X9.42 Diffie-Hellman private key objects

X9.42 Diffie-Hellman private key objects (object class CKO_PRIVATE_KEY, key type CKK_X9_42_DH) hold X9.42 Diffie-Hellman private keys. The following table defines the X9.42 Diffie-Hellman private key object attributes, in addition to the common attributes defined for this object class:

Table 63, X9.42 Diffie-Hellman Private Key Object Attributes

Attribute	Data type	Meaning
CKA_PRIME^1,4,6	Big integer	Prime p (>= 1024 bits, in steps of 256 bits)
CKA_BASE^1,4,6	Big integer	Base g
CKA_SUBPRIME^1,4,6	Big integer	Subprime q (>= 160 bits)
CKA_VALUE^1,4,6,7	Big integer	Private value x

The CKA_PRIME, CKA_BASE and CKA_SUBPRIME attribute values are collectively the "X9.42 Diffie-Hellman domain parameters". Depending on the token, there may be limits on the length of the key components. See the ANSI X9.42 standard for more information on X9.42 Diffie-Hellman keys.

Note that when generating a X9.42 Diffie-Hellman private key, the X9.42 Diffie-Hellman domain parameters are not specified in the key's template. This is because X9.42 Diffie-Hellman private keys are only generated as part of a X9.42 Diffie-Hellman key pair, and the X9.42 Diffie-Hellman domain parameters for the pair are specified in the template for the X9.42 Diffie-Hellman public key.

The following is a sample template for creating a X9.42 Diffie-Hellman private key object:

CK_OBJECT_CLASS class = CKO_PRIVATE_KEY;
CK_KEY_TYPE keyType = CKK_X9_42_DH;
CK_UTF8CHAR label[] = "A X9.42 Diffie-Hellman private key object";
CK_BYTE subject[] = {...};
CK_BYTE id[] = {123};
CK_BYTE prime[] = {...};
CK_BYTE base[] = {...};
CK_BYTE subprime[] = {...};
CK_BYTE value[] = {...};
CK_BBOOL true = CK_TRUE;
CK_ATTRIBUTE template[] = {
{CKA_CLASS, &class, sizeof(class)},
{CKA_KEY_TYPE, &keyType, sizeof(keyType)},
{CKA_TOKEN, &true, sizeof(true)},
{CKA_LABEL, label, sizeof(label)-1},
{CKA_SUBJECT, subject, sizeof(subject)},
{CKA_ID, id, sizeof(id)},
{CKA_SENSITIVE, &true, sizeof(true)},
{CKA_DERIVE, &true, sizeof(true)},
{CKA_PRIME, prime, sizeof(prime)},
{CKA_BASE, base, sizeof(base)},
{CKA_SUBPRIME, subprime, sizeof(subprime)},
{CKA_VALUE, value, sizeof(value)}
};