# zx_cprng_add_entropy

## NAME

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cprng_add_entropy - Add entropy to the kernel CPRNG

## SYNOPSIS

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```
#include <zircon/syscalls.h>

zx_status_t zx_cprng_add_entropy(const void* buffer, size_t buffer_size);
```

## DESCRIPTION

`zx_cprng_add_entropy()` mixes the given entropy into the kernel CPRNG.
a privileged operation.  It will accept at most **ZX_CPRNG_ADD_ENTROPY_MAX_LEN**
bytes of entropy at a time.

## RIGHTS

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TODO(ZX-2399)

## RETURN VALUE

`zx_cprng_add_entropy()` returns **ZX_OK** on success.

## ERRORS

**ZX_ERR_INVALID_ARGS** *buffer_size* is too large, or *buffer* is not a valid
userspace pointer.

## BUGS

This syscall should be very privileged.