/*
* Encode two BigInt, with leading 0s if needed, and concatenate
*/
secure_vector<uint8_t> BigInt::encode_fixed_length_int_pair(const BigInt& n1, const BigInt& n2, size_t bytes)
{
if(n1.bytes() > bytes || n2.bytes() > bytes)
throw Encoding_Error("encode_fixed_length_int_pair: values too large to encode properly");
secure_vector<uint8_t> output(2 * bytes);
n1.binary_encode(output.data() , bytes);
n2.binary_encode(output.data() + bytes, bytes);
return output;
}
/*************************************************
* Encode a BigInt *
*************************************************/
void BigInt::encode(byte output[], const BigInt& n, Base base)
{
if(base == Binary)
n.binary_encode(output);
#ifndef BOTAN_MINIMAL_BIGINT
else if(base == Hexadecimal)
{
SecureVector<byte> binary(n.encoded_size(Binary));
n.binary_encode(binary);
for(u32bit j = 0; j != binary.size(); ++j)
Hex_Encoder::encode(binary[j], output + 2*j);
}
#endif
else if(base == Octal)
{
BigInt copy = n;
const u32bit output_size = n.encoded_size(Octal);
for(u32bit j = 0; j != output_size; ++j)
{
output[output_size - 1 - j] = Charset::digit2char(copy % 8);
copy /= 8;
}
}
else if(base == Decimal)
{
BigInt copy = n;
BigInt remainder;
copy.set_sign(Positive);
const u32bit output_size = n.encoded_size(Decimal);
for(u32bit j = 0; j != output_size; ++j)
{
divide(copy, 10, copy, remainder);
output[output_size - 1 - j] =
Charset::digit2char(remainder.word_at(0));
if(copy.is_zero())
{
if(j < output_size - 1)
{
int extra = output_size - 1 - j;
memmove(output, output + extra, output_size - extra);
memset(output + output_size - extra, 0, extra);
}
break;
}
}
}
else
throw Invalid_Argument("Unknown BigInt encoding method");
}
/*
* Default ElGamal Encrypt Operation
*/
SecureVector<byte> Default_ELG_Op::encrypt(const byte in[], u32bit length,
const BigInt& k) const
{
BigInt m(in, length);
if(m >= p)
throw Invalid_Argument("Default_ELG_Op::encrypt: Input is too large");
BigInt a = powermod_g_p(k);
BigInt b = mod_p.multiply(m, powermod_y_p(k));
SecureVector<byte> output(2*p.bytes());
a.binary_encode(output + (p.bytes() - a.bytes()));
b.binary_encode(output + output.size() / 2 + (p.bytes() - b.bytes()));
return output;
}
//static
void BigInt::encode_1363(uint8_t output[], size_t bytes, const BigInt& n)
{
if(n.bytes() > bytes)
throw Encoding_Error("encode_1363: n is too large to encode properly");
n.binary_encode(output, bytes);
}
SecureVector<byte>
DSA_Signature_Operation::sign(const byte msg[], size_t msg_len,
RandomNumberGenerator& rng)
{
rng.add_entropy(msg, msg_len);
BigInt i(msg, msg_len);
BigInt r = 0, s = 0;
while(r == 0 || s == 0)
{
BigInt k;
do
k.randomize(rng, q.bits());
while(k >= q);
r = mod_q.reduce(powermod_g_p(k));
s = mod_q.multiply(inverse_mod(k, q), mul_add(x, r, i));
}
SecureVector<byte> output(2*q.bytes());
r.binary_encode(&output[output.size() / 2 - r.bytes()]);
s.binary_encode(&output[output.size() - s.bytes()]);
return output;
}
SecureVector<byte>
ECDSA_Signature_Operation::sign(const byte msg[], size_t msg_len,
RandomNumberGenerator& rng)
{
rng.add_entropy(msg, msg_len);
BigInt m(msg, msg_len);
BigInt r = 0, s = 0;
while(r == 0 || s == 0)
{
// This contortion is necessary for the tests
BigInt k;
k.randomize(rng, order.bits());
while(k >= order)
k.randomize(rng, order.bits() - 1);
PointGFp k_times_P = base_point * k;
r = mod_order.reduce(k_times_P.get_affine_x());
s = mod_order.multiply(inverse_mod(k, order), mul_add(x, r, m));
}
SecureVector<byte> output(2*order.bytes());
r.binary_encode(&output[output.size() / 2 - r.bytes()]);
s.binary_encode(&output[output.size() - s.bytes()]);
return output;
}
/*
* Encode a BigInt, with leading 0s if needed
*/
secure_vector<uint8_t> BigInt::encode_1363(const BigInt& n, size_t bytes)
{
if(n.bytes() > bytes)
throw Encoding_Error("encode_1363: n is too large to encode properly");
secure_vector<uint8_t> output(bytes);
n.binary_encode(output.data(), output.size());
return output;
}
std::vector<byte> GOST_3410_PublicKey::x509_subject_public_key() const
{
const BigInt x = public_point().get_affine_x();
const BigInt y = public_point().get_affine_y();
size_t part_size = std::max(x.bytes(), y.bytes());
std::vector<byte> bits(2*part_size);
x.binary_encode(&bits[part_size - x.bytes()]);
y.binary_encode(&bits[2*part_size - y.bytes()]);
// Keys are stored in little endian format (WTF)
for(size_t i = 0; i != part_size / 2; ++i)
{
std::swap(bits[i], bits[part_size-1-i]);
std::swap(bits[part_size+i], bits[2*part_size-1-i]);
}
return DER_Encoder().encode(bits, OCTET_STRING).get_contents_unlocked();
}
