fix: fix issue #159 and refact crypto function

cryptor/crypto_internal.go

@@ -1,6 +1,17 @@
 package cryptor
 
-import "bytes"
+import (
+	"bytes"
+	"crypto"
+	"crypto/rsa"
+	"crypto/sha256"
+	"crypto/sha512"
+	"crypto/x509"
+	"encoding/pem"
+	"errors"
+	"os"
+	"strings"
+)
 
 func generateAesKey(key []byte, size int) []byte {
 	genKey := make([]byte, size)
@@ -35,3 +46,139 @@ func pkcs7UnPadding(src []byte) []byte {
 	unPadding := int(src[length-1])
 	return src[:(length - unPadding)]
 }
+
+func pkcs5Padding(data []byte, blockSize int) []byte {
+	padding := blockSize - len(data)%blockSize
+	padText := bytes.Repeat([]byte{byte(padding)}, padding)
+	return append(data, padText...)
+}
+
+func pkcs5UnPadding(data []byte) []byte {
+	length := len(data)
+	if length == 0 {
+		return nil
+	}
+	padLen := int(data[length-1])
+	if padLen == 0 || padLen > length {
+		return nil
+	}
+	return data[:length-padLen]
+}
+
+func isAesKeyLengthValid(n int) bool {
+	return n == 16 || n == 24 || n == 32
+}
+
+// loadRsaPrivateKey loads and parses a PEM encoded private key file.
+func loadRsaPublicKey(filename string) (*rsa.PublicKey, error) {
+	pubKeyData, err := os.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	block, _ := pem.Decode(pubKeyData)
+	if block == nil {
+		return nil, errors.New("failed to decode PEM block containing the public key")
+	}
+
+	var pubKey *rsa.PublicKey
+	blockType := strings.ToUpper(block.Type)
+
+	if blockType == "RSA PUBLIC KEY" {
+		pubKey, err = x509.ParsePKCS1PublicKey(block.Bytes)
+		if err != nil {
+			key, err := x509.ParsePKIXPublicKey(block.Bytes)
+			if err != nil {
+				return nil, err
+			}
+
+			var ok bool
+			pubKey, ok = key.(*rsa.PublicKey)
+			if !ok {
+				return nil, errors.New("failed to parse RSA private key")
+			}
+		}
+	} else if blockType == "PUBLIC KEY" {
+		key, err := x509.ParsePKIXPublicKey(block.Bytes)
+		if err != nil {
+			return nil, err
+		}
+
+		var ok bool
+		pubKey, ok = key.(*rsa.PublicKey)
+		if !ok {
+			return nil, errors.New("failed to parse RSA private key")
+		}
+
+	} else {
+		return nil, errors.New("unsupported key type")
+	}
+
+	return pubKey, nil
+}
+
+// loadRsaPrivateKey loads and parses a PEM encoded private key file.
+func loadRasPrivateKey(filename string) (*rsa.PrivateKey, error) {
+	priKeyData, err := os.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	block, _ := pem.Decode(priKeyData)
+	if block == nil {
+		return nil, errors.New("failed to decode PEM block containing the private key")
+	}
+
+	var privateKey *rsa.PrivateKey
+	blockType := strings.ToUpper(block.Type)
+
+	// PKCS#1 format
+	if blockType == "RSA PRIVATE KEY" {
+		privateKey, err = x509.ParsePKCS1PrivateKey(block.Bytes)
+		if err != nil {
+			return nil, err
+		}
+	} else if blockType == "PRIVATE KEY" { // PKCS#8 format
+		priKey, err := x509.ParsePKCS8PrivateKey(block.Bytes)
+		if err != nil {
+			return nil, err
+		}
+		var ok bool
+		privateKey, ok = priKey.(*rsa.PrivateKey)
+		if !ok {
+			return nil, errors.New("failed to parse RSA private key")
+		}
+	} else {
+		return nil, errors.New("unsupported key type")
+	}
+
+	return privateKey, nil
+}
+
+// hashData returns the hash value of the data, using the specified hash function
+func hashData(hash crypto.Hash, data []byte) ([]byte, error) {
+	if !hash.Available() {
+		return nil, errors.New("unsupported hash algorithm")
+	}
+
+	var hashed []byte
+
+	switch hash {
+	case crypto.SHA224:
+		h := sha256.Sum224(data)
+		hashed = h[:]
+	case crypto.SHA256:
+		h := sha256.Sum256(data)
+		hashed = h[:]
+	case crypto.SHA384:
+		h := sha512.Sum384(data)
+		hashed = h[:]
+	case crypto.SHA512:
+		h := sha512.Sum512(data)
+		hashed = h[:]
+	default:
+		return nil, errors.New("unsupported hash algorithm")
+	}
+
+	return hashed, nil
+}