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P7S PEM
File conversion

Convert P7S to PEM

Verified by Adam B.· reviewed by FE Editorial ·updated Jun 23, 2026
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Is it possible to convert P7S to PEM?
Yes - P7S converts to PEM.

Converting .p7s to PEM re-encodes the same cryptographic data from binary DER to Base64 text, producing a file that starts with -----BEGIN PKCS7-----. OpenSSL does this in one command; adding -print_certs also extracts the signer's X.509 certificate into the output. The conversion does not recover any email or document content.

Also to PEM: JKS · REQ · PPK

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Tested on macOS, Windows & Linux
Last verified Oct 2026

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Why convert P7S to PEM?

PEM is the standard text format for certificates and cryptographic objects expected by most web servers, inspection tools, and code processing X.509 certificates. Re-encoding the .p7s to .pem lets you inspect the signer's certificate chain, feed it into server configuration, or use it with tools that require Base64 input without a manual binary-to-text conversion step.

How to convert P7S to PEM

OpenSSL OPEN-SOURCE

Run openssl pkcs7 -inform DER -in file.p7s -out file.pem to re-encode the binary signature as Base64 PEM; add -print_certs to also extract the signer's certificate chain into the output.

About these formats

.P7S PKCS #7 / S/MIME Digital Signature (smime.p7s)

A P7S file - usually named smime.p7s - is the digital signature attached to a signed email. It proves the sender's identity and that the message was not altered in transit. You normally do…

Open .P7S details →
.PEM PEM - Base64-encoded certificate / key container (X.509, PKCS)

A PEM file is a text container for cryptographic data - most often an SSL/TLS certificate, a private key, or both. Open it in any text editor to see what the BEGIN line says, then use…

Open .PEM details →

Quality & what to watch

  • If the .p7s is already Base64-encoded (it opens in a text editor starting with -----BEGIN PKCS7-----), use -inform PEM instead of -inform DER in the OpenSSL command.
  • The PEM output contains only the signature and certificate data - it does not recover any email or document content, which is stored separately from a detached .p7s.
  • Adding -print_certs to the OpenSSL command embeds the signer's full certificate chain as -----BEGIN CERTIFICATE----- blocks in the output.

Frequently asked questions

Does converting to PEM validate the signature?
No - re-encoding only changes the format; use openssl smime -verify with the original signed content to verify the signature.
What if the OpenSSL command fails with a parse error?
The file may already be PEM-encoded; try -inform PEM instead of -inform DER.
Does the PEM file contain the email message content?
No - a .p7s is a detached signature; neither the DER original nor the PEM output contains the message body.
Can I use the PEM file in a web server configuration?
The PEM from a .p7s contains the signature object and certificate chain - extract individual certificates with openssl x509 for server use.