var (
    ErrImport                     = fmt.Errorf("ecies: failed to import key")
    ErrInvalidCurve               = fmt.Errorf("ecies: invalid elliptic curve")
    ErrInvalidParams              = fmt.Errorf("ecies: invalid ECIES parameters")
    ErrInvalidPublicKey           = fmt.Errorf("ecies: invalid public key")
    ErrSharedKeyIsPointAtInfinity = fmt.Errorf("ecies: shared key is point at infinity")
    ErrSharedKeyTooBig            = fmt.Errorf("ecies: shared key params are too big")
)

var (
    ErrKeyDataTooLong = fmt.Errorf("ecies: can't supply requested key data")
    ErrSharedTooLong  = fmt.Errorf("ecies: shared secret is too long")
    ErrInvalidMessage = fmt.Errorf("ecies: invalid message")
)

var (
    DefaultCurve                  = ethcrypto.S256()
    ErrUnsupportedECDHAlgorithm   = fmt.Errorf("ecies: unsupported ECDH algorithm")
    ErrUnsupportedECIESParameters = fmt.Errorf("ecies: unsupported ECIES parameters")
)

var (
    ECIES_AES128_SHA256 = &ECIESParams{
        Hash:      sha256.New,
        hashAlgo:  crypto.SHA256,
        Cipher:    aes.NewCipher,
        BlockSize: aes.BlockSize,
        KeyLen:    16,
    }

    ECIES_AES256_SHA256 = &ECIESParams{
        Hash:      sha256.New,
        hashAlgo:  crypto.SHA256,
        Cipher:    aes.NewCipher,
        BlockSize: aes.BlockSize,
        KeyLen:    32,
    }

    ECIES_AES256_SHA384 = &ECIESParams{
        Hash:      sha512.New384,
        hashAlgo:  crypto.SHA384,
        Cipher:    aes.NewCipher,
        BlockSize: aes.BlockSize,
        KeyLen:    32,
    }

    ECIES_AES256_SHA512 = &ECIESParams{
        Hash:      sha512.New,
        hashAlgo:  crypto.SHA512,
        Cipher:    aes.NewCipher,
        BlockSize: aes.BlockSize,
        KeyLen:    32,
    }
)

type ECIESParams struct {
    Hash func() hash.Hash // hash function

    Cipher    func([]byte) (cipher.Block, error) // symmetric cipher
    BlockSize int                                // block size of symmetric cipher
    KeyLen    int                                // length of symmetric key
    // contains filtered or unexported fields
}

type PrivateKey struct {
    PublicKey
    D   *big.Int
}

type PublicKey struct {
    X   *big.Int
    Y   *big.Int
    elliptic.Curve
    Params *ECIESParams
}