Cryptographic Token Interface Standard

PKCS#11

CK_KEY_DERIVATION_STRING_DATA Reference

CK_KEY_DERIVATION_STRING_DATA

. More...


Data Fields

CK_BYTE_PTR pData
 pointer to the byte string. More...

CK_ULONG ulLen
 length of the byte string. More...

Detailed Description

CK_KEY_DERIVATION_STRING_DATA

.
pData pointer to the byte string
ulLen length of the byte string

CK_KEY_DERIVATION_STRING_DATA_PTR

CK_KEY_DERIVATION_STRING_DATA_PTR points to a CK_KEY_DERIVATION_STRING_DATA structure. It is implementation-dependent.

CK_EXTRACT_PARAMS

CK_KEY_EXTRACT_PARAMS provides the parameter to the CKM_EXTRACT_KEY_FROM_KEY mechanism. It specifies which bit of the base key should be used as the first bit of the derived key. It is defined as follows: 

typedef CK_ULONG CK_EXTRACT_PARAMS;

CK_EXTRACT_PARAMS_PTR

CK_EXTRACT_PARAMS_PTR points to a CK_EXTRACT_PARAMS. It is implemenation-dependent.

Miscellaneous simple key derivation mechanisms

Concatenation of a base key and another key

This mechanism, denoted CKM_CONCATENATE_BASE_AND_KEY, derives a secret key from the concatenation of two existing secret keys. The two keys are specified by handles; the values of the keys specified are concatenated together in a buffer.

This mechanism takes a parameter, a CK_OBJECT_HANDLE. This handle produces the key value information which is appended to the end of the base key's value information (the base key is the key whose handle is supplied as an argument to C_DeriveKey).

For example, if the value of the base key is 0x01234567, and the value of the other key is 0x89ABCDEF, then the value of the derived key will be taken from a buffer containing the string 0x0123456789ABCDEF.

If the requested type of key requires more bytes than are available by concatenating the two original keys' values, an error is generated.

This mechanism has the following rules about key sensitivity and extractability:

This mechanism, denoted CKM_CONCATENATE_BASE_AND_DATA, derives a secret key by concatenating data onto the end of a specified secret key. 

This mechanism takes a parameter, a CK_KEY_DERIVATION_STRING_DATA structure, which specifies the length and value of the data which will be appended to the base key to derive another key.

For example, if the value of the base key is 0x01234567, and the value of the data is 0x89ABCDEF, then the value of the derived key will be taken from a buffer containing the string 0x0123456789ABCDEF.

If the requested type of key requires more bytes than are available by concatenating the original key's value and the data, an error is generated.

This mechanism has the following rules about key sensitivity and extractability:

This mechanism, denoted CKM_CONCATENATE_DATA_AND_BASE, derives a secret key by prependting data to the start of a specified secret key. 

This mechanism takes a parameter, a CK_KEY_DERIVATION_STRING_DATA structure, which specifies the length and value of the data which will be prepended to the base key to derive another key.

For example, if the value of the base key is 0x01234567, and the value of the data is 0x89ABCDEF, then the value of the derived key will be taken from a buffer containing the string 0x89ABCDEF01234567.

If the requested type of key requires more bytes than are available by concatenating the data and the original key's value, an error is generated.

This mechanism has the following rules about key sensitivity and extractability:

XORing key derivation, denoted CKM_XOR_BASE_AND_DATA, is a mechanism which provides the capability of deriving a secret key by performing a bit XORing of a key pointed to by a base key handle and some data. 

This mechanism takes a parameter, a CK_KEY_DERIVATION_STRING_DATA structure, which specifies the data with which to XOR the original key's value.

For example, if the value of the base key is 0x01234567, and the value of the data is 0x89ABCDEF, then the value of the derived key will be taken from a buffer containing the string 0x88888888.

If the requested type of key requires more bytes than are available by taking the shorter of the data and the original key's value, an error is generated.

This mechanism has the following rules about key sensitivity and extractability:

Extraction of one key from another key, denoted CKM_EXTRACT_KEY_FROM_KEY, is a mechanism which provides the capability of creating one secret key from the bits of another secret key.

This mechanism has a parameter, a CK_EXTRACT_PARAMS, which specifies which bit of the original key should be used as the first bit of the newly-derived key.

We give an example of how this mechanism works. Suppose a token has a secret key with the 4-byte value 0x329F84A9. We will derive a 2-byte secret key from this key, starting at bit position 21 (i.e., the value of the parameter to the CKM_EXTRACT_KEY_FROM_KEY mechanism is 21).

  1. We write the key's value in binary: 0011 0010 1001 1111 1000 0100 1010 1001. We regard this binary string as holding the 32 bits of the key, labelled as b0, b1, ..., b31.

  2. We then extract 16 consecutive bits (i.e., 2 bytes) from this binary string, starting at bit b21. We obtain the binary string 1001 0101 0010 0110.

  3. The value of the new key is thus 0x9526.

Note that when constructing the value of the derived key, it is permissible to wrap around the end of the binary string representing the original key's value.

If the original key used in this process is sensitive, then the derived key must also be sensitive for the derivation to succeed.

If the requested type of key requires more bytes than the original key has, an error is generated.

This mechanism has the following rules about key sensitivity and extractability:

Field Documentation

CK_BYTE_PTR pData
 

pointer to the byte string.

CK_ULONG ulLen
 

length of the byte string.

RSA Security Inc. Public-Key Cryptography Standards - PKCS#11 - v200