/**
* Initializes the internal {AndreevEcdsaBlindingContext}.
*
* @param {KeyManager} key_manager
* A {KeyManager} containing the signers public key which is necessary
* to extract the elliptic curve public parameter.
* @param {BigInteger} token
* This is used to validate the blinded request.
*/
async initContext(key_manager, token)
{
assert(check.isKeyManagerForEcdsaSign(key_manager));
assert(check.isBigInteger(token));
const context = EcdsaBlindingContext.fromKey(key_manager);
context.blinding_factor = {
a: await util.generateRandomScalar(context.curve),
b: await util.generateRandomScalar(context.curve),
c: await util.generateRandomScalar(context.curve),
d: await util.generateRandomScalar(context.curve)
};
context.hashed_token = util.calculateSha512(token);
this.context = context;
this.key_manager = key_manager;
this.token = token;
}
/**
* Calculates the second part of the ECDSA signature.
* Based on the blinded key packet payload send to the signer.
*
* @param {BlindSignaturePacket} packet
* Key package with prepared raw signature data.
* @returns {BigInteger}
* The unblinded signed signature data.
*/
async requestSecondSignatureParameter(packet)
{
assert(packet instanceof BlindSignaturePacket);
assert(check.isBigInteger(packet.raw_signature));
assert(EcdsaBlindingContext.isValidBlindingContext(this.context));
const hash = util.calculateSha512(packet.raw_signature);
const message = packet.key.pub.trunc_hash(hash.toBuffer());
const blinded_message = this.blind(message);
const signed_blinded_message = await server.requestAndreevEcdsaBlinding(blinded_message, this.context);
return this.unblind(signed_blinded_message);
}
/// TODO
async function prepareBlinding(key_manager)
{
assert(check.isKeyManager(key_manager));
const public_key_package = key_manager.get_primary_keypair().pub;
const curve = public_key_package.curve;
const n = curve.n;
const G = curve.G;
let k = null;
let Ŕ = null;
let ŕ = null;
do {
k = await util.generateRandomScalar(curve);
Ŕ = G.multiply(k);
ŕ = Ŕ.affineX.mod(n);
} while(ŕ.compareTo(BigInteger.ZERO) === 0);
return {k, Ŕ};
}
.then(key_ascii => util.generateKeyFromString(key_ascii))
before(async () => {
this.key_manager = await util.generateKeyFromString(sample_keys.rsa[1024].pub);
});