SSL context options

SSL context optionsSSL context option listing


Context options for ssl:// and tls:// transports.


peer_name string

Peer name to be used. If this value is not set, then the name is guessed based on the hostname used when opening the stream.

verify_peer bool

Require verification of SSL certificate used.

Defaults to true.

verify_peer_name bool

Require verification of peer name.

Defaults to true.

allow_self_signed bool

Allow self-signed certificates. Requires verify_peer.

Defaults to false

cafile string

Location of Certificate Authority file on local filesystem which should be used with the verify_peer context option to authenticate the identity of the remote peer.

capath string

If cafile is not specified or if the certificate is not found there, the directory pointed to by capath is searched for a suitable certificate. capath must be a correctly hashed certificate directory.

local_cert string

Path to local certificate file on filesystem. It must be a PEM encoded file which contains your certificate and private key. It can optionally contain the certificate chain of issuers. The private key also may be contained in a separate file specified by local_pk.

local_pk string

Path to local private key file on filesystem in case of separate files for certificate (local_cert) and private key.

passphrase string

Passphrase with which your local_cert file was encoded.

verify_depth int

Abort if the certificate chain is too deep.

Defaults to no verification.

ciphers string

Sets the list of available ciphers. The format of the string is described in » ciphers(1).

Defaults to DEFAULT.

capture_peer_cert bool

If set to true a peer_certificate context option will be created containing the peer certificate.

capture_peer_cert_chain bool

If set to true a peer_certificate_chain context option will be created containing the certificate chain.

SNI_enabled bool

If set to true server name indication will be enabled. Enabling SNI allows multiple certificates on the same IP address.

disable_compression bool

If set, disable TLS compression. This can help mitigate the CRIME attack vector.

peer_fingerprint string | array

Aborts when the remote certificate digest doesn't match the specified hash.

When a string is used, the length will determine which hashing algorithm is applied, either "md5" (32) or "sha1" (40).

When an array is used, the keys indicate the hashing algorithm name and each corresponding value is the expected digest.

security_level int

Sets the security level. If not specified the library default security level is used. The security levels are described in » SSL_CTX_get_security_level(3).

Available as of PHP 7.2.0 and OpenSSL 1.1.0.


Version Description
7.2.0 Added security_level. Requires OpenSSL >= 1.1.0.


Note: Because ssl:// is the underlying transport for the https:// and ftps:// wrappers, any context options which apply to ssl:// also apply to https:// and ftps://.

Note: For SNI (Server Name Indication) to be available, then PHP must be compiled with OpenSSL 0.9.8j or greater. Use the OPENSSL_TLSEXT_SERVER_NAME to determine whether SNI is supported.

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User Contributed Notes 9 notes

website at meezaan dot net
7 years ago
There is also a crypto_type context. In older versions this was crypto_method. This is referenced on
tianyiw at vip dot qq dot com
1 year ago
Enable SNI (Server Name Indication):
PEM must be contains certificate and private key.
= stream_context_create([
'ssl' => [
'SNI_enabled' => true,
'SNI_server_certs' => [
'' => '/path/',
'' => '/path/',
gabri dot ns at gmail dot com
4 years ago
i usually download root CA certificate from then put it as 'cafile' and it work almost all of the time.

the only problem i'v ever found is when the server does not properly sending intermediete CA certificate, then, you must add it manually to the file.
7 years ago
I am unable to load a PEM that was generated with the stunnel tools. However, I am able to use PHP calls to generate a working PEM that is recognized both by stunnel and php, as outlined here:

This code fragment is now working for me, and with stunnel verify=4, both sides confirm the fingerprint. Oddly, if "tls://" is set below, then TLSv1 is forced, but using "ssl://" allows TLSv1.2:

$stream_context = stream_context_create([ 'ssl' => [
'local_cert' => '/path/to/key.pem',
'peer_fingerprint' => openssl_x509_fingerprint(file_get_contents('/path/to/key.crt')),
'verify_peer' => false,
'verify_peer_name' => false,
'allow_self_signed' => true,
'verify_depth' => 0 ]]);

$fp = stream_socket_client('ssl://',
$errno, $errstr, 30, STREAM_CLIENT_CONNECT, $stream_context);
fwrite($fp, "foo bar\n");
while($line = fgets($fp, 8192)) echo $line;
consatangmail dot com
2 years ago
recommended use "ssl://" transport.

in php 5.5 ~ 7.1
ssl:// transport = ssl_v2|ssl_v3|tls_v1.0|tls_v1.1|tls_v1.2
tls:// transport = tls_v1.0

after 7.2 ssl:// and tls:// transports is same
php 7.2 ~ 7.3 = tls_v1.0|tls_v1.1|tls_v1.2
php 7.4 ~ 8.1 = tls_v1.0|tls_v1.1|tls_v1.2|tls_v1.3
Botjan kufca
14 years ago
CN_match works contrary to intuitive thinking. I came across this when I was developing SSL server implemented in PHP. I stated (in code):

- do not allow self signed certs (works)
- verify peer certs against CA cert (works)
- verify the client's CN against CN_match (does not work), like this:

stream_context_set_option($context, 'ssl', 'CN_match', '*');

I presumed this would match any client with CN below domain.
Unfortunately this is NOT the case. The option above does not do that.

What it really does is this:
- it takes client's CN and compares it to CN_match
- IF CLIENT's CN CONTAINS AN ASTERISK like *, then it is matched against CN_match in wildcard matching fashion

Examples to illustrate behaviour:
(CNM = server's CN_match)
(CCN = client's CN)

-, ---> OK
-, CCN=* ---> OK
-, CCN=* ---> OK
-, CCN=* ---> ERROR

- CNM=*, ---> ERROR
- CNM=*, CCN=* ---> OK

According to PHP sources I believe that the same applies if you are trying to act as Client and the server contains a wildcard certificate. If you set CN_match to and server presents itself with *, the connection is allowed.

Everything above applies to PHP version 5.2.12.
I will supply a patch to support CN_match starting with asterisk.
borbas dot geri at gmail dot com
10 years ago
I used this for Apple Push Notification Service.
Passed in a local certificate filename `cert.pem` trough local_cert option.
Worked fine, when invoked the script directly.

But when I included/required the script from a different location, it stopped working, without any explicit error message.

Resolved by passed in the full path for the file `<FullPathTo>cert.pem`.
mechtecs at gmail dot com
5 years ago
If you want to validate the server against a local certificate, which you already saved, to further validate the target server, you have to use a fullchain.pem. Then the verify_peer option will work. So just get the server certificate, and search the root CA's pem's and copy everything into a single file. For example:

My certificate has the "GeoTrust TLS RSA CA G1" certificate in the chain, so you google that string. Go to the official digicert Geotrust page and download the "GeoTrustTLSRSACAG1.crt" certificate. Then you can use the following command to convert it into the pem format:
openssl x509 -inform DER -in GeoTrustTLSRSACAG1.crt -out GeoTrustTLSRSACAG1.crt.pem -outform PEM
7 years ago
It appears that "allow_self_signed" does not and cannot apply to the local_cert option.

The stunnel verify=4 option, which verifies but ignores a CA, has no analog in these settings, which is unfortunate.

Even more perplexingly, while the "openssl verify -CAfile" is successful, PHP appears unable to use the new ca/crt pair in any configuration.

I did actually link my PHP against a copy of LibreSSL 2.3.8, but PHP oddly is unable to use TLS1.1 or 1.2. It does, however, enable EC secp521r1 (of which my native OpenSSL 0.9.8e is incapable).
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