RSA Security 5.2.2 manual For now, we declare, Unsigned char *encryptedData = Nullptr

Introductory Example

For now, we declare:

unsigned char *encryptedData = NULL_PTR;

For a stream cipher, the length of the encrypted (output) data is equal to the length of the input data. So we allocate dataToEncryptLen bytes with T_malloc:

encryptedData = T_malloc (dataToEncryptLen);

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

The previous code sample uses the Crypto-C routine T_malloc. Crypto-C supplies its own memory management routines to increase code portability and to meet the special requirements of handling encrypted data. The Crypto-C memory management routines reside in the file tstdlib.c; make sure this file is compiled and linked in. These routines are described in Chapter 4 of the Reference Manual and in “Memory-Management Routines” on page 122 of this manual.

In our example, the T_malloc routine from tstdlib.c returns a pointer to the allocated memory. If, for some reason, it cannot allocate memory (for example, when there is not enough memory available), T_malloc will return NULL_PTR. It is imperative to always check the return value of T_malloc, even if you are allocating only a small number of bytes. T_malloc also sets an unsigned char * variable; it is a good idea to initialize this variable to NULL_PTR. See “Step 6: Destroy” on page 20 for more information.

The third argument to B_EncryptUpdate is a pointer to an unsigned int.

B_EncryptUpdate returns a value indicating how many bytes it placed into the output buffer. It will place this value at the address specified by the pointer to the unsigned int. Make the proper declaration:

unsigned int outputLenUpdate;

Crypto-C might not encrypt all the input data during a call to B_EncryptUpdate. Any unprocessed data will be saved in a buffer inside the algorithm object created by Crypto-C and encrypted during a subsequent call to Update (see “Multiple Updates” on page 29) or during the call to B_EncryptFinal (see “Step 5: Final” on page 19). This is why it is important to keep track of how many bytes Crypto-C wrote to the output buffer.

The fourth argument to B_EncryptUpdate is the size of the output buffer. The Update

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