Botan::Encrypted_PSK_Database Class Reference

#include <psk_db.h>

Inheritance diagram for Botan::Encrypted_PSK_Database:

Public Member Functions
	Encrypted_PSK_Database (const secure_vector< uint8_t > &master_key)
secure_vector< uint8_t >	get (const std::string &name) const override
std::string	get_str (const std::string &name) const
bool	is_encrypted () const override
std::set< std::string >	list_names () const override
void	remove (const std::string &name) override
void	set (const std::string &name, const uint8_t psk[], size_t psk_len) override
void	set_str (const std::string &name, const std::string &psk)
template<typename Alloc >
void	set_vec (const std::string &name, const std::vector< uint8_t, Alloc > &psk)
	~Encrypted_PSK_Database ()

Protected Member Functions
virtual void	kv_del (const std::string &index)=0
virtual std::string	kv_get (const std::string &index) const =0
virtual std::set< std::string >	kv_get_all () const =0
virtual void	kv_set (const std::string &index, const std::string &value)=0

Detailed Description

A mixin for an encrypted PSK database. Both keys and values are encrypted with NIST AES-256 key wrapping. Values are padded to obscure their length before encryption, allowing it to be used as a password vault.

Subclasses must implement the virtual calls to handle storing and getting raw (base64 encoded) values.

Definition at line 90 of file psk_db.h.

Constructor & Destructor Documentation

Encrypted_PSK_Database()

Botan::Encrypted_PSK_Database::Encrypted_PSK_Database

(

const secure_vector< uint8_t > &

master_key

)

Parameters

master_key

specifies the master key used to encrypt all keys and value. It can be of any length, but should be at least 256 bits.

Subkeys for the cryptographic algorithms used are derived from this master key. No key stretching is performed; if encrypting a PSK database using a password, it is recommended to use PBKDF2 to derive the database master key.

Definition at line 16 of file psk_db.cpp.

   {
   m_cipher = BlockCipher::create_or_throw("AES-256");
   m_hmac = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");
   m_hmac->set_key(master_key);
 
   m_cipher->set_key(m_hmac->process("wrap"));
   m_hmac->set_key(m_hmac->process("hmac"));
   }

References Botan::BlockCipher::create_or_throw(), and Botan::MessageAuthenticationCode::create_or_throw().

~Encrypted_PSK_Database()

Botan::Encrypted_PSK_Database::~Encrypted_PSK_Database

(

)

Definition at line 26 of file psk_db.cpp.

   {
   // for ~unique_ptr
   }

Member Function Documentation

get()

secure_vector< uint8_t > Botan::Encrypted_PSK_Database::get ( const std::string &  name ) const

overridevirtual

Return the value associated with the specified

Parameters

name	or otherwise throw an exception.

Implements Botan::PSK_Database.

Definition at line 66 of file psk_db.cpp.

   {
   const std::vector<uint8_t> wrapped_name =
      nist_key_wrap_padded(cast_char_ptr_to_uint8(name.data()),
                           name.size(),
                           *m_cipher);
 
   const std::string val_base64 = kv_get(base64_encode(wrapped_name));
 
   if(val_base64.empty())
      throw Invalid_Argument("Named PSK not located");
 
   const secure_vector<uint8_t> val = base64_decode(val_base64);
 
   auto wrap_cipher = m_cipher->new_object();
   wrap_cipher->set_key(m_hmac->process(wrapped_name));
 
   return nist_key_unwrap_padded(val.data(), val.size(), *wrap_cipher);
   }

References Botan::base64_decode(), Botan::base64_encode(), Botan::cast_char_ptr_to_uint8(), kv_get(), name, Botan::nist_key_unwrap_padded(), and Botan::nist_key_wrap_padded().

get_str()

std::string Botan::PSK_Database::get_str ( const std::string &  name ) const

inlineinherited

Get a PSK in the form of a string (eg if the PSK is a password)

Definition at line 59 of file psk_db.h.

         {
         secure_vector<uint8_t> psk = get(name);
         return std::string(cast_uint8_ptr_to_char(psk.data()), psk.size());
         }

References Botan::cast_uint8_ptr_to_char(), and name.

is_encrypted()

bool Botan::Encrypted_PSK_Database::is_encrypted ( ) const

inlineoverridevirtual

Returns if the values in the PSK database are encrypted. If false, saved values are being stored in plaintext.

Implements Botan::PSK_Database.

Definition at line 114 of file psk_db.h.

{ return true; }

kv_del()

virtual void Botan::Encrypted_PSK_Database::kv_del ( const std::string &  index )

protectedpure virtual

Remove an index

Referenced by remove().

kv_get()

virtual std::string Botan::Encrypted_PSK_Database::kv_get ( const std::string &  index ) const

protectedpure virtual

Get a value previously saved with set_raw_value. Should return an empty string if index is not found.

Referenced by get().

kv_get_all()

virtual std::set< std::string > Botan::Encrypted_PSK_Database::kv_get_all ( ) const

protectedpure virtual

Return all indexes in the table.

Referenced by list_names().

kv_set()

virtual void Botan::Encrypted_PSK_Database::kv_set ( const std::string &  index, const std::string &  value  )

protectedpure virtual

Save a encrypted (name.value) pair to the database. Both will be base64 encoded strings.

Referenced by set().

list_names()

std::set< std::string > Botan::Encrypted_PSK_Database::list_names ( ) const

overridevirtual

Return the set of names for which get() will return a value.

Implements Botan::PSK_Database.

Definition at line 31 of file psk_db.cpp.

   {
   const std::set<std::string> encrypted_names = kv_get_all();
 
   std::set<std::string> names;
 
   for(const std::string& enc_name : encrypted_names)
      {
      try
         {
         const secure_vector<uint8_t> raw_name = base64_decode(enc_name);
         const secure_vector<uint8_t> name_bits =
            nist_key_unwrap_padded(raw_name.data(), raw_name.size(), *m_cipher);
 
         std::string pt_name(cast_uint8_ptr_to_char(name_bits.data()), name_bits.size());
         names.insert(pt_name);
         }
      catch(Invalid_Authentication_Tag&)
         {
         }
      }
 
   return names;
   }

References Botan::base64_decode(), Botan::cast_uint8_ptr_to_char(), kv_get_all(), and Botan::nist_key_unwrap_padded().

remove()

void Botan::Encrypted_PSK_Database::remove ( const std::string &  name )

overridevirtual

Remove a PSK from the database

Implements Botan::PSK_Database.

Definition at line 56 of file psk_db.cpp.

   {
   const std::vector<uint8_t> wrapped_name =
      nist_key_wrap_padded(cast_char_ptr_to_uint8(name.data()),
                           name.size(),
                           *m_cipher);
 
   this->kv_del(base64_encode(wrapped_name));
   }

References Botan::base64_encode(), Botan::cast_char_ptr_to_uint8(), kv_del(), name, and Botan::nist_key_wrap_padded().

set()

void Botan::Encrypted_PSK_Database::set ( const std::string &  name, const uint8_t  psk[], size_t  psk_len  )

overridevirtual

Set a value that can later be accessed with get(). If name already exists in the database, the old value will be overwritten.

Implements Botan::PSK_Database.

Definition at line 86 of file psk_db.cpp.

   {
   /*
   * Both as a basic precaution wrt key seperation, and specifically to prevent
   * cut-and-paste attacks against the database, each PSK is encrypted with a
   * distinct key which is derived by hashing the wrapped key name with HMAC.
   */
   const std::vector<uint8_t> wrapped_name =
      nist_key_wrap_padded(cast_char_ptr_to_uint8(name.data()),
                           name.size(),
                           *m_cipher);
 
   auto wrap_cipher = m_cipher->new_object();
   wrap_cipher->set_key(m_hmac->process(wrapped_name));
   const std::vector<uint8_t> wrapped_key = nist_key_wrap_padded(val, len, *wrap_cipher);
 
   this->kv_set(base64_encode(wrapped_name), base64_encode(wrapped_key));
   }

References Botan::base64_encode(), Botan::cast_char_ptr_to_uint8(), kv_set(), name, and Botan::nist_key_wrap_padded().

set_str()

void Botan::PSK_Database::set_str ( const std::string &  name, const std::string &  psk  )

inlineinherited

Definition at line 65 of file psk_db.h.

         {
         set(name, cast_char_ptr_to_uint8(psk.data()), psk.size());
         }

References Botan::cast_char_ptr_to_uint8(), and name.

set_vec()

template<typename Alloc >

void Botan::PSK_Database::set_vec ( const std::string &  name, const std::vector< uint8_t, Alloc > &  psk  )

inlineinherited

Definition at line 71 of file psk_db.h.

         {
         set(name, psk.data(), psk.size());
         }

References name.

---

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

• src/lib/psk_db/psk_db.h
• src/lib/psk_db/psk_db.cpp