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crypto: Add support for AES-CTR

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lukechampine 2019-11-04 17:07:14 -05:00 committed by Andrew Kelley
parent 1657bead46
commit 3d907b2943
1 changed files with 47 additions and 0 deletions
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47
lib/std/crypto/aes.zig
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@ -115,6 +115,14 @@ pub fn decryptBlock(xk: []const u32, dst: []u8, src: []const u8) void {
mem.writeIntSliceBig(u32, dst[12..16], s3);
}
fn xorBytes(dst: []u8, a: []const u8, b: []const u8) usize {
var n = std.math.min(dst.len, std.math.min(a.len, b.len));
for (dst[0..n]) |_, i| {
dst[i] = a[i] ^ b[i];
}
return n;
}
pub const AES128 = AES(128);
pub const AES256 = AES(256);
@ -138,9 +146,48 @@ fn AES(comptime keysize: usize) type {
pub fn decrypt(ctx: Self, dst: []u8, src: []const u8) void {
decryptBlock(ctx.dec[0..], dst, src);
}
pub fn ctr(ctx: Self, dst: []u8, src: []const u8, iv: [16]u8) void {
std.debug.assert(dst.len >= src.len);
var keystream: [16]u8 = undefined;
var ctrbuf = iv;
var n: usize = 0;
while (n < src.len) {
ctx.encrypt(keystream[0..], ctrbuf[0..]);
var ctr_i = std.mem.readIntSliceBig(u128, ctrbuf[0..]);
std.mem.writeIntSliceBig(u128, ctrbuf[0..], ctr_i +% 1);
n += xorBytes(dst[n..], src[n..], keystream);
}
}
};
}
test "ctr" {
// NIST SP 800-38A pp 55-58
{
const key = [_]u8{ 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c };
const iv = [_]u8{ 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff };
const in = [_]u8{
0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96, 0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c, 0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11, 0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17, 0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10,
};
const exp_out = [_]u8{
0x87, 0x4d, 0x61, 0x91, 0xb6, 0x20, 0xe3, 0x26, 0x1b, 0xef, 0x68, 0x64, 0x99, 0x0d, 0xb6, 0xce,
0x98, 0x06, 0xf6, 0x6b, 0x79, 0x70, 0xfd, 0xff, 0x86, 0x17, 0x18, 0x7b, 0xb9, 0xff, 0xfd, 0xff,
0x5a, 0xe4, 0xdf, 0x3e, 0xdb, 0xd5, 0xd3, 0x5e, 0x5b, 0x4f, 0x09, 0x02, 0x0d, 0xb0, 0x3e, 0xab,
0x1e, 0x03, 0x1d, 0xda, 0x2f, 0xbe, 0x03, 0xd1, 0x79, 0x21, 0x70, 0xa0, 0xf3, 0x00, 0x9c, 0xee,
};
var out: [exp_out.len]u8 = undefined;
var aes = AES128.init(key);
aes.ctr(out[0..], in[0..], iv);
testing.expectEqualSlices(u8, exp_out[0..], out[0..]);
}
}
test "encrypt" {
// Appendix B
{