shithub: mc

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Add secure clearing util functions.

--- a/lib/crypto/bld.sub

+++ b/lib/crypto/bld.sub

@@ -20,8 +20,9 @@

 	entropy.myr	# currently assumes a /dev/random

 	rand.myr

-	# constant time arithmetic

+	# utilities for subtle bits

 	ct.myr

+	clear.myr

 	lib ../std:std

 	lib ../sys:sys

--- /dev/null

+++ b/lib/crypto/clear.myr

@@ -1,0 +1,27 @@

+use std

+

+pkg crypto =

+	/* designed to facilitating freeing sensitive data */

+	generic	clear	: (p : @a# -> void)

+	generic	slclear	: (sl : @a[:] -> void)

+	generic free	: (p : @a# -> void)

+	generic slfree	: (sl : @a[:] -> void)

+;;

+

+generic clear = {p : @a#

+	std.memfill(p, 0, sizeof(@a))

+}

+

+generic slclear = {p : @a[:]

+	std.memfill(sl, 0, sizeof(@a)*sl.len)

+}

+

+generic free = {p : @a#

+	clear(p)

+	std.free(p)

+}

+

+generic slfree = {sl : @a[:]

+	slclear(p)

+	std.slfree(p)

+}