Publish the RAND_DRBG API

Fixes #4403

This commit moves the internal header file "internal/rand.h" to
<openssl/rand_drbg.h>, making the RAND_DRBG API public.
The RAND_POOL API remains private, its function prototypes were
moved to "internal/rand_int.h" and converted to lowercase.

Documentation for the new API is work in progress on GitHub #5461.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5462)

1 files changed, 57 insertions, 1 deletions

diff --git a/crypto/include/internal/rand_int.h b/crypto/include/internal/rand_int.h
index fc1abd97bc..d90d9c5f63 100644
--- a/crypto/include/internal/rand_int.h
+++ b/crypto/include/internal/rand_int.h
@@ -15,8 +15,64 @@
  * or in the file LICENSE in the source distribution.
  */
 
-#include <openssl/rand.h>
+#ifndef HEADER_RAND_INT_H
+# define HEADER_RAND_INT_H
+
+# include <openssl/rand.h>
+
+/* forward declaration */
+typedef struct rand_pool_st RAND_POOL;
 
 void rand_cleanup_int(void);
 void rand_drbg_cleanup_int(void);
 void rand_fork(void);
+
+/* Hardware-based seeding functions. */
+size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool);
+size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool);
+
+/* DRBG entropy callbacks. */
+size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
+                             unsigned char **pout,
+                             int entropy, size_t min_len, size_t max_len);
+void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
+                               unsigned char *out, size_t outlen);
+size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len);
+
+
+/*
+ * RAND_POOL functions
+ */
+RAND_POOL *rand_pool_new(int entropy_requested, size_t min_len, size_t max_len);
+void rand_pool_free(RAND_POOL *pool);
+
+const unsigned char *rand_pool_buffer(RAND_POOL *pool);
+unsigned char *rand_pool_detach(RAND_POOL *pool);
+
+size_t rand_pool_entropy(RAND_POOL *pool);
+size_t rand_pool_length(RAND_POOL *pool);
+
+size_t rand_pool_entropy_available(RAND_POOL *pool);
+size_t rand_pool_entropy_needed(RAND_POOL *pool);
+size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte);
+size_t rand_pool_bytes_remaining(RAND_POOL *pool);
+
+size_t rand_pool_add(RAND_POOL *pool,
+                     const unsigned char *buffer, size_t len, size_t entropy);
+unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len);
+size_t rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy);
+
+
+/*
+ * Add random bytes to the pool to acquire requested amount of entropy
+ *
+ * This function is platform specific and tries to acquire the requested
+ * amount of entropy by polling platform specific entropy sources.
+ *
+ * If the function succeeds in acquiring at least |entropy_requested| bits
+ * of entropy, the total entropy count is returned. If it fails, it returns
+ * an entropy count of 0.
+ */
+size_t rand_pool_acquire_entropy(RAND_POOL *pool);
+
+#endif