|Allegro CL version 8.2|
New since 8.2 release.
Arguments: &key method certificate key certificate-password method verify max-depth ca-file ca-directory ciphers crl-check crl-file (prefer-server-cipher-order t)
This function was added by a patch (to versions 8.2 and 9.0) released in April, 2014. You must have updated (with sys:update-allegro or related technique) to use this function.
This function creates and returns an SSL context object (an instance
of the class
excl::ssl-context) suitable for use as
the value of the context keyword argument
The context has values for all relevant arguments. For the arguments method, ciphers, verify, max-depth, and prefer-server-cipher-order, specifying a value in a call to make-ssl-server-stream which is also passed a context object as the value of the context argument causes the associated argument value to be local to that connection (i.e. the specified argument value overrides the value in the context object). The value for the arguments certificate, key, ca-file, ca-directory, certificate-password, crl-file, and crl-check cannot be overridden when a context is provided. It is an error to supply a context and values for any of those arguments.
The keyword arguments are:
:tlsv1+) this argument allows control over the SSL protocol handshake process. Supported SSL protocols are SSLv2, SSLv3, TLSv1, TLSv1.1, and TLSv1.2 from oldest to newest. The method keyword argument can be:
:tlsv1.2. This provide the ability to specify precisely which ssl methods one wants to allow, helping to mitigate downgrade attacks to weaker methods (anything before tlsv1).
:tlsv1+: support TLSv1, TLSv1.1, and TLSv1.2. This is the default.
:sslv3+: support SSLv3, TLSv1, TLSv1.1, and TLSv1.2.
:sslv23: the server will handle SSLv2, SSLv3, and TLSv1. The highest protocol version that is common between the client and server will be selected. This method allows for best compatibility. This option is out of date but supported for backward compatibility.
:sslv2: the server will only handle SSLv2. This option is not recommended as SSLv2 has known security issues (such as susceptibility to man In the middle attacks).
:sslv3: the server will only handle SSLv3. This option is not recommended as SSLv3 has known security issues (such as susceptibility to man In the middle attacks).
:tlsv1: the server will only handle TLSv1.
nil) this argument names a file which contains one or more PEM-encoded certificates. The first (or only) certificate in the file will be used to identify the client (in the case of make-ssl-client-stream). Optionally, subsequent entries in the file may be used to supply intermediate CA certificates (also known as a certificate chain).
nil) this argument is a string or pathname naming a file containing the private RSA key corresponding the the public key in the certificate. The file must be in PEM format. The key can be stored in an encrypted form which requires a pass phrase to read, but in that case the certificate-password must also be specified. If the key is stored in the certificate file, then you needn't specify the key argument.
nil) this argument, if specified, should be a string. If the private key stored with the certificate inside the file named by the certificate argument is encrypted, then this value is used as the key to decrypt it.
nil) this argument can be
:required. Due to the way OpenSSL is implemented, the behavior of peer verification differs for servers and clients; here is the behavior for servers:
:verify nilmeans that the server will not ask the client to supply a certificate and will not do automatic verification if the client supplies a certificate anyway. If the client does provide a certificate, manual verification can be done using get-ssl-peer-certificate and get-ssl-verify-result.
:verify :optionalmeans that the client will be asked to supply a certificate during SSL handshake. The certificate (if supplied) will be automatically verified during SSL handshake. If verification fails, an error will be generated during SSL handshake.
:verify :requiredmeans that the client will be asked to supply a certificate during SSL handshake. The client certificate will be automatically verified during SSL handshake. If the client does not supply a certificate or if verification of the supplied certificate fails, an error will be generated during SSL handshake.
nil) this argument specifies the name of a directory containing a series of trusted Intermediate CA or Root CA certificate files that will be used during peer certificate verification. Each file in the directory should contain one certificate. The files should be named based on the hash value of the certificate subject name. If more than one certificate with the same hash value exists, the extension must be different (e.g. 9d66eef0.0, 9d66eef0.1 etc). The search is performed in the ordering of the extension number, regardless of other properties of the certificates. Use the c_rehash (available via standard OpenSSL distributions) utility to create the necessary links.
nil) this argument controls certificate revocation list (CRL) checking. Its value may be
nil(the default) for no CRL checking,
tfor CRL checking of the peer's certificate (if provided by the peer), or
:allfor CRL checking of all components of the peer's supplied certificate chain. If this argument is non-
nil, the verify argument must also be non-
nil. If you enable CRL checking, you must supply a proper PEM-encoded CRL, even if it contains zero revocations. If you do not supply a CRL, peer verification will never succeed.
nilor not supplied, defaults to the value of the ca-file argument. It is acceptable for CRL to be included amongst other PEM-encoded certificates.
t). The typical behavior when choosing a cipher during an SSLv3 or TLSv1 handshake is to use the client's preference. If this argument is true (the default), the server's preference will be used.
See socket.htm for information on sockets. For information on Secure Sockets, see the section Secure Socket Layer (SSL) in that document.
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This page is new in the 8.2 release.
|Allegro CL version 8.2|
New since 8.2 release.