Botan  2.9.0
Crypto and TLS for C++11
Public Member Functions | List of all members
Botan::DLIES_Decryptor Class Referencefinal

#include <dlies.h>

Inheritance diagram for Botan::DLIES_Decryptor:
Botan::PK_Decryptor

Public Member Functions

secure_vector< uint8_t > decrypt (const uint8_t in[], size_t length) const
 
template<typename Alloc >
secure_vector< uint8_t > decrypt (const std::vector< uint8_t, Alloc > &in) const
 
secure_vector< uint8_t > decrypt_or_random (const uint8_t in[], size_t length, size_t expected_pt_len, RandomNumberGenerator &rng) const
 
secure_vector< uint8_t > decrypt_or_random (const uint8_t in[], size_t length, size_t expected_pt_len, RandomNumberGenerator &rng, const uint8_t required_content_bytes[], const uint8_t required_content_offsets[], size_t required_contents) const
 
 DLIES_Decryptor (const DH_PrivateKey &own_priv_key, RandomNumberGenerator &rng, KDF *kdf, MessageAuthenticationCode *mac, size_t mac_key_len=20)
 
 DLIES_Decryptor (const DH_PrivateKey &own_priv_key, RandomNumberGenerator &rng, KDF *kdf, Cipher_Mode *cipher, size_t cipher_key_len, MessageAuthenticationCode *mac, size_t mac_key_len=20)
 
void set_initialization_vector (const InitializationVector &iv)
 Set the initialization vector for the data decryption method. More...
 

Detailed Description

DLIES Decryption

Definition at line 98 of file dlies.h.

Constructor & Destructor Documentation

◆ DLIES_Decryptor() [1/2]

Botan::DLIES_Decryptor::DLIES_Decryptor ( const DH_PrivateKey own_priv_key,
RandomNumberGenerator rng,
KDF kdf,
MessageAuthenticationCode mac,
size_t  mac_key_len = 20 
)

Stream mode: use KDF to provide a stream of bytes to xor with the message

Parameters
own_priv_keyown (ephemeral) DH private key
rngthe RNG to use
kdfthe KDF that should be used
macthe MAC function that should be used
mac_key_lenkey length of the MAC function. Default = 20 bytes

input = (ephemeral) public key + ciphertext + tag

Definition at line 132 of file dlies.cpp.

136  :
137  DLIES_Decryptor(own_priv_key, rng, kdf, nullptr, 0, mac, mac_key_length)
138  {}
DLIES_Decryptor(const DH_PrivateKey &own_priv_key, RandomNumberGenerator &rng, KDF *kdf, MessageAuthenticationCode *mac, size_t mac_key_len=20)
Definition: dlies.cpp:132

◆ DLIES_Decryptor() [2/2]

Botan::DLIES_Decryptor::DLIES_Decryptor ( const DH_PrivateKey own_priv_key,
RandomNumberGenerator rng,
KDF kdf,
Cipher_Mode cipher,
size_t  cipher_key_len,
MessageAuthenticationCode mac,
size_t  mac_key_len = 20 
)

Block cipher mode

Parameters
own_priv_keyown (ephemeral) DH private key
rngthe RNG to use
kdfthe KDF that should be used
cipherthe block cipher that should be used
cipher_key_lenthe key length of the block cipher
macthe MAC function that should be used
mac_key_lenkey length of the MAC function. Default = 20 bytes

input = (ephemeral) public key + ciphertext + tag

Definition at line 112 of file dlies.cpp.

118  :
119  m_pub_key_size(own_priv_key.public_value().size()),
120  m_ka(own_priv_key, rng, "Raw"),
121  m_kdf(kdf),
122  m_cipher(cipher),
123  m_cipher_key_len(cipher_key_len),
124  m_mac(mac),
125  m_mac_keylen(mac_key_length),
126  m_iv()
127  {
130  }
#define BOTAN_ASSERT_NONNULL(ptr)
Definition: assert.h:107

Member Function Documentation

◆ decrypt() [1/2]

secure_vector< uint8_t > Botan::PK_Decryptor::decrypt ( const uint8_t  in[],
size_t  length 
) const
inherited

Decrypt a ciphertext, throwing an exception if the input seems to be invalid (eg due to an accidental or malicious error in the ciphertext).

Parameters
inthe ciphertext as a byte array
lengththe length of the above byte array
Returns
decrypted message

Definition at line 17 of file pubkey.cpp.

Referenced by Botan::KeyPair::encryption_consistency_check().

18  {
19  uint8_t valid_mask = 0;
20 
21  secure_vector<uint8_t> decoded = do_decrypt(valid_mask, in, length);
22 
23  if(valid_mask == 0)
24  throw Decoding_Error("Invalid public key ciphertext, cannot decrypt");
25 
26  return decoded;
27  }

◆ decrypt() [2/2]

template<typename Alloc >
secure_vector<uint8_t> Botan::PK_Decryptor::decrypt ( const std::vector< uint8_t, Alloc > &  in) const
inlineinherited

Same as above, but taking a vector

Parameters
inthe ciphertext
Returns
decrypted message

Definition at line 109 of file pubkey.h.

References Botan::CryptoBox::decrypt().

110  {
111  return decrypt(in.data(), in.size());
112  }
secure_vector< uint8_t > decrypt(const uint8_t in[], size_t length) const
Definition: pubkey.cpp:17

◆ decrypt_or_random() [1/2]

secure_vector< uint8_t > Botan::PK_Decryptor::decrypt_or_random ( const uint8_t  in[],
size_t  length,
size_t  expected_pt_len,
RandomNumberGenerator rng 
) const
inherited

Decrypt a ciphertext. If the ciphertext is invalid (eg due to invalid padding) or is not the expected length, instead returns a random string of the expected length. Use to avoid oracle attacks, especially against PKCS #1 v1.5 decryption.

Definition at line 78 of file pubkey.cpp.

82  {
83  return decrypt_or_random(in, length, expected_pt_len, rng,
84  nullptr, nullptr, 0);
85  }
secure_vector< uint8_t > decrypt_or_random(const uint8_t in[], size_t length, size_t expected_pt_len, RandomNumberGenerator &rng) const
Definition: pubkey.cpp:78

◆ decrypt_or_random() [2/2]

secure_vector< uint8_t > Botan::PK_Decryptor::decrypt_or_random ( const uint8_t  in[],
size_t  length,
size_t  expected_pt_len,
RandomNumberGenerator rng,
const uint8_t  required_content_bytes[],
const uint8_t  required_content_offsets[],
size_t  required_contents 
) const
inherited

Decrypt a ciphertext. If the ciphertext is invalid (eg due to invalid padding) or is not the expected length, instead returns a random string of the expected length. Use to avoid oracle attacks, especially against PKCS #1 v1.5 decryption.

Additionally checks (also in const time) that: contents[required_content_offsets[i]] == required_content_bytes[i] for 0 <= i < required_contents

Used for example in TLS, which encodes the client version in the content bytes: if there is any timing variation the version check can be used as an oracle to recover the key.

Definition at line 30 of file pubkey.cpp.

References BOTAN_ASSERT, Botan::CT::Mask< T >::is_equal(), Botan::CT::Mask< T >::is_zero(), and Botan::RandomNumberGenerator::random_vec().

37  {
38  const secure_vector<uint8_t> fake_pms = rng.random_vec(expected_pt_len);
39 
40  uint8_t decrypt_valid = 0;
41  secure_vector<uint8_t> decoded = do_decrypt(decrypt_valid, in, length);
42 
43  auto valid_mask = CT::Mask<uint8_t>::is_equal(decrypt_valid, 0xFF);
44  valid_mask &= CT::Mask<uint8_t>(CT::Mask<size_t>::is_zero(decoded.size() ^ expected_pt_len));
45 
46  decoded.resize(expected_pt_len);
47 
48  for(size_t i = 0; i != required_contents_length; ++i)
49  {
50  /*
51  These values are chosen by the application and for TLS are constants,
52  so this early failure via assert is fine since we know 0,1 < 48
53 
54  If there is a protocol that has content checks on the key where
55  the expected offsets are controllable by the attacker this could
56  still leak.
57 
58  Alternately could always reduce the offset modulo the length?
59  */
60 
61  const uint8_t exp = required_content_bytes[i];
62  const uint8_t off = required_content_offsets[i];
63 
64  BOTAN_ASSERT(off < expected_pt_len, "Offset in range of plaintext");
65 
66  auto eq = CT::Mask<uint8_t>::is_equal(decoded[off], exp);
67 
68  valid_mask &= eq;
69  }
70 
71  // If valid_mask is false, assign fake pre master instead
72  valid_mask.select_n(decoded.data(), decoded.data(), fake_pms.data(), expected_pt_len);
73 
74  return decoded;
75  }
#define BOTAN_ASSERT(expr, assertion_made)
Definition: assert.h:55
static Mask< T > is_zero(T x)
Definition: ct_utils.h:141
static Mask< T > is_equal(T x, T y)
Definition: ct_utils.h:149

◆ set_initialization_vector()

void Botan::DLIES_Decryptor::set_initialization_vector ( const InitializationVector iv)
inline

Set the initialization vector for the data decryption method.

Definition at line 140 of file dlies.h.

141  {
142  m_iv = iv;
143  }

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