Botan  1.11.15
Public Types | Public Member Functions | Protected Member Functions | Protected Attributes
Botan::CCM_Encryption Class Reference

#include <ccm.h>

Inheritance diagram for Botan::CCM_Encryption:
Botan::CCM_Mode Botan::AEAD_Mode Botan::Cipher_Mode Botan::Keyed_Transform Botan::Transform

List of all members.

Public Types

typedef SCAN_Name Spec

Public Member Functions

bool authenticated () const override
 CCM_Encryption (BlockCipher *cipher, size_t tag_size=16, size_t L=3)
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_ad (const std::vector< byte, Alloc > &ad)
void set_associated_data (const byte ad[], size_t ad_len) override
template<typename Alloc >
void set_associated_data_vec (const std::vector< byte, Alloc > &ad)
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)
size_t tag_size () const
void update (secure_vector< byte > &blocks, size_t offset=0) override
size_t update_granularity () const
bool valid_keylength (size_t length) const
bool valid_nonce_length (size_t) const override

Protected Member Functions

const secure_vector< byte > & ad_buf () const
const BlockCiphercipher () const
void encode_length (size_t len, byte out[])
secure_vector< byteformat_b0 (size_t msg_size)
secure_vector< byteformat_c0 ()
void inc (secure_vector< byte > &C)
size_t L () const
secure_vector< byte > & msg_buf ()

Protected Attributes

const size_t BS = 16

Detailed Description

CCM Encryption

Definition at line 77 of file ccm.h.


Member Typedef Documentation

typedef SCAN_Name Botan::Transform::Spec [inherited]

Definition at line 27 of file transform.h.


Constructor & Destructor Documentation

Botan::CCM_Encryption::CCM_Encryption ( BlockCipher cipher,
size_t  tag_size = 16,
size_t  L = 3 
) [inline]
Parameters:
ciphera 128-bit block cipher
tag_sizeis how big the auth tag will be (even values between 4 and 16 are accepted)
Llength of L parameter. The total message length must be less than 2**L bytes, and the nonce is 15-L bytes.

Definition at line 87 of file ccm.h.


Member Function Documentation

const secure_vector<byte>& Botan::CCM_Mode::ad_buf ( ) const [inline, protected, inherited]

Definition at line 56 of file ccm.h.

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

{ return m_ad_buf; }
bool Botan::AEAD_Mode::authenticated ( ) const [inline, override, virtual, inherited]

Returns true iff this mode provides authentication as well as confidentiality.

Reimplemented from Botan::Cipher_Mode.

Definition at line 25 of file aead.h.

{ return true; }
const BlockCipher& Botan::CCM_Mode::cipher ( ) const [inline, protected, inherited]

Definition at line 50 of file ccm.h.

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

{ return *m_cipher; }
void Botan::CCM_Mode::clear ( ) [override, virtual, inherited]

Implements Botan::Transform.

Definition at line 34 of file ccm.cpp.

   {
   m_cipher.reset();
   m_msg_buf.clear();
   m_ad_buf.clear();
   }
size_t Botan::CCM_Mode::default_nonce_length ( ) const [override, virtual, inherited]

Default AEAD nonce size (a commonly supported value among AEAD modes, and large enough that random collisions are unlikely).

Reimplemented from Botan::AEAD_Mode.

Definition at line 51 of file ccm.cpp.

References Botan::CCM_Mode::L().

   {
   return (15-L());
   }
void Botan::CCM_Mode::encode_length ( size_t  len,
byte  out[] 
) [protected, inherited]

Definition at line 115 of file ccm.cpp.

References BOTAN_ASSERT, Botan::get_byte(), and Botan::CCM_Mode::L().

Referenced by Botan::CCM_Mode::format_b0().

   {
   const size_t len_bytes = L();

   BOTAN_ASSERT(len_bytes < sizeof(size_t), "Length field fits");

   for(size_t i = 0; i != len_bytes; ++i)
      out[len_bytes-1-i] = get_byte(sizeof(size_t)-1-i, len);

   BOTAN_ASSERT((len >> (len_bytes*8)) == 0, "Message length fits in field");
   }
void Botan::CCM_Encryption::finish ( secure_vector< byte > &  final_block,
size_t  offset = 0 
) [override, virtual]

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 159 of file ccm.cpp.

References Botan::CCM_Mode::ad_buf(), BOTAN_ASSERT, Botan::CCM_Mode::BS, Botan::CCM_Mode::cipher(), Botan::CCM_Mode::format_b0(), Botan::CCM_Mode::format_c0(), Botan::CCM_Mode::inc(), Botan::CCM_Mode::msg_buf(), Botan::CCM_Mode::tag_size(), and Botan::xor_buf().

   {
   BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");

   buffer.insert(buffer.begin() + offset, msg_buf().begin(), msg_buf().end());

   const size_t sz = buffer.size() - offset;
   byte* buf = &buffer[offset];

   const secure_vector<byte>& ad = ad_buf();
   BOTAN_ASSERT(ad.size() % BS == 0, "AD is block size multiple");

   const BlockCipher& E = cipher();

   secure_vector<byte> T(BS);
   E.encrypt(format_b0(sz), T);

   for(size_t i = 0; i != ad.size(); i += BS)
      {
      xor_buf(&T[0], &ad[i], BS);
      E.encrypt(T);
      }

   secure_vector<byte> C = format_c0();
   secure_vector<byte> S0(BS);
   E.encrypt(C, S0);
   inc(C);

   secure_vector<byte> X(BS);

   const byte* buf_end = &buf[sz];

   while(buf != buf_end)
      {
      const size_t to_proc = std::min<size_t>(BS, buf_end - buf);

      xor_buf(&T[0], buf, to_proc);
      E.encrypt(T);

      E.encrypt(C, X);
      xor_buf(buf, &X[0], to_proc);
      inc(C);

      buf += to_proc;
      }

   T ^= S0;

   buffer += std::make_pair(&T[0], tag_size());
   }
secure_vector< byte > Botan::CCM_Mode::format_b0 ( size_t  msg_size) [protected, inherited]

Definition at line 134 of file ccm.cpp.

References Botan::CCM_Mode::BS, Botan::copy_mem(), Botan::CCM_Mode::encode_length(), Botan::CCM_Mode::L(), and Botan::CCM_Mode::tag_size().

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

   {
   secure_vector<byte> B0(BS);

   const byte b_flags = (m_ad_buf.size() ? 64 : 0) + (((tag_size()/2)-1) << 3) + (L()-1);

   B0[0] = b_flags;
   copy_mem(&B0[1], &m_nonce[0], m_nonce.size());
   encode_length(sz, &B0[m_nonce.size()+1]);

   return B0;
   }
secure_vector< byte > Botan::CCM_Mode::format_c0 ( ) [protected, inherited]

Definition at line 147 of file ccm.cpp.

References Botan::CCM_Mode::BS, Botan::copy_mem(), and Botan::CCM_Mode::L().

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

   {
   secure_vector<byte> C(BS);

   const byte a_flags = L()-1;

   C[0] = a_flags;
   copy_mem(&C[1], &m_nonce[0], m_nonce.size());

   return C;
   }
void Botan::CCM_Mode::inc ( secure_vector< byte > &  C) [protected, inherited]

Definition at line 127 of file ccm.cpp.

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

   {
   for(size_t i = 0; i != C.size(); ++i)
      if(++C[C.size()-i-1])
         break;
   }
Key_Length_Specification Botan::CCM_Mode::key_spec ( ) const [override, virtual, inherited]
Returns:
object describing limits on key size

Implements Botan::Keyed_Transform.

Definition at line 67 of file ccm.cpp.

   {
   return m_cipher->key_spec();
   }
size_t Botan::CCM_Mode::L ( ) const [inline, protected, inherited]
size_t Botan::CCM_Encryption::minimum_final_size ( ) const [inline, override, virtual]
Returns:
required minimium size to finalize() - may be any length larger than this.

Implements Botan::Transform.

Definition at line 95 of file ccm.h.

{ return 0; }
secure_vector<byte>& Botan::CCM_Mode::msg_buf ( ) [inline, protected, inherited]

Definition at line 58 of file ccm.h.

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

{ return m_msg_buf; }
std::string Botan::CCM_Mode::name ( ) const [override, virtual, inherited]

Implements Botan::Transform.

Definition at line 41 of file ccm.cpp.

References Botan::CCM_Mode::L(), Botan::CCM_Mode::tag_size(), and Botan::ASN1::to_string().

   {
   return (m_cipher->name() + "/CCM(" + std::to_string(tag_size()) + "," + std::to_string(L())) + ")";
   }
size_t Botan::CCM_Encryption::output_length ( size_t  input_length) const [inline, override, virtual]

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 92 of file ccm.h.

         { return input_length + tag_size(); }
virtual std::string Botan::Transform::provider ( ) const [inline, virtual, inherited]

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.

{ return "core"; }
template<typename Alloc >
void Botan::AEAD_Mode::set_ad ( const std::vector< byte, Alloc > &  ad) [inline, inherited]

Definition at line 48 of file aead.h.

         {
         set_associated_data(&ad[0], ad.size());
         }
void Botan::CCM_Mode::set_associated_data ( const byte  ad[],
size_t  ad_len 
) [override, virtual, inherited]

Set associated data that is not included in the ciphertext but that should be authenticated. Must be called after set_key and before start.

Unless reset by another call, the associated data is kept between messages. Thus, if the AD does not change, calling once (after set_key) is the optimum.

Parameters:
adthe associated data
ad_lenlength of add in bytes

Implements Botan::AEAD_Mode.

Definition at line 77 of file ccm.cpp.

References BOTAN_ASSERT, and Botan::CCM_Mode::BS.

   {
   m_ad_buf.clear();

   if(length)
      {
      // FIXME: support larger AD using length encoding rules
      BOTAN_ASSERT(length < (0xFFFF - 0xFF), "Supported CCM AD length");

      m_ad_buf.push_back(get_byte<u16bit>(0, length));
      m_ad_buf.push_back(get_byte<u16bit>(1, length));
      m_ad_buf += std::make_pair(ad, length);
      while(m_ad_buf.size() % BS)
         m_ad_buf.push_back(0); // pad with zeros to full block size
      }
   }
template<typename Alloc >
void Botan::AEAD_Mode::set_associated_data_vec ( const std::vector< byte, Alloc > &  ad) [inline, inherited]

Definition at line 42 of file aead.h.

         {
         set_associated_data(&ad[0], ad.size());
         }
template<typename Alloc >
void Botan::Keyed_Transform::set_key ( const std::vector< byte, Alloc > &  key) [inline, inherited]

Definition at line 148 of file transform.h.

Referenced by botan_cipher_set_key().

         {
         set_key(&key[0], key.size());
         }
void Botan::Keyed_Transform::set_key ( const SymmetricKey key) [inline, inherited]

Definition at line 153 of file transform.h.

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

         {
         set_key(key.begin(), key.length());
         }
void Botan::Keyed_Transform::set_key ( const byte  key[],
size_t  length 
) [inline, inherited]

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.

         {
         if(!valid_keylength(length))
            throw Invalid_Key_Length(name(), length);
         key_schedule(key, length);
         }
template<typename Alloc >
secure_vector<byte> Botan::Transform::start ( const std::vector< byte, Alloc > &  nonce) [inline, inherited]

Begin processing a message.

Parameters:
noncethe per message nonce

Definition at line 34 of file transform.h.

Referenced by botan_cipher_start().

         {
         return start(&nonce[0], nonce.size());
         }
secure_vector<byte> Botan::Transform::start ( const byte  nonce[],
size_t  nonce_len 
) [inline, inherited]

Begin processing a message.

Parameters:
noncethe per message nonce
nonce_lenlength of nonce

Definition at line 55 of file transform.h.

         {
         return start_raw(nonce, nonce_len);
         }
secure_vector<byte> Botan::Transform::start ( ) [inline, inherited]

Begin processing a message.

Definition at line 63 of file transform.h.

         {
         return start_raw(nullptr, 0);
         }
template<typename Alloc >
secure_vector<byte> Botan::Transform::start_vec ( const std::vector< byte, Alloc > &  nonce) [inline, inherited]

Begin processing a message.

Parameters:
noncethe per message nonce

Definition at line 45 of file transform.h.

         {
         return start(&nonce[0], nonce.size());
         }
size_t Botan::CCM_Mode::tag_size ( ) const [inline, virtual, inherited]

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

Reimplemented from Botan::Cipher_Mode.

Definition at line 41 of file ccm.h.

Referenced by finish(), Botan::CCM_Decryption::finish(), Botan::CCM_Mode::format_b0(), and Botan::CCM_Mode::name().

{ return m_tag_size; }
void Botan::CCM_Mode::update ( secure_vector< byte > &  blocks,
size_t  offset = 0 
) [override, virtual, inherited]

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::Transform.

Definition at line 105 of file ccm.cpp.

References BOTAN_ASSERT.

   {
   BOTAN_ASSERT(buffer.size() >= offset, "Offset is sane");
   const size_t sz = buffer.size() - offset;
   byte* buf = &buffer[offset];

   m_msg_buf.insert(m_msg_buf.end(), buf, buf + sz);
   buffer.resize(offset); // truncate msg
   }
size_t Botan::CCM_Mode::update_granularity ( ) const [virtual, inherited]
Returns:
size of required blocks to update

Implements Botan::Transform.

Definition at line 56 of file ccm.cpp.

   {
   /*
   This value does not particularly matter as regardless CCM_Mode::update
   buffers all input, so in theory this could be 1. However as for instance
   Transform_Filter creates update_granularity() byte buffers, use a
   somewhat large size to avoid bouncing on a tiny buffer.
   */
   return m_cipher->parallel_bytes();
   }
bool Botan::Keyed_Transform::valid_keylength ( size_t  length) const [inline, inherited]

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.

References Botan::Key_Length_Specification::valid_keylength().

         {
         return key_spec().valid_keylength(length);
         }
bool Botan::CCM_Mode::valid_nonce_length ( size_t  nonce_len) const [override, virtual, inherited]

Return true iff nonce_len is a valid length for the nonce

Implements Botan::Transform.

Definition at line 46 of file ccm.cpp.

References Botan::CCM_Mode::L().

   {
   return (n == (15-L()));
   }

Member Data Documentation

const size_t Botan::CCM_Mode::BS = 16 [protected, inherited]

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