This module uses the functions of » OpenSSL for generation and verification of signatures and for sealing (encrypting) and opening (decrypting) data. OpenSSL offers many features that this module currently doesn't support. Some of these may be added in the future.
In order to use the OpenSSL functions you need to install the » OpenSSL package. PHP between versions 4.0.5 and 4.3.1 will work with OpenSSL >= 0.9.5. Other versions (PHP <=4.0.4 and >= 4.3.2) require OpenSSL >= 0.9.6.
You are strongly encouraged to use the most recent OpenSSL version, otherwise your web server could be vulnerable to attack.
To use PHP's OpenSSL support you must also compile PHP
In order for this extension to work, there are
DLL files that must be available to the Windows
PATH. See the FAQ titled "How do I add my PHP directory to the PATH
on Windows" for information on how to do this. Although copying DLL
files from the PHP folder into the Windows system directory also works
(because the system directory is by default in the systems
PATH), it is not recommended.
This extension requires the following files to be in the
Additionally, if you are planning to use the key generation and certificate
signing functions, you will need to install a valid
on your system. As of PHP 4.3.0, we include a sample
configuration file in the
folder of our win32 binary distribution. If you are using PHP 4.2.0 or
later and are missing the file, you can obtain it from
» the OpenSSL home page or by
downloading the PHP 4.3.0 release and using the configuration file from
PHP will search for the
openssl.cnf using the
OPENSSL_CONFenvironmental variable, if set, will be used as the path (including filename) of the configuration file.
SSLEAY_CONFenvironmental variable, if set, will be used as the path (including filename) of the configuration file.
openssl.cnfwill be assumed to be found in the default certificate area, as configured at the time that the openssl DLL was compiled. This is usually means that the default filename is
In your installation, you need to decide whether to install the
configuration file at
whether to install it someplace else and use environmental variables
(possibly on a per-virtual-host basis) to locate the configuration file.
Note that it is possible to override the default path from the script using
the configargs of the functions that require a
Quite a few of the openssl functions require a key or a certificate parameter. PHP 4.0.5 and earlier have to use a key or certificate resource returned by one of the openssl_get_xxx functions. Later versions may use one of the following methods:
file://path/to/cert.pem; the named file must contain a PEM encoded certificate
file://path/to/file.pem- the named file must contain a PEM encoded certificate/private key (it may contain both)
When calling a function that will verify a signature/certificate, the cainfo parameter is an array containing file and directory names that specify the locations of trusted CA files. If a directory is specified, then it must be a correctly formed hashed directory as the openssl command would use.
The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.
The S/MIME functions make use of flags which are specified using a bitfield which can include one or more of the following values:
|PKCS7_TEXT||Adds text/plain content type headers to encrypted/signed message. If decrypting or verifying, it strips those headers from the output - if the decrypted or verified message is not of MIME type text/plain then an error will occur.|
|PKCS7_BINARY||Normally the input message is converted to "canonical" format which is effectively using CR and LF as end of line: as required by the S/MIME specification. When this options is present, no translation occurs. This is useful when handling binary data which may not be in MIME format.|
|PKCS7_NOINTERN||When verifying a message, certificates (if any) included in the message are normally searched for the signing certificate. With this option only the certificates specified in the extracerts parameter of openssl_pkcs7_verify() are used. The supplied certificates can still be used as untrusted CAs however.|
|PKCS7_NOVERIFY||Do not verify the signers certificate of a signed message.|
|PKCS7_NOCHAIN||Do not chain verification of signers certificates: that is don't use the certificates in the signed message as untrusted CAs.|
|PKCS7_NOCERTS||When signing a message the signer's certificate is normally included - with this option it is excluded. This will reduce the size of the signed message but the verifier must have a copy of the signers certificate available locally (passed using the extracerts to openssl_pkcs7_verify() for example).|
|PKCS7_NOATTR||Normally when a message is signed, a set of attributes are included which include the signing time and the supported symmetric algorithms. With this option they are not included.|
|PKCS7_DETACHED||When signing a message, use cleartext signing with the MIME type multipart/signed. This is the default if you do not specify any flags to openssl_pkcs7_sign(). If you turn this option off, the message will be signed using opaque signing, which is more resistant to translation by mail relays but cannot be read by mail agents that do not support S/MIME.|
|PKCS7_NOSIGS||Don't try and verify the signatures on a message|
These constants were added in 4.0.6.
These constants were added in 5.0.0.
These constants were added in 4.3.0.
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