Botan  1.11.10
Public Member Functions | Protected Member Functions | List of all members
Botan::XTS_Encryption Class Reference

#include <xts.h>

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

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)
 
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.

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:53
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 25 of file cipher_mode.h.

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

Implements Botan::Transformation.

Definition at line 62 of file xts.cpp.

References Botan::zeroise().

63  {
64  m_cipher->clear();
65  m_tweak_cipher->clear();
66  zeroise(m_tweak);
67  }
void zeroise(std::vector< T, Alloc > &vec)
Definition: secmem.h:166
size_t Botan::XTS_Mode::default_nonce_length ( ) const
overridevirtualinherited

Return the default size for a nonce

Implements Botan::Transformation.

Definition at line 89 of file xts.cpp.

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

90  {
91  return cipher().block_size();
92  }
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::Transformation.

Definition at line 170 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(), update(), and Botan::xor_buf().

171  {
172  BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
173  const size_t sz = buffer.size() - offset;
174  byte* buf = &buffer[offset];
175 
176  BOTAN_ASSERT(sz >= minimum_final_size(), "Have sufficient final input");
177 
178  const size_t BS = cipher().block_size();
179 
180  if(sz % BS == 0)
181  {
182  update(buffer, offset);
183  }
184  else
185  {
186  // steal ciphertext
187  const size_t full_blocks = ((sz / BS) - 1) * BS;
188  const size_t final_bytes = sz - full_blocks;
189  BOTAN_ASSERT(final_bytes > BS && final_bytes < 2*BS, "Left over size in expected range");
190 
191  secure_vector<byte> last(buf + full_blocks, buf + full_blocks + final_bytes);
192  buffer.resize(full_blocks + offset);
193  update(buffer, offset);
194 
195  xor_buf(last, tweak(), BS);
196  cipher().encrypt(last);
197  xor_buf(last, tweak(), BS);
198 
199  for(size_t i = 0; i != final_bytes - BS; ++i)
200  {
201  last[i] ^= last[i + BS];
202  last[i + BS] ^= last[i];
203  last[i] ^= last[i + BS];
204  }
205 
206  xor_buf(last, tweak() + BS, BS);
207  cipher().encrypt(last);
208  xor_buf(last, tweak() + BS, BS);
209 
210  buffer += last;
211  }
212  }
void xor_buf(T out[], const T in[], size_t length)
Definition: xor_buf.h:23
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:27
uint8_t byte
Definition: types.h:30
const BlockCipher & cipher() const
Definition: xts.h:40
size_t minimum_final_size() const override
Definition: xts.cpp:79
void update(secure_vector< byte > &blocks, size_t offset=0) override
Definition: xts.cpp:141
void encrypt(const byte in[], byte out[]) const
Definition: block_cipher.h:47
const byte * tweak() const
Definition: xts.h:38
virtual size_t block_size() const =0
Key_Length_Specification Botan::XTS_Mode::key_spec ( ) const
overridevirtualinherited
Returns
object describing limits on key size

Implements Botan::Keyed_Transform.

Definition at line 84 of file xts.cpp.

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

85  {
86  return cipher().key_spec().multiple(2);
87  }
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::Transformation.

Definition at line 79 of file xts.cpp.

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

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

80  {
81  return cipher().block_size() + 1;
82  }
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::Transformation.

Definition at line 69 of file xts.cpp.

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

70  {
71  return cipher().name() + "/XTS";
72  }
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::Transformation.

Definition at line 136 of file xts.cpp.

References Botan::XTS_Mode::cipher(), and Botan::round_up().

137  {
138  return round_up(input_length, cipher().block_size());
139  }
const BlockCipher & cipher() const
Definition: xts.h:40
T round_up(T n, T align_to)
Definition: rounding.h:22
virtual std::string Botan::Transformation::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 117 of file transform.h.

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

Definition at line 145 of file transform.h.

146  {
147  set_key(&key[0], key.size());
148  }
void set_key(const std::vector< byte, Alloc > &key)
Definition: transform.h:145
void Botan::Keyed_Transform::set_key ( const SymmetricKey key)
inlineinherited

Definition at line 150 of file transform.h.

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

151  {
152  set_key(key.begin(), key.length());
153  }
void set_key(const std::vector< byte, Alloc > &key)
Definition: transform.h:145
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 160 of file transform.h.

161  {
162  if(!valid_keylength(length))
163  throw Invalid_Key_Length(name(), length);
164  key_schedule(key, length);
165  }
virtual std::string name() const =0
bool valid_keylength(size_t length) const
Definition: transform.h:139
template<typename Alloc >
secure_vector<byte> Botan::Transformation::start ( const std::vector< byte, Alloc > &  nonce)
inlineinherited

Begin processing a message.

Parameters
noncethe per message nonce

Definition at line 31 of file transform.h.

32  {
33  return start(&nonce[0], nonce.size());
34  }
secure_vector< byte > start()
Definition: transform.h:60
secure_vector<byte> Botan::Transformation::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 52 of file transform.h.

53  {
54  return start_raw(nonce, nonce_len);
55  }
virtual secure_vector< byte > start_raw(const byte nonce[], size_t nonce_len)=0
secure_vector<byte> Botan::Transformation::start ( )
inlineinherited

Begin processing a message.

Definition at line 60 of file transform.h.

61  {
62  return start_raw(nullptr, 0);
63  }
virtual secure_vector< byte > start_raw(const byte nonce[], size_t nonce_len)=0
template<typename Alloc >
secure_vector<byte> Botan::Transformation::start_vec ( const std::vector< byte, Alloc > &  nonce)
inlineinherited

Begin processing a message.

Parameters
noncethe per message nonce

Definition at line 42 of file transform.h.

43  {
44  return start(&nonce[0], nonce.size());
45  }
secure_vector< byte > start()
Definition: transform.h:60
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[0]; }
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 paramter which will possibly be resized
offsetan offset into blocks to begin processing

Implements Botan::Transformation.

Definition at line 141 of file xts.cpp.

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

Referenced by finish().

142  {
143  BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
144  const size_t sz = buffer.size() - offset;
145  byte* buf = &buffer[offset];
146 
147  const size_t BS = cipher().block_size();
148 
149  BOTAN_ASSERT(sz % BS == 0, "Input is full blocks");
150  size_t blocks = sz / BS;
151 
152  const size_t blocks_in_tweak = update_granularity() / BS;
153 
154  while(blocks)
155  {
156  const size_t to_proc = std::min(blocks, blocks_in_tweak);
157  const size_t to_proc_bytes = to_proc * BS;
158 
159  xor_buf(buf, tweak(), to_proc_bytes);
160  cipher().encrypt_n(buf, buf, to_proc);
161  xor_buf(buf, tweak(), to_proc_bytes);
162 
163  buf += to_proc * BS;
164  blocks -= to_proc;
165 
166  update_tweak(to_proc);
167  }
168  }
void xor_buf(T out[], const T in[], size_t length)
Definition: xor_buf.h:23
void update_tweak(size_t last_used)
Definition: xts.cpp:123
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:27
uint8_t byte
Definition: types.h:30
const BlockCipher & cipher() const
Definition: xts.h:40
virtual void encrypt_n(const byte in[], byte out[], size_t blocks) const =0
size_t update_granularity() const override
Definition: xts.cpp:74
const byte * tweak() const
Definition: xts.h:38
virtual size_t block_size() const =0
size_t Botan::XTS_Mode::update_granularity ( ) const
overridevirtualinherited
Returns
size of required blocks to update

Implements Botan::Transformation.

Definition at line 74 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().

75  {
76  return cipher().parallel_bytes();
77  }
size_t parallel_bytes() const
Definition: block_cipher.h:35
const BlockCipher & cipher() const
Definition: xts.h:40
void Botan::XTS_Mode::update_tweak ( size_t  last_used)
protectedinherited

Definition at line 123 of file xts.cpp.

References Botan::XTS_Mode::update_granularity().

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

124  {
125  const size_t BS = m_tweak_cipher->block_size();
126 
127  if(which > 0)
128  poly_double(&m_tweak[0], &m_tweak[(which-1)*BS], BS);
129 
130  const size_t blocks_in_tweak = update_granularity() / BS;
131 
132  for(size_t i = 1; i < blocks_in_tweak; ++i)
133  poly_double(&m_tweak[i*BS], &m_tweak[(i-1)*BS], BS);
134  }
size_t update_granularity() const override
Definition: xts.cpp:74
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 139 of file transform.h.

140  {
141  return key_spec().valid_keylength(length);
142  }
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::Transformation.

Definition at line 94 of file xts.cpp.

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

95  {
96  return cipher().block_size() == n;
97  }
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: