Botan  1.11.34
Crypto and TLS for C++11
Public Member Functions | Protected Member Functions | 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
 
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
 
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< byte, Alloc > &key)
 
void set_key (const SymmetricKey &key)
 
void set_key (const byte key[], size_t length)
 
template<typename Alloc >
void start (const std::vector< byte, Alloc > &nonce)
 
void start (const byte nonce[], size_t nonce_len)
 
void start ()
 
virtual size_t tag_size () const
 
void update (secure_vector< byte > &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
 

Protected Member Functions

const BlockCiphercipher () const
 
size_t feedback () const
 
secure_vector< byte > & keystream_buf ()
 
secure_vector< byte > & shift_register ()
 

Detailed Description

CFB Decryption

Definition at line 84 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 93 of file cfb.h.

93  :
94  CFB_Mode(cipher, feedback_bits) {}
CFB_Mode(BlockCipher *cipher, size_t feedback_bits)
Definition: cfb.cpp:14
const BlockCipher & cipher() const
Definition: cfb.h:43

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 145 of file cipher_mode.h.

145 { return false; }

§ cipher()

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

§ clear()

void Botan::CFB_Mode::clear ( )
overridevirtualinherited

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
Definition: cfb.cpp:29

§ default_nonce_length()

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

Implements Botan::Cipher_Mode.

Definition at line 63 of file cfb.cpp.

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

64  {
65  return cipher().block_size();
66  }
const BlockCipher & cipher() const
Definition: cfb.h:43
virtual size_t block_size() const =0

§ feedback()

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

Definition at line 45 of file cfb.h.

Referenced by Botan::CFB_Mode::CFB_Mode(), Botan::CFB_Mode::name(), Botan::CFB_Encryption::process(), process(), and Botan::CFB_Mode::update_granularity().

45 { return m_feedback_bytes; }

§ finish()

void Botan::CFB_Decryption::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::Cipher_Mode.

Definition at line 151 of file cfb.cpp.

References Botan::Cipher_Mode::update().

152  {
153  update(buffer, offset);
154  }
void update(secure_vector< byte > &buffer, size_t offset=0)
Definition: cipher_mode.h:81

§ key_spec()

Key_Length_Specification Botan::CFB_Mode::key_spec ( ) const
overridevirtualinherited
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:43
virtual Key_Length_Specification key_spec() const =0

§ keystream_buf()

secure_vector<byte>& Botan::CFB_Mode::keystream_buf ( )
inlineprotectedinherited

Definition at line 49 of file cfb.h.

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

49 { return m_keystream_buf; }

§ minimum_final_size()

size_t Botan::CFB_Mode::minimum_final_size ( ) const
overridevirtualinherited
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
overridevirtualinherited

Implements Botan::Cipher_Mode.

Definition at line 35 of file cfb.cpp.

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

Referenced by Botan::CFB_Mode::CFB_Mode(), and 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:47
virtual std::string name() const =0
const BlockCipher & cipher() const
Definition: cfb.h:43

§ output_length()

size_t Botan::CFB_Mode::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 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 120 of file cfb.cpp.

References Botan::BlockCipher::block_size(), Botan::CFB_Mode::cipher(), Botan::copy_mem(), Botan::BlockCipher::encrypt(), Botan::CFB_Mode::feedback(), Botan::CFB_Mode::keystream_buf(), Botan::CT::min(), Botan::CFB_Mode::shift_register(), and Botan::xor_buf().

121  {
122  const size_t BS = cipher().block_size();
123 
124  secure_vector<byte>& state = shift_register();
125  const size_t shift = feedback();
126  size_t left = sz;
127 
128  while(left)
129  {
130  const size_t took = std::min(shift, left);
131 
132  // first update shift register with ciphertext
133  if (BS - shift > 0)
134  {
135  copy_mem(state.data(), &state[shift], BS - shift);
136  }
137  copy_mem(&state[BS-shift], buf, took);
138 
139  // then decrypt
140  xor_buf(buf, &keystream_buf()[0], took);
141 
142  // then update keystream
143  cipher().encrypt(state, keystream_buf());
144 
145  buf += took;
146  left -= took;
147  }
148  return sz;
149  }
void xor_buf(T out[], const T in[], size_t length)
Definition: mem_ops.h:115
secure_vector< byte > & shift_register()
Definition: cfb.h:47
size_t feedback() const
Definition: cfb.h:45
void encrypt(const byte in[], byte out[]) const
Definition: block_cipher.h:80
secure_vector< byte > & keystream_buf()
Definition: cfb.h:49
const BlockCipher & cipher() const
Definition: cfb.h:43
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:68
T min(T a, T b)
Definition: ct_utils.h:180
virtual size_t block_size() const =0

§ 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 202 of file cipher_mode.h.

202 { return "base"; }

§ reset()

void Botan::CFB_Mode::reset ( )
overridevirtualinherited

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.

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

30  {
31  m_shift_register.clear();
32  m_keystream_buf.clear();
33  }

§ set_key() [1/3]

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

Set the symmetric key of this transform

Parameters
keycontains the key material

Definition at line 172 of file cipher_mode.h.

Referenced by botan_cipher_set_key().

173  {
174  set_key(key.data(), key.size());
175  }
void set_key(const std::vector< byte, Alloc > &key)
Definition: cipher_mode.h:172

§ 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 181 of file cipher_mode.h.

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

182  {
183  set_key(key.begin(), key.length());
184  }
void set_key(const std::vector< byte, Alloc > &key)
Definition: cipher_mode.h:172

§ set_key() [3/3]

void Botan::Cipher_Mode::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 191 of file cipher_mode.h.

192  {
193  if(!valid_keylength(length))
194  throw Invalid_Key_Length(name(), length);
195  key_schedule(key, length);
196  }
virtual std::string name() const =0
bool valid_keylength(size_t length) const
Definition: cipher_mode.h:162

§ shift_register()

secure_vector<byte>& Botan::CFB_Mode::shift_register ( )
inlineprotectedinherited

Definition at line 47 of file cfb.h.

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

47 { return m_shift_register; }

§ start() [1/3]

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

Begin processing a message.

Parameters
noncethe per message nonce

Definition at line 38 of file cipher_mode.h.

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

39  {
40  start_msg(nonce.data(), nonce.size());
41  }
virtual void start_msg(const byte nonce[], size_t nonce_len)=0

§ start() [2/3]

void Botan::Cipher_Mode::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 48 of file cipher_mode.h.

49  {
50  start_msg(nonce, nonce_len);
51  }
virtual void start_msg(const byte nonce[], size_t nonce_len)=0

§ start() [3/3]

void Botan::Cipher_Mode::start ( )
inlineinherited

Begin processing a message.

Definition at line 56 of file cipher_mode.h.

57  {
58  return start_msg(nullptr, 0);
59  }
virtual void start_msg(const byte 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::CCM_Mode, Botan::OCB_Mode, Botan::TLS::TLS_CBC_HMAC_AEAD_Mode, Botan::ChaCha20Poly1305_Mode, Botan::GCM_Mode, and Botan::EAX_Mode.

Definition at line 150 of file cipher_mode.h.

Referenced by botan_cipher_get_tag_length().

150 { return 0; }

§ update()

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

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

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

Definition at line 81 of file cipher_mode.h.

References BOTAN_ASSERT.

Referenced by botan_cipher_update(), Botan::ECB_Encryption::finish(), Botan::XTS_Encryption::finish(), Botan::ChaCha20Poly1305_Encryption::finish(), Botan::CBC_Encryption::finish(), Botan::CFB_Encryption::finish(), Botan::EAX_Encryption::finish(), Botan::XTS_Decryption::finish(), Botan::ECB_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().

82  {
83  BOTAN_ASSERT(buffer.size() >= offset, "Offset ok");
84  byte* buf = buffer.data() + offset;
85  const size_t buf_size = buffer.size() - offset;
86 
87  const size_t written = process(buf, buf_size);
88  buffer.resize(offset + written);
89  }
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:27
virtual size_t process(uint8_t msg[], size_t msg_len)=0
std::uint8_t byte
Definition: types.h:31

§ update_granularity()

size_t Botan::CFB_Mode::update_granularity ( ) const
overridevirtualinherited
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 162 of file cipher_mode.h.

163  {
164  return key_spec().valid_keylength(length);
165  }
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
overridevirtualinherited
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::cipher(), Botan::BlockCipher::encrypt(), and Botan::CFB_Mode::name().

69  {
70  return (n == cipher().block_size());
71  }
const BlockCipher & cipher() const
Definition: cfb.h:43

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