openssl_pkcs7_verify

(PHP 4 >= 4.0.6, PHP 5, PHP 7)

openssl_pkcs7_verify — Verifies the signature of an S/MIME signed message

Description

mixed openssl_pkcs7_verify ( string $filename , int $flags [, string $outfilename [, array $cainfo [, string $extracerts [, string $content ]]]] )

openssl_pkcs7_verify() reads the S/MIME message contained in the given file and examines the digital signature.

Parameters

filename: Path to the message.
flags: flags can be used to affect how the signature is verified - see PKCS7 constants for more information.
outfilename: If the outfilename is specified, it should be a string holding the name of a file into which the certificates of the persons that signed the messages will be stored in PEM format.
cainfo: If the cainfo is specified, it should hold information about the trusted CA certificates to use in the verification process - see certificate verification for more information about this parameter.
extracerts: If the extracerts is specified, it is the filename of a file containing a bunch of certificates to use as untrusted CAs.
content: You can specify a filename with content that will be filled with the verified data, but with the signature information stripped.

Return Values

Returns TRUE if the signature is verified, FALSE if it is not correct (the message has been tampered with, or the signing certificate is invalid), or -1 on error.

Changelog

Version	Description
5.1.0	The `content` parameter was added.

Notes

Note: As specified in RFC 2045, lines may not be longer than 76 characters in the filename parameter.

User Contributed Notes

Krzychu

2 years ago


To read signed message in base64 (not encrypted with priv&pub key):

You can just decode content by "base64_decode" or "imap_base64" functions and then erase by hand(regexp) sign from bottom of mail. Unfortunately  in my case (mail from Outlook) that  message (decoded by "base64_decode") has some additional special chars in some places (ie. before every attachment encoded base_64) what make message e-mail unable to parse.

After couple of hours I solved this:
It's needed to save single e-mail and use 2x "openssl_pkcs7_verify" function in row on original email (with headers and content in base64 ):
  1st use - extract sign (certificate) from e-mail and save to file *.cert
  2nd use - extract (with use that *.cert file) decoded message to  file*.out

Code:
  $handle  =  imap_open('mailbox.eml', '', '');

  $msg = 'home/john/tmp/email1.eml';
  imap_savebody($handle, $msg,  1);

  openssl_pkcs7_verify($msg, 0, $msg . '.cert');
  openssl_pkcs7_verify($msg, 0, $msg . '.cert', array(), $msg . '.cert', $msg.'.out');

  $email_content = file_get_contents($msg . '.out');