Botan 3.8.1
Crypto and TLS for C&
ofb.cpp
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1/*
2* OFB Mode
3* (C) 1999-2007,2014 Jack Lloyd
4*
5* Botan is released under the Simplified BSD License (see license.txt)
6*/
7
8#include <botan/internal/ofb.h>
9
10#include <botan/exceptn.h>
11#include <botan/mem_ops.h>
12#include <botan/internal/fmt.h>
13
14namespace Botan {
15
16OFB::OFB(std::unique_ptr<BlockCipher> cipher) :
17 m_cipher(std::move(cipher)), m_buffer(m_cipher->block_size()), m_buf_pos(0) {}
18
19void OFB::clear() {
20 m_cipher->clear();
21 zeroise(m_buffer);
22 m_buf_pos = 0;
23}
24
26 return m_cipher->has_keying_material();
27}
28
29size_t OFB::buffer_size() const {
30 return m_buffer.size(); // block size
31}
32
33void OFB::key_schedule(std::span<const uint8_t> key) {
34 m_cipher->set_key(key);
35
36 // Set a default all-zeros IV
37 set_iv(nullptr, 0);
38}
39
40std::string OFB::name() const {
41 return fmt("OFB({})", m_cipher->name());
42}
43
44size_t OFB::default_iv_length() const {
45 return m_cipher->block_size();
46}
47
48bool OFB::valid_iv_length(size_t iv_len) const {
49 return (iv_len <= m_cipher->block_size());
50}
51
53 return m_cipher->key_spec();
54}
55
56std::unique_ptr<StreamCipher> OFB::new_object() const {
57 return std::make_unique<OFB>(m_cipher->new_object());
58}
59
60void OFB::cipher_bytes(const uint8_t in[], uint8_t out[], size_t length) {
61 while(length >= m_buffer.size() - m_buf_pos) {
62 xor_buf(out, in, &m_buffer[m_buf_pos], m_buffer.size() - m_buf_pos);
63 length -= (m_buffer.size() - m_buf_pos);
64 in += (m_buffer.size() - m_buf_pos);
65 out += (m_buffer.size() - m_buf_pos);
66 m_cipher->encrypt(m_buffer);
67 m_buf_pos = 0;
68 }
69 xor_buf(out, in, &m_buffer[m_buf_pos], length);
70 m_buf_pos += length;
71}
72
73void OFB::set_iv_bytes(const uint8_t iv[], size_t iv_len) {
74 if(!valid_iv_length(iv_len)) {
75 throw Invalid_IV_Length(name(), iv_len);
76 }
77
78 zeroise(m_buffer);
79 BOTAN_ASSERT_NOMSG(m_buffer.size() >= iv_len);
80 copy_mem(&m_buffer[0], iv, iv_len);
81
82 m_cipher->encrypt(m_buffer);
83 m_buf_pos = 0;
84}
85
86void OFB::seek(uint64_t /*offset*/) {
87 throw Not_Implemented("OFB does not support seeking");
88}
89} // namespace Botan
#define BOTAN_ASSERT_NOMSG(expr)
Definition assert.h:61
size_t default_iv_length() const override
Definition ofb.cpp:44
std::string name() const override
Definition ofb.cpp:40
void clear() override
Definition ofb.cpp:19
bool valid_iv_length(size_t iv_len) const override
Definition ofb.cpp:48
size_t buffer_size() const override
Definition ofb.cpp:29
bool has_keying_material() const override
Definition ofb.cpp:25
OFB(std::unique_ptr< BlockCipher > cipher)
Definition ofb.cpp:16
void seek(uint64_t offset) override
Definition ofb.cpp:86
Key_Length_Specification key_spec() const override
Definition ofb.cpp:52
std::unique_ptr< StreamCipher > new_object() const override
Definition ofb.cpp:56
void set_iv(const uint8_t iv[], size_t iv_len)
void cipher(const uint8_t in[], uint8_t out[], size_t len)
void zeroise(std::vector< T, Alloc > &vec)
Definition secmem.h:115
std::string fmt(std::string_view format, const T &... args)
Definition fmt.h:53
constexpr void xor_buf(ranges::contiguous_output_range< uint8_t > auto &&out, ranges::contiguous_range< uint8_t > auto &&in)
Definition mem_ops.h:344
constexpr void copy_mem(T *out, const T *in, size_t n)
Definition mem_ops.h:149