问题描述
我想从 SecureGMC java 做一个简单的加密,然后使用 AES/GCM/PKCS5Padding 在 PHP 中解密。我假设要解密的数据来自本地银行,它强调 IV_SIZE=96 和 TAG_BIT_LENGTH=128;他们向我推荐了这个 link 作为参考。从我读到的内容来看,openssl_decrypt() 似乎是最好的选择,但是,我在解密 Java 时找不到任何可供我发送的 $tag 变量. openssl_decrypt() 甚至推荐用于此吗?
密码.java
public class SecuredGCMUsage {
public static int AES_KEY_SIZE = 256 ;
public static int IV_SIZE = 96 ;
public static int TAG_BIT_LENGTH = 128 ;
public static String ALGO_TRANSFORMATION_STRING = "AES/GCM/PKCS5Padding" ;
public static void main(String args[]) {
String messagetoEncrypt = "Testing message to decrypt" ;
byte[] aadData = "".getBytes() ; // Any random data can be used as tag. Some common examples Could be domain name...
// Use different key+IV pair for encrypting/decrypting different parameters
// Generating Key
SecretKey aesKey = null ;
try {
KeyGenerator keygen = KeyGenerator.getInstance("AES") ; // Specifying algorithm key will be used for
keygen.init(AES_KEY_SIZE) ; // Specifying Key size to be used,Note: This would need JCE Unlimited Strength to be installed explicitly
aesKey = keygen.generateKey() ;
} catch(NoSuchAlgorithmException noSuchAlgoExc) { System.out.println("Key being request is for AES algorithm,but this cryptographic algorithm is not available in the environment " + noSuchAlgoExc) ; System.exit(1) ; }
// Generating IV
byte iv[] = new byte[IV_SIZE];
SecureRandom secRandom = new SecureRandom() ;
secRandom.nextBytes(iv); // SecureRandom initialized using self-seeding
// Initialize GCM Parameters
GCMParameterSpec gcmParamSpec = new GCMParameterSpec(TAG_BIT_LENGTH,iv) ;
byte[] encryptedText = aesEncrypt(messagetoEncrypt,aesKey,gcmParamSpec,aadData) ;
System.out.println("Encrypted Text = " + Base64.getEncoder().encodetoString(encryptedText) ) ;
byte[] decryptedText = aesDecrypt(encryptedText,aadData) ; // Same key,IV and GCM Specs for decryption as used for encryption.
System.out.println("Decrypted text " + new String(decryptedText)) ;
// Make sure not to repeat Key + IV pair,for encrypting more than one plaintext.
secRandom.nextBytes(iv);
}
public static byte[] aesEncrypt(String message,SecretKey aesKey,GCMParameterSpec gcmParamSpec,byte[] aadData) {
Cipher c = null ;
try {
c = Cipher.getInstance(ALGO_TRANSFORMATION_STRING); // Transformation specifies algortihm,mode of operation and padding
}catch(NoSuchAlgorithmException noSuchAlgoExc) {System.out.println("Exception while encrypting. Algorithm being requested is not available in this environment " + noSuchAlgoExc); System.exit(1); }
catch(NoSuchPaddingException noSuchPaddingExc) {System.out.println("Exception while encrypting. Padding Scheme being requested is not available this environment " + noSuchPaddingExc); System.exit(1); }
try {
c.init(Cipher.ENCRYPT_MODE,new SecureRandom()) ;
} catch(InvalidKeyException invalidKeyExc) {System.out.println("Exception while encrypting. Key being used is not valid. It Could be due to invalid encoding,wrong length or uninitialized " + invalidKeyExc) ; System.exit(1); }
catch(InvalidAlgorithmParameterException invalidAlgoParamExc) {System.out.println("Exception while encrypting. Algorithm parameters being specified are not valid " + invalidAlgoParamExc) ; System.exit(1); }
try {
c.updateAAD(aadData) ; // add AAD tag data before encrypting
}catch(IllegalArgumentException illegalArgumentExc) {System.out.println("Exception thrown while encrypting. Byte array might be null " +illegalArgumentExc ); System.exit(1);}
catch(IllegalStateException illegalStateExc) {System.out.println("Exception thrown while encrypting. CIpher is in an illegal state " +illegalStateExc); System.exit(1);}
catch(UnsupportedOperationException unsupportedExc) {System.out.println("Exception thrown while encrypting. Provider might not be supporting this method " +unsupportedExc); System.exit(1);}
byte[] cipherTextInByteArr = null ;
try {
cipherTextInByteArr = c.doFinal(message.getBytes()) ;
} catch(IllegalBlockSizeException illegalBlockSizeExc) {System.out.println("Exception while encrypting,due to block size " + illegalBlockSizeExc) ; System.exit(1); }
catch(BadPaddingException badPaddingExc) {System.out.println("Exception while encrypting,due to padding scheme " + badPaddingExc) ; System.exit(1); }
return cipherTextInByteArr ;
}
public static byte[] aesDecrypt(byte[] encryptedMessage,byte[] aadData) {
Cipher c = null ;
try {
c = Cipher.getInstance(ALGO_TRANSFORMATION_STRING); // Transformation specifies algortihm,mode of operation and padding
} catch(NoSuchAlgorithmException noSuchAlgoExc) {System.out.println("Exception while decrypting. Algorithm being requested is not available in environment " + noSuchAlgoExc); System.exit(1); }
catch(NoSuchPaddingException noSuchAlgoExc) {System.out.println("Exception while decrypting. Padding scheme being requested is not available in environment " + noSuchAlgoExc); System.exit(1); }
try {
c.init(Cipher.DECRYPT_MODE,wrong length or uninitialized " + invalidKeyExc) ; System.exit(1); }
catch(InvalidAlgorithmParameterException invalidParamSpecExc) {System.out.println("Exception while encrypting. Algorithm Param being used is not valid. " + invalidParamSpecExc) ; System.exit(1); }
try {
c.updateAAD(aadData) ; // Add AAD details before decrypting
}catch(IllegalArgumentException illegalArgumentExc) {System.out.println("Exception thrown while encrypting. Byte array might be null " +illegalArgumentExc ); System.exit(1);}
catch(IllegalStateException illegalStateExc) {System.out.println("Exception thrown while encrypting. CIpher is in an illegal state " +illegalStateExc); System.exit(1);}
byte[] plainTextInByteArr = null ;
try {
plainTextInByteArr = c.doFinal(encryptedMessage) ;
} catch(IllegalBlockSizeException illegalBlockSizeExc) {System.out.println("Exception while decryption,due to block size " + illegalBlockSizeExc) ; System.exit(1); }
catch(BadPaddingException badPaddingExc) {System.out.println("Exception while decryption,due to padding scheme " + badPaddingExc) ; System.exit(1); }
return plainTextInByteArr ;
}
}
cipher.java 会产生
ENCRYPTED- WHcLaJZWwTTKD1fVkmOoH0KpShZRn/LIDQwp9Djz+0MG7bp+gO+4pHCmGw==
KEY- 4A5wU7DQ0orJv91J8eZu2yMcr6sHyuAiKaNe5KdM7iw=
IV- cG8zFrxyYSeXvwx7bxQrCp6LxaZ8GQhxUcrGJkZTzfKJaErLztV9dy/iz123cw/4wEz44IMtpNR0OZSz2SA+zZLfsge3m/WJlS9xwNSYjatzYMm123hpyStcFKedi+A8
DECRYPTED TEXT- Testing message to dencrypt
decryption.java(仅解密) - 我已隔离到一个新类中,用于仅处理解密数据以模拟生产。
public class SecuredGCMUsage {
public static int AES_KEY_SIZE = 256 ;
public static int IV_SIZE = 96 ;
public static int TAG_BIT_LENGTH = 128 ;
public static String ALGO_TRANSFORMATION_STRING = "AES/GCM/PKCS5Padding" ;
public static void main(String args[]) {
// ARGS DETAILS
String payloadText = "WHcLaJZWwTTKD1fVkmOoH0KpShZRn/LIDQwp9Djz+0MG7bp+gO+4pHCmGw==";
String payloadKey = "4A5wU7DQ0orJv91J8eZu2yMcr6sHyuAiKaNe5KdM7iw=";
String payloadIv = "cG8zFrxyYSeXvwx7bxQrCp6LxaZ8GQhxUcrGJkZTzfKJaErLztV9dy/iz123cw/4wEz44IMtpNR0OZSz2SA+zZLfsge3m/WJlS9xwNSYjatzYMm123hpyStcFKedi+A8";
byte[] aadData2 = "testing.com".getBytes() ;
byte[] encryptedText2 = Base64.getDecoder().decode(payloadText);
byte[] decodedKey = Base64.getDecoder().decode(payloadKey);
byte[] iv = Base64.getDecoder().decode(payloadIv);
GCMParameterSpec gcmParamSpec2 = new GCMParameterSpec(TAG_BIT_LENGTH,iv) ;
SecretKey aesKey2 = new SecretKeySpec(decodedKey,decodedKey.length,"AES");
byte[] decryptedText2 = aesDecrypt(
encryptedText2,aesKey2,gcmParamSpec2,aadData2
) ; // Same key,IV and GCM Specs for decryption as used for encryption.
System.out.println("DECRYPTED TEXT- " + new String(decryptedText2)) ;
}
public static byte[] aesDecrypt(byte[] encryptedMessage,wrong length or uninitialized " + invalidKeyExc) ; System.exit(1); }
catch(InvalidAlgorithmParameterException invalidParamSpecExc) {System.out.println("Exception while encrypting. Algorithm Param being used is not valid. " + invalidParamSpecExc) ; System.exit(1); }
try {
// c.updateAAD(aadData) ; // Add AAD details before decrypting
}catch(IllegalArgumentException illegalArgumentExc) {System.out.println("Exception thrown while encrypting. Byte array might be null " +illegalArgumentExc ); System.exit(1);}
catch(IllegalStateException illegalStateExc) {System.out.println("Exception thrown while encrypting. CIpher is in an illegal state " +illegalStateExc); System.exit(1);}
byte[] plainTextInByteArr = null ;
try {
plainTextInByteArr = c.doFinal(encryptedMessage) ;
} catch(IllegalBlockSizeException illegalBlockSizeExc) {System.out.println("Exception while decryption,due to padding scheme " + badPaddingExc) ; System.exit(1); }
return plainTextInByteArr ;
}
}
结果(成功)
DECRYPTED TEXT- Testing message to dencrypt
然而,我的斗争是在解密.PHP 中,那里经常失败。
public static function decrypt_aes_gcm_pkcs5padding ($data)
{
$ciphertext = $data["encryptedPayload"];
$key = $data["encryptedSessionKey"];
$iv = $data["iv"];
// $aad = "";
$encrypt = base64_decode($ciphertext);
$ivlen = openssl_cipher_iv_length($cipher = "aes-256-gcm");
$tag_length = 16;
$iv = substr($encrypt,$ivlen);
$tag = substr($encrypt,-$tag_length);
$ciphertext = substr($encrypt,$ivlen,-$tag_length);
$ciphertext_raw = openssl_decrypt($ciphertext,$cipher,$key,OPENSSL_NO_PADDING,$iv,$tag);
return $ciphertext_raw;
}
结果(失败)
解决方法
PHP代码解密失败,IV、密文、标签判断错误。
Java 代码中的Cipher#doFinal()
隐式连接密文和标签 (ciphertext | tag
)。相比之下,IV 既不是隐式也不是显式连接。但是,PHP 代码假定 IV 也已连接 (iv | ciphertext | tag
)。因此,基于此假设执行的分离失败。
由于传递给 openssl_decrypt()
的密文由于前面的分离而不是 Base64 编码,因此必须设置 OPENSSL_RAW_DATA
标志(值:1)。 GCM 不使用填充。 OPENSSL_ZERO_PADDING
标志(值:2)禁用填充,但不需要显式设置,因为它是为 GCM 隐式设置的。 OPENSSL_NO_PADDING
标志(值:3)仅在非对称加密的上下文中定义,不应在对称加密的上下文中使用。如果设置,它与OPENSSL_RAW_DATA | OPENSSL_ZERO_PADDING
的效果相同,在这种情况下恰好是正确的,但通常是无意中设置了OPENSSL_RAW_DATA
。
以下 PHP 实现正确解密 Java 代码的数据:
// Data from C# side
$encrypt = base64_decode('7iJzLyqHMu3sVsUI4dCghjbf4gsQaFto/4L+6ccywRgq33hcWKOrz/pF');
$key = base64_decode('ZQE3/FMRH1wOCFJWuaRpsizC/ltMFlxJvTYu0J4oN+Q=');
$iv = base64_decode('SzlX3ihgFwBwUcDdWatoNTQ9BcMQ5nJoJqoV2eBtQuh/uP+eceqdUiVZldwOiUX8m5qIDYpyeqz7z8a+7xRWNUL3xnlcKBEemCrASLCG2tKpEXXMQD+a9t2v2WGUKQ6D');
$aad = "sample aad";
$tagLength = 16;
$tag = substr($encrypt,strlen($encrypt) - $tagLength,$tagLength);
$ciphertext = substr($encrypt,strlen($encrypt) - $tagLength);
$ciphertext_raw = openssl_decrypt($ciphertext,'aes-256-gcm',$key,OPENSSL_RAW_DATA,$iv,$tag,$aad);
print($ciphertext_raw);
使用 Java 代码生成测试数据的地方。
Java 代码为参考代码,不可更改。不过,需要注意以下几点:
- GCM 是一种流密码模式,不使用填充。因此,应在 Java 代码中指定
AES/GCM/NoPadding
而不是AES/GCM/PKCS5Padding
。但是,SunJCE 提供程序会忽略PKCS5Padding
规范并且不会填充,因此这没有影响。 - 对于 GCM,建议使用 12 字节的 nonce/IV。在 Java(参考)代码中,位和字节混淆,因此使用了 96 字节的 nonce/IV。由于对于 GCM,如果 nonce/IV 不是 12 个字节(here),则重新计算,因此算法处理了实际上太长的 nonce/IV,因此不会导致 PHP 代码中的解密失败,但是仍然不符合推荐的长度。