KangarooTwelve is a family of two fast and secure extendable-output
functions (XOFs): KT128 and KT256. These functions generalize
traditional hash functions by allowing arbitrary output lengths.
KangarooTwelve was designed by SHA-3 authors. It aims to deliver
higher performance than the SHA-3 and SHAKE functions defined in
FIPS 202, while preserving their flexibility and core security
principles.
On high-end platforms, it can take advantage of parallelism,
whether through multiple CPU cores or SIMD instructions.
As modern SHA-3 constructions, KT128 and KT256 can serve as
general-purpose hash functions and can be used, for example, in
key-derivation, and with arbitrarily large inputs.
RFC9861: https://datatracker.ietf.org/doc/rfc9861/
I would like a chance to review this before it lands, please. Feel free
to submit the work again without changes and I will make review
comments.
In the meantime, these reverts avoid intermittent CI failures, and
remove bad patterns from occurring in the standard library that other
users might copy.
Revert "std.crypto: improve KT documentation, use key_length for B3 key length (#25807)"
This reverts commit 4b593a6c24797484e68a668818736b0f6a8d81a2.
Revert "crypto - threaded K12: separate context computation from thread spawning (#25793)"
This reverts commit ee4df4ad3edad160fb737a1935cd86bc2f9cfbbe.
Revert "crypto.kt128: when using incremental hashing, use SIMD when possible (#25783)"
This reverts commit bf9082518c32ce7d53d011777bf8d8056472cbf9.
Revert "Add std.crypto.hash.sha3.{KT128,KT256} - RFC 9861. (#25593)"
This reverts commit 95c76b1b4aa7302966281c6b9b7f6cadea3cf7a6.
KT128 and KT256 are fast, secure cryptographic hash functions based on Keccak (SHA-3).
They can be seen as the modern version of SHA-3, and evolution of SHAKE, with better performance.
After the SHA-3 competition, the Keccak team proposed these variants in 2016, and the constructions underwent 8 years of public scrutiny before being standardized in October 2025 as RFC 9861.
They uses a tree-hashing mode on top of TurboSHAKE, providing both high security and excellent performance, especially on large inputs.
They support arbitrary-length output and optional customization strings.
Hashing of very large inputs can be done using multiple threads, for high throughput.
KT128 provides 128-bit security strength, equivalent to AES-128 and SHAKE128, which is sufficient for virtually all applications.
KT256 provides 256-bit security strength, equivalent to SHA-512. For virtually all applications, KT128 is enough (equivalent to SHA-256 or BLAKE3).
For small inputs, TurboSHAKE128 and TurboSHAKE256 (which KT128 and KT256 are based on) can be used instead as they have less overhead.
https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-185.pdf
This adds useful standard SHA3-based constructions from the
NIST SP 800-185 document:
- cSHAKE: similar to the SHAKE extensible hash function, but
with the addition of a context parameter.
- KMAC: SHAKE-based authentication / keyed XOF
- TupleHash: unambiguous hashing of tuples
These are required by recent protocols and specifications.
They also offer properties that none of the currently available
constructions in the stdlib offer, especially the ability to safely
hash tuples.
Other keyed hash functions/XOFs will fall back to using HMAC, which
is suboptimal from a performance perspective, but fine from a
security perspective.
The TurboSHAKE paper just got published:
https://eprint.iacr.org/2023/342.pdf
and unlike the previous K12 paper, suggests 0x1F instead of 0x01
as the default value for "D".
* Fix SHA3 with streaming
Leftover bytes should be added to the buffer, not to the state.
(or, always to the state; we can and probably should eventually get
rid of the buffer)
Fixes#14851
* Add a test for SHA-3 with streaming
Make the Keccak permutation public, as it's useful for more than
SHA-3 (kMAC, SHAKE, TurboSHAKE, TupleHash, etc).
Our Keccak implementation was accepting f as a comptime parameter,
but always used 64-bit words and 200 byte states, so it actually
didn't work with anything besides f=1600.
That has been fixed. The ability to use reduced-round versions
was also added in order to support M14 and K12.
The state was constantly converted back and forth between bytes
and words, even though only a part of the state is actually used
for absorbing and squeezing bytes. It was changed to something
similar to the other permutations we have, so we can avoid extra
copies, and eventually add vectorized implementations.
In addition, the SHAKE extendable output function (XOF) was
added (SHAKE128, SHAKE256). It is required by newer schemes,
such as the Kyber post-quantum key exchange mechanism, whose
implementation is currently blocked by SHAKE missing from our
standard library.
Breaking change: `Keccak_256` and `Keccak_512` were renamed to
`Keccak256` and `Keccak512` for consistency with all other
hash functions.
In sponge-based constructions, the block size is not the same as
the state size. For practical purposes, it's the same as the rate.
Size this is a constant for a given type, we don't need to keep
a copy of that value in the state itself. Just use the constant
directly. This saves some bytes and may even be slightly faster.
More importantly:
Fixes#14128
We already have a LICENSE file that covers the Zig Standard Library. We
no longer need to remind everyone that the license is MIT in every single
file.
Previously this was introduced to clarify the situation for a fork of
Zig that made Zig's LICENSE file harder to find, and replaced it with
their own license that required annual payments to their company.
However that fork now appears to be dead. So there is no need to
reinforce the copyright notice in every single file.
- use `PascalCase` for all types. So, AES256GCM is now Aes256Gcm.
- consistently use `_length` instead of mixing `_size` and `_length` for the
constants we expose
- Use `minimum_key_length` when it represents an actual minimum length.
Otherwise, use `key_length`.
- Require output buffers (for ciphertexts, macs, hashes) to be of the right
size, not at least of that size in some functions, and the exact size elsewhere.
- Use a `_bits` suffix instead of `_length` when a size is represented as a
number of bits to avoid confusion.
- Functions returning a constant-sized slice are now defined as a slice instead
of a pointer + a runtime assertion. This is the case for most hash functions.
- Use `camelCase` for all functions instead of `snake_case`.
No functional changes, but these are breaking API changes.
- This avoids having multiple `init()` functions for every combination
of optional parameters
- The API is consistent across all hash functions
- New options can be added later without breaking existing applications.
For example, this is going to come in handy if we implement parallelization
for BLAKE2 and BLAKE3.
- We don't have a mix of snake_case and camelCase functions any more, at
least in the public crypto API
Support for BLAKE2 salt and personalization (more commonly called context)
parameters have been implemented by the way to illustrate this.
Justification:
- reset() is unnecessary; states that have to be reused can be copied
- reset() is error-prone. Copying a previous state prevents forgetting
struct members.
- reset() forces implementation to store sensitive data (key, initial state)
in memory even when they are not needed.
- reset() is confusing as it has a different meaning elsewhere in Zig.
Instead of having all primitives and constructions share the same namespace,
they are now organized by category and function family.
Types within the same category are expected to share the exact same API.
* Implements #3768. This is a sweeping breaking change that requires
many (trivial) edits to Zig source code. Array values no longer
coerced to slices; however one may use `&` to obtain a reference to
an array value, which may then be coerced to a slice.
* Adds `IrInstruction::dump`, for debugging purposes. It's useful to
call to inspect the instruction when debugging Zig IR.
* Fixes bugs with result location semantics. See the new behavior test
cases, and compile error test cases.
* Fixes bugs with `@typeInfo` not properly resolving const values.
* Behavior tests are passing but std lib tests are not yet. There
is more work to do before merging this branch.
