Botan 3.3.0
Crypto and TLS for C&
hash.h
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1/*
2* Hash Function Base Class
3* (C) 1999-2008 Jack Lloyd
4*
5* Botan is released under the Simplified BSD License (see license.txt)
6*/
7
8#ifndef BOTAN_HASH_FUNCTION_BASE_CLASS_H_
9#define BOTAN_HASH_FUNCTION_BASE_CLASS_H_
10
11#include <botan/buf_comp.h>
12#include <memory>
13#include <string>
14#include <string_view>
15
16namespace Botan {
17
18/**
19* This class represents hash function (message digest) objects
20*/
22 public:
23 /**
24 * Create an instance based on a name, or return null if the
25 * algo/provider combination cannot be found. If provider is
26 * empty then best available is chosen.
27 */
28 static std::unique_ptr<HashFunction> create(std::string_view algo_spec, std::string_view provider = "");
29
30 /**
31 * Create an instance based on a name
32 * If provider is empty then best available is chosen.
33 * @param algo_spec algorithm name
34 * @param provider provider implementation to use
35 * Throws Lookup_Error if not found.
36 */
37 static std::unique_ptr<HashFunction> create_or_throw(std::string_view algo_spec, std::string_view provider = "");
38
39 /**
40 * @return list of available providers for this algorithm, empty if not available
41 * @param algo_spec algorithm name
42 */
43 static std::vector<std::string> providers(std::string_view algo_spec);
44
45 /**
46 * @return provider information about this implementation. Default is "base",
47 * might also return "sse2", "avx2", "openssl", or some other arbitrary string.
48 */
49 virtual std::string provider() const { return "base"; }
50
51 ~HashFunction() override = default;
52
53 /**
54 * Reset the state.
55 */
56 virtual void clear() = 0;
57
58 /**
59 * @return the hash function name
60 */
61 virtual std::string name() const = 0;
62
63 /**
64 * @return hash block size as defined for this algorithm
65 */
66 virtual size_t hash_block_size() const { return 0; }
67
68 /**
69 * Return a new hash object with the same state as *this. This
70 * allows computing the hash of several messages with a common
71 * prefix more efficiently than would otherwise be possible.
72 *
73 * This function should be called `clone` but that was already
74 * used for the case of returning an uninitialized object.
75 * @return new hash object
76 */
77 virtual std::unique_ptr<HashFunction> copy_state() const = 0;
78
79 /**
80 * @return new object representing the same algorithm as *this
81 */
82 virtual std::unique_ptr<HashFunction> new_object() const = 0;
83
84 /**
85 * @return new object representing the same algorithm as *this
86 */
87 HashFunction* clone() const { return this->new_object().release(); }
88};
89
90} // namespace Botan
91
92#endif
virtual std::string provider() const
Definition hash.h:49
HashFunction * clone() const
Definition hash.h:87
virtual size_t hash_block_size() const
Definition hash.h:66
virtual std::unique_ptr< HashFunction > copy_state() const =0
virtual std::unique_ptr< HashFunction > new_object() const =0
virtual std::string name() const =0
virtual void clear()=0
~HashFunction() override=default
#define BOTAN_PUBLIC_API(maj, min)
Definition compiler.h:31