RSA Security Projection Television 5.2.2 Uživatelský manuál stáhnout pdf (Strana 204)

Block Ciphers

182 RSA BSAFE Crypto-C Developer’s Guide

Now that you have a key, you need an algorithm chooser and a surrender context.

This is a speedy function, so you can use a properly cast

NULL_PTR for the surrender

context; but you do want to build a chooser:

Step 4: Update

Enter the data to encrypt with B_EncryptUpdate. The Reference Manual Chapter 2 entry

for

AI_FeedbackCipher states that you may pass (B_ALGORITHM_OBJ)NULL_PTR for all

randomAlgorithm

arguments. Once you have your input, call B_EncryptUpdate.

Remember that DES is a block cipher and requires input that is a multiple of eight

bytes. Because you set

fbParams.paddingMethodName

to "pad" (see page 180), Crypto-

C will pad to make the input a multiple of eight bytes. That means that the output

buffer should be at least eight bytes longer than the input length. DES is a fast

algorithm, so for small amounts of data it is reasonable to pass a properly cast

NULL_PTR for the surrender context. If you want to pass a surrender context, refer to

the following code sample:

B_ALGORITHM_METHOD *DES_CBC_CHOOSER[] = {

&AM_CBC_ENCRYPT,

&AM_DES_ENCRYPT,

&AM_SHA_RANDOM,

(B_ALGORITHM_METHOD *)NULL_PTR

};

if ((status = B_EncryptInit

(encryptionObject, desKey, DES_CBC_CHOOSER,

(A_SURRENDER_CTX *)NULL_PTR)) != 0)

break;

static char *dataToEncrypt = "Encrypt this sentence.";

unsigned char *encryptedData = NULL_PTR;

unsigned int outputBufferSize;

unsigned int outputLenUpdate, outputLenFinal;

unsigned int encryptedDataLen;

encryptedDataLen = dataToEncryptLen + 8;

encryptedData = T_malloc (encryptedDataLen);

if ((status = (encryptedData == NULL_PTR)) != 0)

break;

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RSA Security Projection Television 5.2.2 Uživatelský manuál Strana 204