Initial commit

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

pub/common/laosiji/crypto.go

@@ -0,0 +1,89 @@
+package laosiji
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/base64"
+	"errors"
+)
+
+var (
+	ErrInvalidCipher  = errors.New("laosiji crypto: invalid ciphertext length")
+	ErrInvalidPadding = errors.New("laosiji crypto: invalid pkcs7 padding")
+)
+
+func AesKey(appkey string) []byte {
+	key := make([]byte, 16)
+	copy(key, appkey)
+	return key
+}
+
+func EncryptBase64(plain []byte, appkey string) (string, error) {
+	block, err := aes.NewCipher(AesKey(appkey))
+	if err != nil {
+		return "", err
+	}
+	padded := pkcs7Pad(plain, block.BlockSize())
+	out := make([]byte, len(padded))
+	ecbEncrypt(block, out, padded)
+	return base64.StdEncoding.EncodeToString(out), nil
+}
+
+func DecryptBase64(b64 string, appkey string) ([]byte, error) {
+	ct, err := base64.StdEncoding.DecodeString(b64)
+	if err != nil {
+		return nil, err
+	}
+	block, err := aes.NewCipher(AesKey(appkey))
+	if err != nil {
+		return nil, err
+	}
+	bs := block.BlockSize()
+	if len(ct) == 0 || len(ct)%bs != 0 {
+		return nil, ErrInvalidCipher
+	}
+	out := make([]byte, len(ct))
+	ecbDecrypt(block, out, ct)
+	return pkcs7Unpad(out, bs)
+}
+
+func ecbEncrypt(block cipher.Block, dst, src []byte) {
+	bs := block.BlockSize()
+	for len(src) > 0 {
+		block.Encrypt(dst[:bs], src[:bs])
+		src = src[bs:]
+		dst = dst[bs:]
+	}
+}
+
+func ecbDecrypt(block cipher.Block, dst, src []byte) {
+	bs := block.BlockSize()
+	for len(src) > 0 {
+		block.Decrypt(dst[:bs], src[:bs])
+		src = src[bs:]
+		dst = dst[bs:]
+	}
+}
+
+func pkcs7Pad(data []byte, blockSize int) []byte {
+	pad := blockSize - len(data)%blockSize
+	return append(data, bytes.Repeat([]byte{byte(pad)}, pad)...)
+}
+
+func pkcs7Unpad(data []byte, blockSize int) ([]byte, error) {
+	n := len(data)
+	if n == 0 || n%blockSize != 0 {
+		return nil, ErrInvalidPadding
+	}
+	pad := int(data[n-1])
+	if pad == 0 || pad > blockSize {
+		return nil, ErrInvalidPadding
+	}
+	for i := n - pad; i < n; i++ {
+		if int(data[i]) != pad {
+			return nil, ErrInvalidPadding
+		}
+	}
+	return data[:n-pad], nil
+}