Botan  1.11.26
Public Types | Public Member Functions | Protected Member Functions | List of all members
Botan::XTS_Encryption Class Referencefinal

#include <xts.h>

Inheritance diagram for Botan::XTS_Encryption:
Botan::XTS_Mode Botan::Cipher_Mode Botan::Keyed_Transform Botan::Transform

Public Types

typedef SCAN_Name Spec
 

Public Member Functions

virtual bool authenticated () const
 
void clear () override
 
size_t default_nonce_length () const override
 
void finish (secure_vector< byte > &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
 
virtual std::string provider () const
 
template<typename Alloc >
void set_key (const std::vector< byte, Alloc > &key)
 
void set_key (const SymmetricKey &key)
 
void set_key (const byte key[], size_t length)
 
template<typename Alloc >
secure_vector< bytestart (const std::vector< byte, Alloc > &nonce)
 
secure_vector< bytestart (const byte nonce[], size_t nonce_len)
 
secure_vector< bytestart ()
 
template<typename Alloc >
secure_vector< bytestart_vec (const std::vector< byte, Alloc > &nonce)
 
virtual size_t tag_size () const
 
void update (secure_vector< byte > &blocks, size_t offset=0) override
 
size_t update_granularity () const override
 
bool valid_keylength (size_t length) const
 
bool valid_nonce_length (size_t n) const override
 
 XTS_Encryption (BlockCipher *cipher)
 

Protected Member Functions

const BlockCiphercipher () const
 
const bytetweak () const
 
void update_tweak (size_t last_used)
 

Detailed Description

IEEE P1619 XTS Encryption

Definition at line 55 of file xts.h.

Member Typedef Documentation

typedef SCAN_Name Botan::Transform::Spec
inherited

Definition at line 27 of file transform.h.

Constructor & Destructor Documentation

Botan::XTS_Encryption::XTS_Encryption ( BlockCipher cipher)
inline

Definition at line 58 of file xts.h.

58 : XTS_Mode(cipher) {}
XTS_Mode(BlockCipher *cipher)
Definition: xts.cpp:51
const BlockCipher & cipher() const
Definition: xts.h:40

Member Function Documentation

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 26 of file cipher_mode.h.

26 { return false; }
const BlockCipher& Botan::XTS_Mode::cipher ( ) const
inlineprotectedinherited
void Botan::XTS_Mode::clear ( )
overridevirtualinherited

Implements Botan::Transform.

Definition at line 60 of file xts.cpp.

References Botan::zeroise().

61  {
62  m_cipher->clear();
63  m_tweak_cipher->clear();
64  zeroise(m_tweak);
65  }
void zeroise(std::vector< T, Alloc > &vec)
Definition: secmem.h:186
size_t Botan::XTS_Mode::default_nonce_length ( ) const
overridevirtualinherited

Return the default size for a nonce

Implements Botan::Transform.

Definition at line 87 of file xts.cpp.

References Botan::BlockCipher::block_size(), and Botan::XTS_Mode::cipher().

88  {
89  return cipher().block_size();
90  }
const BlockCipher & cipher() const
Definition: xts.h:40
virtual size_t block_size() const =0
void Botan::XTS_Encryption::finish ( secure_vector< byte > &  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::Transform.

Definition at line 168 of file xts.cpp.

References Botan::BlockCipher::block_size(), BOTAN_ASSERT, Botan::XTS_Mode::cipher(), Botan::BlockCipher::encrypt(), Botan::XTS_Mode::minimum_final_size(), Botan::XTS_Mode::tweak(), Botan::Transform::update(), and Botan::xor_buf().

169  {
170  BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
171  const size_t sz = buffer.size() - offset;
172  byte* buf = buffer.data() + offset;
173 
174  BOTAN_ASSERT(sz >= minimum_final_size(), "Have sufficient final input");
175 
176  const size_t BS = cipher().block_size();
177 
178  if(sz % BS == 0)
179  {
180  update(buffer, offset);
181  }
182  else
183  {
184  // steal ciphertext
185  const size_t full_blocks = ((sz / BS) - 1) * BS;
186  const size_t final_bytes = sz - full_blocks;
187  BOTAN_ASSERT(final_bytes > BS && final_bytes < 2*BS, "Left over size in expected range");
188 
189  secure_vector<byte> last(buf + full_blocks, buf + full_blocks + final_bytes);
190  buffer.resize(full_blocks + offset);
191  update(buffer, offset);
192 
193  xor_buf(last, tweak(), BS);
194  cipher().encrypt(last);
195  xor_buf(last, tweak(), BS);
196 
197  for(size_t i = 0; i != final_bytes - BS; ++i)
198  {
199  last[i] ^= last[i + BS];
200  last[i + BS] ^= last[i];
201  last[i] ^= last[i + BS];
202  }
203 
204  xor_buf(last, tweak() + BS, BS);
205  cipher().encrypt(last);
206  xor_buf(last, tweak() + BS, BS);
207 
208  buffer += last;
209  }
210  }
void xor_buf(T out[], const T in[], size_t length)
Definition: mem_ops.h:90
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:27
const BlockCipher & cipher() const
Definition: xts.h:40
size_t minimum_final_size() const override
Definition: xts.cpp:77
void update(secure_vector< byte > &blocks, size_t offset=0) override
Definition: xts.cpp:139
void encrypt(const byte in[], byte out[]) const
Definition: block_cipher.h:62
const byte * tweak() const
Definition: xts.h:38
virtual size_t block_size() const =0
std::uint8_t byte
Definition: types.h:31
Key_Length_Specification Botan::XTS_Mode::key_spec ( ) const
overridevirtualinherited
Returns
object describing limits on key size

Implements Botan::Keyed_Transform.

Definition at line 82 of file xts.cpp.

References Botan::XTS_Mode::cipher(), Botan::SymmetricAlgorithm::key_spec(), and Botan::Key_Length_Specification::multiple().

83  {
84  return cipher().key_spec().multiple(2);
85  }
Key_Length_Specification multiple(size_t n) const
Definition: key_spec.h:82
const BlockCipher & cipher() const
Definition: xts.h:40
virtual Key_Length_Specification key_spec() const =0
size_t Botan::XTS_Mode::minimum_final_size ( ) const
overridevirtualinherited
Returns
required minimium size to finalize() - may be any length larger than this.

Implements Botan::Transform.

Definition at line 77 of file xts.cpp.

References Botan::BlockCipher::block_size(), and Botan::XTS_Mode::cipher().

Referenced by finish(), and Botan::XTS_Decryption::finish().

78  {
79  return cipher().block_size() + 1;
80  }
const BlockCipher & cipher() const
Definition: xts.h:40
virtual size_t block_size() const =0
std::string Botan::XTS_Mode::name ( ) const
overridevirtualinherited

Implements Botan::Transform.

Definition at line 67 of file xts.cpp.

References Botan::XTS_Mode::cipher(), and Botan::SymmetricAlgorithm::name().

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

68  {
69  return cipher().name() + "/XTS";
70  }
virtual std::string name() const =0
const BlockCipher & cipher() const
Definition: xts.h:40
size_t Botan::XTS_Encryption::output_length ( size_t  input_length) const
overridevirtual

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::Transform.

Definition at line 134 of file xts.cpp.

135  {
136  return input_length;
137  }
virtual std::string Botan::Transform::provider ( ) const
inlinevirtualinherited

Return some short name describing the provider of this tranformation. Useful in cases where multiple implementations are available (eg, different implementations of AES). Default "core" is used for the 'standard' implementation included in the library.

Definition at line 120 of file transform.h.

120 { return "core"; }
template<typename Alloc >
void Botan::Keyed_Transform::set_key ( const std::vector< byte, Alloc > &  key)
inlineinherited

Definition at line 148 of file transform.h.

Referenced by botan_cipher_set_key().

149  {
150  set_key(key.data(), key.size());
151  }
void set_key(const std::vector< byte, Alloc > &key)
Definition: transform.h:148
void Botan::Keyed_Transform::set_key ( const SymmetricKey key)
inlineinherited

Definition at line 153 of file transform.h.

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

154  {
155  set_key(key.begin(), key.length());
156  }
void set_key(const std::vector< byte, Alloc > &key)
Definition: transform.h:148
void Botan::Keyed_Transform::set_key ( const byte  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 163 of file transform.h.

164  {
165  if(!valid_keylength(length))
166  throw Invalid_Key_Length(name(), length);
167  key_schedule(key, length);
168  }
virtual std::string name() const =0
bool valid_keylength(size_t length) const
Definition: transform.h:142
template<typename Alloc >
secure_vector<byte> Botan::Transform::start ( const std::vector< byte, Alloc > &  nonce)
inlineinherited

Begin processing a message.

Parameters
noncethe per message nonce

Definition at line 34 of file transform.h.

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

35  {
36  return start(nonce.data(), nonce.size());
37  }
secure_vector< byte > start()
Definition: transform.h:63
secure_vector<byte> Botan::Transform::start ( const byte  nonce[],
size_t  nonce_len 
)
inlineinherited

Begin processing a message.

Parameters
noncethe per message nonce
nonce_lenlength of nonce

Definition at line 55 of file transform.h.

56  {
57  return start_raw(nonce, nonce_len);
58  }
virtual secure_vector< byte > start_raw(const byte nonce[], size_t nonce_len)=0
secure_vector<byte> Botan::Transform::start ( )
inlineinherited

Begin processing a message.

Definition at line 63 of file transform.h.

64  {
65  return start_raw(nullptr, 0);
66  }
virtual secure_vector< byte > start_raw(const byte nonce[], size_t nonce_len)=0
template<typename Alloc >
secure_vector<byte> Botan::Transform::start_vec ( const std::vector< byte, Alloc > &  nonce)
inlineinherited

Begin processing a message.

Parameters
noncethe per message nonce

Definition at line 45 of file transform.h.

46  {
47  return start(nonce.data(), nonce.size());
48  }
secure_vector< byte > start()
Definition: transform.h:63
virtual size_t Botan::Cipher_Mode::tag_size ( ) const
inlinevirtualinherited

Return the size of the authentication tag used (in bytes)

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

Definition at line 31 of file cipher_mode.h.

Referenced by botan_cipher_get_tag_length().

31 { return 0; }
const byte* Botan::XTS_Mode::tweak ( ) const
inlineprotectedinherited

Definition at line 38 of file xts.h.

Referenced by finish(), Botan::XTS_Decryption::finish(), update(), and Botan::XTS_Decryption::update().

38 { return m_tweak.data(); }
void Botan::XTS_Encryption::update ( secure_vector< byte > &  blocks,
size_t  offset = 0 
)
overridevirtual

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

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

Implements Botan::Transform.

Definition at line 139 of file xts.cpp.

References Botan::BlockCipher::block_size(), BOTAN_ASSERT, Botan::XTS_Mode::cipher(), Botan::BlockCipher::encrypt_n(), Botan::CT::min(), Botan::XTS_Mode::tweak(), Botan::XTS_Mode::update_granularity(), Botan::XTS_Mode::update_tweak(), and Botan::xor_buf().

140  {
141  BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
142  const size_t sz = buffer.size() - offset;
143  byte* buf = buffer.data() + offset;
144 
145  const size_t BS = cipher().block_size();
146 
147  BOTAN_ASSERT(sz % BS == 0, "Input is full blocks");
148  size_t blocks = sz / BS;
149 
150  const size_t blocks_in_tweak = update_granularity() / BS;
151 
152  while(blocks)
153  {
154  const size_t to_proc = std::min(blocks, blocks_in_tweak);
155  const size_t to_proc_bytes = to_proc * BS;
156 
157  xor_buf(buf, tweak(), to_proc_bytes);
158  cipher().encrypt_n(buf, buf, to_proc);
159  xor_buf(buf, tweak(), to_proc_bytes);
160 
161  buf += to_proc * BS;
162  blocks -= to_proc;
163 
164  update_tweak(to_proc);
165  }
166  }
void xor_buf(T out[], const T in[], size_t length)
Definition: mem_ops.h:90
void update_tweak(size_t last_used)
Definition: xts.cpp:121
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:27
const BlockCipher & cipher() const
Definition: xts.h:40
T min(T a, T b)
Definition: ct_utils.h:148
virtual void encrypt_n(const byte in[], byte out[], size_t blocks) const =0
size_t update_granularity() const override
Definition: xts.cpp:72
const byte * tweak() const
Definition: xts.h:38
virtual size_t block_size() const =0
std::uint8_t byte
Definition: types.h:31
size_t Botan::XTS_Mode::update_granularity ( ) const
overridevirtualinherited
Returns
size of required blocks to update

Implements Botan::Transform.

Definition at line 72 of file xts.cpp.

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

Referenced by update(), Botan::XTS_Decryption::update(), Botan::XTS_Mode::update_tweak(), and Botan::XTS_Mode::XTS_Mode().

73  {
74  return cipher().parallel_bytes();
75  }
size_t parallel_bytes() const
Definition: block_cipher.h:50
const BlockCipher & cipher() const
Definition: xts.h:40
void Botan::XTS_Mode::update_tweak ( size_t  last_used)
protectedinherited

Definition at line 121 of file xts.cpp.

References Botan::XTS_Mode::update_granularity().

Referenced by update(), Botan::XTS_Decryption::update(), and Botan::XTS_Mode::valid_nonce_length().

122  {
123  const size_t BS = m_tweak_cipher->block_size();
124 
125  if(which > 0)
126  poly_double(m_tweak.data(), &m_tweak[(which-1)*BS], BS);
127 
128  const size_t blocks_in_tweak = update_granularity() / BS;
129 
130  for(size_t i = 1; i < blocks_in_tweak; ++i)
131  poly_double(&m_tweak[i*BS], &m_tweak[(i-1)*BS], BS);
132  }
size_t update_granularity() const override
Definition: xts.cpp:72
bool Botan::Keyed_Transform::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 142 of file transform.h.

143  {
144  return key_spec().valid_keylength(length);
145  }
bool valid_keylength(size_t length) const
Definition: key_spec.h:51
virtual Key_Length_Specification key_spec() const =0
bool Botan::XTS_Mode::valid_nonce_length ( size_t  nonce_len) const
overridevirtualinherited

Return true iff nonce_len is a valid length for the nonce

Implements Botan::Transform.

Definition at line 92 of file xts.cpp.

References Botan::BlockCipher::block_size(), Botan::XTS_Mode::cipher(), Botan::copy_mem(), Botan::XTS_Mode::name(), and Botan::XTS_Mode::update_tweak().

93  {
94  return cipher().block_size() == n;
95  }
const BlockCipher & cipher() const
Definition: xts.h:40
virtual size_t block_size() const =0

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