Botan  1.10.9
Public Member Functions | List of all members
Botan::OFB Class Reference

#include <ofb.h>

Inheritance diagram for Botan::OFB:
Botan::StreamCipher Botan::SymmetricAlgorithm Botan::Algorithm

Public Member Functions

void cipher (const byte in[], byte out[], size_t length)
 
void cipher1 (byte buf[], size_t len)
 
void clear ()
 
OFBclone () const
 
Key_Length_Specification key_spec () const
 
size_t maximum_keylength () const
 
size_t minimum_keylength () const
 
std::string name () const
 
 OFB (BlockCipher *cipher)
 
void set_iv (const byte iv[], size_t iv_len)
 
void set_key (const SymmetricKey &key)
 
void set_key (const byte key[], size_t length)
 
bool valid_iv_length (size_t iv_len) const
 
bool valid_keylength (size_t length) const
 
 ~OFB ()
 

Detailed Description

Output Feedback Mode

Definition at line 19 of file ofb.h.

Constructor & Destructor Documentation

Botan::OFB::OFB ( BlockCipher cipher)
Parameters
cipherthe underlying block cipher to use

Definition at line 17 of file ofb.cpp.

References Botan::BlockCipher::block_size(), and Botan::MemoryRegion< T >::resize().

17  : permutation(ciph)
18  {
19  position = 0;
20  buffer.resize(permutation->block_size());
21  }
void resize(size_t n)
Definition: secmem.h:211
virtual size_t block_size() const =0
Botan::OFB::~OFB ( )

Definition at line 26 of file ofb.cpp.

27  {
28  delete permutation;
29  }

Member Function Documentation

void Botan::OFB::cipher ( const byte  in[],
byte  out[],
size_t  len 
)
virtual

Encrypt or decrypt a message

Parameters
inthe plaintext
outthe byte array to hold the output, i.e. the ciphertext
lenthe length of both in and out in bytes

Implements Botan::StreamCipher.

Definition at line 63 of file ofb.cpp.

References Botan::BlockCipher::encrypt(), Botan::MemoryRegion< T >::size(), and Botan::xor_buf().

64  {
65  while(length >= buffer.size() - position)
66  {
67  xor_buf(out, in, &buffer[position], buffer.size() - position);
68  length -= (buffer.size() - position);
69  in += (buffer.size() - position);
70  out += (buffer.size() - position);
71  permutation->encrypt(buffer);
72  position = 0;
73  }
74  xor_buf(out, in, &buffer[position], length);
75  position += length;
76  }
size_t size() const
Definition: secmem.h:29
void encrypt(const byte in[], byte out[]) const
Definition: block_cipher.h:47
void xor_buf(byte out[], const byte in[], size_t length)
Definition: xor_buf.h:21
void Botan::StreamCipher::cipher1 ( byte  buf[],
size_t  len 
)
inlineinherited

Encrypt or decrypt a message

Parameters
bufthe plaintext / ciphertext
lenthe length of buf in bytes

Definition at line 34 of file stream_cipher.h.

Referenced by Botan::Lion::decrypt_n(), and Botan::Lion::encrypt_n().

35  { cipher(buf, buf, len); }
virtual void cipher(const byte in[], byte out[], size_t len)=0
void Botan::OFB::clear ( )
virtual

Zeroize internal state

Implements Botan::Algorithm.

Definition at line 34 of file ofb.cpp.

References Botan::Algorithm::clear(), and Botan::zeroise().

35  {
36  permutation->clear();
37  zeroise(buffer);
38  position = 0;
39  }
virtual void clear()=0
void zeroise(MemoryRegion< T > &vec)
Definition: secmem.h:415
OFB* Botan::OFB::clone ( ) const
inlinevirtual

Get a new object representing the same algorithm as *this

Implements Botan::StreamCipher.

Definition at line 36 of file ofb.h.

37  { return new OFB(permutation->clone()); }
virtual BlockCipher * clone() const =0
OFB(BlockCipher *cipher)
Definition: ofb.cpp:17
Key_Length_Specification Botan::OFB::key_spec ( ) const
inlinevirtual
Returns
object describing limits on key size

Implements Botan::SymmetricAlgorithm.

Definition at line 29 of file ofb.h.

30  {
31  return permutation->key_spec();
32  }
virtual Key_Length_Specification key_spec() const =0
size_t Botan::SymmetricAlgorithm::maximum_keylength ( ) const
inlineinherited
Returns
minimum allowed key length

Definition at line 33 of file sym_algo.h.

34  {
35  return key_spec().maximum_keylength();
36  }
size_t maximum_keylength() const
Definition: key_spec.h:69
virtual Key_Length_Specification key_spec() const =0
size_t Botan::SymmetricAlgorithm::minimum_keylength ( ) const
inlineinherited
Returns
maxmium allowed key length

Definition at line 41 of file sym_algo.h.

42  {
43  return key_spec().minimum_keylength();
44  }
size_t minimum_keylength() const
Definition: key_spec.h:61
virtual Key_Length_Specification key_spec() const =0
std::string Botan::OFB::name ( ) const
virtual
Returns
name of this algorithm

Implements Botan::Algorithm.

Definition at line 55 of file ofb.cpp.

References Botan::Algorithm::name().

Referenced by set_iv().

56  {
57  return ("OFB(" + permutation->name() + ")");
58  }
virtual std::string name() const =0
void Botan::OFB::set_iv ( const byte  iv[],
size_t  iv_len 
)
virtual

Resync the cipher using the IV

Parameters
ivthe initialization vector
iv_lenthe length of the IV in bytes

Reimplemented from Botan::StreamCipher.

Definition at line 81 of file ofb.cpp.

References Botan::MemoryRegion< T >::copy(), Botan::BlockCipher::encrypt(), name(), valid_iv_length(), and Botan::zeroise().

82  {
83  if(!valid_iv_length(iv_len))
84  throw Invalid_IV_Length(name(), iv_len);
85 
86  zeroise(buffer);
87  buffer.copy(0, iv, iv_len);
88 
89  permutation->encrypt(buffer);
90  position = 0;
91  }
std::string name() const
Definition: ofb.cpp:55
void copy(const T in[], size_t n)
Definition: secmem.h:120
void encrypt(const byte in[], byte out[]) const
Definition: block_cipher.h:47
void zeroise(MemoryRegion< T > &vec)
Definition: secmem.h:415
bool valid_iv_length(size_t iv_len) const
Definition: ofb.h:26
void Botan::SymmetricAlgorithm::set_key ( const SymmetricKey key)
inlineinherited
void Botan::SymmetricAlgorithm::set_key ( const byte  key[],
size_t  length 
)
inlineinherited

Set the symmetric key of this object.

Parameters
keythe to be set as a byte array.
lengthin bytes of key param

Definition at line 68 of file sym_algo.h.

69  {
70  if(!valid_keylength(length))
71  throw Invalid_Key_Length(name(), length);
72  key_schedule(key, length);
73  }
bool valid_keylength(size_t length) const
Definition: sym_algo.h:51
virtual std::string name() const =0
bool Botan::OFB::valid_iv_length ( size_t  iv_len) const
inlinevirtual
Parameters
iv_lenthe length of the IV in bytes
Returns
if the length is valid for this algorithm

Reimplemented from Botan::StreamCipher.

Definition at line 26 of file ofb.h.

References block_size.

Referenced by set_iv().

27  { return (iv_len <= permutation->block_size()); }
size_t block_size
Definition: ossl_md.cpp:41
bool Botan::SymmetricAlgorithm::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 51 of file sym_algo.h.

Referenced by Botan::aont_package(), Botan::aont_unpackage(), Botan::HMAC_RNG::HMAC_RNG(), Botan::Lion::Lion(), Botan::Randpool::Randpool(), and Botan::EAX_Base::valid_keylength().

52  {
53  return key_spec().valid_keylength(length);
54  }
bool valid_keylength(size_t length) const
Definition: key_spec.h:51
virtual Key_Length_Specification key_spec() const =0

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