Botan::SIV_Decryption Class Reference

#include <siv.h>

Inheritance diagram for Botan::SIV_Decryption:

Public Member Functions
bool	authenticated () const override
void	clear () override
size_t	default_nonce_length () const override
void	finish (secure_vector< uint8_t > &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_ad (const std::vector< uint8_t, Alloc > &ad)
void	set_associated_data (const uint8_t ad[], size_t ad_len) override
void	set_associated_data_n (size_t n, const uint8_t ad[], size_t ad_len)
template<typename Alloc >
void	set_associated_data_vec (const std::vector< uint8_t, Alloc > &ad)
template<typename Alloc >
void	set_key (const std::vector< uint8_t, Alloc > &key)
void	set_key (const SymmetricKey &key)
void	set_key (const uint8_t key[], size_t length)
	SIV_Decryption (BlockCipher *cipher)
template<typename Alloc >
void	start (const std::vector< uint8_t, Alloc > &nonce)
void	start (const uint8_t nonce[], size_t nonce_len)
void	start ()
size_t	tag_size () const override
void	update (secure_vector< uint8_t > &buffer, size_t offset=0)
size_t	update_granularity () const override
bool	valid_keylength (size_t length) const
bool	valid_nonce_length (size_t) const override

Static Public Member Functions
static std::unique_ptr< AEAD_Mode >	create (const std::string &algo, Cipher_Dir direction, const std::string &provider="")
static std::unique_ptr< AEAD_Mode >	create_or_throw (const std::string &algo, Cipher_Dir direction, const std::string &provider="")
static std::vector< std::string >	providers (const std::string &algo_spec)

Protected Member Functions
size_t	block_size () const
StreamCipher &	ctr ()
secure_vector< uint8_t > &	msg_buf ()
secure_vector< uint8_t >	S2V (const uint8_t text[], size_t text_len)
void	set_ctr_iv (secure_vector< uint8_t > V)

Detailed Description

SIV Decryption

Definition at line 104 of file siv.h.

Constructor & Destructor Documentation

SIV_Decryption()

Botan::SIV_Decryption::SIV_Decryption ( BlockCipher *  cipher )

inlineexplicit

Parameters

cipher

a 128-bit block cipher

Definition at line 110 of file siv.h.

: SIV_Mode(cipher) {}

Member Function Documentation

authenticated()

bool Botan::AEAD_Mode::authenticated ( ) const

inlineoverridevirtualinherited

Returns

true iff this mode provides authentication as well as confidentiality.

Reimplemented from Botan::Cipher_Mode.

Definition at line 47 of file aead.h.

{ return true; }

block_size()

size_t Botan::SIV_Mode::block_size ( ) const

inlineprotectedinherited

Definition at line 60 of file siv.h.

Referenced by finish(), Botan::SIV_Mode::S2V(), and Botan::SIV_Mode::set_associated_data_n().

{ return m_bs; }

clear()

void Botan::SIV_Mode::clear ( )

overridevirtualinherited

Zeroise all state See also reset_msg()

Implements Botan::Cipher_Mode.

Definition at line 33 of file siv.cpp.

References Botan::SIV_Mode::reset().

   {
   m_ctr->clear();
   m_mac->clear();
   reset();
   }

create()

std::unique_ptr< AEAD_Mode > Botan::AEAD_Mode::create ( const std::string &  algo, Cipher_Dir  direction, const std::string &  provider = ""  )

staticinherited

Create an AEAD mode

Parameters

algo	the algorithm to create
direction	specify if this should be an encryption or decryption AEAD
provider	optional specification for provider to use

Returns

an AEAD mode or a null pointer if not available

Definition at line 52 of file aead.cpp.

References Botan::SCAN_Name::algo_name(), Botan::SCAN_Name::arg(), Botan::SCAN_Name::arg_as_integer(), Botan::SCAN_Name::arg_count(), Botan::BlockCipher::create(), Botan::ENCRYPTION, Botan::parse_algorithm_name(), Botan::Cipher_Mode::provider(), and Botan::split_on().

Referenced by Botan::Cipher_Mode::create(), Botan::AEAD_Mode::create_or_throw(), and Botan::get_aead().

   {
#if defined(BOTAN_HAS_AEAD_CHACHA20_POLY1305)
   if(algo == "ChaCha20Poly1305")
      {
      if(dir == ENCRYPTION)
         return std::unique_ptr<AEAD_Mode>(new ChaCha20Poly1305_Encryption);
      else
         return std::unique_ptr<AEAD_Mode>(new ChaCha20Poly1305_Decryption);

      }
#endif

   if(algo.find('/') != std::string::npos)
      {
      const std::vector<std::string> algo_parts = split_on(algo, '/');
      const std::string cipher_name = algo_parts[0];
      const std::vector<std::string> mode_info = parse_algorithm_name(algo_parts[1]);

      if(mode_info.empty())
         return std::unique_ptr<AEAD_Mode>();

      std::ostringstream alg_args;

      alg_args << '(' << cipher_name;
      for(size_t i = 1; i < mode_info.size(); ++i)
         alg_args << ',' << mode_info[i];
      for(size_t i = 2; i < algo_parts.size(); ++i)
         alg_args << ',' << algo_parts[i];
      alg_args << ')';

      const std::string mode_name = mode_info[0] + alg_args.str();
      return AEAD_Mode::create(mode_name, dir);
      }

#if defined(BOTAN_HAS_BLOCK_CIPHER)

   SCAN_Name req(algo);

   if(req.arg_count() == 0)
      {
      return std::unique_ptr<AEAD_Mode>();
      }

   std::unique_ptr<BlockCipher> bc(BlockCipher::create(req.arg(0), provider));

   if(!bc)
      {
      return std::unique_ptr<AEAD_Mode>();
      }

#if defined(BOTAN_HAS_AEAD_CCM)
   if(req.algo_name() == "CCM")
      {
      size_t tag_len = req.arg_as_integer(1, 16);
      size_t L_len = req.arg_as_integer(2, 3);
      if(dir == ENCRYPTION)
         return std::unique_ptr<AEAD_Mode>(new CCM_Encryption(bc.release(), tag_len, L_len));
      else
         return std::unique_ptr<AEAD_Mode>(new CCM_Decryption(bc.release(), tag_len, L_len));
      }
#endif

#if defined(BOTAN_HAS_AEAD_GCM)
   if(req.algo_name() == "GCM")
      {
      size_t tag_len = req.arg_as_integer(1, 16);
      if(dir == ENCRYPTION)
         return std::unique_ptr<AEAD_Mode>(new GCM_Encryption(bc.release(), tag_len));
      else
         return std::unique_ptr<AEAD_Mode>(new GCM_Decryption(bc.release(), tag_len));
      }
#endif

#if defined(BOTAN_HAS_AEAD_OCB)
   if(req.algo_name() == "OCB")
      {
      size_t tag_len = req.arg_as_integer(1, 16);
      if(dir == ENCRYPTION)
         return std::unique_ptr<AEAD_Mode>(new OCB_Encryption(bc.release(), tag_len));
      else
         return std::unique_ptr<AEAD_Mode>(new OCB_Decryption(bc.release(), tag_len));
      }
#endif

#if defined(BOTAN_HAS_AEAD_EAX)
   if(req.algo_name() == "EAX")
      {
      size_t tag_len = req.arg_as_integer(1, bc->block_size());
      if(dir == ENCRYPTION)
         return std::unique_ptr<AEAD_Mode>(new EAX_Encryption(bc.release(), tag_len));
      else
         return std::unique_ptr<AEAD_Mode>(new EAX_Decryption(bc.release(), tag_len));
      }
#endif

#if defined(BOTAN_HAS_AEAD_SIV)
   if(req.algo_name() == "SIV")
      {
      if(dir == ENCRYPTION)
         return std::unique_ptr<AEAD_Mode>(new SIV_Encryption(bc.release()));
      else
         return std::unique_ptr<AEAD_Mode>(new SIV_Decryption(bc.release()));
      }
#endif

#endif

   return std::unique_ptr<AEAD_Mode>();
   }

create_or_throw()

std::unique_ptr< AEAD_Mode > Botan::AEAD_Mode::create_or_throw ( const std::string &  algo, Cipher_Dir  direction, const std::string &  provider = ""  )

staticinherited

Create an AEAD mode, or throw

Parameters

algo	the algorithm to create
direction	specify if this should be an encryption or decryption AEAD
provider	optional specification for provider to use

Returns

an AEAD mode, or throw an exception

Definition at line 42 of file aead.cpp.

References Botan::AEAD_Mode::create(), and Botan::Cipher_Mode::provider().

Referenced by Botan::TLS::Connection_Cipher_State::Connection_Cipher_State(), Botan::TLS::Session::decrypt(), Botan::TLS::Session::encrypt(), Botan::mceies_decrypt(), and Botan::mceies_encrypt().

   {
   if(auto aead = AEAD_Mode::create(algo, dir, provider))
      return aead;

   throw Lookup_Error("AEAD", algo, provider);
   }

ctr()

StreamCipher& Botan::SIV_Mode::ctr ( )

inlineprotectedinherited

Definition at line 62 of file siv.h.

Referenced by Botan::SIV_Encryption::finish(), finish(), and Botan::SIV_Mode::set_ctr_iv().

{ return *m_ctr; }

default_nonce_length()

size_t Botan::AEAD_Mode::default_nonce_length ( ) const

inlineoverridevirtualinherited

Returns

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

Implements Botan::Cipher_Mode.

Reimplemented in Botan::TLS::TLS_CBC_HMAC_AEAD_Mode, and Botan::CCM_Mode.

Definition at line 97 of file aead.h.

{ return 12; }

finish()

void Botan::SIV_Decryption::finish ( secure_vector< uint8_t > &  final_block, size_t  offset = 0  )

overridevirtual

Complete processing of a message.

Parameters

final_block	in/out parameter which must be at least minimum_final_size() bytes, and will be set to any final output
offset	an offset into final_block to begin processing

Implements Botan::Cipher_Mode.

Definition at line 172 of file siv.cpp.

References Botan::SIV_Mode::block_size(), BOTAN_ASSERT, Botan::StreamCipher::cipher(), Botan::constant_time_compare(), Botan::SIV_Mode::ctr(), Botan::SIV_Mode::msg_buf(), Botan::SIV_Mode::S2V(), Botan::SIV_Mode::set_ctr_iv(), T, and Botan::SIV_Mode::tag_size().

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

   if(msg_buf().size() > 0)
      {
      buffer.insert(buffer.begin() + offset, msg_buf().begin(), msg_buf().end());
      msg_buf().clear();
      }

   const size_t sz = buffer.size() - offset;

   BOTAN_ASSERT(sz >= tag_size(), "We have the tag");

   secure_vector<uint8_t> V(buffer.data() + offset,
                            buffer.data() + offset + block_size());

   if(buffer.size() != offset + V.size())
      {
      set_ctr_iv(V);

      ctr().cipher(buffer.data() + offset + V.size(),
                   buffer.data() + offset,
                   buffer.size() - offset - V.size());
      }

   const secure_vector<uint8_t> T = S2V(buffer.data() + offset, buffer.size() - offset - V.size());

   if(!constant_time_compare(T.data(), V.data(), T.size()))
      throw Integrity_Failure("SIV tag check failed");

   buffer.resize(buffer.size() - tag_size());
   }

key_spec()

Key_Length_Specification Botan::SIV_Mode::key_spec ( ) const

overridevirtualinherited

Returns

object describing limits on key size

Implements Botan::Cipher_Mode.

Definition at line 68 of file siv.cpp.

   {
   return m_mac->key_spec().multiple(2);
   }

minimum_final_size()

size_t Botan::SIV_Decryption::minimum_final_size ( ) const

inlineoverridevirtual

Returns

required minimium size to finalize() - may be any length larger than this.

Implements Botan::Cipher_Mode.

Definition at line 120 of file siv.h.

{ return tag_size(); }

msg_buf()

secure_vector<uint8_t>& Botan::SIV_Mode::msg_buf ( )

inlineprotectedinherited

Definition at line 66 of file siv.h.

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

{ return m_msg_buf; }

name()

std::string Botan::SIV_Mode::name ( ) const

overridevirtualinherited

Implements Botan::Cipher_Mode.

Definition at line 47 of file siv.cpp.

Referenced by Botan::SIV_Mode::set_associated_data_n().

   {
   return m_name;
   }

output_length()

size_t Botan::SIV_Decryption::output_length ( size_t  input_length ) const

inlineoverridevirtual

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 114 of file siv.h.

References BOTAN_ASSERT.

         {
         BOTAN_ASSERT(input_length >= tag_size(), "Sufficient input");
         return input_length - tag_size();
         }

process()

size_t Botan::SIV_Mode::process ( uint8_t  msg[], size_t  msg_len  )

overridevirtualinherited

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

msg	the message to be processed
msg_len	length of the message in bytes

Implements Botan::Cipher_Mode.

Definition at line 106 of file siv.cpp.

   {
   // all output is saved for processing in finish
   m_msg_buf.insert(m_msg_buf.end(), buf, buf + sz);
   return 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 236 of file cipher_mode.h.

Referenced by Botan::AEAD_Mode::create(), Botan::Cipher_Mode::create(), Botan::AEAD_Mode::create_or_throw(), and Botan::Cipher_Mode::create_or_throw().

{ return "base"; }

providers()

std::vector< std::string > Botan::Cipher_Mode::providers ( const std::string &  algo_spec )

staticinherited

Returns

list of available providers for this algorithm, empty if not available

Parameters

algo_spec

algorithm name

Definition at line 173 of file cipher_mode.cpp.

References Botan::Cipher_Mode::create(), and Botan::ENCRYPTION.

   {
   const std::vector<std::string>& possible = { "base", "openssl" };
   std::vector<std::string> providers;
   for(auto&& prov : possible)
      {
      std::unique_ptr<Cipher_Mode> mode = Cipher_Mode::create(algo_spec, ENCRYPTION, prov);
      if(mode)
         {
         providers.push_back(prov); // available
         }
      }
   return providers;
   }

reset()

void Botan::SIV_Mode::reset ( )

overridevirtualinherited

Resets just the message specific state and allows encrypting again under the existing key

Implements Botan::Cipher_Mode.

Definition at line 40 of file siv.cpp.

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

   {
   m_nonce.clear();
   m_msg_buf.clear();
   m_ad_macs.clear();
   }

S2V()

secure_vector< uint8_t > Botan::SIV_Mode::S2V ( const uint8_t  text[], size_t  text_len  )

protectedinherited

Definition at line 113 of file siv.cpp.

References Botan::SIV_Mode::block_size(), Botan::poly_double_n(), and Botan::xor_buf().

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

   {
   const std::vector<uint8_t> zeros(block_size());

   secure_vector<uint8_t> V = m_mac->process(zeros.data(), zeros.size());

   for(size_t i = 0; i != m_ad_macs.size(); ++i)
      {
      poly_double_n(V.data(), V.size());
      V ^= m_ad_macs[i];
      }

   if(m_nonce.size())
      {
      poly_double_n(V.data(), V.size());
      V ^= m_nonce;
      }

   if(text_len < block_size())
      {
      poly_double_n(V.data(), V.size());
      xor_buf(V.data(), text, text_len);
      V[text_len] ^= 0x80;
      return m_mac->process(V);
      }

   m_mac->update(text, text_len - block_size());
   xor_buf(V.data(), &text[text_len - block_size()], block_size());
   m_mac->update(V);

   return m_mac->final();
   }

set_ad()

template<typename Alloc >

void Botan::AEAD_Mode::set_ad ( const std::vector< uint8_t, Alloc > &  ad )

inlineinherited

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

See set_associated_data().

Parameters

ad	the associated data

Definition at line 88 of file aead.h.

Referenced by Botan::TLS::write_record().

         {
         set_associated_data(ad.data(), ad.size());
         }

set_associated_data()

void Botan::SIV_Mode::set_associated_data ( const uint8_t  ad[], size_t  ad_len  )

inlineoverridevirtualinherited

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

ad	the associated data
ad_len	length of add in bytes

Implements Botan::AEAD_Mode.

Definition at line 36 of file siv.h.

         {
         set_associated_data_n(0, ad, ad_len);
         }

set_associated_data_n()

void Botan::SIV_Mode::set_associated_data_n ( size_t  n, const uint8_t  ad[], size_t  ad_len  )

inherited

Sets the nth element of the vector of associated data

Parameters

n	index into the AD vector
ad	associated data
ad_len	length of associated data in bytes

Definition at line 81 of file siv.cpp.

References Botan::SIV_Mode::block_size(), Botan::SIV_Mode::name(), and Botan::ASN1::to_string().

   {
   const size_t max_ads = block_size() * 8 - 2;
   if(n > max_ads)
      throw Invalid_Argument(name() + " allows no more than " + std::to_string(max_ads) + " ADs");

   if(n >= m_ad_macs.size())
      m_ad_macs.resize(n+1);

   m_ad_macs[n] = m_mac->process(ad, length);
   }

set_associated_data_vec()

template<typename Alloc >

void Botan::AEAD_Mode::set_associated_data_vec ( const std::vector< uint8_t, Alloc > &  ad )

inlineinherited

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

See set_associated_data().

Parameters

ad	the associated data

Definition at line 73 of file aead.h.

         {
         set_associated_data(ad.data(), ad.size());
         }

set_ctr_iv()

void Botan::SIV_Mode::set_ctr_iv ( secure_vector< uint8_t >  V )

protectedinherited

Definition at line 146 of file siv.cpp.

References Botan::SIV_Mode::ctr(), and Botan::StreamCipher::set_iv().

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

   {
   V[m_bs-8] &= 0x7F;
   V[m_bs-4] &= 0x7F;

   ctr().set_iv(V.data(), V.size());
   }

set_key() [1/3]

template<typename Alloc >

void Botan::Cipher_Mode::set_key ( const std::vector< uint8_t, Alloc > &  key )

inlineinherited

Set the symmetric key of this transform

Parameters

key	contains the key material

Definition at line 206 of file cipher_mode.h.

Referenced by botan_cipher_set_key().

         {
         set_key(key.data(), key.size());
         }

set_key() [2/3]

void Botan::Cipher_Mode::set_key ( const SymmetricKey &  key )

inlineinherited

Set the symmetric key of this transform

Parameters

key	contains the key material

Definition at line 215 of file cipher_mode.h.

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

         {
         set_key(key.begin(), key.length());
         }

set_key() [3/3]

void Botan::Cipher_Mode::set_key ( const uint8_t  key[], size_t  length  )

inlineinherited

Set the symmetric key of this transform

Parameters

key	contains the key material
length	in bytes of key param

Definition at line 225 of file cipher_mode.h.

         {
         if(!valid_keylength(length))
            throw Invalid_Key_Length(name(), length);
         key_schedule(key, length);
         }

start() [1/3]

template<typename Alloc >

void Botan::Cipher_Mode::start ( const std::vector< uint8_t, Alloc > &  nonce )

inlineinherited

Begin processing a message.

Parameters

nonce

the per message nonce

Definition at line 72 of file cipher_mode.h.

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

         {
         start_msg(nonce.data(), nonce.size());
         }

start() [2/3]

void Botan::Cipher_Mode::start ( const uint8_t  nonce[], size_t  nonce_len  )

inlineinherited

Begin processing a message.

Parameters

nonce	the per message nonce
nonce_len	length of nonce

Definition at line 82 of file cipher_mode.h.

         {
         start_msg(nonce, nonce_len);
         }

start() [3/3]

void Botan::Cipher_Mode::start ( )

inlineinherited

Begin processing a message.

Definition at line 90 of file cipher_mode.h.

         {
         return start_msg(nullptr, 0);
         }

tag_size()

size_t Botan::SIV_Mode::tag_size ( ) const

inlineoverridevirtualinherited

Returns

the size of the authentication tag used (in bytes)

Reimplemented from Botan::Cipher_Mode.

Definition at line 53 of file siv.h.

Referenced by finish().

{ return 16; }

update()

void Botan::Cipher_Mode::update ( secure_vector< uint8_t > &  buffer, size_t  offset = 0  )

inlineinherited

Process some data. Input must be in size update_granularity() uint8_t blocks.

Parameters

buffer	in/out parameter which will possibly be resized
offset	an offset into blocks to begin processing

Definition at line 115 of file cipher_mode.h.

References BOTAN_ASSERT.

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

         {
         BOTAN_ASSERT(buffer.size() >= offset, "Offset ok");
         uint8_t* buf = buffer.data() + offset;
         const size_t buf_size = buffer.size() - offset;

         const size_t written = process(buf, buf_size);
         buffer.resize(offset + written);
         }

update_granularity()

size_t Botan::SIV_Mode::update_granularity ( ) const

overridevirtualinherited

Returns

size of required blocks to update

Implements Botan::Cipher_Mode.

Definition at line 57 of file siv.cpp.

   {
   /*
   This value does not particularly matter as regardless SIV_Mode::update
   buffers all input, so in theory this could be 1. However as for instance
   Transform_Filter creates update_granularity() uint8_t buffers, use a
   somewhat large size to avoid bouncing on a tiny buffer.
   */
   return 128;
   }

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

length

the key length to be checked.

Returns

true if the key length is valid.

Definition at line 196 of file cipher_mode.h.

         {
         return key_spec().valid_keylength(length);
         }

valid_nonce_length()

bool Botan::SIV_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 52 of file siv.cpp.

   {
   return true;
   }

---

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

• src/lib/modes/aead/siv/siv.h
• src/lib/modes/aead/siv/siv.cpp