Zilog EZ80F91AZA - Manual (Page 44)

UM020107-1211 SSL Configuration
ZTP Network Security SSL Plug-In
User Manual
38
MIGKAkEA3uxiDPwIuoU6r22inWehs84FBTvrD8bQufdCltw6RAoV+DM5PHkyMLoH\
KEThy65yDANqA0s4tukYX+jEg98IFQJBAKK+9mbWv9G6WqQExbjrjxKUJG863bYR\
QlwmO9kd6hs6rQDa1g1E5UQ9SOrUcs6cLGzuSQYE+0K8G7UEknvAKTYCAgCg"};
ASN1_ENC_DATA DheParams =
{
PEM_ENCODED_DATA,
sizeof(DH_Params_Pem)-1,
DH_Params_Pem
};
The p and g values must be encoded as a sequence of two ASN.1 DER integers. The first
integer is the value of the prime modulus, p, and the second integer is the value of the gen-
erator, g. The SSL library assumes that p and g have been chosen appropriately. The ASN.1
DER data can optionally be Base64-encoded (as shown in the example above).
The variable used to specify the DH parameters must be of type ASN1_ENC_DATA block.
The encoding member of the data structure indicates whether the DH parameters are
DER_ENCODED_DATA (i.e., DER-encoded ASN.1 data) or BASE64_DER_ENCODED_DATA
(i.e., Base64 DER-encoded ASN.1 data). Base64 DER-encoded ASN.1 data is also known
as PEM encoding and, therefore, the encoding member of the
ASN1_ENC_DATA variable
can be specified as PEM_ENCODED_DATA .
The length and pData members of the ASN1_ENC_DATA structure indicate the number
of bytes in the encoded data and the address of the first byte of the encoded data.
How to Generate Ephemeral Diffie-Hellman Parameters
The ZTP Network Security SSL Plug-In does not include any utilities to generate Diffie-
Hellman parameters. Third-party utilities must be used to generate Ephemeral Diffie-Hell-
man parameters, if required; Zilog does not recommend or endorse any such utilities. This
section describes how to generate Diffie-Hellman parameters using the
dhparam com-
mand in OpenSSL.
To generate a Diffie-Hellman parameter, enter the following command at the OpenSSL
command prompt:
OpenSSL> dhparam -text -out dh_param.txt 512
This command will produce an output file named dh_param.txt that contains the prime
modulus and generator in text format, as well as a Base64-encoded ASN.1 DER data
block containing the DH parameters. The maximum length of the DH modulus is 512 bits.
An example of the contents of the text file is shown in the following code fragment:
Diffie-Hellman-Parameters: (512 bit)
Note: