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2.2.13 ALG_ID

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The ALG_ID type is used to denote an algorithm type for cryptographic keys. An implementation SHOULD<26> support all of the values shown in the following table. Implementations MAY<27> choose to support other algorithms and values not shown here; if they do, they SHOULD reuse the values specified in [MSDN-CRYPTO] in order to avoid collisions. Implementations MAY<28> restrict the set of supported algorithms based on administrative policy.

 Algorithm used

 Value for ALG_ID

 Entropy

 Key length

CALG_AES_256

0x6610

256

32

CALG_3DES

0x6603

168

24

 In this table, Entropy represents the number of bits of true randomness in the algorithm's key material, while Key length represents the total size of the key in bytes. For CALG_3DES, the difference between entropy and key length is due to the parity bits included in the key. For more information, see [TDEA].

This type is declared as follows:

 typedef unsigned int ALG_ID;