Problem - Kevin Tafuro

This function never fails (save for a catastrophic error in encryption), and it returns
the address of the output buffer.
Here is an implementation of this generator API, which makes use of the block
cipher interface we developed in Recipe 5.5:
/* NOTE: This code should be augmented to reseed after each request
/* for pseudo-random data, as discussed in Recipe 11.6
/*
#ifndef WIN32
#include
#include
#else
#include
#endif
/* if encryption operations fail, you passed in a bad key size or are using a
* hardware API that failed. In that case, be sure to perform error checking.
*/
typedef struct {
SPC_KEY_SCHED ks;
unsigned char ctr[SPC_BLOCK_SZ];
unsigned char lo[SPC_BLOCK_SZ]; /* Leftover block of output */
int ix; /* index into lo */
int kl; /* The length of key used to key the cipher */
} SPC_BCPRNG_CTX;
#ifndef WIN32
static pthread_mutex_t spc_bcprng_mutex = PTHREAD_MUTEX_INITIALIZER;
#define SPC_BCPRNG_LOCK( ) pthread_mutex_lock(&spc_bcprng_mutex);
#define SPC_BCPRNG_UNLOCK( ) pthread_mutex_unlock(&spc_bcprng_mutex);
#else
static HANDLE hSpcBCPRNGMutex;
#define SPC_BCPRNG_LOCK( ) WaitForSingleObject(hSpcBCPRNGMutex, INFINITE)
#define SPC_BCPRNG_UNLOCK( ) ReleaseMutex(hSpcBCPRNGMutex)
#endif
static void spc_increment_counter(SPC_BCPRNG_CTX *prng) {
int i = SPC_BLOCK_SZ;
}
while (i--)
if (++prng->ctr[i]) return;
void spc_bcprng_init(SPC_BCPRNG_CTX *prng, unsigned char *key, int kl,
unsigned char *x, int xl) {
int i = 0;
SPC_BCPRNG_LOCK( );
SPC_ENCRYPT_INIT(&(prng->ks), key, kl);
memset(prng->ctr, 0, SPC_BLOCK_SZ);
Using an Application-Level Generator | 585
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