LIX. OpenSSL functions| Warning | This module is EXPERIMENTAL. That means, that the behaviour of these functions, these function names, in concreto ANYTHING documented here can change in a future release of PHP WITHOUT NOTICE. Be warned, and use this module at your own risk. |
This module uses the functions of OpenSSL for generation and verification
of signatures and for sealing (encrypting) and opening (decrypting)
data. PHP-4.0.4pl1 requires OpenSSL >= 0.9.6, but PHP-4.0.5 and greater
with also work with OpenSSL >= 0.9.5.
Note: Please keep in mind that this extension is still considered
experimental!
OpenSSL offers many features that this module currently doesn't support.
Some of these may be added in the future.
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:
Certificates
An X.509 resource returned from
openssl_x509_read A string having the format
file://path/to/cert.pem; the named file must
contain a PEM encoded certificate A string containing the content of a certificate,
PEM encoded
Public/Private Keys
A key resource returned from
openssl_get_publickey() or
openssl_get_privatekey() For public keys only: an X.509
resource A string having the format
file://path/to/file.pem - the named file must
contain a PEM encoded certificate/private key (it may contain
both) A string containing the content of a
certificate/key, PEM encoded For private keys, you may also use the syntax
array($key, $passphrase) where $key represents a
key specified using the file:// or textual content notation above, and
$passphrase represents a string containing the passphrase for that
private key
When calling a function that will verify a signature/certificate, the
cainfo parameter is an array containing file and
directory names the 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 S/MIME functions make use of flags which are specified using a
bitfield which can include one or more of the following values:
Table 1. PKCS7 CONSTANTS | Constant | Description |
|---|
| 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 the
flags parameter to
openssl_pkcs7_sign() if you do not specify any
flags. 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 |
Note: These constants were added in 4.0.6.
|
