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//
// Copyright (c) SAS Institute Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
package p11token
import (
"crypto"
"crypto/rsa"
"errors"
"math"
"math/big"
"github.com/miekg/pkcs11"
"github.com/sassoftware/relic/v7/lib/x509tools"
)
// Convert token RSA public key to *rsa.PublicKey
func (key *Key) toRsaKey() (crypto.PublicKey, error) {
modulus := key.token.getAttribute(key.pub, pkcs11.CKA_MODULUS)
exponent := key.token.getAttribute(key.pub, pkcs11.CKA_PUBLIC_EXPONENT)
if len(modulus) == 0 || len(exponent) == 0 {
return nil, errors.New("unable to retrieve RSA public key")
}
n := new(big.Int).SetBytes(modulus)
e := new(big.Int).SetBytes(exponent)
eInt := e.Int64()
if !e.IsInt64() || eInt > math.MaxInt || eInt < 3 {
return nil, errors.New("RSA exponent is out of bounds")
}
return &rsa.PublicKey{N: n, E: int(eInt)}, nil
}
func (key *Key) newPssMech(opts *rsa.PSSOptions) (*pkcs11.Mechanism, error) {
var hashAlg, mgfType uint
switch opts.Hash {
case crypto.SHA1:
hashAlg = pkcs11.CKM_SHA_1
mgfType = pkcs11.CKG_MGF1_SHA1
case crypto.SHA224:
hashAlg = pkcs11.CKM_SHA224
mgfType = pkcs11.CKG_MGF1_SHA224
case crypto.SHA256:
hashAlg = pkcs11.CKM_SHA256
mgfType = pkcs11.CKG_MGF1_SHA256
case crypto.SHA384:
hashAlg = pkcs11.CKM_SHA384
mgfType = pkcs11.CKG_MGF1_SHA384
case crypto.SHA512:
hashAlg = pkcs11.CKM_SHA512
mgfType = pkcs11.CKG_MGF1_SHA512
default:
return nil, errors.New("unsupported hash type for PSS")
}
saltLength := opts.SaltLength
switch saltLength {
case rsa.PSSSaltLengthAuto:
pub := key.pubParsed.(*rsa.PublicKey)
saltLength = (pub.N.BitLen()+7)/8 - 2 - opts.Hash.Size()
case rsa.PSSSaltLengthEqualsHash:
saltLength = opts.Hash.Size()
}
args := make([]byte, ulongSize*3)
putUlong(args, hashAlg)
putUlong(args[ulongSize:], mgfType)
putUlong(args[ulongSize*2:], uint(saltLength))
return pkcs11.NewMechanism(pkcs11.CKM_RSA_PKCS_PSS, args), nil
}
// Sign a digest using token RSA private key
func (key *Key) signRSA(digest []byte, opts crypto.SignerOpts) ([]byte, error) {
var mech *pkcs11.Mechanism
if opts == nil || opts.HashFunc() == 0 {
return nil, errors.New("signer options are required")
} else if pss, ok := opts.(*rsa.PSSOptions); ok {
var err error
mech, err = key.newPssMech(pss)
if err != nil {
return nil, err
}
} else {
var ok bool
digest, ok = x509tools.MarshalDigest(opts.HashFunc(), digest)
if !ok {
return nil, errors.New("unsupported hash function")
}
mech = pkcs11.NewMechanism(pkcs11.CKM_RSA_PKCS, nil)
}
err := key.token.ctx.SignInit(key.token.sh, []*pkcs11.Mechanism{mech}, key.priv)
if err != nil {
return nil, err
}
return key.token.ctx.Sign(key.token.sh, digest)
}
// Generate RSA-specific public and private key attributes from a PrivateKey
func rsaImportAttrs(priv *rsa.PrivateKey) (pubAttrs, privAttrs []*pkcs11.Attribute, err error) {
if len(priv.Primes) != 2 || priv.Precomputed.Dp == nil || priv.Precomputed.Dq == nil || priv.Precomputed.Qinv == nil {
// multi-prime keys and keys without the precomputed values are rare
// enough not to be interesting
return nil, nil, errors.New("unsupported RSA key")
}
pubAttrs = []*pkcs11.Attribute{
pkcs11.NewAttribute(pkcs11.CKA_PUBLIC_EXPONENT, big.NewInt(int64(priv.E)).Bytes()),
pkcs11.NewAttribute(pkcs11.CKA_MODULUS, priv.N.Bytes()),
}
privAttrs = []*pkcs11.Attribute{
pkcs11.NewAttribute(pkcs11.CKA_PUBLIC_EXPONENT, big.NewInt(int64(priv.E)).Bytes()),
pkcs11.NewAttribute(pkcs11.CKA_MODULUS, priv.N.Bytes()),
pkcs11.NewAttribute(pkcs11.CKA_PRIVATE_EXPONENT, priv.D.Bytes()),
pkcs11.NewAttribute(pkcs11.CKA_PRIME_1, priv.Primes[0].Bytes()),
pkcs11.NewAttribute(pkcs11.CKA_PRIME_2, priv.Primes[1].Bytes()),
pkcs11.NewAttribute(pkcs11.CKA_EXPONENT_1, priv.Precomputed.Dp.Bytes()),
pkcs11.NewAttribute(pkcs11.CKA_EXPONENT_2, priv.Precomputed.Dq.Bytes()),
pkcs11.NewAttribute(pkcs11.CKA_COEFFICIENT, priv.Precomputed.Qinv.Bytes()),
}
return
}
// Generate RSA-specific public attributes to generate an RSA key in the token
func rsaGenerateAttrs(bits uint) ([]*pkcs11.Attribute, *pkcs11.Mechanism, error) {
if bits < 1024 || bits > 4096 {
return nil, nil, errors.New("unsupported number of bits")
}
pubExponent := []byte{1, 0, 1} // 65537
attrs := []*pkcs11.Attribute{
pkcs11.NewAttribute(pkcs11.CKA_MODULUS_BITS, bits),
pkcs11.NewAttribute(pkcs11.CKA_PUBLIC_EXPONENT, pubExponent),
}
mech := pkcs11.NewMechanism(pkcs11.CKM_RSA_X9_31_KEY_PAIR_GEN, nil)
return attrs, mech, nil
}
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