Java 解密 SHA 加密字符串
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Decrypt SHA encrypted string
提问by Gapchoos
I have encrypted a string using the above code.
我使用上面的代码加密了一个字符串。
public String encrypt(String generatedKey)
{
try {
MessageDigest md = MessageDigest.getInstance("SHA");
md.update(generatedKey.getBytes("UTF-8"));
byte digest[] = md.digest();
return (new BASE64Encoder()).encode(digest);
}
catch (Exception e) {
return null;
}
}
Similarly i need a code to decrypt the above generated code. How can i do this?
同样，我需要一个代码来解密上面生成的代码。我怎样才能做到这一点？
回答by venki
I am pretty sure that we cannot decode a SHA encrypted string directly.
我很确定我们不能直接解码 SHA 加密的字符串。
See this for a clear explanation: How to decrypt SHA-256 encrypted String?
请参阅此以获得明确的解释：如何解密 SHA-256 加密的字符串？
回答by Mehmet Ata?
SHA is a digest algorithm, not an encryption algorithm. Digest values are not decryptable. That's why they are secure. Two different inputs may give same digest values. But it is a very little possibility. For sha256 it is 1/(2^256).
SHA 是摘要算法，而不是加密算法。摘要值不可解密。这就是为什么它们是安全的。两个不同的输入可能给出相同的摘要值。但这种可能性很小。对于 sha256，它是 1/(2^256)。
Output of digest algorithms have constant length. For SHA256 it is always 256 bit, regardless of your input length, 1 bit or 100 Gbs. If we could decrypt 256 bit digest value and have the original 1Gb input back, we would never need compression algorithms :)
摘要算法的输出具有恒定长度。对于 SHA256，它始终为 256 位，无论您的输入长度是 1 位还是 100 Gbs。如果我们可以解密 256 位摘要值并返回原始 1Gb 输入，我们将永远不需要压缩算法:)
回答by heffaklump
Message digests produce a small "fingerprint" of a larger set of data. It's a one way procedure.
消息摘要生成较大数据集的小“指纹”。这是一种单向程序。
What you probably is looking for is encryption.
您可能正在寻找的是加密。
Key key = new SecretKeySpec(secret.getBytes(), ALGORITHM);
// Encrypt
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] encryptedData = cipher.doFinal(plainText);
// Decrypt
cipher.init(Cipher.DECRYPT_MODE, key)
byte[] decryptedData = cipher.doFinal(encryptedData);
Where ALGORITHM can be one of http://docs.oracle.com/javase/6/docs/technotes/guides/security/StandardNames.html#Cipher
其中 ALGORITHM 可以是 http://docs.oracle.com/javase/6/docs/technotes/guides/security/StandardNames.html#Cipher 之一
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