pkcs1.go

Documentation: github.com/tjfoc/gmsm/x509

     1  /*
     2  Copyright Suzhou Tongji Fintech Research Institute 2017 All Rights Reserved.
     3  Licensed under the Apache License, Version 2.0 (the "License");
     4  you may not use this file except in compliance with the License.
     5  You may obtain a copy of the License at
     6  
     7  	http://www.apache.org/licenses/LICENSE-2.0
     8  
     9  Unless required by applicable law or agreed to in writing, software
    10  distributed under the License is distributed on an "AS IS" BASIS,
    11  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  See the License for the specific language governing permissions and
    13  limitations under the License.
    14  */
    15  
    16  package x509
    17  
    18  import (
    19  	"crypto/rsa"
    20  	"encoding/asn1"
    21  	"errors"
    22  	"math/big"
    23  )
    24  
    25  // pkcs1PrivateKey is a structure which mirrors the PKCS#1 ASN.1 for an RSA private key.
    26  type pkcs1PrivateKey struct {
    27  	Version int
    28  	N       *big.Int
    29  	E       int
    30  	D       *big.Int
    31  	P       *big.Int
    32  	Q       *big.Int
    33  	// We ignore these values, if present, because rsa will calculate them.
    34  	Dp   *big.Int `asn1:"optional"`
    35  	Dq   *big.Int `asn1:"optional"`
    36  	Qinv *big.Int `asn1:"optional"`
    37  
    38  	AdditionalPrimes []pkcs1AdditionalRSAPrime `asn1:"optional,omitempty"`
    39  }
    40  
    41  type pkcs1AdditionalRSAPrime struct {
    42  	Prime *big.Int
    43  
    44  	// We ignore these values because rsa will calculate them.
    45  	Exp   *big.Int
    46  	Coeff *big.Int
    47  }
    48  
    49  // ParsePKCS1PrivateKey returns an RSA private key from its ASN.1 PKCS#1 DER encoded form.
    50  func ParsePKCS1PrivateKey(der []byte) (*rsa.PrivateKey, error) {
    51  	var priv pkcs1PrivateKey
    52  	rest, err := asn1.Unmarshal(der, &priv)
    53  	if len(rest) > 0 {
    54  		return nil, asn1.SyntaxError{Msg: "trailing data"}
    55  	}
    56  	if err != nil {
    57  		return nil, err
    58  	}
    59  
    60  	if priv.Version > 1 {
    61  		return nil, errors.New("x509: unsupported private key version")
    62  	}
    63  
    64  	if priv.N.Sign() <= 0 || priv.D.Sign() <= 0 || priv.P.Sign() <= 0 || priv.Q.Sign() <= 0 {
    65  		return nil, errors.New("x509: private key contains zero or negative value")
    66  	}
    67  
    68  	key := new(rsa.PrivateKey)
    69  	key.PublicKey = rsa.PublicKey{
    70  		E: priv.E,
    71  		N: priv.N,
    72  	}
    73  
    74  	key.D = priv.D
    75  	key.Primes = make([]*big.Int, 2+len(priv.AdditionalPrimes))
    76  	key.Primes[0] = priv.P
    77  	key.Primes[1] = priv.Q
    78  	for i, a := range priv.AdditionalPrimes {
    79  		if a.Prime.Sign() <= 0 {
    80  			return nil, errors.New("x509: private key contains zero or negative prime")
    81  		}
    82  		key.Primes[i+2] = a.Prime
    83  		// We ignore the other two values because rsa will calculate
    84  		// them as needed.
    85  	}
    86  
    87  	err = key.Validate()
    88  	if err != nil {
    89  		return nil, err
    90  	}
    91  	key.Precompute()
    92  
    93  	return key, nil
    94  }
    95  
    96  // MarshalPKCS1PrivateKey converts a private key to ASN.1 DER encoded form.
    97  func MarshalPKCS1PrivateKey(key *rsa.PrivateKey) []byte {
    98  	key.Precompute()
    99  
   100  	version := 0
   101  	if len(key.Primes) > 2 {
   102  		version = 1
   103  	}
   104  
   105  	priv := pkcs1PrivateKey{
   106  		Version: version,
   107  		N:       key.N,
   108  		E:       key.PublicKey.E,
   109  		D:       key.D,
   110  		P:       key.Primes[0],
   111  		Q:       key.Primes[1],
   112  		Dp:      key.Precomputed.Dp,
   113  		Dq:      key.Precomputed.Dq,
   114  		Qinv:    key.Precomputed.Qinv,
   115  	}
   116  
   117  	priv.AdditionalPrimes = make([]pkcs1AdditionalRSAPrime, len(key.Precomputed.CRTValues))
   118  	for i, values := range key.Precomputed.CRTValues {
   119  		priv.AdditionalPrimes[i].Prime = key.Primes[2+i]
   120  		priv.AdditionalPrimes[i].Exp = values.Exp
   121  		priv.AdditionalPrimes[i].Coeff = values.Coeff
   122  	}
   123  
   124  	b, _ := asn1.Marshal(priv)
   125  	return b
   126  }
   127  
   128  // rsaPublicKey reflects the ASN.1 structure of a PKCS#1 public key.
   129  type rsaPublicKey struct {
   130  	N *big.Int
   131  	E int
   132  }
   133
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