RSA Security Projection Television 5.2.2 Manual de usuario descargar pdf (Pagina 225)

100

101

Chapter 6 Symmetric-Key Operations 203

Block Ciphers

Step 3a: Creating a Key Object

Step 3b: Setting the Key Data

Now you need to set the key size and pass the bytes of key data. According to the

Reference Manual entry for

AI_AES_CBCPad, the compatible KI type is KI_Item. A key

anywhere from 1-255 bytes is supported. Here, you can use a random 24-byte key. For

most applications, a 128-bit key should be sufficient.]

At this point, you can write the key data to

aesKeyItem.data

. In the sample code, we

fill

aesKeyItem.data

with random bytes:

Once you have passed in the key data, dispose of

aesKeyItem

, because it is no longer

necessary. Crypto-C has already initialized the key object with the necessary data.

/* Create a key object */

if ((status = B_CreateKeyObject (&aesKey)) != 0)

break;

#define KEY_SIZE 24 /* number of bytes in the key */

ITEM aesKeyItem = {NULL, 0};

/* Step 3b: Set the key object with a random AES key */

aesKeyItem.len = KEY_SIZE;

aesKeyItem.data = T_malloc (rc6KeyItem.len);

if ((status = (aesKeyItem.data == NULL_PTR)) != 0)

break;

if ((status = B_GenerateRandomBytes

(randomAlgorithm, aesKeyItem.data, aesKeyItem.len,

(A_SURRENDER_CTX *)NULL_PTR)) != 0)

break;

if ((status = B_SetKeyInfo (aesKey, KI_Item, (POINTER)&aesKeyItem)) != 0)

break;

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RSA Security Projection Television 5.2.2 Manual de usuario Pagina 225

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