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

#include <ctr.h>

Inheritance diagram for Botan::CTR_BE:
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 ()
 
CTR_BEclone () const
 
 CTR_BE (BlockCipher *cipher)
 
Key_Length_Specification key_spec () const
 
size_t maximum_keylength () const
 
size_t minimum_keylength () const
 
std::string name () const
 
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
 
 ~CTR_BE ()
 

Detailed Description

CTR-BE (Counter mode, big-endian)

Definition at line 19 of file ctr.h.

Constructor & Destructor Documentation

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

Definition at line 17 of file ctr.cpp.

17  :
18  permutation(ciph),
19  counter(256 * permutation->block_size()),
20  buffer(counter.size()),
21  position(0)
22  {
23  }
size_t size() const
Definition: secmem.h:29
virtual size_t block_size() const =0
Botan::CTR_BE::~CTR_BE ( )

Definition at line 28 of file ctr.cpp.

29  {
30  delete permutation;
31  }

Member Function Documentation

void Botan::CTR_BE::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 66 of file ctr.cpp.

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

67  {
68  while(length >= buffer.size() - position)
69  {
70  xor_buf(out, in, &buffer[position], buffer.size() - position);
71  length -= (buffer.size() - position);
72  in += (buffer.size() - position);
73  out += (buffer.size() - position);
74  increment_counter();
75  }
76  xor_buf(out, in, &buffer[position], length);
77  position += length;
78  }
size_t size() const
Definition: secmem.h:29
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::CTR_BE::clear ( )
virtual

Zeroize internal state

Implements Botan::Algorithm.

Definition at line 36 of file ctr.cpp.

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

37  {
38  permutation->clear();
39  zeroise(buffer);
40  zeroise(counter);
41  position = 0;
42  }
virtual void clear()=0
void zeroise(MemoryRegion< T > &vec)
Definition: secmem.h:415
CTR_BE* Botan::CTR_BE::clone ( ) const
inlinevirtual

Get a new object representing the same algorithm as *this

Implements Botan::StreamCipher.

Definition at line 36 of file ctr.h.

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

Implements Botan::SymmetricAlgorithm.

Definition at line 29 of file ctr.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::CTR_BE::name ( ) const
virtual
Returns
name of this algorithm

Implements Botan::Algorithm.

Definition at line 58 of file ctr.cpp.

References Botan::Algorithm::name().

Referenced by set_iv().

59  {
60  return ("CTR-BE(" + permutation->name() + ")");
61  }
virtual std::string name() const =0
void Botan::CTR_BE::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 83 of file ctr.cpp.

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

84  {
85  if(!valid_iv_length(iv_len))
86  throw Invalid_IV_Length(name(), iv_len);
87 
88  const size_t bs = permutation->block_size();
89 
90  zeroise(counter);
91 
92  counter.copy(0, iv, iv_len);
93 
94  /*
95  * Set counter blocks to IV, IV + 1, ... IV + 255
96  */
97  for(size_t i = 1; i != 256; ++i)
98  {
99  counter.copy(i*bs, &counter[(i-1)*bs], bs);
100 
101  for(size_t j = 0; j != bs; ++j)
102  if(++counter[i*bs + (bs - 1 - j)])
103  break;
104  }
105 
106  permutation->encrypt_n(&counter[0], &buffer[0], 256);
107  position = 0;
108  }
std::string name() const
Definition: ctr.cpp:58
void copy(const T in[], size_t n)
Definition: secmem.h:120
bool valid_iv_length(size_t iv_len) const
Definition: ctr.h:26
virtual void encrypt_n(const byte in[], byte out[], size_t blocks) const =0
void zeroise(MemoryRegion< T > &vec)
Definition: secmem.h:415
virtual size_t block_size() const =0
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::CTR_BE::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 ctr.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: