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124 lines
3.6 KiB
Go
124 lines
3.6 KiB
Go
// Package cfca handles cfca issued key and certificate
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package cfca
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import (
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"crypto/cipher"
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"encoding/asn1"
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"errors"
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"fmt"
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"math/big"
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"github.com/emmansun/gmsm/padding"
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"github.com/emmansun/gmsm/pkcs"
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"github.com/emmansun/gmsm/sm2"
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"github.com/emmansun/gmsm/sm3"
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"github.com/emmansun/gmsm/sm4"
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"github.com/emmansun/gmsm/smx509"
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)
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// CFCA私有格式，在SADK中把它定义为PKCS12_SM2
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type cfcaKeyPairData struct {
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Version int `asn1:"default:1"`
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EncryptedKey keyData
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Certificate certData
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}
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// 被加密的私钥数据
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type keyData struct {
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ContentType asn1.ObjectIdentifier
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Algorithm asn1.ObjectIdentifier
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EncryptedContent asn1.RawValue
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}
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// 对应的证书
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type certData struct {
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ContentType asn1.ObjectIdentifier
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Content asn1.RawContent
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}
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var (
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oidSM2Data = asn1.ObjectIdentifier{1, 2, 156, 10197, 6, 1, 4, 2, 1}
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oidSM4 = asn1.ObjectIdentifier{1, 2, 156, 10197, 1, 104} // SADK中认为这就是SM4_CBC，不知道是不是历史原因
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oidSM4CBC = asn1.ObjectIdentifier{1, 2, 156, 10197, 1, 104, 2}
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)
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// ParseSM2 parses the der data, returns private key and related certificate, it's CFCA private structure.
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func ParseSM2(password, data []byte) (*sm2.PrivateKey, *smx509.Certificate, error) {
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var keys cfcaKeyPairData
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if _, err := asn1.Unmarshal(data, &keys); err != nil {
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return nil, nil, err
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}
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if !keys.Certificate.ContentType.Equal(oidSM2Data) {
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return nil, nil, fmt.Errorf("cfca: unsupported content type oid <%v>", keys.Certificate.ContentType)
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}
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if !keys.EncryptedKey.ContentType.Equal(oidSM2Data) {
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return nil, nil, fmt.Errorf("cfca: unsupported content type oid <%v>", keys.EncryptedKey.ContentType)
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}
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if !keys.EncryptedKey.Algorithm.Equal(oidSM4) && !keys.EncryptedKey.Algorithm.Equal(oidSM4CBC) {
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return nil, nil, fmt.Errorf("cfca: unsupported algorithm <%v>", keys.EncryptedKey.Algorithm)
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}
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ivkey := sm3.Kdf(password, 32)
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marshalledIV, err := asn1.Marshal(ivkey[:16])
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if err != nil {
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return nil, nil, err
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}
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pk, err := pkcs.SM4CBC.Decrypt(ivkey[16:], &asn1.RawValue{FullBytes: marshalledIV}, keys.EncryptedKey.EncryptedContent.Bytes)
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if err != nil {
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return nil, nil, err
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}
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d := new(big.Int).SetBytes(pk) // here we do NOT check if the d is in (0, N) or not
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// Create private key from *big.Int
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prvKey := new(sm2.PrivateKey)
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prvKey.Curve = sm2.P256()
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prvKey.D = d
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prvKey.PublicKey.X, prvKey.PublicKey.Y = prvKey.ScalarBaseMult(prvKey.D.Bytes())
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cert, err := smx509.ParseCertificate(keys.Certificate.Content)
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if err != nil {
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return nil, nil, err
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}
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if !prvKey.PublicKey.Equal(cert.PublicKey) {
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return nil, nil, errors.New("cfca: public key and private key do not match")
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}
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return prvKey, cert, nil
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}
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// MarshalSM2 encodes sm2 private key and related certificate to cfca defined format
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func MarshalSM2(password []byte, key *sm2.PrivateKey, cert *smx509.Certificate) ([]byte, error) {
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if len(password) == 0 {
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return nil, errors.New("cfca: invalid password")
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}
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ivkey := sm3.Kdf(password, 32)
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block, err := sm4.NewCipher(ivkey[16:])
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if err != nil {
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return nil, err
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}
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mode := cipher.NewCBCEncrypter(block, ivkey[:16])
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pkcs7 := padding.NewPKCS7Padding(uint(block.BlockSize()))
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plainText := pkcs7.Pad(key.D.Bytes())
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ciphertext := make([]byte, len(plainText))
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mode.CryptBlocks(ciphertext, plainText)
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ciphertext, err = asn1.Marshal(ciphertext)
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if err != nil {
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return nil, err
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}
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keys := cfcaKeyPairData{
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Version: 1,
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EncryptedKey: keyData{
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ContentType: oidSM2Data,
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Algorithm: oidSM4,
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EncryptedContent: asn1.RawValue{FullBytes: ciphertext},
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},
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Certificate: certData{
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ContentType: oidSM2Data,
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Content: cert.Raw,
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},
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}
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return asn1.Marshal(keys)
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}
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