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 } 122
