github.com/gocuntian/go@v0.0.0-20160610041250-fee02d270bf8/src/crypto/x509/pkcs1.go (about)

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package x509
     6  
     7  import (
     8  	"crypto/rsa"
     9  	"encoding/asn1"
    10  	"errors"
    11  	"math/big"
    12  )
    13  
    14  // pkcs1PrivateKey is a structure which mirrors the PKCS#1 ASN.1 for an RSA private key.
    15  type pkcs1PrivateKey struct {
    16  	Version int
    17  	N       *big.Int
    18  	E       int
    19  	D       *big.Int
    20  	P       *big.Int
    21  	Q       *big.Int
    22  	// We ignore these values, if present, because rsa will calculate them.
    23  	Dp   *big.Int `asn1:"optional"`
    24  	Dq   *big.Int `asn1:"optional"`
    25  	Qinv *big.Int `asn1:"optional"`
    26  
    27  	AdditionalPrimes []pkcs1AdditionalRSAPrime `asn1:"optional,omitempty"`
    28  }
    29  
    30  type pkcs1AdditionalRSAPrime struct {
    31  	Prime *big.Int
    32  
    33  	// We ignore these values because rsa will calculate them.
    34  	Exp   *big.Int
    35  	Coeff *big.Int
    36  }
    37  
    38  // ParsePKCS1PrivateKey returns an RSA private key from its ASN.1 PKCS#1 DER encoded form.
    39  func ParsePKCS1PrivateKey(der []byte) (*rsa.PrivateKey, error) {
    40  	var priv pkcs1PrivateKey
    41  	rest, err := asn1.Unmarshal(der, &priv)
    42  	if len(rest) > 0 {
    43  		return nil, asn1.SyntaxError{Msg: "trailing data"}
    44  	}
    45  	if err != nil {
    46  		return nil, err
    47  	}
    48  
    49  	if priv.Version > 1 {
    50  		return nil, errors.New("x509: unsupported private key version")
    51  	}
    52  
    53  	if priv.N.Sign() <= 0 || priv.D.Sign() <= 0 || priv.P.Sign() <= 0 || priv.Q.Sign() <= 0 {
    54  		return nil, errors.New("x509: private key contains zero or negative value")
    55  	}
    56  
    57  	key := new(rsa.PrivateKey)
    58  	key.PublicKey = rsa.PublicKey{
    59  		E: priv.E,
    60  		N: priv.N,
    61  	}
    62  
    63  	key.D = priv.D
    64  	key.Primes = make([]*big.Int, 2+len(priv.AdditionalPrimes))
    65  	key.Primes[0] = priv.P
    66  	key.Primes[1] = priv.Q
    67  	for i, a := range priv.AdditionalPrimes {
    68  		if a.Prime.Sign() <= 0 {
    69  			return nil, errors.New("x509: private key contains zero or negative prime")
    70  		}
    71  		key.Primes[i+2] = a.Prime
    72  		// We ignore the other two values because rsa will calculate
    73  		// them as needed.
    74  	}
    75  
    76  	err = key.Validate()
    77  	if err != nil {
    78  		return nil, err
    79  	}
    80  	key.Precompute()
    81  
    82  	return key, nil
    83  }
    84  
    85  // MarshalPKCS1PrivateKey converts a private key to ASN.1 DER encoded form.
    86  func MarshalPKCS1PrivateKey(key *rsa.PrivateKey) []byte {
    87  	key.Precompute()
    88  
    89  	version := 0
    90  	if len(key.Primes) > 2 {
    91  		version = 1
    92  	}
    93  
    94  	priv := pkcs1PrivateKey{
    95  		Version: version,
    96  		N:       key.N,
    97  		E:       key.PublicKey.E,
    98  		D:       key.D,
    99  		P:       key.Primes[0],
   100  		Q:       key.Primes[1],
   101  		Dp:      key.Precomputed.Dp,
   102  		Dq:      key.Precomputed.Dq,
   103  		Qinv:    key.Precomputed.Qinv,
   104  	}
   105  
   106  	priv.AdditionalPrimes = make([]pkcs1AdditionalRSAPrime, len(key.Precomputed.CRTValues))
   107  	for i, values := range key.Precomputed.CRTValues {
   108  		priv.AdditionalPrimes[i].Prime = key.Primes[2+i]
   109  		priv.AdditionalPrimes[i].Exp = values.Exp
   110  		priv.AdditionalPrimes[i].Coeff = values.Coeff
   111  	}
   112  
   113  	b, _ := asn1.Marshal(priv)
   114  	return b
   115  }
   116  
   117  // rsaPublicKey reflects the ASN.1 structure of a PKCS#1 public key.
   118  type rsaPublicKey struct {
   119  	N *big.Int
   120  	E int
   121  }