},"What MIME type is associated with .p7s for S/MIME signatures?","For signed-only S/MIME signature objects, the registered media type is application/pkcs7-signature, and the S/MIME specification explicitly associates it with the .p7s file extension.",{"question":85,"answer":86},"Can I verify a .p7s file by itself?","You can inspect what’s inside (such as certificates and signature metadata), but verification typically requires the original signed content because .p7s is often a detached signature.",{"question":88,"answer":89},"What standards define what a .p7s contains?","The underlying syntax is defined by PKCS #7 / Cryptographic Message Syntax (RFC 2315), and S/MIME usage (including the .p7s extension for application/pkcs7-signature) is defined in RFC 8551.",[],[92],"application/pkcs7-signature",[94,100,106,112,118,123,128,133],{"ext":95,"name":96,"category":7,"categoryName":8,"popularity":97,"summary":98,"howToOs":99},"pfx","Personal Information Exchange (PFX)",78,".pfx is a PKCS #12 (PFX) container used to bundle certificates and (often) the associated private key into a single, typically password-protected file for import/export between systems.",[13,14,15,16,17],{"ext":101,"name":102,"category":7,"categoryName":8,"popularity":103,"summary":104,"howToOs":105},"pem","PEM-encoded Certificate",75,".pem is a text-based container format commonly used to store X.509 certificates, certificate chains, and sometimes private keys in Base64 with BEGIN/END markers. It is widely used by TLS software such as OpenSSL and Apache HTTP Server.",[13,14,15,16,17],{"ext":107,"name":108,"category":7,"categoryName":8,"popularity":109,"summary":110,"howToOs":111},"p12","PKCS#12 Certificate Bundle",65,".p12 is a PKCS #12 (also called PFX) container used to bundle an X.509 certificate chain together with its corresponding private key, typically protected by a password. It’s commonly opened/imported by certificate/key management tools such as Apple Keychain Access and OpenSSL.",[13,14,15,16,17],{"ext":113,"name":114,"category":7,"categoryName":8,"popularity":115,"summary":116,"howToOs":117},"csr","PKCS #10 Certificate Signing Request",55,".csr files are certificate signing requests used to obtain an X.509 certificate from a certificate authority (CA). They commonly contain a PKCS #10 request encoded as PEM (text) or DER (binary) and can be inspected or generated with OpenSSL.",[13,14,15,16,17],{"ext":119,"name":120,"category":7,"categoryName":8,"popularity":115,"summary":121,"howToOs":122},"der","DER-encoded X.509 Certificate",".der files most commonly contain binary DER-encoded ASN.1 data, especially X.509 certificates. They are typically opened for inspection or conversion using certificate tools such as OpenSSL.",[13,14,15,16,17],{"ext":124,"name":125,"category":7,"categoryName":8,"popularity":115,"summary":126,"howToOs":127},"p7b","PKCS #7 Certificate Bundle (P7B)",".p7b is a PKCS #7 container most commonly used to bundle X.509 certificates (and sometimes certificate revocation lists) for import or exchange. It typically does not include a private key and is often used in S/MIME and certificate deployment workflows.",[13,14,15,16,17],{"ext":129,"name":130,"category":7,"categoryName":8,"popularity":10,"summary":131,"howToOs":132},"ac","X.509 Attribute Certificate",".ac most commonly refers to an X.509 Attribute Certificate (authorization certificate) used in PKIX systems to carry privileges/roles separately from an identity certificate.",[13,14,15,16,17],{"ext":134,"name":135,"category":7,"categoryName":8,"popularity":136,"summary":137,"howToOs":138},"p7c","PKCS #7 / CMS certificate container (certs-only SignedData)",25,".p7c is a PKCS #7/CMS container most commonly used to carry X.509 certificates (often a “certs-only”/degenerate SignedData structure). It’s typically opened or inspected with certificate tools or OpenSSL rather than a document viewer.",[13,14,15,16,17],[140,143,146],{"label":141,"to":142},"Home","/",{"label":144,"to":145},"File Extension Index","/file-extension",{"label":147,"to":148},".P7S","/file-extension/p7s","category-certificates","/category/certificates","Learn what .P7S files are, how to open them on every platform, common fixes, and security best practices.",[13,14,15,16,17],[154,157,160,163,166],{"os":13,"label":155,"to":156},"Open .P7S on Windows","/how-to/open-p7s-on-windows",{"os":14,"label":158,"to":159},"Open .P7S on Mac","/how-to/open-p7s-on-mac",{"os":15,"label":161,"to":162},"Open .P7S on Linux","/how-to/open-p7s-on-linux",{"os":16,"label":164,"to":165},"Open .P7S on iOS","/how-to/open-p7s-on-ios",{"os":17,"label":167,"to":168},"Open .P7S on Android","/how-to/open-p7s-on-android",[54,61,68],[57,58,59],[],"untrusted_source",[174,178],{"name":175,"description":176,"affiliateUrl":177},"Avast","Avast offers free and premium antivirus software that protects against viruses, malware, ransomware, and phishing. Scan files before opening them to ensure safety.","https://www.avast.com/lp-aff-consumer-store?expid=inf601",{"name":179,"description":180,"affiliateUrl":181},"Norton","Norton 360 delivers comprehensive antivirus protection, VPN, and identity theft monitoring. Scan files for threats before opening to keep your device secure.","http://buy.norton.com/aff_home?utm_campaign=en-ww_nor_n36_aff_nas_nau_nah_cj_nad_low:_sec_nat_mktc_norton_360"]