Initial zhanlu OpenAI proxy

internal/auth/aes.go

@@ -0,0 +1,85 @@
+package auth
+
+import (
+	"crypto/aes"
+	"encoding/base64"
+	"errors"
+	"fmt"
+)
+
+func DecryptCredential(ciphertextBase64, key string) (string, error) {
+	ciphertext, err := base64.StdEncoding.DecodeString(ciphertextBase64)
+	if err != nil {
+		return "", err
+	}
+	if len(ciphertext) == 0 || len(ciphertext)%aes.BlockSize != 0 {
+		return "", errors.New("invalid AES ciphertext length")
+	}
+
+	block, err := aes.NewCipher(repeatKey(key, aes.BlockSize))
+	if err != nil {
+		return "", err
+	}
+
+	plain := make([]byte, len(ciphertext))
+	for start := 0; start < len(ciphertext); start += aes.BlockSize {
+		block.Decrypt(plain[start:start+aes.BlockSize], ciphertext[start:start+aes.BlockSize])
+	}
+
+	plain, err = unpadPKCS7(plain, aes.BlockSize)
+	if err != nil {
+		return "", err
+	}
+	return string(plain), nil
+}
+
+func EncryptCredential(plaintext, key string) (string, error) {
+	block, err := aes.NewCipher(repeatKey(key, aes.BlockSize))
+	if err != nil {
+		return "", err
+	}
+	plain := padPKCS7([]byte(plaintext), aes.BlockSize)
+	out := make([]byte, len(plain))
+	for start := 0; start < len(plain); start += aes.BlockSize {
+		block.Encrypt(out[start:start+aes.BlockSize], plain[start:start+aes.BlockSize])
+	}
+	return base64.StdEncoding.EncodeToString(out), nil
+}
+
+func repeatKey(key string, size int) []byte {
+	src := []byte(key)
+	out := make([]byte, size)
+	if len(src) == 0 {
+		return out
+	}
+	for i := range out {
+		out[i] = src[i%len(src)]
+	}
+	return out
+}
+
+func unpadPKCS7(in []byte, blockSize int) ([]byte, error) {
+	if len(in) == 0 || len(in)%blockSize != 0 {
+		return nil, errors.New("invalid padded data length")
+	}
+	pad := int(in[len(in)-1])
+	if pad == 0 || pad > blockSize || pad > len(in) {
+		return nil, fmt.Errorf("invalid padding size %d", pad)
+	}
+	for _, b := range in[len(in)-pad:] {
+		if int(b) != pad {
+			return nil, errors.New("invalid padding bytes")
+		}
+	}
+	return in[:len(in)-pad], nil
+}
+
+func padPKCS7(in []byte, blockSize int) []byte {
+	pad := blockSize - len(in)%blockSize
+	out := make([]byte, len(in)+pad)
+	copy(out, in)
+	for i := len(in); i < len(out); i++ {
+		out[i] = byte(pad)
+	}
+	return out
+}