xs/vendor/github.com/tjfoc/gmsm/sm4/utils.go

86 lines
2 KiB
Go

package sm4
import (
"crypto/rand"
"crypto/x509"
"encoding/pem"
"errors"
"io/ioutil"
)
// ReadKeyFromPem will return SM4Key from PEM format data.
func ReadKeyFromPem(data []byte, pwd []byte) (SM4Key, error) {
block, _ := pem.Decode(data)
if block == nil {
return nil, errors.New("SM4: pem decode failed")
}
if x509.IsEncryptedPEMBlock(block) {
if block.Type != "SM4 ENCRYPTED KEY" {
return nil, errors.New("SM4: unknown type")
}
if pwd == nil {
return nil, errors.New("SM4: need passwd")
}
data, err := x509.DecryptPEMBlock(block, pwd)
if err != nil {
return nil, err
}
return data, nil
}
if block.Type != "SM4 KEY" {
return nil, errors.New("SM4: unknown type")
}
return block.Bytes, nil
}
// ReadKeyFromPemFile will return SM4Key from filename that saved PEM format data.
func ReadKeyFromPemFile(FileName string, pwd []byte) (SM4Key, error) {
data, err := ioutil.ReadFile(FileName)
if err != nil {
return nil, err
}
return ReadKeyFromPem(data, pwd)
}
// WriteKeyToPem will convert SM4Key to PEM format data and return it.
func WriteKeyToPem(key SM4Key, pwd []byte) ([]byte, error) {
if pwd != nil {
block, err := x509.EncryptPEMBlock(rand.Reader,
"SM4 ENCRYPTED KEY", key, pwd, x509.PEMCipherAES256) //Use AES256 algorithms to encrypt SM4KEY
if err != nil {
return nil, err
}
return pem.EncodeToMemory(block), nil
} else {
block := &pem.Block{
Type: "SM4 KEY",
Bytes: key,
}
return pem.EncodeToMemory(block), nil
}
}
// WriteKeyToPemFile will convert SM4Key to PEM format data, then write it
// into the input filename.
func WriteKeyToPemFile(FileName string, key SM4Key, pwd []byte) error {
var block *pem.Block
var err error
if pwd != nil {
block, err = x509.EncryptPEMBlock(rand.Reader,
"SM4 ENCRYPTED KEY", key, pwd, x509.PEMCipherAES256)
if err != nil {
return err
}
} else {
block = &pem.Block{
Type: "SM4 KEY",
Bytes: key,
}
}
pemBytes := pem.EncodeToMemory(block)
err = ioutil.WriteFile(FileName, pemBytes, 0666)
if err != nil {
return err
}
return nil
}