/*
Copyright IBM Corp. 2016 All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

		 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package bccsp

import (
	"crypto"
	"hash"
)

// Key represents a cryptographic key
type Key interface {

	// Bytes converts this key to its byte representation,
	// if this operation is allowed.
	Bytes() ([]byte, error)

	// SKI returns the subject key identifier of this key.
	SKI() []byte

	// Symmetric returns true if this key is a symmetric key,
	// false is this key is asymmetric
	Symmetric() bool

	// Private returns true if this key is a private key,
	// false otherwise.
	Private() bool

	// PublicKey returns the corresponding public key part of an asymmetric public/private key pair.
	// This method returns an error in symmetric key schemes.
	PublicKey() (Key, error)
}

// KeyGenOpts contains options for key-generation with a CSP.
type KeyGenOpts interface {

	// Algorithm returns the key generation algorithm identifier (to be used).
	Algorithm() string

	// Ephemeral returns true if the key to generate has to be ephemeral,
	// false otherwise.
	Ephemeral() bool
}

// KeyDerivOpts contains options for key-derivation with a CSP.
type KeyDerivOpts interface {

	// Algorithm returns the key derivation algorithm identifier (to be used).
	Algorithm() string

	// Ephemeral returns true if the key to derived has to be ephemeral,
	// false otherwise.
	Ephemeral() bool
}

// KeyImportOpts contains options for importing the raw material of a key with a CSP.
type KeyImportOpts interface {

	// Algorithm returns the key importation algorithm identifier (to be used).
	Algorithm() string

	// Ephemeral returns true if the key generated has to be ephemeral,
	// false otherwise.
	Ephemeral() bool
}

// HashOpts contains options for hashing with a CSP.
type HashOpts interface {

	// Algorithm returns the hash algorithm identifier (to be used).
	Algorithm() string
}

// SignerOpts contains options for signing with a CSP.
type SignerOpts interface {
	crypto.SignerOpts
}

// EncrypterOpts contains options for encrypting with a CSP.
type EncrypterOpts interface{}

// DecrypterOpts contains options for decrypting with a CSP.
type DecrypterOpts interface{}

// BCCSP is the blockchain cryptographic service provider that offers
// the implementation of cryptographic standards and algorithms.
type BCCSP interface {

	// KeyGen generates a key using opts.
	KeyGen(opts KeyGenOpts) (k Key, err error)

	// KeyDeriv derives a key from k using opts.
	// The opts argument should be appropriate for the primitive used.
	KeyDeriv(k Key, opts KeyDerivOpts) (dk Key, err error)

	// KeyImport imports a key from its raw representation using opts.
	// The opts argument should be appropriate for the primitive used.
	KeyImport(raw interface{}, opts KeyImportOpts) (k Key, err error)

	// GetKey returns the key this CSP associates to
	// the Subject Key Identifier ski.
	GetKey(ski []byte) (k Key, err error)

	// Hash hashes messages msg using options opts.
	// If opts is nil, the default hash function will be used.
	Hash(msg []byte, opts HashOpts) (hash []byte, err error)

	// GetHash returns and instance of hash.Hash using options opts.
	// If opts is nil, the default hash function will be returned.
	GetHash(opts HashOpts) (h hash.Hash, err error)

	// Sign signs digest using key k.
	// The opts argument should be appropriate for the algorithm used.
	//
	// Note that when a signature of a hash of a larger message is needed,
	// the caller is responsible for hashing the larger message and passing
	// the hash (as digest).
	Sign(k Key, digest []byte, opts SignerOpts) (signature []byte, err error)

	// Verify verifies signature against key k and digest
	// The opts argument should be appropriate for the algorithm used.
	Verify(k Key, signature, digest []byte, opts SignerOpts) (valid bool, err error)

	// Encrypt encrypts plaintext using key k.
	// The opts argument should be appropriate for the algorithm used.
	Encrypt(k Key, plaintext []byte, opts EncrypterOpts) (ciphertext []byte, err error)

	// Decrypt decrypts ciphertext using key k.
	// The opts argument should be appropriate for the algorithm used.
	Decrypt(k Key, ciphertext []byte, opts DecrypterOpts) (plaintext []byte, err error)
}