EC2N::EC2N(BufferedTransformation &bt)
: m_field(BERDecodeGF2NP(bt))
{
BERSequenceDecoder seq(bt);
m_field->BERDecodeElement(seq, m_a);
m_field->BERDecodeElement(seq, m_b);
// skip optional seed
if (!seq.EndReached())
{
SecByteBlock seed;
unsigned int unused;
BERDecodeBitString(seq, seed, unused);
}
seq.MessageEnd();
}
void DL_PrivateKey_EC<EC>::BERDecodeKey2(BufferedTransformation &bt, bool parametersPresent, unsigned int size)
{
BERSequenceDecoder seq(bt);
word32 version;
BERDecodeUnsigned<word32>(seq, version, INTEGER, 1, 1); // check version
BERGeneralDecoder dec(seq, OCTET_STRING);
if (!dec.IsDefiniteLength())
BERDecodeError();
Integer x;
x.Decode(dec, dec.RemainingLength());
dec.MessageEnd();
if (!parametersPresent && seq.PeekByte() != (CONTEXT_SPECIFIC | CONSTRUCTED | 0))
BERDecodeError();
if (!seq.EndReached() && seq.PeekByte() == (CONTEXT_SPECIFIC | CONSTRUCTED | 0))
{
BERGeneralDecoder parameters(seq, CONTEXT_SPECIFIC | CONSTRUCTED | 0);
AccessGroupParameters().BERDecode(parameters);
parameters.MessageEnd();
}
if (!seq.EndReached())
{
// skip over the public element
SecByteBlock subjectPublicKey;
unsigned int unusedBits;
BERGeneralDecoder publicKey(seq, CONTEXT_SPECIFIC | CONSTRUCTED | 1);
BERDecodeBitString(publicKey, subjectPublicKey, unusedBits);
publicKey.MessageEnd();
Element Q;
if (!(unusedBits == 0 && GetGroupParameters().GetCurve().DecodePoint(Q, subjectPublicKey, subjectPublicKey.size())))
BERDecodeError();
}
seq.MessageEnd();
SetPrivateExponent(x);
}
