digests.go

Documentation: github.com/sassoftware/relic/lib/x509tools

     1  //
     2  // Copyright (c) SAS Institute Inc.
     3  //
     4  // Licensed under the Apache License, Version 2.0 (the "License");
     5  // you may not use this file except in compliance with the License.
     6  // You may obtain a copy of the License at
     7  //
     8  //     http://www.apache.org/licenses/LICENSE-2.0
     9  //
    10  // Unless required by applicable law or agreed to in writing, software
    11  // distributed under the License is distributed on an "AS IS" BASIS,
    12  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  // See the License for the specific language governing permissions and
    14  // limitations under the License.
    15  //
    16  
    17  package x509tools
    18  
    19  import (
    20  	"crypto"
    21  	"crypto/x509/pkix"
    22  	"encoding/asn1"
    23  	"strings"
    24  	"sync"
    25  )
    26  
    27  var (
    28  	// RFC 3279
    29  	OidDigestMD5  = asn1.ObjectIdentifier{1, 2, 840, 113549, 2, 5}
    30  	OidDigestSHA1 = asn1.ObjectIdentifier{1, 3, 14, 3, 2, 26}
    31  	// RFC 5758
    32  	OidDigestSHA224 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 4}
    33  	OidDigestSHA256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 1}
    34  	OidDigestSHA384 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 2}
    35  	OidDigestSHA512 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 3}
    36  )
    37  
    38  var HashOids = map[crypto.Hash]asn1.ObjectIdentifier{
    39  	crypto.MD5:    OidDigestMD5,
    40  	crypto.SHA1:   OidDigestSHA1,
    41  	crypto.SHA224: OidDigestSHA224,
    42  	crypto.SHA256: OidDigestSHA256,
    43  	crypto.SHA384: OidDigestSHA384,
    44  	crypto.SHA512: OidDigestSHA512,
    45  }
    46  
    47  var HashNames = map[crypto.Hash]string{
    48  	crypto.MD5:    "MD5",
    49  	crypto.SHA1:   "SHA1",
    50  	crypto.SHA224: "SHA-224",
    51  	crypto.SHA256: "SHA-256",
    52  	crypto.SHA384: "SHA-384",
    53  	crypto.SHA512: "SHA-512",
    54  }
    55  
    56  var (
    57  	hashesByName map[string]crypto.Hash
    58  	once         sync.Once
    59  )
    60  
    61  func HashShortName(hash crypto.Hash) string {
    62  	return normalName(HashNames[hash])
    63  }
    64  
    65  func normalName(name string) string {
    66  	return strings.Replace(strings.ToLower(name), "-", "", 1)
    67  }
    68  
    69  func HashByName(name string) crypto.Hash {
    70  	name = normalName(name)
    71  	once.Do(func() {
    72  		hashesByName = make(map[string]crypto.Hash, len(HashNames))
    73  		for h, hn := range HashNames {
    74  			hashesByName[normalName(hn)] = h
    75  		}
    76  	})
    77  	return hashesByName[name]
    78  }
    79  
    80  type digestInfo struct {
    81  	DigestAlgorithm pkix.AlgorithmIdentifier
    82  	Digest          []byte
    83  }
    84  
    85  // Pack a digest along with an algorithm identifier. Mainly useful for
    86  // PKCS#1v1.5 padding (RSA).
    87  func MarshalDigest(hash crypto.Hash, digest []byte) (der []byte, ok bool) {
    88  	alg, ok := PkixDigestAlgorithm(hash)
    89  	if !ok {
    90  		return nil, false
    91  	}
    92  	der, err := asn1.Marshal(digestInfo{alg, digest})
    93  	if err != nil {
    94  		return nil, false
    95  	}
    96  	return der, true
    97  }
    98
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