-
-/*
- * If every byte of the input contains |entropy_per_bytes| bits of entropy,
- * how many bytes does one need to obtain at least |bits| bits of entropy?
- */
-#define ENTROPY_TO_BYTES(bits, entropy_per_bytes) \
- (((bits) + ((entropy_per_bytes) - 1))/(entropy_per_bytes))
-
-
-/*
- * Checks whether the |pool|'s entropy is available to the caller.
- * This is the case when entropy count and buffer length are high enough.
- * Returns
- *
- * |entropy| if the entropy count and buffer size is large enough
- * 0 otherwise
- */
-size_t rand_pool_entropy_available(RAND_POOL *pool)
-{
- if (pool->entropy < pool->requested_entropy)
- return 0;
-
- if (pool->len < pool->min_len)
- return 0;
-
- return pool->entropy;
-}
-
-/*
- * Returns the (remaining) amount of entropy needed to fill
- * the random pool.
- */
-
-size_t rand_pool_entropy_needed(RAND_POOL *pool)
-{
- if (pool->entropy < pool->requested_entropy)
- return pool->requested_entropy - pool->entropy;
-
- return 0;
-}
-
-/*
- * Returns the number of bytes needed to fill the pool, assuming
- * the input has 'entropy_per_byte' entropy bits per byte.
- * In case of an error, 0 is returned.
- */
-
-size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte)
-{
- size_t bytes_needed;
- size_t entropy_needed = rand_pool_entropy_needed(pool);
-
- if (entropy_per_byte < 1 || entropy_per_byte > 8) {
- RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
- return 0;
- }
-
- bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_per_byte);
-
- if (bytes_needed > pool->max_len - pool->len) {
- /* not enough space left */
- RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
- return 0;
- }
-
- if (pool->len < pool->min_len &&
- bytes_needed < pool->min_len - pool->len)
- /* to meet the min_len requirement */
- bytes_needed = pool->min_len - pool->len;
-
- return bytes_needed;
-}
-
-/* Returns the remaining number of bytes available */
-size_t rand_pool_bytes_remaining(RAND_POOL *pool)
-{
- return pool->max_len - pool->len;
-}
-
-/*
- * Add random bytes to the random pool.
- *
- * It is expected that the |buffer| contains |len| bytes of
- * random input which contains at least |entropy| bits of
- * randomness.
- *
- * Return available amount of entropy after this operation.
- * (see rand_pool_entropy_available(pool))
- */
-size_t rand_pool_add(RAND_POOL *pool,
- const unsigned char *buffer, size_t len, size_t entropy)
-{
- if (len > pool->max_len - pool->len) {
- RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
- return 0;
- }
-
- if (len > 0) {
- memcpy(pool->buffer + pool->len, buffer, len);
- pool->len += len;
- pool->entropy += entropy;
- }
-
- return rand_pool_entropy_available(pool);
-}
-
-/*
- * Start to add random bytes to the random pool in-place.
- *
- * Reserves the next |len| bytes for adding random bytes in-place
- * and returns a pointer to the buffer.
- * The caller is allowed to copy up to |len| bytes into the buffer.
- * If |len| == 0 this is considered a no-op and a NULL pointer
- * is returned without producing an error message.
- *
- * After updating the buffer, rand_pool_add_end() needs to be called
- * to finish the udpate operation (see next comment).
- */
-unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
-{
- if (len == 0)
- return NULL;
-
- if (len > pool->max_len - pool->len) {
- RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
- return NULL;
- }
-
- return pool->buffer + pool->len;
-}
-
-/*
- * Finish to add random bytes to the random pool in-place.
- *
- * Finishes an in-place update of the random pool started by
- * rand_pool_add_begin() (see previous comment).
- * It is expected that |len| bytes of random input have been added
- * to the buffer which contain at least |entropy| bits of randomness.
- * It is allowed to add less bytes than originally reserved.
- */
-size_t rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
-{
- if (len > pool->max_len - pool->len) {
- RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
- return 0;
- }
-
- if (len > 0) {
- pool->len += len;
- pool->entropy += entropy;
- }
-
- return rand_pool_entropy_available(pool);
-}
-