Ascon is the family of cryptographic constructions standardized by NIST
for lightweight cryptography.
The Zig standard library already included the Ascon permutation itself,
but higher-level constructions built on top of it were intentionally
postponed until NIST released the final specification.
That specification has now been published as NIST SP 800-232:
https://csrc.nist.gov/pubs/sp/800/232/final
With this publication, we can now confidently include these constructions
in the standard library.
In ed25519.zig, we checked if a test succeeds, in which case we
returned an error. This was confusing, and Andrew pointed out that
Zig weights branches against errors by default.
The Zig standard library lacked schemes that resist nonce reuse.
AES-SIV and AES-GCM-SIV are the standard options for this.
AES-GCM-SIV can be very useful when Zig is used to target embedded
systems, and AES-SIV is especially useful for key wrapping.
Also take it as an opportunity to add a bunch of test vectors to
modes.ctr and make sure it works with block ciphers whose size is
not 16.
Add verifyStrict() functions for cofactorless verification.
Also:
- Support messages < 64 characters in the test vectors
- Allow mulDoubleBasePublic to return the identity as a regular
value. There are valid use cases for this.
I noticed this by stress testing my tls server implementation. From time to time curl (and other tools: ab, vegeta) will report invalid signature. I trace the problem to the way how std lib is encoding raw signature into der format. Using raw signature I got in some cases different encoding using std and openssl. Std is not producing minimal der when signature `r` or `s` integers has leading zero(es).
Here is an example to illustrate difference. Notice leading 00 in `s`
integer which is removed in openssl encoding but not in std encoding.
```Zig
const std = @import("std");
test "ecdsa signature to der" {
// raw signature r and s bytes
const raw = hexToBytes(
\\ 49 63 0c 94 95 2e ff 4b 02 bf 35 c4 97 9e a7 24
\\ 20 dc 94 de aa 1b 17 ff e1 49 25 3e 34 ef e8 d0
\\ c4 43 aa 7b a9 f3 9c b9 f8 72 7d d7 0c 9a 13 1e
\\
\\ 00 56 85 43 d3 d4 05 62 a1 1d d8 a1 45 44 b5 dd
\\ 62 9f d1 e0 ab f1 cd 4a 85 d0 1f 5d 11 d9 f8 89
\\ 89 d4 59 0c b0 6e ea 3c 19 6a f7 0b 1a 4a ce f1
);
// encoded by openssl
const expected = hexToBytes(
\\ 30 63 02 30
\\ 49 63 0c 94 95 2e ff 4b 02 bf 35 c4 97 9e a7 24
\\ 20 dc 94 de aa 1b 17 ff e1 49 25 3e 34 ef e8 d0
\\ c4 43 aa 7b a9 f3 9c b9 f8 72 7d d7 0c 9a 13 1e
\\
\\ 02 2f
\\ 56 85 43 d3 d4 05 62 a1 1d d8 a1 45 44 b5 dd
\\ 62 9f d1 e0 ab f1 cd 4a 85 d0 1f 5d 11 d9 f8 89
\\ 89 d4 59 0c b0 6e ea 3c 19 6a f7 0b 1a 4a ce f1
);
// encoded by std
const actual = hexToBytes(
\\ 30 64 02 30
\\ 49 63 0c 94 95 2e ff 4b 02 bf 35 c4 97 9e a7 24
\\ 20 dc 94 de aa 1b 17 ff e1 49 25 3e 34 ef e8 d0
\\ c4 43 aa 7b a9 f3 9c b9 f8 72 7d d7 0c 9a 13 1e
\\
\\ 02 30
\\ 00 56 85 43 d3 d4 05 62 a1 1d d8 a1 45 44 b5 dd
\\ 62 9f d1 e0 ab f1 cd 4a 85 d0 1f 5d 11 d9 f8 89
\\ 89 d4 59 0c b0 6e ea 3c 19 6a f7 0b 1a 4a ce f1
);
_ = actual;
const Ecdsa = std.crypto.sign.ecdsa.EcdsaP384Sha384;
const sig = Ecdsa.Signature.fromBytes(raw);
var buf: [Ecdsa.Signature.der_encoded_length_max]u8 = undefined;
const encoded = sig.toDer(&buf);
try std.testing.expectEqualSlices(u8, &expected, encoded);
}
pub fn hexToBytes(comptime hex: []const u8) [removeNonHex(hex).len / 2]u8 {
@setEvalBranchQuota(1000 * 100);
const hex2 = comptime removeNonHex(hex);
comptime var res: [hex2.len / 2]u8 = undefined;
_ = comptime std.fmt.hexToBytes(&res, hex2) catch unreachable;
return res;
}
fn removeNonHex(comptime hex: []const u8) []const u8 {
@setEvalBranchQuota(1000 * 100);
var res: [hex.len]u8 = undefined;
var i: usize = 0;
for (hex) |c| {
if (std.ascii.isHex(c)) {
res[i] = c;
i += 1;
}
}
return res[0..i];
}
```
Trimming leading zeroes from signature integers fixes encoding.
The TLS 1.2 implementation was incorrectly hardcoded to always send the
secp256r1 public key in the client key exchange message, regardless of
which elliptic curve the server actually negotiated.
This caused TLS handshake failures with servers that preferred other curves
like X25519.
This fix:
- Tracks the negotiated named group from the server key exchange message
- Dynamically selects the correct public key (X25519, secp256r1, or
secp384r1) based on what the server negotiated
- Properly constructs the client key exchange message with the
appropriate key size for each curve type
Fixes TLS 1.2 connections to servers like ziglang.freetls.fastly.net
that prefer X25519 over secp256r1.
It is important we copy the left-overs in the message *before* we XOR
it into the ciphertext, because if we're encrypting in-place (i.e., m ==
c), we will manipulate the message that will be used for tag generation.
This will generate faulty tags when message length doesn't conform with
16 byte blocks.
* std.Io.Reader: fix confused semantics of rebase. Before it was
ambiguous whether it was supposed to be based on end or seek. Now it
is clearly based on seek, with an added assertion for clarity.
* std.crypto.tls.Client: fix panic due to not enough buffer size
available. Also, avoid unnecessary rebasing.
* std.http.Reader: introduce max_head_len to limit HTTP header length.
This prevents crash in underlying reader which may require a minimum
buffer length.
* std.http.Client: choose better buffer sizes for streams and TLS
client. Crucially, the buffer shared by HTTP reader and TLS client
needs to be big enough for all http headers *and* the max TLS record
size. Bump HTTP header size default from 4K to 8K.
fixes#24872
I have noticed however that there are still fetch problems
Validate wildcard certificates as specified in RFC 6125.
In particular, `*.example.com` should match `foo.example.com` but
NOT `bar.foo.example.com` as it previously did.
`Aegis256XGeneric` behaves differently than `Aegis128XGeneric` in that
it currently encrypts associated data instead of just absorbing it. Even
though the end result is the same, there's no point in encrypting and
copying the ad into a buffer that gets overwritten anyway. This fix
makes `Aegis256XGeneric` behave the same as `Aegis128XGeneric`.
Basically everything that has a direct replacement or no uses left.
Notable omissions:
- std.ArrayHashMap: Too much fallout, needs a separate cleanup.
- std.debug.runtime_safety: Too much fallout.
- std.heap.GeneralPurposeAllocator: Lots of references to it remain, not
a simple find and replace as "debug allocator" is not equivalent to
"general purpose allocator".
- std.io.Reader: Is being reworked at the moment.
- std.unicode.utf8Decode(): No replacement, needs a new API first.
- Manifest backwards compat options: Removal would break test data used
by TestFetchBuilder.
- panic handler needs to be a namespace: Many tests still rely on it
being a function, needs a separate cleanup.
added adapter to AnyWriter and GenericWriter to help bridge the gap
between old and new API
make std.testing.expectFmt work at compile-time
std.fmt no longer has a dependency on std.unicode. Formatted printing
was never properly unicode-aware. Now it no longer pretends to be.
Breakage/deprecations:
* std.fs.File.reader -> std.fs.File.deprecatedReader
* std.fs.File.writer -> std.fs.File.deprecatedWriter
* std.io.GenericReader -> std.io.Reader
* std.io.GenericWriter -> std.io.Writer
* std.io.AnyReader -> std.io.Reader
* std.io.AnyWriter -> std.io.Writer
* std.fmt.format -> std.fmt.deprecatedFormat
* std.fmt.fmtSliceEscapeLower -> std.ascii.hexEscape
* std.fmt.fmtSliceEscapeUpper -> std.ascii.hexEscape
* std.fmt.fmtSliceHexLower -> {x}
* std.fmt.fmtSliceHexUpper -> {X}
* std.fmt.fmtIntSizeDec -> {B}
* std.fmt.fmtIntSizeBin -> {Bi}
* std.fmt.fmtDuration -> {D}
* std.fmt.fmtDurationSigned -> {D}
* {} -> {f} when there is a format method
* format method signature
- anytype -> *std.io.Writer
- inferred error set -> error{WriteFailed}
- options -> (deleted)
* std.fmt.Formatted
- now takes context type explicitly
- no fmt string
preparing to rearrange std.io namespace into an interface
how to upgrade:
std.io.getStdIn() -> std.fs.File.stdin()
std.io.getStdOut() -> std.fs.File.stdout()
std.io.getStdErr() -> std.fs.File.stderr()
