Botan  2.4.0
Crypto and TLS for C++11
Public Member Functions | Static Public Member Functions | Protected Member Functions | Protected Attributes | List of all members
Botan::CFB_Decryption Class Referencefinal

#include <cfb.h>

Inheritance diagram for Botan::CFB_Decryption:
Botan::CFB_Mode Botan::Cipher_Mode

Public Member Functions

virtual bool authenticated () const
 
 CFB_Decryption (BlockCipher *cipher, size_t feedback_bits)
 
void clear () override final
 
size_t default_nonce_length () const override final
 
void finish (secure_vector< uint8_t > &final_block, size_t offset=0) override
 
Key_Length_Specification key_spec () const override final
 
size_t minimum_final_size () const override final
 
std::string name () const override final
 
size_t output_length (size_t input_length) const override final
 
size_t process (uint8_t buf[], size_t size) override
 
virtual std::string provider () const
 
void reset () override final
 
template<typename Alloc >
void set_key (const std::vector< uint8_t, Alloc > &key)
 
void set_key (const SymmetricKey &key)
 
void set_key (const uint8_t key[], size_t length)
 
template<typename Alloc >
void start (const std::vector< uint8_t, Alloc > &nonce)
 
void start (const uint8_t nonce[], size_t nonce_len)
 
void start ()
 
virtual size_t tag_size () const
 
void update (secure_vector< uint8_t > &buffer, size_t offset=0)
 
size_t update_granularity () const override final
 
bool valid_keylength (size_t length) const
 
bool valid_nonce_length (size_t n) const override final
 

Static Public Member Functions

static std::vector< std::string > providers (const std::string &algo_spec)
 

Protected Member Functions

size_t block_size () const
 
const BlockCiphercipher () const
 
size_t feedback () const
 
void shift_register ()
 

Protected Attributes

secure_vector< uint8_t > m_keystream
 
size_t m_keystream_pos = 0
 
secure_vector< uint8_t > m_state
 

Detailed Description

CFB Decryption

Definition at line 85 of file cfb.h.

Constructor & Destructor Documentation

◆ CFB_Decryption()

Botan::CFB_Decryption::CFB_Decryption ( BlockCipher cipher,
size_t  feedback_bits 
)
inline

If feedback_bits is zero, cipher->block_size() bytes will be used.

Parameters
cipherblock cipher to use
feedback_bitsnumber of bits fed back into the shift register, must be a multiple of 8

Definition at line 94 of file cfb.h.

94  :
95  CFB_Mode(cipher, feedback_bits) {}
CFB_Mode(BlockCipher *cipher, size_t feedback_bits)
Definition: cfb.cpp:13
const BlockCipher & cipher() const
Definition: cfb.h:46

Member Function Documentation

◆ authenticated()

virtual bool Botan::Cipher_Mode::authenticated ( ) const
inlinevirtualinherited
Returns
true iff this mode provides authentication as well as confidentiality.

Reimplemented in Botan::AEAD_Mode.

Definition at line 151 of file cipher_mode.h.

151 { return false; }

◆ block_size()

size_t Botan::CFB_Mode::block_size ( ) const
inlineprotectedinherited

◆ cipher()

const BlockCipher& Botan::CFB_Mode::cipher ( ) const
inlineprotectedinherited

◆ clear()

void Botan::CFB_Mode::clear ( )
finaloverridevirtualinherited

Zeroise all state See also reset_msg()

Implements Botan::Cipher_Mode.

Definition at line 23 of file cfb.cpp.

References Botan::CFB_Mode::reset().

24  {
25  m_cipher->clear();
26  reset();
27  }
void reset() override final
Definition: cfb.cpp:29

◆ default_nonce_length()

size_t Botan::CFB_Mode::default_nonce_length ( ) const
finaloverridevirtualinherited
Returns
the default size for a nonce

Implements Botan::Cipher_Mode.

Definition at line 63 of file cfb.cpp.

References Botan::CFB_Mode::block_size().

64  {
65  return block_size();
66  }
size_t block_size() const
Definition: cfb.h:47

◆ feedback()

size_t Botan::CFB_Mode::feedback ( ) const
inlineprotectedinherited

◆ finish()

void Botan::CFB_Decryption::finish ( secure_vector< uint8_t > &  final_block,
size_t  offset = 0 
)
overridevirtual

Complete processing of a message.

Parameters
final_blockin/out parameter which must be at least minimum_final_size() bytes, and will be set to any final output
offsetan offset into final_block to begin processing

Implements Botan::Cipher_Mode.

Definition at line 215 of file cfb.cpp.

References Botan::Cipher_Mode::update().

216  {
217  update(buffer, offset);
218  }
void update(secure_vector< uint8_t > &buffer, size_t offset=0)
Definition: cipher_mode.h:87

◆ key_spec()

Key_Length_Specification Botan::CFB_Mode::key_spec ( ) const
finaloverridevirtualinherited
Returns
object describing limits on key size

Implements Botan::Cipher_Mode.

Definition at line 58 of file cfb.cpp.

References Botan::CFB_Mode::cipher(), and Botan::SymmetricAlgorithm::key_spec().

59  {
60  return cipher().key_spec();
61  }
const BlockCipher & cipher() const
Definition: cfb.h:46
virtual Key_Length_Specification key_spec() const =0

◆ minimum_final_size()

size_t Botan::CFB_Mode::minimum_final_size ( ) const
finaloverridevirtualinherited
Returns
required minimium size to finalize() - may be any length larger than this.

Implements Botan::Cipher_Mode.

Definition at line 53 of file cfb.cpp.

54  {
55  return 0;
56  }

◆ name()

std::string Botan::CFB_Mode::name ( ) const
finaloverridevirtualinherited

Implements Botan::Cipher_Mode.

Definition at line 35 of file cfb.cpp.

References Botan::CFB_Mode::block_size(), Botan::CFB_Mode::cipher(), Botan::CFB_Mode::feedback(), Botan::SymmetricAlgorithm::name(), and Botan::ASN1::to_string().

Referenced by Botan::CFB_Mode::valid_nonce_length().

36  {
37  if(feedback() == cipher().block_size())
38  return cipher().name() + "/CFB";
39  else
40  return cipher().name() + "/CFB(" + std::to_string(feedback()*8) + ")";
41  }
size_t feedback() const
Definition: cfb.h:45
std::string to_string(const BER_Object &obj)
Definition: asn1_obj.cpp:108
virtual std::string name() const =0
const BlockCipher & cipher() const
Definition: cfb.h:46
size_t block_size() const
Definition: cfb.h:47

◆ output_length()

size_t Botan::CFB_Mode::output_length ( size_t  input_length) const
finaloverridevirtualinherited

Returns the size of the output if this transform is used to process a message with input_length bytes. Will throw if unable to give a precise answer.

Implements Botan::Cipher_Mode.

Definition at line 43 of file cfb.cpp.

44  {
45  return input_length;
46  }

◆ process()

size_t Botan::CFB_Decryption::process ( uint8_t  msg[],
size_t  msg_len 
)
overridevirtual

Process message blocks

Input must be a multiple of update_granularity

Processes msg in place and returns bytes written. Normally this will be either msg_len (indicating the entire message was processed) or for certain AEAD modes zero (indicating that the mode requires the entire message be processed in one pass).

Parameters
msgthe message to be processed
msg_lenlength of the message in bytes

Implements Botan::Cipher_Mode.

Definition at line 176 of file cfb.cpp.

References Botan::CFB_Mode::feedback(), Botan::CFB_Mode::m_keystream, Botan::CFB_Mode::m_keystream_pos, and Botan::CFB_Mode::shift_register().

177  {
178  const size_t shift = feedback();
179 
180  size_t left = sz;
181 
182  if(m_keystream_pos != 0)
183  {
184  const size_t take = std::min<size_t>(left, shift - m_keystream_pos);
185 
186  xor_copy(buf, m_keystream.data() + m_keystream_pos, take);
187 
188  m_keystream_pos += take;
189  left -= take;
190  buf += take;
191 
192  if(m_keystream_pos == shift)
193  {
194  shift_register();
195  }
196  }
197 
198  while(left >= shift)
199  {
200  xor_copy(buf, m_keystream.data(), shift);
201  left -= shift;
202  buf += shift;
203  shift_register();
204  }
205 
206  if(left > 0)
207  {
208  xor_copy(buf, m_keystream.data(), left);
209  m_keystream_pos += left;
210  }
211 
212  return sz;
213  }
secure_vector< uint8_t > m_keystream
Definition: cfb.h:50
size_t feedback() const
Definition: cfb.h:45
void shift_register()
Definition: cfb.cpp:100
size_t m_keystream_pos
Definition: cfb.h:51

◆ provider()

virtual std::string Botan::Cipher_Mode::provider ( ) const
inlinevirtualinherited
Returns
provider information about this implementation. Default is "base", might also return "sse2", "avx2", "openssl", or some other arbitrary string.

Reimplemented in Botan::GCM_Mode.

Definition at line 208 of file cipher_mode.h.

208 { return "base"; }

◆ providers()

std::vector< std::string > Botan::Cipher_Mode::providers ( const std::string &  algo_spec)
staticinherited
Returns
list of available providers for this algorithm, empty if not available
Parameters
algo_specalgorithm name

Definition at line 158 of file cipher_mode.cpp.

References Botan::ENCRYPTION, and Botan::get_cipher_mode().

159  {
160  const std::vector<std::string>& possible = { "base", "openssl" };
161  std::vector<std::string> providers;
162  for(auto&& prov : possible)
163  {
164  std::unique_ptr<Cipher_Mode> mode(get_cipher_mode(algo_spec, ENCRYPTION, prov));
165  if(mode)
166  {
167  providers.push_back(prov); // available
168  }
169  }
170  return providers;
171  }
Cipher_Mode * get_cipher_mode(const std::string &algo, Cipher_Dir direction, const std::string &provider)
Definition: cipher_mode.cpp:40
static std::vector< std::string > providers(const std::string &algo_spec)

◆ reset()

void Botan::CFB_Mode::reset ( )
finaloverridevirtualinherited

Resets just the message specific state and allows encrypting again under the existing key

Implements Botan::Cipher_Mode.

Definition at line 29 of file cfb.cpp.

References Botan::CFB_Mode::m_keystream, and Botan::CFB_Mode::m_state.

Referenced by Botan::CFB_Mode::clear().

30  {
31  m_state.clear();
32  m_keystream.clear();
33  }
secure_vector< uint8_t > m_keystream
Definition: cfb.h:50
secure_vector< uint8_t > m_state
Definition: cfb.h:49

◆ set_key() [1/3]

template<typename Alloc >
void Botan::Cipher_Mode::set_key ( const std::vector< uint8_t, Alloc > &  key)
inlineinherited

Set the symmetric key of this transform

Parameters
keycontains the key material

Definition at line 178 of file cipher_mode.h.

Referenced by botan_cipher_set_key(), and Botan::TLS::TLS_CBC_HMAC_AEAD_Mode::key_spec().

179  {
180  set_key(key.data(), key.size());
181  }
void set_key(const std::vector< uint8_t, Alloc > &key)
Definition: cipher_mode.h:178

◆ set_key() [2/3]

void Botan::Cipher_Mode::set_key ( const SymmetricKey key)
inlineinherited

Set the symmetric key of this transform

Parameters
keycontains the key material

Definition at line 187 of file cipher_mode.h.

References Botan::OctetString::begin(), and Botan::OctetString::length().

188  {
189  set_key(key.begin(), key.length());
190  }
void set_key(const std::vector< uint8_t, Alloc > &key)
Definition: cipher_mode.h:178

◆ set_key() [3/3]

void Botan::Cipher_Mode::set_key ( const uint8_t  key[],
size_t  length 
)
inlineinherited

Set the symmetric key of this transform

Parameters
keycontains the key material
lengthin bytes of key param

Definition at line 197 of file cipher_mode.h.

198  {
199  if(!valid_keylength(length))
200  throw Invalid_Key_Length(name(), length);
201  key_schedule(key, length);
202  }
virtual std::string name() const =0
bool valid_keylength(size_t length) const
Definition: cipher_mode.h:168

◆ shift_register()

void Botan::CFB_Mode::shift_register ( )
protectedinherited

Definition at line 100 of file cfb.cpp.

References Botan::CFB_Mode::block_size(), Botan::CFB_Mode::cipher(), Botan::copy_mem(), Botan::BlockCipher::encrypt(), Botan::CFB_Mode::feedback(), Botan::CFB_Mode::m_keystream, Botan::CFB_Mode::m_keystream_pos, and Botan::CFB_Mode::m_state.

Referenced by Botan::CFB_Encryption::process(), and process().

101  {
102  const size_t shift = feedback();
103  const size_t carryover = block_size() - shift;
104 
105  if(carryover > 0)
106  {
107  copy_mem(m_state.data(), &m_state[shift], carryover);
108  }
109  copy_mem(&m_state[carryover], m_keystream.data(), shift);
111  m_keystream_pos = 0;
112  }
secure_vector< uint8_t > m_keystream
Definition: cfb.h:50
size_t feedback() const
Definition: cfb.h:45
const BlockCipher & cipher() const
Definition: cfb.h:46
secure_vector< uint8_t > m_state
Definition: cfb.h:49
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:97
size_t m_keystream_pos
Definition: cfb.h:51
void encrypt(const uint8_t in[], uint8_t out[]) const
Definition: block_cipher.h:81
size_t block_size() const
Definition: cfb.h:47

◆ start() [1/3]

template<typename Alloc >
void Botan::Cipher_Mode::start ( const std::vector< uint8_t, Alloc > &  nonce)
inlineinherited

Begin processing a message.

Parameters
noncethe per message nonce

Definition at line 44 of file cipher_mode.h.

Referenced by botan_cipher_start(), Botan::TLS::check_tls_cbc_padding(), Botan::TLS::TLS_CBC_HMAC_AEAD_Encryption::set_associated_data(), and Botan::TLS::write_record().

45  {
46  start_msg(nonce.data(), nonce.size());
47  }
virtual void start_msg(const uint8_t nonce[], size_t nonce_len)=0

◆ start() [2/3]

void Botan::Cipher_Mode::start ( const uint8_t  nonce[],
size_t  nonce_len 
)
inlineinherited

Begin processing a message.

Parameters
noncethe per message nonce
nonce_lenlength of nonce

Definition at line 54 of file cipher_mode.h.

55  {
56  start_msg(nonce, nonce_len);
57  }
virtual void start_msg(const uint8_t nonce[], size_t nonce_len)=0

◆ start() [3/3]

void Botan::Cipher_Mode::start ( )
inlineinherited

Begin processing a message.

Definition at line 62 of file cipher_mode.h.

63  {
64  return start_msg(nullptr, 0);
65  }
virtual void start_msg(const uint8_t nonce[], size_t nonce_len)=0

◆ tag_size()

virtual size_t Botan::Cipher_Mode::tag_size ( ) const
inlinevirtualinherited
Returns
the size of the authentication tag used (in bytes)

Reimplemented in Botan::SIV_Mode, Botan::OCB_Mode, Botan::CCM_Mode, Botan::TLS::TLS_CBC_HMAC_AEAD_Mode, Botan::ChaCha20Poly1305_Mode, Botan::GCM_Mode, and Botan::EAX_Mode.

Definition at line 156 of file cipher_mode.h.

Referenced by botan_cipher_get_tag_length().

156 { return 0; }

◆ update()

void Botan::Cipher_Mode::update ( secure_vector< uint8_t > &  buffer,
size_t  offset = 0 
)
inlineinherited

Process some data. Input must be in size update_granularity() uint8_t blocks.

Parameters
bufferin/out parameter which will possibly be resized
offsetan offset into blocks to begin processing

Definition at line 87 of file cipher_mode.h.

References BOTAN_ASSERT.

Referenced by botan_cipher_update(), Botan::XTS_Encryption::finish(), Botan::ChaCha20Poly1305_Encryption::finish(), Botan::CFB_Encryption::finish(), Botan::CBC_Encryption::finish(), Botan::EAX_Encryption::finish(), Botan::XTS_Decryption::finish(), finish(), Botan::CTS_Encryption::finish(), Botan::CBC_Decryption::finish(), Botan::TLS::TLS_CBC_HMAC_AEAD_Encryption::finish(), Botan::CTS_Decryption::finish(), and Botan::TLS::TLS_CBC_HMAC_AEAD_Decryption::finish().

88  {
89  BOTAN_ASSERT(buffer.size() >= offset, "Offset ok");
90  uint8_t* buf = buffer.data() + offset;
91  const size_t buf_size = buffer.size() - offset;
92 
93  const size_t written = process(buf, buf_size);
94  buffer.resize(offset + written);
95  }
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:29
virtual size_t process(uint8_t msg[], size_t msg_len)=0

◆ update_granularity()

size_t Botan::CFB_Mode::update_granularity ( ) const
finaloverridevirtualinherited
Returns
size of required blocks to update

Implements Botan::Cipher_Mode.

Definition at line 48 of file cfb.cpp.

References Botan::CFB_Mode::feedback().

49  {
50  return feedback();
51  }
size_t feedback() const
Definition: cfb.h:45

◆ valid_keylength()

bool Botan::Cipher_Mode::valid_keylength ( size_t  length) const
inlineinherited

Check whether a given key length is valid for this algorithm.

Parameters
lengththe key length to be checked.
Returns
true if the key length is valid.

Definition at line 168 of file cipher_mode.h.

169  {
170  return key_spec().valid_keylength(length);
171  }
virtual Key_Length_Specification key_spec() const =0
bool valid_keylength(size_t length) const
Definition: key_spec.h:51

◆ valid_nonce_length()

bool Botan::CFB_Mode::valid_nonce_length ( size_t  nonce_len) const
finaloverridevirtualinherited
Returns
true iff nonce_len is a valid length for the nonce

Implements Botan::Cipher_Mode.

Definition at line 68 of file cfb.cpp.

References Botan::CFB_Mode::block_size(), Botan::CFB_Mode::cipher(), Botan::BlockCipher::encrypt(), Botan::CFB_Mode::m_keystream, Botan::CFB_Mode::m_keystream_pos, Botan::CFB_Mode::m_state, and Botan::CFB_Mode::name().

69  {
70  return (n == 0 || n == block_size());
71  }
size_t block_size() const
Definition: cfb.h:47

Member Data Documentation

◆ m_keystream

secure_vector<uint8_t> Botan::CFB_Mode::m_keystream
protectedinherited

◆ m_keystream_pos

size_t Botan::CFB_Mode::m_keystream_pos = 0
protectedinherited

◆ m_state

secure_vector<uint8_t> Botan::CFB_Mode::m_state
protectedinherited

The documentation for this class was generated from the following files: