SSLCIPH (JANUS DEFINE parameter)

SSLCIPH xxx — Limit SSL ciphers offered by this port

SSLCIPH is a parameter on JANUS DEFINE, which defines and sets characteristics of a Janus port.

This parameter lets you limit the stream ciphers (encryption algorithms) that this port offers for SSL connections. A Janus port whose definition includes an SSL parameter supports Janus Network Security SSL (Secure Sockets Layer) or TLS (Transport Layer Security) encrypted connections.

Typically, SSLCIPH is allowed to default to 0: all the Janus-supported ciphers are available, and the cipher that is ultimately used depends on the outcome of the handshake negotiation with the client that seeks the service at this port. The negotiation selects the strongest available cipher that the client can support.

However, to make only a subset of the server ciphers available, you can specify SSLCIPH followed by the (bitmask) value that selects the subset. For example, SSLCIPH 2 indicates that only strong RC4 encryption is available. It is probably a good idea to disable export ciphers as they are weakened by design, and given that the current preferred cipher is AES, it might make sense to set SSLCIPH to X'03C0' to force AES bulk encryption.

Currently, these ciphers are supported:

Bit	TLS specification symbol	Description
X'0001'	TLS_RSA_EXPORT_WITH_RC4_40_MD5	RC4 bulk cipher with MD5 digest algorithm with 40 bits of the 128 bit RC4 key transmitted encrypted, the rest transmitted "in the clear" (unencrypted). This is considered a weak level of encryption because of the small number of bits in the unencrypted part of the key.
X'0002'	TLS_RSA_WITH_RC4_128_MD5	RC4 bulk cipher with the MD5 digest algorithm with all 128 bits of the RC4 key transmitted encrypted. This is considered a fairly strong encryption algorithm although MD5 is generally deprecated as a digest algorithm.
X'0004'	TLS_RSA_WITH_RC4_128_SHA	RC4 bulk cipher with the SHA digest algorithm with all 128 bits of the RC4 key transmitted encrypted. This is considered a fairly strong encryption algorithm and is preferable to TLS_RSA_WITH_RC4_128_MD5 because SHA is considered a superior digest algorithm.
X'0008'	TLS_RSA_EXPORT_WITH_DES40_CBC_SHA	DES bulk cipher with SHA digest algorithm with 40 bits of the 56 bit DES key transmitted encrypted, the rest transmitted "in the clear" (unencrypted). This is considered a weak level of encryption because of the small number of bits in the unencrypted part of the key.
X'0010'	TLS_RSA_WITH_DES_CBC_SHA	DES bulk cipher with SHA digest algorithm with all 56 bits of the DES key transmitted encrypted. This is considered a weak level of encryption because of the small number of bits in the key.
X'0020'	TLS_RSA_WITH_3DES_EDE_CBC_SHA	Triple-DES bulk cipher with SHA digest algorithm with an encrypted 168 bit key. This is considered a fairly strong level of encryption.
X'0040'	TLS_RSA_WITH_AES_128_CBC_SHA	AES bulk cipher with SHA digest algorithm with an encrypted 128 bit key and encrypting 128 bit blocks. This is considered a strong level of encryption.
X'0080'	TLS_RSA_WITH_AES_256_CBC_SHA	AES bulk cipher with SHA digest algorithm with an encrypted 256 bit key and encrypting 256 bit blocks. This is considered a strong level of encryption.
X'0100'	TLS_RSA_WITH_AES_128_CBC_SHA256	AES bulk cipher with SHA-256 digest algorithm with an encrypted 128 bit key and encrypting 128 bit blocks. This is considered a strong level of encryption.
X'0200'	TLS_RSA_WITH_AES_256_CBC_SHA256	AES bulk cipher with SHA-256 digest algorithm with an encrypted 256 bit key and encrypting 256 bit blocks. This is considered a strong level of encryption.

SSLCIPH is valid for SRVSOCK, WEBSERV, OPENSERV, and SDS port types.

See also

• SSLPROT (JANUS DEFINE parameter)
• List of Janus commands
• List of JANUS DEFINE parameters