Source file src/pkg/crypto/x509/pkcs1.go

     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) (key *rsa.PrivateKey, err error) {
    40		var priv pkcs1PrivateKey
    41		rest, err := asn1.Unmarshal(der, &priv)
    42		if len(rest) > 0 {
    43			err = asn1.SyntaxError{Msg: "trailing data"}
    44			return
    45		}
    46		if err != nil {
    47			return
    48		}
    49	
    50		if priv.Version > 1 {
    51			return nil, errors.New("x509: unsupported private key version")
    52		}
    53	
    54		if priv.N.Sign() <= 0 || priv.D.Sign() <= 0 || priv.P.Sign() <= 0 || priv.Q.Sign() <= 0 {
    55			return nil, errors.New("private key contains zero or negative value")
    56		}
    57	
    58		key = new(rsa.PrivateKey)
    59		key.PublicKey = rsa.PublicKey{
    60			E: priv.E,
    61			N: priv.N,
    62		}
    63	
    64		key.D = priv.D
    65		key.Primes = make([]*big.Int, 2+len(priv.AdditionalPrimes))
    66		key.Primes[0] = priv.P
    67		key.Primes[1] = priv.Q
    68		for i, a := range priv.AdditionalPrimes {
    69			if a.Prime.Sign() <= 0 {
    70				return nil, errors.New("private key contains zero or negative prime")
    71			}
    72			key.Primes[i+2] = a.Prime
    73			// We ignore the other two values because rsa will calculate
    74			// them as needed.
    75		}
    76	
    77		err = key.Validate()
    78		if err != nil {
    79			return nil, err
    80		}
    81		key.Precompute()
    82	
    83		return
    84	}
    85	
    86	// MarshalPKCS1PrivateKey converts a private key to ASN.1 DER encoded form.
    87	func MarshalPKCS1PrivateKey(key *rsa.PrivateKey) []byte {
    88		key.Precompute()
    89	
    90		version := 0
    91		if len(key.Primes) > 2 {
    92			version = 1
    93		}
    94	
    95		priv := pkcs1PrivateKey{
    96			Version: version,
    97			N:       key.N,
    98			E:       key.PublicKey.E,
    99			D:       key.D,
   100			P:       key.Primes[0],
   101			Q:       key.Primes[1],
   102			Dp:      key.Precomputed.Dp,
   103			Dq:      key.Precomputed.Dq,
   104			Qinv:    key.Precomputed.Qinv,
   105		}
   106	
   107		priv.AdditionalPrimes = make([]pkcs1AdditionalRSAPrime, len(key.Precomputed.CRTValues))
   108		for i, values := range key.Precomputed.CRTValues {
   109			priv.AdditionalPrimes[i].Prime = key.Primes[2+i]
   110			priv.AdditionalPrimes[i].Exp = values.Exp
   111			priv.AdditionalPrimes[i].Coeff = values.Coeff
   112		}
   113	
   114		b, _ := asn1.Marshal(priv)
   115		return b
   116	}
   117	
   118	// rsaPublicKey reflects the ASN.1 structure of a PKCS#1 public key.
   119	type rsaPublicKey struct {
   120		N *big.Int
   121		E int
   122	}