All encrypted client streams now enable peer verification by default. By default, this will use OpenSSL's default CA bundle to verify the peer certificate. In most cases, no changes will need to be made to communicate with servers with valid SSL certificates, as distributors generally configure OpenSSL to use known good CA bundles.
The default CA bundle may be overridden on a global basis by setting
either the openssl.cafile or openssl.capath configuration setting, or on a
per request basis by using the
cafile or
capath
context options.
While not recommended in general, it is possible to disable peer
certificate verification for a request by setting the
verify_peer
context option to FALSE, and to disable peer name validation by setting
the
verify_peer_name
context option to FALSE.
Support has been added for extracting and verifying certificate fingerprints. openssl_x509_fingerprint() has been added to extract a fingerprint from an X.509 certificate, and two SSL stream context options have been added: capture_peer_cert to capture the peer's X.509 certificate, and peer_fingerprint to assert that the peer's certificate should match the given fingerprint.
The default ciphers used by PHP have been updated to a more secure list based on the » Mozilla cipher recommendations, with two additional exclusions: anonymous Diffie-Hellman ciphers, and RC4.
This list can be accessed via the new
OPENSSL_DEFAULT_STREAM_CIPHERS constant, and can be
overridden (as in previous PHP versions) by setting the
ciphers
context option.
SSL/TLS compression has been disabled by default to mitigate the CRIME
attack. PHP 5.4.13 added a
disable_compression
context option to allow compression to be disabled: this is now set to
TRUE (that is, compression is disabled) by default.
The honor_cipher_order SSL context option has been
added to allow encrypted stream servers to mitigate BEAST vulnerabilities
by preferring the server's ciphers to the client's.
The protocol and cipher that were negotiated for an encrypted stream can
now be accessed via stream_get_meta_data() or
stream_context_get_options() when the
capture_session_meta SSL context option is set to
TRUE.
<?php
$ctx = stream_context_create(['ssl' => [
'capture_session_meta' => TRUE
]]);
$html = file_get_contents('https://google.com/', FALSE, $ctx);
$meta = stream_context_get_options($ctx)['ssl']['session_meta'];
var_dump($meta);
?>
The above example will output:
array(4) {
["protocol"]=>
string(5) "TLSv1"
["cipher_name"]=>
string(20) "ECDHE-RSA-AES128-SHA"
["cipher_bits"]=>
int(128)
["cipher_version"]=>
string(11) "TLSv1/SSLv3"
}
Encrypted client streams already support perfect forward secrecy, as it is generally controlled by the server. PHP encrypted server streams using certificates capable of perfect forward secrecy do not need to take any additional action to enable PFS; however a number of new SSL context options have been added to allow more control over PFS and deal with any compatibility issues that may arise.
ecdh_curveThis option allows the selection of a specific curve for use with ECDH ciphers. If not specified, prime256v1 will be used.
dh_paramA path to a file containing parametrs for Diffie-Hellman key exchange, such as that created by the following command:
openssl dhparam -out /path/to/my/certs/dh-2048.pem 2048
single_dh_use
If set to TRUE, a new key pair will be created when using
Diffie-Hellman parameters, thereby improving forward secrecy.
single_ecdh_use
If set to TRUE, a new key pair will always be generated when ECDH
cipher suites are negotiated. This improves forward secrecy.
It is now possible to select specific versions of SSL and TLS via the
crypto_method SSL context option or by specifying a
specific transport when creating a stream wrapper (for example, by calling
stream_socket_client() or
stream_socket_server()).
The crypto_method SSL context option accepts a
bitmask enumerating the protocols that are permitted, as does the
crypto_type of
stream_socket_enable_crypto().
| Protocol(s) | Client flag | Server flag | Transport |
|---|---|---|---|
| Any TLS or SSL version | STREAM_CRYPTO_METHOD_ANY_CLIENT |
STREAM_CRYPTO_METHOD_ANY_SERVER |
ssl:// |
| Any TLS version | STREAM_CRYPTO_METHOD_TLS_CLIENT |
STREAM_CRYPTO_METHOD_TLS_SERVER |
tls:// |
| TLS 1.0 | STREAM_CRYPTO_METHOD_TLSv_1_0_CLIENT |
STREAM_CRYPTO_METHOD_TLSv_1_0_SERVER |
tlsv1.0:// |
| TLS 1.1 | STREAM_CRYPTO_METHOD_TLSv_1_1_CLIENT |
STREAM_CRYPTO_METHOD_TLSv_1_1_SERVER |
tlsv1.1:// |
| TLS 1.2 | STREAM_CRYPTO_METHOD_TLSv_1_2_CLIENT |
STREAM_CRYPTO_METHOD_TLSv_1_2_SERVER |
tlsv1.2:// |
| SSL 3 | STREAM_CRYPTO_METHOD_SSLv3_CLIENT |
STREAM_CRYPTO_METHOD_SSLv3_SERVER |
sslv3:// |
<?php
// Requiring TLS 1.0 or better when using file_get_contents():
$ctx = stream_context_create([
'ssl' => [
'crypto_method' => STREAM_CRYPTO_METHOD_TLS_CLIENT,
],
]);
$html = file_get_contents('https://google.com/', false, $ctx);
// Requiring TLS 1.1 or 1.2:
$ctx = stream_context_create([
'ssl' => [
'crypto_method' => STREAM_CRYPTO_METHOD_TLSv_1_1_CLIENT |
STREAM_CRYPTO_METHOD_TLSv_1_2_CLIENT,
],
]);
$html = file_get_contents('https://google.com/', false, $ctx);
// Connecting using the tlsv1.2:// stream socket transport.
$sock = stream_socket_client('tlsv1.2://google.com:443/');
?>
The openssl_get_cert_locations() function has been added: it returns the default locations PHP will search when looking for CA bundles.
<?php
var_dump(openssl_get_cert_locations());
?>
The above example will output:
array(8) {
["default_cert_file"]=>
string(21) "/etc/pki/tls/cert.pem"
["default_cert_file_env"]=>
string(13) "SSL_CERT_FILE"
["default_cert_dir"]=>
string(18) "/etc/pki/tls/certs"
["default_cert_dir_env"]=>
string(12) "SSL_CERT_DIR"
["default_private_dir"]=>
string(20) "/etc/pki/tls/private"
["default_default_cert_area"]=>
string(12) "/etc/pki/tls"
["ini_cafile"]=>
string(0) ""
["ini_capath"]=>
string(0) ""
}