1//==- BLAKE3.h - BLAKE3 C++ wrapper for LLVM ---------------------*- C++ -*-==//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This is a C++ wrapper of the BLAKE3 C interface.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_SUPPORT_BLAKE3_H
14#define LLVM_SUPPORT_BLAKE3_H
15
16#include "llvm-c/blake3.h"
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/StringRef.h"
19
20namespace llvm {
21
22/// The constant \p LLVM_BLAKE3_OUT_LEN provides the default output length,
23/// 32 bytes, which is recommended for most callers.
24///
25/// Outputs shorter than the default length of 32 bytes (256 bits) provide
26/// less security. An N-bit BLAKE3 output is intended to provide N bits of
27/// first and second preimage resistance and N/2 bits of collision
28/// resistance, for any N up to 256. Longer outputs don't provide any
29/// additional security.
30///
31/// Shorter BLAKE3 outputs are prefixes of longer ones. Explicitly
32/// requesting a short output is equivalent to truncating the default-length
33/// output.
34template <size_t NumBytes = LLVM_BLAKE3_OUT_LEN>
35using BLAKE3Result = std::array<uint8_t, NumBytes>;
36
37/// A class that wraps the BLAKE3 algorithm.
38class BLAKE3 {
39public:
40  BLAKE3() { init(); }
41
42  /// Reinitialize the internal state
43  void init() { llvm_blake3_hasher_init(&Hasher); }
44
45  /// Digest more data.
46  void update(ArrayRef<uint8_t> Data) {
47    llvm_blake3_hasher_update(&Hasher, Data.data(), Data.size());
48  }
49
50  /// Digest more data.
51  void update(StringRef Str) {
52    llvm_blake3_hasher_update(&Hasher, Str.data(), Str.size());
53  }
54
55  /// Finalize the hasher and put the result in \p Result.
56  /// This doesn't modify the hasher itself, and it's possible to finalize again
57  /// after adding more input.
58  template <size_t NumBytes = LLVM_BLAKE3_OUT_LEN>
59  void final(BLAKE3Result<NumBytes> &Result) {
60    llvm_blake3_hasher_finalize(&Hasher, Result.data(), Result.size());
61  }
62
63  /// Finalize the hasher and return an output of any length, given in bytes.
64  /// This doesn't modify the hasher itself, and it's possible to finalize again
65  /// after adding more input.
66  template <size_t NumBytes = LLVM_BLAKE3_OUT_LEN>
67  BLAKE3Result<NumBytes> final() {
68    BLAKE3Result<NumBytes> Result;
69    llvm_blake3_hasher_finalize(&Hasher, Result.data(), Result.size());
70    return Result;
71  }
72
73  /// Return the current output for the digested data since the last call to
74  /// init().
75  ///
76  /// Other hash functions distinguish between \p result() and \p final(), with
77  /// \p result() allowing more calls into \p update(), but there's no
78  // difference for the BLAKE3 hash function.
79  template <size_t NumBytes = LLVM_BLAKE3_OUT_LEN>
80  BLAKE3Result<NumBytes> result() {
81    return final<NumBytes>();
82  }
83
84  /// Returns a BLAKE3 hash for the given data.
85  template <size_t NumBytes = LLVM_BLAKE3_OUT_LEN>
86  static BLAKE3Result<NumBytes> hash(ArrayRef<uint8_t> Data) {
87    BLAKE3 Hasher;
88    Hasher.update(Data);
89    return Hasher.final<NumBytes>();
90  }
91
92private:
93  llvm_blake3_hasher Hasher;
94};
95
96/// Like \p BLAKE3 but using a class-level template parameter for specifying the
97/// hash size of the \p final() and \p result() functions.
98///
99/// This is useful for using BLAKE3 as the hasher type for \p HashBuilder with
100/// non-default hash sizes.
101template <size_t NumBytes> class TruncatedBLAKE3 : public BLAKE3 {
102public:
103  /// Finalize the hasher and put the result in \p Result.
104  /// This doesn't modify the hasher itself, and it's possible to finalize again
105  /// after adding more input.
106  void final(BLAKE3Result<NumBytes> &Result) { return BLAKE3::final(Result); }
107
108  /// Finalize the hasher and return an output of any length, given in bytes.
109  /// This doesn't modify the hasher itself, and it's possible to finalize again
110  /// after adding more input.
111  BLAKE3Result<NumBytes> final() { return BLAKE3::final<NumBytes>(); }
112
113  /// Return the current output for the digested data since the last call to
114  /// init().
115  ///
116  /// Other hash functions distinguish between \p result() and \p final(), with
117  /// \p result() allowing more calls into \p update(), but there's no
118  // difference for the BLAKE3 hash function.
119  BLAKE3Result<NumBytes> result() { return BLAKE3::result<NumBytes>(); }
120};
121
122} // namespace llvm
123
124#endif
125