Botan 2.19.2
Crypto and TLS for C&
cipher_mode.h
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1/*
2* Cipher Modes
3* (C) 2013,2016 Jack Lloyd
4*
5* Botan is released under the Simplified BSD License (see license.txt)
6*/
7
8#ifndef BOTAN_CIPHER_MODE_H_
9#define BOTAN_CIPHER_MODE_H_
10
11#include <botan/secmem.h>
12#include <botan/sym_algo.h>
13#include <botan/exceptn.h>
14#include <string>
15#include <vector>
16
17namespace Botan {
18
19/**
20* The two possible directions for cipher filters, determining whether they
21* actually perform encryption or decryption.
22*/
24
25/**
26* Interface for cipher modes
27*/
29 {
30 public:
31 /**
32 * @return list of available providers for this algorithm, empty if not available
33 * @param algo_spec algorithm name
34 */
35 static std::vector<std::string> providers(const std::string& algo_spec);
36
37 /**
38 * Create an AEAD mode
39 * @param algo the algorithm to create
40 * @param direction specify if this should be an encryption or decryption AEAD
41 * @param provider optional specification for provider to use
42 * @return an AEAD mode or a null pointer if not available
43 */
44 static std::unique_ptr<Cipher_Mode> create(const std::string& algo,
45 Cipher_Dir direction,
46 const std::string& provider = "");
47
48 /**
49 * Create an AEAD mode, or throw
50 * @param algo the algorithm to create
51 * @param direction specify if this should be an encryption or decryption AEAD
52 * @param provider optional specification for provider to use
53 * @return an AEAD mode, or throw an exception
54 */
55 static std::unique_ptr<Cipher_Mode> create_or_throw(const std::string& algo,
56 Cipher_Dir direction,
57 const std::string& provider = "");
58
59 /*
60 * Prepare for processing a message under the specified nonce
61 */
62 virtual void start_msg(const uint8_t nonce[], size_t nonce_len) = 0;
63
64 /**
65 * Begin processing a message.
66 * @param nonce the per message nonce
67 */
68 template<typename Alloc>
69 void start(const std::vector<uint8_t, Alloc>& nonce)
70 {
71 start_msg(nonce.data(), nonce.size());
72 }
73
74 /**
75 * Begin processing a message.
76 * @param nonce the per message nonce
77 * @param nonce_len length of nonce
78 */
79 void start(const uint8_t nonce[], size_t nonce_len)
80 {
81 start_msg(nonce, nonce_len);
82 }
83
84 /**
85 * Begin processing a message.
86 */
87 void start()
88 {
89 return start_msg(nullptr, 0);
90 }
91
92 /**
93 * Process message blocks
94 *
95 * Input must be a multiple of update_granularity
96 *
97 * Processes msg in place and returns bytes written. Normally
98 * this will be either msg_len (indicating the entire message was
99 * processed) or for certain AEAD modes zero (indicating that the
100 * mode requires the entire message be processed in one pass).
101 *
102 * @param msg the message to be processed
103 * @param msg_len length of the message in bytes
104 */
105 virtual size_t process(uint8_t msg[], size_t msg_len) = 0;
106
107 /**
108 * Process some data. Input must be in size update_granularity() uint8_t blocks.
109 * @param buffer in/out parameter which will possibly be resized
110 * @param offset an offset into blocks to begin processing
111 */
112 void update(secure_vector<uint8_t>& buffer, size_t offset = 0)
113 {
114 BOTAN_ASSERT(buffer.size() >= offset, "Offset ok");
115 uint8_t* buf = buffer.data() + offset;
116 const size_t buf_size = buffer.size() - offset;
117
118 const size_t written = process(buf, buf_size);
119 buffer.resize(offset + written);
120 }
121
122 /**
123 * Complete processing of a message.
124 *
125 * @param final_block in/out parameter which must be at least
126 * minimum_final_size() bytes, and will be set to any final output
127 * @param offset an offset into final_block to begin processing
128 */
129 virtual void finish(secure_vector<uint8_t>& final_block, size_t offset = 0) = 0;
130
131 /**
132 * Returns the size of the output if this transform is used to process a
133 * message with input_length bytes. In most cases the answer is precise.
134 * If it is not possible to precise (namely for CBC decryption) instead a
135 * lower bound is returned.
136 */
137 virtual size_t output_length(size_t input_length) const = 0;
138
139 /**
140 * @return size of required blocks to update
141 */
142 virtual size_t update_granularity() const = 0;
143
144 /**
145 * @return required minimium size to finalize() - may be any
146 * length larger than this.
147 */
148 virtual size_t minimum_final_size() const = 0;
149
150 /**
151 * @return the default size for a nonce
152 */
153 virtual size_t default_nonce_length() const = 0;
154
155 /**
156 * @return true iff nonce_len is a valid length for the nonce
157 */
158 virtual bool valid_nonce_length(size_t nonce_len) const = 0;
159
160 /**
161 * Resets just the message specific state and allows encrypting again under the existing key
162 */
163 virtual void reset() = 0;
164
165 /**
166 * @return true iff this mode provides authentication as well as
167 * confidentiality.
168 */
169 virtual bool authenticated() const { return false; }
170
171 /**
172 * @return the size of the authentication tag used (in bytes)
173 */
174 virtual size_t tag_size() const { return 0; }
175
176 /**
177 * @return provider information about this implementation. Default is "base",
178 * might also return "sse2", "avx2", "openssl", or some other arbitrary string.
179 */
180 virtual std::string provider() const { return "base"; }
181 };
182
183/**
184* Get a cipher mode by name (eg "AES-128/CBC" or "Serpent/XTS")
185* @param algo_spec cipher name
186* @param direction ENCRYPTION or DECRYPTION
187* @param provider provider implementation to choose
188*/
189inline Cipher_Mode* get_cipher_mode(const std::string& algo_spec,
190 Cipher_Dir direction,
191 const std::string& provider = "")
192 {
193 return Cipher_Mode::create(algo_spec, direction, provider).release();
194 }
195
196}
197
198#endif
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:55
virtual void start_msg(const uint8_t nonce[], size_t nonce_len)=0
virtual std::string provider() const
Definition: cipher_mode.h:180
static std::unique_ptr< Cipher_Mode > create(const std::string &algo, Cipher_Dir direction, const std::string &provider="")
Definition: cipher_mode.cpp:50
void start(const uint8_t nonce[], size_t nonce_len)
Definition: cipher_mode.h:79
virtual size_t process(uint8_t msg[], size_t msg_len)=0
virtual size_t default_nonce_length() const =0
virtual void reset()=0
void start(const std::vector< uint8_t, Alloc > &nonce)
Definition: cipher_mode.h:69
virtual size_t output_length(size_t input_length) const =0
virtual bool authenticated() const
Definition: cipher_mode.h:169
virtual void finish(secure_vector< uint8_t > &final_block, size_t offset=0)=0
virtual size_t tag_size() const
Definition: cipher_mode.h:174
void update(secure_vector< uint8_t > &buffer, size_t offset=0)
Definition: cipher_mode.h:112
virtual size_t minimum_final_size() const =0
virtual size_t update_granularity() const =0
virtual bool valid_nonce_length(size_t nonce_len) const =0
#define BOTAN_PUBLIC_API(maj, min)
Definition: compiler.h:31
Definition: alg_id.cpp:13
Cipher_Mode * get_cipher_mode(const std::string &algo_spec, Cipher_Dir direction, const std::string &provider="")
Definition: cipher_mode.h:189
Cipher_Dir
Definition: cipher_mode.h:23
@ DECRYPTION
Definition: cipher_mode.h:23
@ ENCRYPTION
Definition: cipher_mode.h:23
std::vector< T, secure_allocator< T > > secure_vector
Definition: secmem.h:65