RSA Security 5.2.2 manual Init

Block Ciphers

rc2Params.effectiveKeyBits = 80; ivItem.data = initVector; ivItem.len = BLOCK_SIZE;

fbParams.encryptionMethodName = (unsigned char *)"rc2"; fbParams.encryptionParams = NULL_PTR; fbParams.feedbackMethodName = (unsigned char *)"cbc"; fbParams.feedbackParams = (POINTER)&ivItem; fbParams.paddingMethodName = (unsigned char *)"pad"; fbParams.paddingParams = NULL_PTR;

if ((status = B_SetAlgorithmInfo

(rc2Encrypter, AI_FeedbackCipher, (POINTER)&fbParams)) != 0) break;

Step 3: Init

You need a key before you can initialize the algorithm object for encryption.

Step 3a: Creating a Key Object

B_KEY_OBJ rc2Key = (B_KEY_OBJ)NULL_PTR;

if ((status = B_CreateKeyObject (&rc2Key)) != 0) break

Step 3b: Setting the Key Object

You are using 80 effective key bits. That does not mean you need exactly ten bytes of key data, although for security reasons, it is important to use at least ten bytes. You can generate 24 bytes (192 bits) of key data and the algorithm will still work at 80 effective bits. Thus, in the future, if you want to increase the effective key bits, you do not have to change the code that generates key data, only the effective key bit parameter.

Key generation is almost the same as with DES, but you will use a different KI. In the Reference Manual Chapter 2 entry for AI_FeedbackCipher, you see you have a choice of KIs. Because your key is going to be 24 bytes, you cannot use KI_8Byte, so choose KI_Item. Looking up KI_Item in Chapter 3 of the Reference Manual, you find that the info you supply to B_SetKeyInfo is a pointer to an ITEM struct, which is:

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