Botan 3.3.0
Crypto and TLS for C&
Public Member Functions | Protected Member Functions | List of all members
Botan::FPE_FE1 Class Referencefinal

#include <fpe_fe1.h>

Inheritance diagram for Botan::FPE_FE1:
Botan::SymmetricAlgorithm

Public Member Functions

void clear () override
 
BigInt decrypt (const BigInt &x, const uint8_t tweak[], size_t tweak_len) const
 
BigInt decrypt (const BigInt &x, uint64_t tweak) const
 
BigInt encrypt (const BigInt &x, const uint8_t tweak[], size_t tweak_len) const
 
BigInt encrypt (const BigInt &x, uint64_t tweak) const
 
 FPE_FE1 (const BigInt &n, size_t rounds=5, bool compat_mode=false, std::string_view mac_algo="HMAC(SHA-256)")
 
bool has_keying_material () const override
 
Key_Length_Specification key_spec () const override
 
size_t maximum_keylength () const
 
size_t minimum_keylength () const
 
std::string name () const override
 
void set_key (const SymmetricKey &key)
 
void set_key (const uint8_t key[], size_t length)
 
void set_key (std::span< const uint8_t > key)
 
bool valid_keylength (size_t length) const
 
 ~FPE_FE1 () override
 

Protected Member Functions

void assert_key_material_set () const
 
void assert_key_material_set (bool predicate) const
 

Detailed Description

Format Preserving Encryption using the scheme FE1 from the paper "Format-Preserving Encryption" by Bellare, Rogaway, et al (https://eprint.iacr.org/2009/251)

Definition at line 24 of file fpe_fe1.h.

Constructor & Destructor Documentation

◆ FPE_FE1()

Botan::FPE_FE1::FPE_FE1 ( const BigInt & n,
size_t rounds = 5,
bool compat_mode = false,
std::string_view mac_algo = "HMAC(SHA-256)" )
Parameters
nthe modulus. All plaintext and ciphertext values must be less than this.
roundsthe number of rounds to use. Must be at least 3.
compat_modeAn error in versions before 2.5.0 chose incorrect values for a and b. Set compat_mode to true to select this version.
mac_algothe PRF to use as the encryption function

Definition at line 61 of file fpe_fe1.cpp.

61 : m_rounds(rounds) {
62 if(m_rounds < 3) {
63 throw Invalid_Argument("FPE_FE1 rounds too small");
64 }
65
67
68 m_n_bytes = BigInt::encode(n);
69
70 if(m_n_bytes.size() > MAX_N_BYTES) {
71 throw Invalid_Argument("N is too large for FPE encryption");
72 }
73
74 factor(n, m_a, m_b);
75
76 if(compat_mode) {
77 if(m_a < m_b) {
78 std::swap(m_a, m_b);
79 }
80 } else {
81 if(m_a > m_b) {
82 std::swap(m_a, m_b);
83 }
84 }
85
86 mod_a = std::make_unique<Modular_Reducer>(m_a);
87}
static std::vector< uint8_t > encode(const BigInt &n)
Definition bigint.h:749
static std::unique_ptr< MessageAuthenticationCode > create_or_throw(std::string_view algo_spec, std::string_view provider="")
Definition mac.cpp:148

References Botan::MessageAuthenticationCode::create_or_throw(), and Botan::BigInt::encode().

◆ ~FPE_FE1()

Botan::FPE_FE1::~FPE_FE1 ( )
overridedefault

Member Function Documentation

◆ assert_key_material_set() [1/2]

void Botan::SymmetricAlgorithm::assert_key_material_set ( ) const
inlineprotectedinherited

Definition at line 139 of file sym_algo.h.

virtual bool has_keying_material() const =0
void assert_key_material_set() const
Definition sym_algo.h:139

References Botan::SymmetricAlgorithm::assert_key_material_set().

Referenced by Botan::SymmetricAlgorithm::assert_key_material_set(), Botan::Salsa20::cipher_bytes(), Botan::AES_128::decrypt_n(), Botan::AES_192::decrypt_n(), Botan::AES_256::decrypt_n(), Botan::ARIA_128::decrypt_n(), Botan::ARIA_192::decrypt_n(), Botan::ARIA_256::decrypt_n(), Botan::Blowfish::decrypt_n(), Botan::Camellia_128::decrypt_n(), Botan::Camellia_192::decrypt_n(), Botan::Camellia_256::decrypt_n(), Botan::CAST_128::decrypt_n(), Botan::DES::decrypt_n(), Botan::TripleDES::decrypt_n(), Botan::GOST_28147_89::decrypt_n(), Botan::IDEA::decrypt_n(), Botan::Kuznyechik::decrypt_n(), Botan::Lion::decrypt_n(), Botan::Noekeon::decrypt_n(), Botan::SEED::decrypt_n(), Botan::Serpent::decrypt_n(), Botan::SHACAL2::decrypt_n(), Botan::SM4::decrypt_n(), Botan::Threefish_512::decrypt_n(), Botan::Twofish::decrypt_n(), Botan::AES_128::encrypt_n(), Botan::AES_192::encrypt_n(), Botan::AES_256::encrypt_n(), Botan::ARIA_128::encrypt_n(), Botan::ARIA_192::encrypt_n(), Botan::ARIA_256::encrypt_n(), Botan::Blowfish::encrypt_n(), Botan::Camellia_128::encrypt_n(), Botan::Camellia_192::encrypt_n(), Botan::Camellia_256::encrypt_n(), Botan::CAST_128::encrypt_n(), Botan::DES::encrypt_n(), Botan::TripleDES::encrypt_n(), Botan::GOST_28147_89::encrypt_n(), Botan::IDEA::encrypt_n(), Botan::Kuznyechik::encrypt_n(), Botan::Lion::encrypt_n(), Botan::Noekeon::encrypt_n(), Botan::SEED::encrypt_n(), Botan::Serpent::encrypt_n(), Botan::SHACAL2::encrypt_n(), Botan::SM4::encrypt_n(), Botan::Threefish_512::encrypt_n(), Botan::Twofish::encrypt_n(), Botan::GHASH::final(), Botan::GHASH::ghash_update(), Botan::ChaCha::seek(), Botan::CTR_BE::seek(), Botan::Salsa20::seek(), Botan::OCB_Mode::set_associated_data_n(), Botan::Salsa20::set_iv_bytes(), Botan::GHASH::update(), and Botan::GHASH::update_associated_data().

◆ assert_key_material_set() [2/2]

void Botan::SymmetricAlgorithm::assert_key_material_set ( bool predicate) const
inlineprotectedinherited

Definition at line 141 of file sym_algo.h.

141 {
142 if(!predicate) {
143 throw_key_not_set_error();
144 }
145 }

◆ clear()

void Botan::FPE_FE1::clear ( )
overridevirtual

Reset the internal state. This includes not just the key, but any partial message that may have been in process.

Implements Botan::SymmetricAlgorithm.

Definition at line 91 of file fpe_fe1.cpp.

91 {
92 m_mac->clear();
93}

◆ decrypt() [1/2]

BigInt Botan::FPE_FE1::decrypt ( const BigInt & x,
const uint8_t tweak[],
size_t tweak_len ) const

Decrypt X from and onto the group Z_n using key and tweak

Parameters
xthe ciphertext to encrypt <= n
tweakmust match the value used to encrypt
tweak_lenlength of tweak

Definition at line 156 of file fpe_fe1.cpp.

156 {
157 const secure_vector<uint8_t> tweak_mac = compute_tweak_mac(tweak, tweak_len);
158
159 BigInt X = input;
160 secure_vector<uint8_t> tmp;
161
162 BigInt W, R, Fi;
163 for(size_t i = 0; i != m_rounds; ++i) {
164 ct_divide(X, m_a, R, W);
165
166 Fi = F(R, m_rounds - i - 1, tweak_mac, tmp);
167 X = m_b * mod_a->reduce(W - Fi) + R;
168 }
169
170 return X;
171}
FE_25519 X
Definition ge.cpp:25
void ct_divide(const BigInt &x, const BigInt &y, BigInt &q_out, BigInt &r_out)
Definition divide.cpp:48

References Botan::ct_divide(), and X.

Referenced by decrypt(), and Botan::FPE::fe1_decrypt().

◆ decrypt() [2/2]

BigInt Botan::FPE_FE1::decrypt ( const BigInt & x,
uint64_t tweak ) const

Definition at line 179 of file fpe_fe1.cpp.

179 {
180 uint8_t tweak8[8];
181 store_be(tweak, tweak8);
182 return decrypt(x, tweak8, sizeof(tweak8));
183}
BigInt decrypt(const BigInt &x, const uint8_t tweak[], size_t tweak_len) const
Definition fpe_fe1.cpp:156
constexpr void store_be(T in, OutR &&out_range)
Definition loadstor.h:358

References decrypt(), and Botan::store_be().

◆ encrypt() [1/2]

BigInt Botan::FPE_FE1::encrypt ( const BigInt & x,
const uint8_t tweak[],
size_t tweak_len ) const

Encrypt X from and onto the group Z_n using key and tweak

Parameters
xthe plaintext to encrypt <= n
tweakwill modify the ciphertext
tweak_lenlength of tweak

Definition at line 139 of file fpe_fe1.cpp.

139 {
140 const secure_vector<uint8_t> tweak_mac = compute_tweak_mac(tweak, tweak_len);
141
142 BigInt X = input;
143
144 secure_vector<uint8_t> tmp;
145
146 BigInt L, R, Fi;
147 for(size_t i = 0; i != m_rounds; ++i) {
148 ct_divide(X, m_b, L, R);
149 Fi = F(R, i, tweak_mac, tmp);
150 X = m_a * R + mod_a->reduce(L + Fi);
151 }
152
153 return X;
154}

References Botan::ct_divide(), and X.

Referenced by encrypt(), and Botan::FPE::fe1_encrypt().

◆ encrypt() [2/2]

BigInt Botan::FPE_FE1::encrypt ( const BigInt & x,
uint64_t tweak ) const

Definition at line 173 of file fpe_fe1.cpp.

173 {
174 uint8_t tweak8[8];
175 store_be(tweak, tweak8);
176 return encrypt(x, tweak8, sizeof(tweak8));
177}
BigInt encrypt(const BigInt &x, const uint8_t tweak[], size_t tweak_len) const
Definition fpe_fe1.cpp:139

References encrypt(), and Botan::store_be().

◆ has_keying_material()

bool Botan::FPE_FE1::has_keying_material ( ) const
overridevirtual
Returns
true if a key has been set on this object

Implements Botan::SymmetricAlgorithm.

Definition at line 103 of file fpe_fe1.cpp.

103 {
104 return m_mac->has_keying_material();
105}

◆ key_spec()

Key_Length_Specification Botan::FPE_FE1::key_spec ( ) const
overridevirtual
Returns
object describing limits on key size

Implements Botan::SymmetricAlgorithm.

Definition at line 99 of file fpe_fe1.cpp.

99 {
100 return m_mac->key_spec();
101}

◆ maximum_keylength()

size_t Botan::SymmetricAlgorithm::maximum_keylength ( ) const
inlineinherited
Returns
maximum allowed key length

Definition at line 95 of file sym_algo.h.

95{ return key_spec().maximum_keylength(); }
size_t maximum_keylength() const
Definition sym_algo.h:54
virtual Key_Length_Specification key_spec() const =0

◆ minimum_keylength()

size_t Botan::SymmetricAlgorithm::minimum_keylength ( ) const
inlineinherited
Returns
minimum allowed key length

Definition at line 100 of file sym_algo.h.

100{ return key_spec().minimum_keylength(); }
size_t minimum_keylength() const
Definition sym_algo.h:49

◆ name()

std::string Botan::FPE_FE1::name ( ) const
overridevirtual
Returns
the algorithm name

Implements Botan::SymmetricAlgorithm.

Definition at line 95 of file fpe_fe1.cpp.

95 {
96 return fmt("FPE_FE1({},{})", m_mac->name(), m_rounds);
97}
std::string fmt(std::string_view format, const T &... args)
Definition fmt.h:53

References Botan::fmt().

◆ set_key() [1/3]

void Botan::SymmetricAlgorithm::set_key ( const SymmetricKey & key)
inlineinherited

◆ set_key() [2/3]

void Botan::SymmetricAlgorithm::set_key ( const uint8_t 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 126 of file sym_algo.h.

126{ set_key(std::span{key, length}); }

References Botan::SymmetricAlgorithm::set_key().

Referenced by Botan::SymmetricAlgorithm::set_key().

◆ set_key() [3/3]

void Botan::SymmetricAlgorithm::set_key ( std::span< const uint8_t > key)
inherited

Set the symmetric key of this object.

Parameters
keythe contiguous byte range to be set.

Definition at line 17 of file sym_algo.cpp.

17 {
18 if(!valid_keylength(key.size())) {
19 throw Invalid_Key_Length(name(), key.size());
20 }
21 key_schedule(key);
22}
bool valid_keylength(size_t length) const
Definition sym_algo.h:107
virtual std::string name() const =0

References Botan::SymmetricAlgorithm::name(), and Botan::SymmetricAlgorithm::valid_keylength().

◆ valid_keylength()

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 107 of file sym_algo.h.

107{ return key_spec().valid_keylength(length); }
bool valid_keylength(size_t length) const
Definition sym_algo.h:42

Referenced by Botan::SymmetricAlgorithm::set_key().


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