Initial commit

pkg/stringcrypt/stringcrypt.go

@@ -0,0 +1,70 @@
+package stringcrypt
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"math/big"
+)
+
+type EncryptedString struct {
+	ciphertext []byte
+	key        []byte
+}
+
+func Encrypt(plaintext string) EncryptedString {
+	data := []byte(plaintext)
+	key := make([]byte, len(data))
+	if _, err := rand.Read(key); err != nil {
+		panic(fmt.Sprintf("stringcrypt: rand.Read failed: %v", err))
+	}
+
+	ciphertext := make([]byte, len(data))
+	for i := range data {
+		ciphertext[i] = data[i] ^ key[i]
+	}
+
+	return EncryptedString{ciphertext: ciphertext, key: key}
+}
+
+func (e EncryptedString) Decrypt() string {
+	plaintext := make([]byte, len(e.ciphertext))
+	for i := range e.ciphertext {
+		plaintext[i] = e.ciphertext[i] ^ e.key[i]
+	}
+	return string(plaintext)
+}
+
+func (e EncryptedString) CiphertextB64() string {
+	return base64.StdEncoding.EncodeToString(e.ciphertext)
+}
+
+func (e EncryptedString) KeyB64() string {
+	return base64.StdEncoding.EncodeToString(e.key)
+}
+
+func GenerateRuntimeDecryptCall(ctB64, keyB64 string) string {
+	return fmt.Sprintf(
+		`(func() string {
+			_ct, _ := base64.StdEncoding.DecodeString(%q)
+			_ky, _ := base64.StdEncoding.DecodeString(%q)
+			_pt := make([]byte, len(_ct))
+			for _i := range _ct {
+				_pt[_i] = _ct[_i] ^ _ky[_i]
+			}
+			return string(_pt)
+		})()`, ctB64, keyB64)
+}
+
+func RandomIdent(prefix string, length int) string {
+	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	b := make([]byte, length)
+	for i := range b {
+		n, err := rand.Int(rand.Reader, big.NewInt(int64(len(charset))))
+		if err != nil {
+			panic(fmt.Sprintf("stringcrypt: rand.Int failed: %v", err))
+		}
+		b[i] = charset[n.Int64()]
+	}
+	return prefix + string(b)
+}