add included

internal/util/rsa_util.go

@@ -0,0 +1,30 @@
+package util
+
+import (
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/base64"
+	"encoding/pem"
+	"errors"
+)
+
+// EncryptWithPublicKey encrypts data with a PEM public key and returns base64 encoded string
+func EncryptWithPublicKey(data string, pemBytes []byte) (string, error) {
+	block, _ := pem.Decode(pemBytes)
+	if block == nil {
+		return "", errors.New("failed to parse PEM block containing the public key")
+	}
+	pub, err := x509.ParsePKIXPublicKey(block.Bytes)
+	if err != nil {
+		return "", err
+	}
+	pubKey, ok := pub.(*rsa.PublicKey)
+	if !ok {
+		return "", errors.New("not RSA public key")
+	}
+	ciphertext, err := rsa.EncryptPKCS1v15(nil, pubKey, []byte(data))
+	if err != nil {
+		return "", err
+	}
+	return base64.StdEncoding.EncodeToString(ciphertext), nil
+}