mirror of
https://github.com/emmansun/gmsm.git
synced 2025-04-22 02:06:18 +08:00
108 lines
3.4 KiB
Go
108 lines
3.4 KiB
Go
package pkcs7
|
|
|
|
import (
|
|
"bytes"
|
|
"crypto"
|
|
"crypto/rand"
|
|
"encoding/asn1"
|
|
"errors"
|
|
|
|
"github.com/emmansun/gmsm/pkcs"
|
|
"github.com/emmansun/gmsm/sm2"
|
|
"github.com/emmansun/gmsm/smx509"
|
|
)
|
|
|
|
// ErrUnsupportedAlgorithm tells you when our quick dev assumptions have failed
|
|
var ErrUnsupportedAlgorithm = errors.New("pkcs7: cannot decrypt data: only RSA, SM2, DES, DES-EDE3, AES and SM4 supported")
|
|
|
|
// ErrNotEncryptedContent is returned when attempting to Decrypt data that is not encrypted data
|
|
var ErrNotEncryptedContent = errors.New("pkcs7: content data is NOT a decryptable data type")
|
|
|
|
type decryptable interface {
|
|
GetRecipient(cert *smx509.Certificate) *recipientInfo
|
|
GetEncryptedContentInfo() *encryptedContentInfo
|
|
}
|
|
|
|
// Decrypt decrypts encrypted content info for recipient cert and private key
|
|
func (p7 *PKCS7) Decrypt(cert *smx509.Certificate, pkey crypto.PrivateKey) ([]byte, error) {
|
|
return p7.decrypt(cert, pkey, false)
|
|
}
|
|
|
|
// DecryptCFCA decrypts encrypted content info for recipient cert and private key whose SM2 encrypted key is C1C2C3 format
|
|
// and without 0x4 prefix.
|
|
func (p7 *PKCS7) DecryptCFCA(cert *smx509.Certificate, pkey crypto.PrivateKey) ([]byte, error) {
|
|
return p7.decrypt(cert, pkey, true)
|
|
}
|
|
|
|
func (p7 *PKCS7) decrypt(cert *smx509.Certificate, pkey crypto.PrivateKey, isCFCA bool) ([]byte, error) {
|
|
decryptableData, ok := p7.raw.(decryptable)
|
|
if !ok {
|
|
return nil, ErrNotEncryptedContent
|
|
}
|
|
recipient := decryptableData.GetRecipient(cert)
|
|
if recipient == nil {
|
|
return nil, errors.New("pkcs7: no enveloped recipient for provided certificate")
|
|
}
|
|
|
|
switch pkey := pkey.(type) {
|
|
case crypto.Decrypter:
|
|
// Generic case to handle anything that provides the crypto.Decrypter interface.
|
|
encryptedKey := recipient.EncryptedKey
|
|
var decrypterOpts crypto.DecrypterOpts
|
|
if _, ok := pkey.(*sm2.PrivateKey); ok && isCFCA {
|
|
encryptedKey = make([]byte, len(recipient.EncryptedKey)+1)
|
|
encryptedKey[0] = 0x04
|
|
copy(encryptedKey[1:], recipient.EncryptedKey)
|
|
decrypterOpts = sm2.NewPlainDecrypterOpts(sm2.C1C2C3)
|
|
}
|
|
|
|
contentKey, err := pkey.Decrypt(rand.Reader, encryptedKey, decrypterOpts)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return decryptableData.GetEncryptedContentInfo().decrypt(contentKey)
|
|
}
|
|
return nil, ErrUnsupportedAlgorithm
|
|
}
|
|
|
|
// DecryptUsingPSK decrypts encrypted data using caller provided
|
|
// pre-shared secret
|
|
func (p7 *PKCS7) DecryptUsingPSK(key []byte) ([]byte, error) {
|
|
data, ok := p7.raw.(encryptedData)
|
|
if !ok {
|
|
return nil, ErrNotEncryptedContent
|
|
}
|
|
return data.EncryptedContentInfo.decrypt(key)
|
|
}
|
|
|
|
func (eci encryptedContentInfo) getCiphertext() (ciphertext []byte) {
|
|
// EncryptedContent can either be constructed of multple OCTET STRINGs
|
|
// or _be_ a tagged OCTET STRING
|
|
if eci.EncryptedContent.IsCompound {
|
|
// Complex case to concat all of the children OCTET STRINGs
|
|
var buf bytes.Buffer
|
|
cypherbytes := eci.EncryptedContent.Bytes
|
|
for {
|
|
var part []byte
|
|
cypherbytes, _ = asn1.Unmarshal(cypherbytes, &part)
|
|
buf.Write(part)
|
|
if cypherbytes == nil {
|
|
break
|
|
}
|
|
}
|
|
ciphertext = buf.Bytes()
|
|
} else {
|
|
// Simple case, the bytes _are_ the cyphertext
|
|
ciphertext = eci.EncryptedContent.Bytes
|
|
}
|
|
return
|
|
}
|
|
|
|
func (eci encryptedContentInfo) decrypt(key []byte) ([]byte, error) {
|
|
cipher, err := pkcs.GetCipher(eci.ContentEncryptionAlgorithm)
|
|
if err != nil {
|
|
return nil, ErrUnsupportedAlgorithm
|
|
}
|
|
return cipher.Decrypt(key, &eci.ContentEncryptionAlgorithm.Parameters, eci.getCiphertext())
|
|
}
|