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 
20 namespace 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.
34 template <size_t NumBytes = LLVM_BLAKE3_OUT_LEN>
35 using BLAKE3Result = std::array<uint8_t, NumBytes>;
36 
37 /// A class that wraps the BLAKE3 algorithm.
38 class BLAKE3 {
39 public:
BLAKE3()40   BLAKE3() { init(); }
41 
42   /// Reinitialize the internal state
init()43   void init() { llvm_blake3_hasher_init(&Hasher); }
44 
45   /// Digest more data.
update(ArrayRef<uint8_t> Data)46   void update(ArrayRef<uint8_t> Data) {
47     llvm_blake3_hasher_update(&Hasher, Data.data(), Data.size());
48   }
49 
50   /// Digest more data.
update(StringRef Str)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>
final(BLAKE3Result<NumBytes> & Result)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>
final()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>
result()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>
hash(ArrayRef<uint8_t> Data)86   static BLAKE3Result<NumBytes> hash(ArrayRef<uint8_t> Data) {
87     BLAKE3 Hasher;
88     Hasher.update(Data);
89     return Hasher.final<NumBytes>();
90   }
91 
92 private:
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.
101 template <size_t NumBytes> class TruncatedBLAKE3 : public BLAKE3 {
102 public:
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.
final(BLAKE3Result<NumBytes> & Result)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.
final()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.
result()119   BLAKE3Result<NumBytes> result() { return BLAKE3::result<NumBytes>(); }
120 };
121 
122 } // namespace llvm
123 
124 #endif
125