openssl_pkcs7_verify() reads the
S/MIME message contained in the filename specified by filename and examines the
digital signature. It 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.
flags can be used to
affect how the signature is verified - see PKCS7 constants
for more information.
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.
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.
If the extracerts is
specified, it is the filename of a file containing a bunch of
certificates to use as untrusted CAs.
注: This function was added in 4.0.6.