146 lines
4.6 KiB
Go
146 lines
4.6 KiB
Go
// Copyright (c) 2013 Kyle Isom <kyle@tyrfingr.is>
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// Copyright (c) 2012 The Go Authors. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package ecies
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// This file contains parameters for ECIES encryption, specifying the
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// symmetric encryption and HMAC parameters.
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import (
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"crypto"
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"crypto/aes"
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"crypto/cipher"
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"crypto/elliptic"
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"crypto/sha256"
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"crypto/sha512"
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"errors"
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"fmt"
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"hash"
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ethcrypto "github.com/ethereum/go-ethereum/crypto"
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)
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var (
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DefaultCurve = ethcrypto.S256()
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ErrUnsupportedECDHAlgorithm = errors.New("ecies: unsupported ECDH algorithm")
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ErrUnsupportedECIESParameters = errors.New("ecies: unsupported ECIES parameters")
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ErrInvalidKeyLen = fmt.Errorf("ecies: invalid key size (> %d) in ECIESParams", maxKeyLen)
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)
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// KeyLen is limited to prevent overflow of the counter
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// in concatKDF. While the theoretical limit is much higher,
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// no known cipher uses keys larger than 512 bytes.
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const maxKeyLen = 512
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type ECIESParams struct {
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Hash func() hash.Hash // hash function
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hashAlgo crypto.Hash
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Cipher func([]byte) (cipher.Block, error) // symmetric cipher
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BlockSize int // block size of symmetric cipher
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KeyLen int // length of symmetric key
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}
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// Standard ECIES parameters:
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// * ECIES using AES128 and HMAC-SHA-256-16
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// * ECIES using AES256 and HMAC-SHA-256-32
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// * ECIES using AES256 and HMAC-SHA-384-48
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// * ECIES using AES256 and HMAC-SHA-512-64
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var (
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ECIES_AES128_SHA256 = &ECIESParams{
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Hash: sha256.New,
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hashAlgo: crypto.SHA256,
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Cipher: aes.NewCipher,
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BlockSize: aes.BlockSize,
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KeyLen: 16,
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}
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ECIES_AES192_SHA384 = &ECIESParams{
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Hash: sha512.New384,
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hashAlgo: crypto.SHA384,
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Cipher: aes.NewCipher,
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BlockSize: aes.BlockSize,
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KeyLen: 24,
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}
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ECIES_AES256_SHA256 = &ECIESParams{
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Hash: sha256.New,
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hashAlgo: crypto.SHA256,
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Cipher: aes.NewCipher,
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BlockSize: aes.BlockSize,
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KeyLen: 32,
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}
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ECIES_AES256_SHA384 = &ECIESParams{
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Hash: sha512.New384,
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hashAlgo: crypto.SHA384,
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Cipher: aes.NewCipher,
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BlockSize: aes.BlockSize,
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KeyLen: 32,
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}
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ECIES_AES256_SHA512 = &ECIESParams{
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Hash: sha512.New,
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hashAlgo: crypto.SHA512,
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Cipher: aes.NewCipher,
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BlockSize: aes.BlockSize,
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KeyLen: 32,
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}
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)
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var paramsFromCurve = map[elliptic.Curve]*ECIESParams{
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ethcrypto.S256(): ECIES_AES128_SHA256,
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elliptic.P256(): ECIES_AES128_SHA256,
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elliptic.P384(): ECIES_AES192_SHA384,
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elliptic.P521(): ECIES_AES256_SHA512,
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}
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func AddParamsForCurve(curve elliptic.Curve, params *ECIESParams) {
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paramsFromCurve[curve] = params
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}
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// ParamsFromCurve selects parameters optimal for the selected elliptic curve.
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// Only the curves P256, P384, and P512 are supported.
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func ParamsFromCurve(curve elliptic.Curve) (params *ECIESParams) {
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return paramsFromCurve[curve]
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}
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func pubkeyParams(key *PublicKey) (*ECIESParams, error) {
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params := key.Params
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if params == nil {
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if params = ParamsFromCurve(key.Curve); params == nil {
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return nil, ErrUnsupportedECIESParameters
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}
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}
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if params.KeyLen > maxKeyLen {
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return nil, ErrInvalidKeyLen
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}
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return params, nil
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}
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