1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
/*
* OCB Mode
* (C) 2013 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#ifndef BOTAN_AEAD_OCB_H__
#define BOTAN_AEAD_OCB_H__
#include <botan/aead.h>
#include <botan/block_cipher.h>
#include <botan/buf_filt.h>
#include <memory>
namespace Botan {
class L_computer;
/**
* OCB Mode (base class for OCB_Encryption and OCB_Decryption). Note
* that OCB is patented, but is freely licensed in some circumstances.
*
* @see "The OCB Authenticated-Encryption Algorithm" internet draft
http://tools.ietf.org/html/draft-irtf-cfrg-ocb-03
* @see Free Licenses http://www.cs.ucdavis.edu/~rogaway/ocb/license.htm
* @see OCB home page http://www.cs.ucdavis.edu/~rogaway/ocb
*/
class BOTAN_DLL OCB_Mode : public AEAD_Mode
{
public:
secure_vector<byte> start(const byte nonce[], size_t nonce_len) override;
void set_associated_data(const byte ad[], size_t ad_len) override;
std::string name() const override;
size_t update_granularity() const override;
Key_Length_Specification key_spec() const override;
bool valid_nonce_length(size_t) const override;
size_t tag_size() const override { return m_tag_size; }
void clear() override;
~OCB_Mode();
protected:
/**
* @param cipher the 128-bit block cipher to use
* @param tag_size is how big the auth tag will be
*/
OCB_Mode(BlockCipher* cipher, size_t tag_size);
void key_schedule(const byte key[], size_t length) override;
// fixme make these private
std::unique_ptr<BlockCipher> m_cipher;
std::unique_ptr<L_computer> m_L;
size_t m_block_index = 0;
secure_vector<byte> m_checksum;
secure_vector<byte> m_offset;
secure_vector<byte> m_ad_hash;
private:
secure_vector<byte> update_nonce(const byte nonce[], size_t nonce_len);
size_t m_tag_size = 0;
secure_vector<byte> m_last_nonce;
secure_vector<byte> m_stretch;
};
class BOTAN_DLL OCB_Encryption : public OCB_Mode
{
public:
/**
* @param cipher the 128-bit block cipher to use
* @param tag_size is how big the auth tag will be
*/
OCB_Encryption(BlockCipher* cipher, size_t tag_size = 16) :
OCB_Mode(cipher, tag_size) {}
size_t output_length(size_t input_length) const override
{ return input_length + tag_size(); }
size_t minimum_final_size() const override { return 0; }
void update(secure_vector<byte>& blocks, size_t offset = 0) override;
void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
private:
void encrypt(byte input[], size_t blocks);
};
class BOTAN_DLL OCB_Decryption : public OCB_Mode
{
public:
/**
* @param cipher the 128-bit block cipher to use
* @param tag_size is how big the auth tag will be
*/
OCB_Decryption(BlockCipher* cipher, size_t tag_size = 16) :
OCB_Mode(cipher, tag_size) {}
size_t output_length(size_t input_length) const override
{
BOTAN_ASSERT(input_length > tag_size(), "Sufficient input");
return input_length - tag_size();
}
size_t minimum_final_size() const override { return tag_size(); }
void update(secure_vector<byte>& blocks, size_t offset = 0) override;
void finish(secure_vector<byte>& final_block, size_t offset = 0) override;
private:
void decrypt(byte input[], size_t blocks);
};
}
#endif
|
