Syntax for All Other Cipher Suite Specifications
For any cipher suite list that is not specified in a connection factory of a Java client, use the OpenSSL syntax. In particular, C clients and the ssl_server_ciphers configuration parameter require OpenSSL syntax.
In OpenSSL syntax, specifying a cipher suite name adds that cipher suite to the list. Each cipher suite name can be preceded by a qualifier. Cipher suite names are case-sensitive. The following table describes the qualifiers available using OpenSSL syntax.
| Qualifier | Description |
|---|---|
| / | When entered as the first item in the list, this option causes EMS to begin with an empty list, and add the ciphers that follow the slash.
If the / does not prefix the cipher list, then EMS prefixes the cipher list with the OpenSSL cipher string DEFAULT. This modifier can only be used at the beginning of the list. If the / appears elsewhere, the syntax of the cipher suite list will be incorrect and cause an error. |
| + | Moves the cipher to the end of the list.
This qualifier is used to move an existing cipher. It can not be used to add a new cipher to the list. |
| - | Remove the cipher from the list of ciphers. When this option is used, the cipher can be added later on in the list of ciphers. |
| ! | Permanently disable the cipher within the list of ciphers. Use this option if you wish to remove a cipher and you do not want later items in the list to add the cipher to the list. This qualifier takes precedence over all other qualifiers. |
| ALL | All ciphers from the list (except null ciphers). You can use this keyword to add or remove all ciphers.
At least one cipher suite must be present or the SSL connection fails to initialize. So, after using -ALL, you should add at least one cipher to the list. |
This example specifies cipher suites in the ssl_server_ciphers configuration parameter.
ssl_server_ciphers = -ALL:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384
ssl_server_ciphers = !ECDHE-RSA-AES128-GCM-SHA256:ALL