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

#include <cbc.h>

Inheritance diagram for Botan::CTS_Decryption:
Botan::CBC_Decryption Botan::CBC_Mode Botan::Cipher_Mode

Public Member Functions

virtual bool authenticated () const
 
void clear () override
 
 CTS_Decryption (BlockCipher *cipher)
 
size_t default_nonce_length () const override
 
void finish (secure_vector< uint8_t > &final_block, size_t offset=0) override
 
Key_Length_Specification key_spec () const override
 
size_t minimum_final_size () const override
 
std::string name () const override
 
size_t output_length (size_t input_length) const override
 
size_t process (uint8_t buf[], size_t size) override
 
virtual std::string provider () const
 
void reset () override
 
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
 
bool valid_keylength (size_t length) const
 
bool valid_nonce_length (size_t n) const override
 

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
 
const BlockCipherModePaddingMethodpadding () const
 
secure_vector< uint8_t > & state ()
 
uint8_t * state_ptr ()
 

Detailed Description

CBC Decryption with ciphertext stealing (CBC-CS3 variant)

Definition at line 137 of file cbc.h.

Constructor & Destructor Documentation

◆ CTS_Decryption()

Botan::CTS_Decryption::CTS_Decryption ( BlockCipher cipher)
inlineexplicit
Parameters
cipherblock cipher to use

Definition at line 143 of file cbc.h.

143 : CBC_Decryption(cipher, nullptr) {}
CBC_Decryption(BlockCipher *cipher, BlockCipherModePaddingMethod *padding)
Definition: cbc.h:117
const BlockCipher & cipher() const
Definition: cbc.h:41

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::CBC_Mode::block_size ( ) const
inlineprotectedinherited

◆ cipher()

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

◆ clear()

void Botan::CBC_Mode::clear ( )
overridevirtualinherited

Zeroise all state See also reset_msg()

Implements Botan::Cipher_Mode.

Definition at line 26 of file cbc.cpp.

References Botan::CBC_Mode::reset().

27  {
28  m_cipher->clear();
29  reset();
30  }
void reset() override
Definition: cbc.cpp:32

◆ default_nonce_length()

size_t Botan::CBC_Mode::default_nonce_length ( ) const
overridevirtualinherited
Returns
the default size for a nonce

Implements Botan::Cipher_Mode.

Definition at line 55 of file cbc.cpp.

References Botan::CBC_Mode::block_size().

56  {
57  return block_size();
58  }
size_t block_size() const
Definition: cbc.h:51

◆ finish()

void Botan::CTS_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

Reimplemented from Botan::CBC_Decryption.

Definition at line 268 of file cbc.cpp.

References Botan::CBC_Mode::block_size(), BOTAN_ASSERT, Botan::CBC_Mode::cipher(), Botan::BlockCipher::decrypt(), Botan::CBC_Mode::name(), Botan::CBC_Mode::state_ptr(), Botan::Cipher_Mode::update(), and Botan::xor_buf().

269  {
270  BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
271  const size_t sz = buffer.size() - offset;
272  uint8_t* buf = buffer.data() + offset;
273 
274  const size_t BS = block_size();
275 
276  if(sz < BS + 1)
277  throw Encoding_Error(name() + ": insufficient data to decrypt");
278 
279  if(sz % BS == 0)
280  {
281  // swap last two blocks
282 
283  for(size_t i = 0; i != BS; ++i)
284  std::swap(buffer[buffer.size()-BS+i], buffer[buffer.size()-2*BS+i]);
285 
286  update(buffer, offset);
287  }
288  else
289  {
290  const size_t full_blocks = ((sz / BS) - 1) * BS;
291  const size_t final_bytes = sz - full_blocks;
292  BOTAN_ASSERT(final_bytes > BS && final_bytes < 2*BS, "Left over size in expected range");
293 
294  secure_vector<uint8_t> last(buf + full_blocks, buf + full_blocks + final_bytes);
295  buffer.resize(full_blocks + offset);
296  update(buffer, offset);
297 
298  cipher().decrypt(last.data());
299 
300  xor_buf(last.data(), &last[BS], final_bytes - BS);
301 
302  for(size_t i = 0; i != final_bytes - BS; ++i)
303  std::swap(last[i], last[i + BS]);
304 
305  cipher().decrypt(last.data());
306  xor_buf(last.data(), state_ptr(), BS);
307 
308  buffer += last;
309  }
310  }
std::string name() const override
Definition: cbc.cpp:37
void update(secure_vector< uint8_t > &buffer, size_t offset=0)
Definition: cipher_mode.h:87
void decrypt(const uint8_t in[], uint8_t out[]) const
Definition: block_cipher.h:91
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:29
void xor_buf(uint8_t out[], const uint8_t in[], size_t length)
Definition: mem_ops.h:163
uint8_t * state_ptr()
Definition: cbc.h:53
size_t block_size() const
Definition: cbc.h:51
const BlockCipher & cipher() const
Definition: cbc.h:41

◆ key_spec()

Key_Length_Specification Botan::CBC_Mode::key_spec ( ) const
overridevirtualinherited
Returns
object describing limits on key size

Implements Botan::Cipher_Mode.

Definition at line 50 of file cbc.cpp.

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

51  {
52  return cipher().key_spec();
53  }
virtual Key_Length_Specification key_spec() const =0
const BlockCipher & cipher() const
Definition: cbc.h:41

◆ minimum_final_size()

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

Reimplemented from Botan::CBC_Decryption.

Definition at line 263 of file cbc.cpp.

References Botan::CBC_Mode::block_size().

264  {
265  return block_size() + 1;
266  }
size_t block_size() const
Definition: cbc.h:51

◆ name()

std::string Botan::CBC_Mode::name ( ) const
overridevirtualinherited

Implements Botan::Cipher_Mode.

Definition at line 37 of file cbc.cpp.

References Botan::CBC_Mode::cipher(), Botan::BlockCipherModePaddingMethod::name(), Botan::SymmetricAlgorithm::name(), and Botan::CBC_Mode::padding().

Referenced by Botan::CBC_Encryption::finish(), Botan::CTS_Encryption::finish(), Botan::CBC_Decryption::finish(), finish(), and Botan::CBC_Mode::valid_nonce_length().

38  {
39  if(m_padding)
40  return cipher().name() + "/CBC/" + padding().name();
41  else
42  return cipher().name() + "/CBC/CTS";
43  }
const BlockCipherModePaddingMethod & padding() const
Definition: cbc.h:43
virtual std::string name() const =0
const BlockCipher & cipher() const
Definition: cbc.h:41
virtual std::string name() const =0

◆ output_length()

size_t Botan::CBC_Decryption::output_length ( size_t  input_length) const
overridevirtualinherited

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 196 of file cbc.cpp.

197  {
198  return input_length; // precise for CTS, worst case otherwise
199  }

◆ padding()

const BlockCipherModePaddingMethod& Botan::CBC_Mode::padding ( ) const
inlineprotectedinherited

Definition at line 43 of file cbc.h.

References BOTAN_ASSERT_NONNULL.

Referenced by Botan::CBC_Encryption::finish(), Botan::CBC_Decryption::finish(), and Botan::CBC_Mode::name().

44  {
45  BOTAN_ASSERT_NONNULL(m_padding);
46  return *m_padding;
47  }
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:81

◆ process()

size_t Botan::CBC_Decryption::process ( uint8_t  msg[],
size_t  msg_len 
)
overridevirtualinherited

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 206 of file cbc.cpp.

References Botan::CBC_Mode::block_size(), BOTAN_ASSERT, Botan::CBC_Mode::cipher(), Botan::copy_mem(), Botan::BlockCipher::decrypt_n(), Botan::CBC_Mode::state_ptr(), and Botan::xor_buf().

207  {
208  const size_t BS = block_size();
209 
210  BOTAN_ASSERT(sz % BS == 0, "Input is full blocks");
211  size_t blocks = sz / BS;
212 
213  while(blocks)
214  {
215  const size_t to_proc = std::min(BS * blocks, m_tempbuf.size());
216 
217  cipher().decrypt_n(buf, m_tempbuf.data(), to_proc / BS);
218 
219  xor_buf(m_tempbuf.data(), state_ptr(), BS);
220  xor_buf(&m_tempbuf[BS], buf, to_proc - BS);
221  copy_mem(state_ptr(), buf + (to_proc - BS), BS);
222 
223  copy_mem(buf, m_tempbuf.data(), to_proc);
224 
225  buf += to_proc;
226  blocks -= to_proc / BS;
227  }
228 
229  return sz;
230  }
virtual void decrypt_n(const uint8_t in[], uint8_t out[], size_t blocks) const =0
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:29
void xor_buf(uint8_t out[], const uint8_t in[], size_t length)
Definition: mem_ops.h:163
uint8_t * state_ptr()
Definition: cbc.h:53
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:97
size_t block_size() const
Definition: cbc.h:51
const BlockCipher & cipher() const
Definition: cbc.h:41

◆ 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::CBC_Decryption::reset ( )
overridevirtualinherited

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

Reimplemented from Botan::CBC_Mode.

Definition at line 252 of file cbc.cpp.

References Botan::CBC_Mode::state(), and Botan::zeroise().

253  {
254  zeroise(state());
255  zeroise(m_tempbuf);
256  }
secure_vector< uint8_t > & state()
Definition: cbc.h:49
void zeroise(std::vector< T, Alloc > &vec)
Definition: secmem.h:181

◆ 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

◆ 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

◆ state()

secure_vector<uint8_t>& Botan::CBC_Mode::state ( )
inlineprotectedinherited

Definition at line 49 of file cbc.h.

Referenced by Botan::CBC_Encryption::process(), and Botan::CBC_Decryption::reset().

49 { return m_state; }

◆ state_ptr()

uint8_t* Botan::CBC_Mode::state_ptr ( )
inlineprotectedinherited

Definition at line 53 of file cbc.h.

Referenced by Botan::CTS_Encryption::finish(), finish(), Botan::CBC_Encryption::process(), and Botan::CBC_Decryption::process().

53 { return m_state.data(); }

◆ 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(), Botan::CFB_Decryption::finish(), Botan::CTS_Encryption::finish(), Botan::CBC_Decryption::finish(), Botan::TLS::TLS_CBC_HMAC_AEAD_Encryption::finish(), 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::CBC_Mode::update_granularity ( ) const
overridevirtualinherited
Returns
size of required blocks to update

Implements Botan::Cipher_Mode.

Definition at line 45 of file cbc.cpp.

References Botan::CBC_Mode::cipher(), and Botan::BlockCipher::parallel_bytes().

46  {
47  return cipher().parallel_bytes();
48  }
size_t parallel_bytes() const
Definition: block_cipher.h:63
const BlockCipher & cipher() const
Definition: cbc.h:41

◆ 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::CTS_Decryption::valid_nonce_length ( size_t  nonce_len) const
overridevirtual
Returns
true iff nonce_len is a valid length for the nonce

Reimplemented from Botan::CBC_Mode.

Definition at line 258 of file cbc.cpp.

References Botan::CBC_Mode::block_size().

259  {
260  return (n == block_size());
261  }
size_t block_size() const
Definition: cbc.h:51

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