github.com/aswedchain/aswed@v1.0.1/crypto/ecies/params.go (about)

     1  // Copyright (c) 2013 Kyle Isom <kyle@tyrfingr.is>
     2  // Copyright (c) 2012 The Go Authors. All rights reserved.
     3  //
     4  // Redistribution and use in source and binary forms, with or without
     5  // modification, are permitted provided that the following conditions are
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     7  //
     8  //    * Redistributions of source code must retain the above copyright
     9  // notice, this list of conditions and the following disclaimer.
    10  //    * Redistributions in binary form must reproduce the above
    11  // copyright notice, this list of conditions and the following disclaimer
    12  // in the documentation and/or other materials provided with the
    13  // distribution.
    14  //    * Neither the name of Google Inc. nor the names of its
    15  // contributors may be used to endorse or promote products derived from
    16  // this software without specific prior written permission.
    17  //
    18  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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    20  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    21  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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    25  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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    27  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    28  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    29  
    30  package ecies
    31  
    32  // This file contains parameters for ECIES encryption, specifying the
    33  // symmetric encryption and HMAC parameters.
    34  
    35  import (
    36  	"crypto"
    37  	"crypto/aes"
    38  	"crypto/cipher"
    39  	"crypto/elliptic"
    40  	"crypto/sha256"
    41  	"crypto/sha512"
    42  	"fmt"
    43  	"hash"
    44  
    45  	ethcrypto "github.com/aswedchain/aswed/crypto"
    46  )
    47  
    48  var (
    49  	DefaultCurve                  = ethcrypto.S256()
    50  	ErrUnsupportedECDHAlgorithm   = fmt.Errorf("ecies: unsupported ECDH algorithm")
    51  	ErrUnsupportedECIESParameters = fmt.Errorf("ecies: unsupported ECIES parameters")
    52  	ErrInvalidKeyLen              = fmt.Errorf("ecies: invalid key size (> %d) in ECIESParams", maxKeyLen)
    53  )
    54  
    55  // KeyLen is limited to prevent overflow of the counter
    56  // in concatKDF. While the theoretical limit is much higher,
    57  // no known cipher uses keys larger than 512 bytes.
    58  const maxKeyLen = 512
    59  
    60  type ECIESParams struct {
    61  	Hash      func() hash.Hash // hash function
    62  	hashAlgo  crypto.Hash
    63  	Cipher    func([]byte) (cipher.Block, error) // symmetric cipher
    64  	BlockSize int                                // block size of symmetric cipher
    65  	KeyLen    int                                // length of symmetric key
    66  }
    67  
    68  // Standard ECIES parameters:
    69  // * ECIES using AES128 and HMAC-SHA-256-16
    70  // * ECIES using AES256 and HMAC-SHA-256-32
    71  // * ECIES using AES256 and HMAC-SHA-384-48
    72  // * ECIES using AES256 and HMAC-SHA-512-64
    73  
    74  var (
    75  	ECIES_AES128_SHA256 = &ECIESParams{
    76  		Hash:      sha256.New,
    77  		hashAlgo:  crypto.SHA256,
    78  		Cipher:    aes.NewCipher,
    79  		BlockSize: aes.BlockSize,
    80  		KeyLen:    16,
    81  	}
    82  
    83  	ECIES_AES256_SHA256 = &ECIESParams{
    84  		Hash:      sha256.New,
    85  		hashAlgo:  crypto.SHA256,
    86  		Cipher:    aes.NewCipher,
    87  		BlockSize: aes.BlockSize,
    88  		KeyLen:    32,
    89  	}
    90  
    91  	ECIES_AES256_SHA384 = &ECIESParams{
    92  		Hash:      sha512.New384,
    93  		hashAlgo:  crypto.SHA384,
    94  		Cipher:    aes.NewCipher,
    95  		BlockSize: aes.BlockSize,
    96  		KeyLen:    32,
    97  	}
    98  
    99  	ECIES_AES256_SHA512 = &ECIESParams{
   100  		Hash:      sha512.New,
   101  		hashAlgo:  crypto.SHA512,
   102  		Cipher:    aes.NewCipher,
   103  		BlockSize: aes.BlockSize,
   104  		KeyLen:    32,
   105  	}
   106  )
   107  
   108  var paramsFromCurve = map[elliptic.Curve]*ECIESParams{
   109  	ethcrypto.S256(): ECIES_AES128_SHA256,
   110  	elliptic.P256():  ECIES_AES128_SHA256,
   111  	elliptic.P384():  ECIES_AES256_SHA384,
   112  	elliptic.P521():  ECIES_AES256_SHA512,
   113  }
   114  
   115  func AddParamsForCurve(curve elliptic.Curve, params *ECIESParams) {
   116  	paramsFromCurve[curve] = params
   117  }
   118  
   119  // ParamsFromCurve selects parameters optimal for the selected elliptic curve.
   120  // Only the curves P256, P384, and P512 are supported.
   121  func ParamsFromCurve(curve elliptic.Curve) (params *ECIESParams) {
   122  	return paramsFromCurve[curve]
   123  }
   124  
   125  func pubkeyParams(key *PublicKey) (*ECIESParams, error) {
   126  	params := key.Params
   127  	if params == nil {
   128  		if params = ParamsFromCurve(key.Curve); params == nil {
   129  			return nil, ErrUnsupportedECIESParameters
   130  		}
   131  	}
   132  	if params.KeyLen > maxKeyLen {
   133  		return nil, ErrInvalidKeyLen
   134  	}
   135  	return params, nil
   136  }