This structure holds the physical key size and the effective key size for a given key. The metric used is bits. The number of effective bits is the number of key bits that can be used in a cryptographic operation compared with the number of bits that may be present in the key. When the number of effective bits is less than the number of actual bits, this is known as "dumbing down".

typedef struct cssm_key_size {
    uint32 KeySizeInBits;/* Key size in bits */
    uint32 EffectiveKeySizeInBits; /* Effective key size in bits */
} CSSM_KEYSIZE, *CSSM_KEYSIZE_PTR

Definitions:

KeySizeInBits

The actual number of bits in a key.

EffectiveKeySizeInBits

The number of key bits that can be used for cryptographic operations.