Botan: src/pubkey/rsa/rsa.cpp Source File

Botan 1.10.17

rsa.cpp
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1 /*
2 * RSA
3 * (C) 1999-2010 Jack Lloyd
4 *
5 * Distributed under the terms of the Botan license
6 */
7
8 #include <botan/rsa.h>
9 #include <botan/libstate.h>
10 #include <botan/parsing.h>
11 #include <botan/numthry.h>
12 #include <botan/keypair.h>
13 #include <botan/internal/assert.h>
14
15 namespace Botan {
16
17 /*
18 * Create a RSA private key
19 */
20 RSA_PrivateKey::RSA_PrivateKey(RandomNumberGenerator& rng,
21 size_t bits, size_t exp)
22 {
23 if(bits < 512)
24 throw Invalid_Argument(algo_name() + ": Can't make a key that is only " +
25 to_string(bits) + " bits long");
26 if(exp < 3 || exp % 2 == 0)
27 throw Invalid_Argument(algo_name() + ": Invalid encryption exponent");
28
29 e = exp;
30
31 do
32 {
33 p = random_prime(rng, (bits + 1) / 2, e);
34 q = random_prime(rng, bits - p.bits(), e);
35 n = p * q;
36 } while(n.bits() != bits);
37
38 d = inverse_mod(e, lcm(p - 1, q - 1));
39 d1 = d % (p - 1);
40 d2 = d % (q - 1);
41 c = inverse_mod(q, p);
42
43 gen_check(rng);
44 }
45
46 /*
47 * Check Private RSA Parameters
48 */
49 bool RSA_PrivateKey::check_key(RandomNumberGenerator& rng, bool strong) const
50 {
51 if(!IF_Scheme_PrivateKey::check_key(rng, strong))
52 return false;
53
54 if(!strong)
55 return true;
56
57 if((e * d) % lcm(p - 1, q - 1) != 1)
58 return false;
59
60 return KeyPair::signature_consistency_check(rng, *this, "EMSA4(SHA-1)");
61 }
62
63 RSA_Private_Operation::RSA_Private_Operation(const RSA_PrivateKey& rsa) :
64 n(rsa.get_n()),
65 q(rsa.get_q()),
66 c(rsa.get_c()),
67 powermod_e_n(rsa.get_e(), rsa.get_n()),
68 powermod_d1_p(rsa.get_d1(), rsa.get_p()),
69 powermod_d2_q(rsa.get_d2(), rsa.get_q()),
70 mod_p(rsa.get_p())
71 {
72 BigInt k(global_state().global_rng(), n.bits() - 1);
73 blinder = Blinder(powermod_e_n(k), inverse_mod(k, n), n);
74 }
75
76 BigInt RSA_Private_Operation::private_op(const BigInt& m) const
77 {
78 if(m >= n)
79 throw Invalid_Argument("RSA private op - input is too large");
80
81 BigInt j1 = powermod_d1_p(m);
82 BigInt j2 = powermod_d2_q(m);
83
84 j1 = mod_p.reduce(sub_mul(j1, j2, c));
85
86 return mul_add(j1, q, j2);
87 }
88
89 SecureVector<byte>
90 RSA_Private_Operation::sign(const byte msg[], size_t msg_len,
91 RandomNumberGenerator&)
92 {
93 /* We don't check signatures against powermod_e_n here because
94 PK_Signer checks verification consistency for all signature
95 algorithms.
96 */
97
98 BigInt m(msg, msg_len);
99 BigInt x = blinder.unblind(private_op(blinder.blind(m)));
100 return BigInt::encode_1363(x, n.bytes());
101 }
102
103 /*
104 * RSA Decryption Operation
105 */
106 SecureVector<byte>
107 RSA_Private_Operation::decrypt(const byte msg[], size_t msg_len)
108 {
109 BigInt m(msg, msg_len);
110 BigInt x = blinder.unblind(private_op(blinder.blind(m)));
111
112 BOTAN_ASSERT(m == powermod_e_n(x),
113 "RSA private op failed consistency check");
114
115 return BigInt::encode(x);
116 }
117
118 }
Botan::RSA_Private_Operation::sign
SecureVector< byte > sign(const byte msg[], size_t msg_len, RandomNumberGenerator &rng)
Definition: rsa.cpp:90
Botan::IF_Scheme_PublicKey::n
BigInt n
Definition: if_algo.h:51
Botan::KeyPair::signature_consistency_check
bool signature_consistency_check(RandomNumberGenerator &rng, const Private_Key &key, const std::string &padding)
Definition: keypair.cpp:47
Botan::BigInt
Definition: bigint.h:22
Botan::RandomNumberGenerator
Definition: rng.h:20
Botan::IF_Scheme_PrivateKey::d2
BigInt d2
Definition: if_algo.h:101
Botan::BigInt::bits
size_t bits() const
Definition: bigint.cpp:254
Botan::RSA_PublicKey::algo_name
std::string algo_name() const
Definition: rsa.h:24
Botan::RSA_PrivateKey::check_key
bool check_key(RandomNumberGenerator &rng, bool) const
Definition: rsa.cpp:49
Botan::IF_Scheme_PublicKey::e
BigInt e
Definition: if_algo.h:51
Botan::Invalid_Argument
std::invalid_argument Invalid_Argument
Definition: exceptn.h:20
Botan::BigInt::encode
static SecureVector< byte > encode(const BigInt &n, Base base=Binary)
Definition: big_code.cpp:64
Botan::RSA_Private_Operation::RSA_Private_Operation
RSA_Private_Operation(const RSA_PrivateKey &rsa)
Definition: rsa.cpp:63
BOTAN_ASSERT
#define BOTAN_ASSERT(expr, msg)
Definition: assert.h:19
Botan::byte
unsigned char byte
Definition: types.h:22
Botan::Blinder::unblind
BigInt unblind(const BigInt &x) const
Definition: blinding.cpp:42
Botan::Private_Key::gen_check
void gen_check(RandomNumberGenerator &rng) const
Definition: pk_keys.cpp:49
Botan::Global_State_Management::global_state
Library_State & global_state()
Definition: global_state.cpp:32
Botan::RSA_Private_Operation::decrypt
SecureVector< byte > decrypt(const byte msg[], size_t msg_len)
Definition: rsa.cpp:107
Botan::IF_Scheme_PrivateKey::d1
BigInt d1
Definition: if_algo.h:101
Botan::RSA_PrivateKey
Definition: rsa.h:47
Botan
Definition: algo_base.h:14
Botan::BigInt::bytes
size_t bytes() const
Definition: bigint.cpp:246
Botan::IF_Scheme_PrivateKey::q
BigInt q
Definition: if_algo.h:101
Botan::Blinder
Definition: blinding.h:19
Botan::Blinder::blind
BigInt blind(const BigInt &x) const
Definition: blinding.cpp:29
Botan::inverse_mod
BigInt inverse_mod(const BigInt &n, const BigInt &mod)
Definition: numthry.cpp:314
Botan::IF_Scheme_PrivateKey::d
BigInt d
Definition: if_algo.h:101
Botan::IF_Scheme_PrivateKey::check_key
bool check_key(RandomNumberGenerator &rng, bool) const
Definition: if_algo.cpp:121
Botan::sub_mul
BigInt sub_mul(const BigInt &a, const BigInt &b, const BigInt &c)
Definition: mp_numth.cpp:60
Botan::Modular_Reducer::reduce
BigInt reduce(const BigInt &x) const
Definition: reducer.cpp:32
Botan::IF_Scheme_PrivateKey::c
BigInt c
Definition: if_algo.h:101
Botan::to_string
std::string to_string(u64bit n, size_t min_len)
Definition: parsing.cpp:42
Botan::SecureVector< byte >
Botan::RSA_PrivateKey::RSA_PrivateKey
RSA_PrivateKey(const AlgorithmIdentifier &alg_id, const MemoryRegion< byte > &key_bits, RandomNumberGenerator &rng)
Definition: rsa.h:53
Botan::BigInt::encode_1363
static SecureVector< byte > encode_1363(const BigInt &n, size_t bytes)
Definition: big_code.cpp:78
Botan::lcm
BigInt lcm(const BigInt &a, const BigInt &b)
Definition: numthry.cpp:195
Botan::mul_add
BigInt mul_add(const BigInt &a, const BigInt &b, const BigInt &c)
Definition: mp_numth.cpp:33
Botan::random_prime
BigInt random_prime(RandomNumberGenerator &rng, size_t bits, const BigInt &coprime, size_t equiv, size_t modulo)
Definition: make_prm.cpp:17
Botan::IF_Scheme_PrivateKey::p
BigInt p
Definition: if_algo.h:101