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cprng_draw.md

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zx_cprng_draw

SUMMARY

Draw from the kernel's CPRNG.

DECLARATION

#include <zircon/syscalls.h>

void zx_cprng_draw(void* buffer, size_t buffer_size);

DESCRIPTION

zx_cprng_draw() draws random bytes from the kernel CPRNG. This data should be suitable for cryptographic applications.

Clients that require a large volume of randomness should consider using these bytes to seed a user-space random number generator for better performance. "Large" here would mean a large multiple of ZX_CPRNG_DRAW_MAX_LEN, which is currently 256. As always, test the actual latency of your call site before optimizing.

RIGHTS

None.

NOTES

zx_cprng_draw() terminates the calling process if buffer is not a valid userspace pointer.

There are no other error conditions. If its arguments are valid, zx_cprng_draw() will succeed.

SEE ALSO