public override bool Equals(object obj)
{
var o = obj as PrivateKey;
return(!ReferenceEquals(o, null) && mBytes.SequenceEqual(o.mBytes) && ChainCode.SequenceEqual(o.ChainCode));
}
/// <summary>
/// Obtains the parent private key if provided the parent public key. This key must be a private key.
/// </summary>
/// <param name="parentPublicKey">The public key of the parent of this extended key.</param>
/// <returns>Returns the private key of the parent of this extended key.</returns>
public ExtendedKey GetParentPrivateKey(ExtendedKey parentPublicKey)
{
// Verify this key is a private key
if (KeyType != EthereumEcdsaKeyType.Private)
{
// This key is not a private key.
throw new ArgumentNullException("Could not obtain parent private key. Can only obtain the parent private key of a private key. This key is a public key.");
}
else if (parentPublicKey == null)
{
// The public key is null.
throw new ArgumentNullException("Could not obtain parent private key. Provided parent public key argument is null.");
}
else if (parentPublicKey.KeyType == EthereumEcdsaKeyType.Private)
{
// The public key was not a public key.
throw new ArgumentException("Could not obtain parent private key. Provided parent public key argument is not a public key.");
}
else if (Hardened)
{
throw new ArgumentException("Could not obtain parent private key if this key is a hardened key.");
}
else if (Depth == 0)
{
throw new ArgumentException("Could not obtain parent private key for this key because this key is a top level key.");
}
else if (!parentPublicKey.IsChild(this))
{
// The provided parent public key is not a parent.
throw new ArgumentException("Could not obtain parent private key for this key because the provided parent public key argument is not a parent to this key.");
}
// Obtain the hash used to derive this current key, from the parent.
byte[] hash = parentPublicKey.ComputeChildHash(ChildIndex, parentPublicKey.InternalKey.ToPublicKeyArray(true, false));
// Set the child key data as the first 32 bytes of "hash"
byte[] childKeyData = new byte[EthereumEcdsa.PRIVATE_KEY_SIZE];
Array.Copy(hash, 0, childKeyData, 0, childKeyData.Length);
// Initialize the child chain code
byte[] childChainCode = new byte[CHAIN_CODE_SIZE];
// We derive the child chain code as the data immediately following key data.
Array.Copy(hash, 32, childChainCode, 0, childChainCode.Length);
// Verify the chain code is equal
if (!ChainCode.SequenceEqual(childChainCode))
{
throw new ArgumentException("Derived chain code from the parent at this key's child index that did not match this key's chain code.");
}
// Convert the key data to an integer
BigInteger childKeyInt = BigIntegerConverter.GetBigInteger(childKeyData, false, childChainCode.Length);
// Convert this private key to an integer
byte[] thisKeyData = InternalKey.ToPrivateKeyArray();
BigInteger thisKeyInt = BigIntegerConverter.GetBigInteger(thisKeyData, false, thisKeyData.Length);
// Compute our parent key
BigInteger parentPrivateKeyInt = ((thisKeyInt - childKeyInt) + Secp256k1Curve.N) % Secp256k1Curve.N;
// Obtain our new key from this
byte[] computedParentKeyData = BigIntegerConverter.GetBytes(parentPrivateKeyInt, EthereumEcdsa.PRIVATE_KEY_SIZE);
// Obtain the parent private key
EthereumEcdsa parentPrivateKey = EthereumEcdsa.Create(computedParentKeyData, EthereumEcdsaKeyType.Private);
// Create the parent extended private key
return(new ExtendedKey(parentPrivateKey, parentPublicKey.ChainCode, parentPublicKey.Depth, parentPublicKey.ChildIndex, parentPublicKey.Fingerprint));
}