如何在Java中散列密码？
我需要对密码进行哈希处理以存储在数据库中。如何用Java做到这一点？
我希望使用纯文本密码，添加随机盐，然后将盐和哈希密码存储在数据库中。
然后，当用户想要登录时，我可以使用其提交的密码，从其帐户信息中添加随机盐，对其进行哈希处理，然后查看其是否等同于其帐户信息所存储的哈希密码。
回答：
实际上，你可以使用Java运行时内置的工具来执行此操作。Java 6中的SunJCE支持PBKDF2，这是用于密码哈希的一种很好的算法。
byte[] salt = new byte[16];random.nextBytes(salt);
KeySpec spec = new PBEKeySpec("password".toCharArray(), salt, 65536, 128);
SecretKeyFactory f = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
byte[] hash = f.generateSecret(spec).getEncoded();
Base64.Encoder enc = Base64.getEncoder();
System.out.printf("salt: %s%n", enc.encodeToString(salt));
System.out.printf("hash: %s%n", enc.encodeToString(hash));
这是可用于PBKDF2密码身份验证的实用程序类：
import java.security.NoSuchAlgorithmException;import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.util.Arrays;
import java.util.Base64;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
/**
* Hash passwords for storage, and test passwords against password tokens.
*
* Instances of this class can be used concurrently by multiple threads.
*
* @author erickson
* @see <a href="http://stackoverflow.com/a/2861125/3474">StackOverflow</a>
*/
public final class PasswordAuthentication
{
/**
* Each token produced by this class uses this identifier as a prefix.
*/
public static final String ID = "$31$";
/**
* The minimum recommended cost, used by default
*/
public static final int DEFAULT_COST = 16;
private static final String ALGORITHM = "PBKDF2WithHmacSHA1";
private static final int SIZE = 128;
private static final Pattern layout = Pattern.compile("\\$31\\$(\\d\\d?)\\$(.{43})");
private final SecureRandom random;
private final int cost;
public PasswordAuthentication()
{
this(DEFAULT_COST);
}
/**
* Create a password manager with a specified cost
*
* @param cost the exponential computational cost of hashing a password, 0 to 30
*/
public PasswordAuthentication(int cost)
{
iterations(cost); /* Validate cost */
this.cost = cost;
this.random = new SecureRandom();
}
private static int iterations(int cost)
{
if ((cost < 0) || (cost > 30))
throw new IllegalArgumentException("cost: " + cost);
return 1 << cost;
}
/**
* Hash a password for storage.
*
* @return a secure authentication token to be stored for later authentication
*/
public String hash(char[] password)
{
byte[] salt = new byte[SIZE / 8];
random.nextBytes(salt);
byte[] dk = pbkdf2(password, salt, 1 << cost);
byte[] hash = new byte[salt.length + dk.length];
System.arraycopy(salt, 0, hash, 0, salt.length);
System.arraycopy(dk, 0, hash, salt.length, dk.length);
Base64.Encoder enc = Base64.getUrlEncoder().withoutPadding();
return ID + cost + '$' + enc.encodeToString(hash);
}
/**
* Authenticate with a password and a stored password token.
*
* @return true if the password and token match
*/
public boolean authenticate(char[] password, String token)
{
Matcher m = layout.matcher(token);
if (!m.matches())
throw new IllegalArgumentException("Invalid token format");
int iterations = iterations(Integer.parseInt(m.group(1)));
byte[] hash = Base64.getUrlDecoder().decode(m.group(2));
byte[] salt = Arrays.copyOfRange(hash, 0, SIZE / 8);
byte[] check = pbkdf2(password, salt, iterations);
int zero = 0;
for (int idx = 0; idx < check.length; ++idx)
zero |= hash[salt.length + idx] ^ check[idx];
return zero == 0;
}
private static byte[] pbkdf2(char[] password, byte[] salt, int iterations)
{
KeySpec spec = new PBEKeySpec(password, salt, iterations, SIZE);
try {
SecretKeyFactory f = SecretKeyFactory.getInstance(ALGORITHM);
return f.generateSecret(spec).getEncoded();
}
catch (NoSuchAlgorithmException ex) {
throw new IllegalStateException("Missing algorithm: " + ALGORITHM, ex);
}
catch (InvalidKeySpecException ex) {
throw new IllegalStateException("Invalid SecretKeyFactory", ex);
}
}
/**
* Hash a password in an immutable {@code String}.
*
* <p>Passwords should be stored in a {@code char[]} so that it can be filled
* with zeros after use instead of lingering on the heap and elsewhere.
*
* @deprecated Use {@link #hash(char[])} instead
*/
@Deprecated
public String hash(String password)
{
return hash(password.toCharArray());
}
/**
* Authenticate with a password in an immutable {@code String} and a stored
* password token.
*
* @deprecated Use {@link #authenticate(char[],String)} instead.
* @see #hash(String)
*/
@Deprecated
public boolean authenticate(String password, String token)
{
return authenticate(password.toCharArray(), token);
}
}
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