AES加解密工具类

AesCbcWithIntegrity.java

import org.apache.commons.codec.binary.Base64;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.UnsupportedEncodingException;
import java.security.GeneralSecurityException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.KeySpec;
import java.util.Arrays;

/**
 * Simple library for the "right" defaults for AES key generation, encryption,
 * and decryption using 128-bit AES, CBC, PKCS5 padding, and a random 16-byte IV
 * with SHA1PRNG. Integrity with HmacSHA256.
 *
 * @author chenyun
 * @date 2019-05-16
 */
public class AesCbcWithIntegrity {
    private static final String CIPHER_TRANSFORMATION = "AES/CBC/PKCS5Padding";
    private static final String CIPHER = "AES";
    private static final int AES_KEY_LENGTH_BITS = 128;
    private static final int IV_LENGTH_BYTES = 16;
    private static final int PBE_ITERATION_COUNT = 10000;
    private static final int PBE_SALT_LENGTH_BITS = AES_KEY_LENGTH_BITS;
    private static final String PBE_ALGORITHM = "PBKDF2WithHmacSHA1";

    private static final String HMAC_ALGORITHM = "HmacSHA256";
    private static final int HMAC_KEY_LENGTH_BITS = 256;

    /**
     * Converts the given AES/HMAC keys into a base64 encoded string suitable for
     * storage. Sister function of keys.
     *
     * @param keys The combined aes and hmac keys
     * @return a base 64 encoded AES string and hmac key as base64(aesKey) : base64(hmacKey)
     */
    public static String keyString(SecretKeys keys) {
        return keys.toString();
    }

    /**
     * An aes key derived from a base64 encoded key. This does not generate the
     * key. It's not random or a PBE key.
     *
     * @param keysStr a base64 encoded AES key / hmac key as base64(aesKey) : base64(hmacKey).
     * @return an AES and HMAC key set suitable for other functions.
     */
    public static SecretKeys deriveKey(String keysStr) throws InvalidKeyException {
        String[] keysArr = keysStr.split(":");

        if (keysArr.length != 2) {
            throw new IllegalArgumentException("Cannot parse aesKey:hmacKey");

        } else {
            byte[] confidentialityKey = Base64.decodeBase64(keysArr[0]);
            if (confidentialityKey.length != AES_KEY_LENGTH_BITS / 8) {
                throw new InvalidKeyException("Base64 decoded key is not " + AES_KEY_LENGTH_BITS + " bytes");
            }
            byte[] integrityKey = Base64.decodeBase64(keysArr[1]);
            if (integrityKey.length != HMAC_KEY_LENGTH_BITS / 8) {
                throw new InvalidKeyException("Base64 decoded key is not " + HMAC_KEY_LENGTH_BITS + " bytes");
            }

            return new SecretKeys(
                    new SecretKeySpec(confidentialityKey, 0, confidentialityKey.length, CIPHER),
                    new SecretKeySpec(integrityKey, HMAC_ALGORITHM));
        }
    }

    /**
     * A function that generates random AES and HMAC keys and prints out exceptions but
     * doesn't throw them since none should be encountered. If they are
     * encountered, the return value is null.
     *
     * @return The AES and HMAC keys.
     * @throws GeneralSecurityException if AES is not implemented on this system,
     * or a suitable RNG is not available
     */
    public static SecretKeys generateKey() throws GeneralSecurityException {
        KeyGenerator keyGen = KeyGenerator.getInstance(CIPHER);
        // No need to provide a SecureRandom or set a seed since that will
        // happen automatically.
        keyGen.init(AES_KEY_LENGTH_BITS);
        SecretKey confidentialityKey = keyGen.generateKey();

        //Now make the HMAC key
        byte[] integrityKeyBytes = randomBytes(HMAC_KEY_LENGTH_BITS / 8);
        SecretKey integrityKey = new SecretKeySpec(integrityKeyBytes, HMAC_ALGORITHM);

        return new SecretKeys(confidentialityKey, integrityKey);
    }

    /**
     * A function that generates password-based AES and HMAC keys. It prints out exceptions but
     * doesn't throw them since none should be encountered. If they are
     * encountered, the return value is null.
     *
     * @param password The password to derive the keys from.
     * @return The AES and HMAC keys.
     * @throws GeneralSecurityException if AES is not implemented on this system,
     * or a suitable RNG is not available
     */
    public static SecretKeys generateKeyFromPassword(String password, byte[] salt) throws GeneralSecurityException {
        //Get enough random bytes for both the AES key and the HMAC key:
        KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt,
                PBE_ITERATION_COUNT, AES_KEY_LENGTH_BITS + HMAC_KEY_LENGTH_BITS);
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(PBE_ALGORITHM);
        byte[] keyBytes = keyFactory.generateSecret(keySpec).getEncoded();

        // Split the random bytes into two parts:
        byte[] confidentialityKeyBytes = copyOfRange(keyBytes, 0, AES_KEY_LENGTH_BITS / 8);
        byte[] integrityKeyBytes = copyOfRange(keyBytes, AES_KEY_LENGTH_BITS / 8, AES_KEY_LENGTH_BITS / 8 + HMAC_KEY_LENGTH_BITS / 8);

        //Generate the AES key
        SecretKey confidentialityKey = new SecretKeySpec(confidentialityKeyBytes, CIPHER);

        //Generate the HMAC key
        SecretKey integrityKey = new SecretKeySpec(integrityKeyBytes, HMAC_ALGORITHM);

        return new SecretKeys(confidentialityKey, integrityKey);
    }

    /**
     * A function that generates password-based AES and HMAC keys. See generateKeyFromPassword.
     *
     * @param password The password to derive the AES/HMAC keys from
     * @param salt A string version of the salt; base64 encoded.
     * @return The AES and HMAC keys.
     * @throws GeneralSecurityException
     */
    public static SecretKeys generateKeyFromPassword(String password, String salt) throws GeneralSecurityException {
        return generateKeyFromPassword(password, Base64.decodeBase64(salt));
    }

    /**
     * Generates a random salt.
     *
     * @return The random salt suitable for generateKeyFromPassword.
     */
    public static byte[] generateSalt() {
        return randomBytes(PBE_SALT_LENGTH_BITS);
    }

    /**
     * Converts the given salt into a base64 encoded string suitable for
     * storage.
     *
     * @param salt
     * @return a base 64 encoded salt string suitable to pass into generateKeyFromPassword.
     */
    public static String saltString(byte[] salt) {
        return Base64.encodeBase64String(salt);
    }


    /**
     * Creates a random Initialization Vector (IV) of IV_LENGTH_BYTES.
     *
     * @return The byte array of this IV
     */
    public static byte[] generateIv() {
        return randomBytes(IV_LENGTH_BYTES);
    }

    private static byte[] randomBytes(int length) {
        SecureRandom random = new SecureRandom();
        byte[] b = new byte[length];
        random.nextBytes(b);
        return b;
    }

    /*
     * -----------------------------------------------------------------
     * Encryption
     * -----------------------------------------------------------------
     */

    /**
     * Generates a random IV and encrypts this plain text with the given key. Then attaches
     * a hashed MAC, which is contained in the CipherTextIvMac class.
     *
     * @param plaintext The text that will be encrypted, which
     * will be serialized with UTF-8
     * @param secretKeys The AES and HMAC keys with which to encrypt
     * @return a tuple of the IV, ciphertext, mac
     * @throws GeneralSecurityException if AES is not implemented on this system
     * @throws UnsupportedEncodingException if UTF-8 is not supported in this system
     */
    public static CipherTextIvMac encrypt(String plaintext, SecretKeys secretKeys)
            throws UnsupportedEncodingException, GeneralSecurityException {
        return encrypt(plaintext, secretKeys, "UTF-8");
    }

    /**
     * Generates a random IV and encrypts this plain text with the given key. Then attaches
     * a hashed MAC, which is contained in the CipherTextIvMac class.
     *
     * @param plaintext The bytes that will be encrypted
     * @param secretKeys The AES and HMAC keys with which to encrypt
     * @return a tuple of the IV, ciphertext, mac
     * @throws GeneralSecurityException if AES is not implemented on this system
     * @throws UnsupportedEncodingException if the specified encoding is invalid
     */
    public static CipherTextIvMac encrypt(String plaintext, SecretKeys secretKeys, String encoding)
            throws UnsupportedEncodingException, GeneralSecurityException {
        return encrypt(plaintext.getBytes(encoding), secretKeys);
    }

    /**
     * Generates a random IV and encrypts this plain text with the given key. Then attaches
     * a hashed MAC, which is contained in the CipherTextIvMac class.
     *
     * @param plaintext The text that will be encrypted
     * @param secretKeys The combined AES and HMAC keys with which to encrypt
     * @return a tuple of the IV, ciphertext, mac
     * @throws GeneralSecurityException if AES is not implemented on this system
     */
    public static CipherTextIvMac encrypt(byte[] plaintext, SecretKeys secretKeys)
            throws GeneralSecurityException {
        byte[] iv = generateIv();
        Cipher aesCipherForEncryption = Cipher.getInstance(CIPHER_TRANSFORMATION);
        aesCipherForEncryption.init(Cipher.ENCRYPT_MODE, secretKeys.getConfidentialityKey(), new IvParameterSpec(iv));

        /*
         * Now we get back the IV that will actually be used. Some Android
         * versions do funny stuff w/ the IV, so this is to work around bugs:
         */
        iv = aesCipherForEncryption.getIV();
        byte[] byteCipherText = aesCipherForEncryption.doFinal(plaintext);
        byte[] ivCipherConcat = CipherTextIvMac.ivCipherConcat(iv, byteCipherText);

        byte[] integrityMac = generateMac(ivCipherConcat, secretKeys.getIntegrityKey());
        return new CipherTextIvMac(byteCipherText, iv, integrityMac);
    }

    /*
     * -----------------------------------------------------------------
     * Decryption
     * -----------------------------------------------------------------
     */

    /**
     * AES CBC decrypt.
     *
     * @param civ The cipher text, IV, and mac
     * @param secretKeys The AES and HMAC keys
     * @param encoding The string encoding to use to decode the bytes after decryption
     * @return A string derived from the decrypted bytes (not base64 encoded)
     * @throws GeneralSecurityException if AES is not implemented on this system
     * @throws UnsupportedEncodingException if the encoding is unsupported
     */
    public static String decryptString(CipherTextIvMac civ, SecretKeys secretKeys, String encoding)
            throws UnsupportedEncodingException, GeneralSecurityException {
        return new String(decrypt(civ, secretKeys), encoding);
    }

    /**
     * AES CBC decrypt.
     *
     * @param civ The cipher text, IV, and mac
     * @param secretKeys The AES and HMAC keys
     * @return A string derived from the decrypted bytes, which are interpreted
     * as a UTF-8 String
     * @throws GeneralSecurityException if AES is not implemented on this system
     * @throws UnsupportedEncodingException if UTF-8 is not supported
     */
    public static String decryptString(CipherTextIvMac civ, SecretKeys secretKeys)
            throws UnsupportedEncodingException, GeneralSecurityException {
        return decryptString(civ, secretKeys, "UTF-8");
    }

    /**
     * AES CBC decrypt.
     *
     * @param civ the cipher text, iv, and mac
     * @param secretKeys the AES and HMAC keys
     * @return The raw decrypted bytes
     * @throws GeneralSecurityException if MACs don't match or AES is not implemented
     */
    public static byte[] decrypt(CipherTextIvMac civ, SecretKeys secretKeys)
            throws GeneralSecurityException {

        byte[] ivCipherConcat = CipherTextIvMac.ivCipherConcat(civ.getIv(), civ.getCipherText());
        byte[] computedMac = generateMac(ivCipherConcat, secretKeys.getIntegrityKey());
        if (constantTimeEq(computedMac, civ.getMac())) {
            Cipher aesCipherForDecryption = Cipher.getInstance(CIPHER_TRANSFORMATION);
            aesCipherForDecryption.init(Cipher.DECRYPT_MODE, secretKeys.getConfidentialityKey(),
                    new IvParameterSpec(civ.getIv()));
            return aesCipherForDecryption.doFinal(civ.getCipherText());
        } else {
            throw new GeneralSecurityException("MAC stored in civ does not match computed MAC.");
        }
    }

    /*
     * -----------------------------------------------------------------
     * Helper Code
     * -----------------------------------------------------------------
     */

    /**
     * Generate the mac based on HMAC_ALGORITHM
     *
     * @param integrityKey The key used for hmac
     * @param byteCipherText the cipher text
     * @return A byte array of the HMAC for the given key and ciphertext
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeyException
     */
    public static byte[] generateMac(byte[] byteCipherText, SecretKey integrityKey) throws NoSuchAlgorithmException, InvalidKeyException {
        //Now compute the mac for later integrity checking
        Mac sha256_HMAC = Mac.getInstance(HMAC_ALGORITHM);
        sha256_HMAC.init(integrityKey);
        return sha256_HMAC.doFinal(byteCipherText);
    }

    /**
     * Holder class that has both the secret AES key for encryption (confidentiality)
     * and the secret HMAC key for integrity.
     */

    public static class SecretKeys {
        private SecretKey confidentialityKey;
        private SecretKey integrityKey;

        /**
         * Construct the secret keys container.
         *
         * @param confidentialityKeyIn The AES key
         * @param integrityKeyIn the HMAC key
         */
        public SecretKeys(SecretKey confidentialityKeyIn, SecretKey integrityKeyIn) {
            setConfidentialityKey(confidentialityKeyIn);
            setIntegrityKey(integrityKeyIn);
        }

        public SecretKey getConfidentialityKey() {
            return confidentialityKey;
        }

        public void setConfidentialityKey(SecretKey confidentialityKey) {
            this.confidentialityKey = confidentialityKey;
        }

        public SecretKey getIntegrityKey() {
            return integrityKey;
        }

        public void setIntegrityKey(SecretKey integrityKey) {
            this.integrityKey = integrityKey;
        }

        /**
         * Encodes the two keys as a string
         *
         * @return base64(confidentialityKey):base64(integrityKey)
         */
        @Override
        public String toString() {
            return Base64.encodeBase64String(getConfidentialityKey().getEncoded())
                    + ":" + Base64.encodeBase64String(getIntegrityKey().getEncoded());
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + confidentialityKey.hashCode();
            result = prime * result + integrityKey.hashCode();
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            SecretKeys other = (SecretKeys) obj;
            if (!integrityKey.equals(other.integrityKey)) {
                return false;
            }
            if (!confidentialityKey.equals(other.confidentialityKey)) {
                return false;
            }
            return true;
        }
    }


    /**
     * Simple constant-time equality of two byte arrays. Used for security to avoid timing attacks.
     *
     * @param a
     * @param b
     * @return true iff the arrays are exactly equal.
     */
    public static boolean constantTimeEq(byte[] a, byte[] b) {
        if (a.length != b.length) {
            return false;
        }
        int result = 0;
        for (int i = 0; i < a.length; i++) {
            result |= a[i] ^ b[i];
        }
        return result == 0;
    }

    /**
     * Holder class that allows us to bundle ciphertext and IV together.
     */
    public static class CipherTextIvMac {
        private final byte[] cipherText;
        private final byte[] iv;
        private final byte[] mac;

        public byte[] getCipherText() {
            return cipherText;
        }

        public byte[] getIv() {
            return iv;
        }

        public byte[] getMac() {
            return mac;
        }

        /**
         * Construct a new bundle of ciphertext and IV.
         *
         * @param c The ciphertext
         * @param i The IV
         * @param h The mac
         */
        public CipherTextIvMac(byte[] c, byte[] i, byte[] h) {
            cipherText = new byte[c.length];
            System.arraycopy(c, 0, cipherText, 0, c.length);
            iv = new byte[i.length];
            System.arraycopy(i, 0, iv, 0, i.length);
            mac = new byte[h.length];
            System.arraycopy(h, 0, mac, 0, h.length);
        }

        /**
         * Constructs a new bundle of ciphertext and IV from a string of the
         * format <code>base64(iv):base64(ciphertext)</code>.
         *
         * @param base64IvAndCiphertext A string of the format
         * <code>iv:ciphertext</code> The IV and ciphertext must each
         * be base64-encoded.
         */
        public CipherTextIvMac(String base64IvAndCiphertext) {
            String[] civArray = base64IvAndCiphertext.split(":");
            if (civArray.length != 3) {
                throw new IllegalArgumentException("Cannot parse iv:mac:ciphertext");
            } else {
                iv = Base64.decodeBase64(civArray[0]);
                mac = Base64.decodeBase64(civArray[1]);
                cipherText = Base64.decodeBase64(civArray[2]);
            }
        }

        /**
         * Concatinate the IV to the cipherText using array copy.
         * This is used e.g. before computing mac.
         *
         * @param iv The IV to prepend
         * @param cipherText the cipherText to append
         * @return iv:cipherText, a new byte array.
         */
        public static byte[] ivCipherConcat(byte[] iv, byte[] cipherText) {
            byte[] combined = new byte[iv.length + cipherText.length];
            System.arraycopy(iv, 0, combined, 0, iv.length);
            System.arraycopy(cipherText, 0, combined, iv.length, cipherText.length);
            return combined;
        }

        /**
         * Encodes this ciphertext, IV, mac as a string.
         *
         * @return base64(iv) : base64(mac) : base64(ciphertext).
         * The iv and mac go first because they're fixed length.
         */
        @Override
        public String toString() {
            String ivString = Base64.encodeBase64String(iv);
            String cipherTextString = Base64.encodeBase64String(cipherText);
            String macString = Base64.encodeBase64String(mac);
            return String.format(ivString + ":" + macString + ":" + cipherTextString);
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + Arrays.hashCode(cipherText);
            result = prime * result + Arrays.hashCode(iv);
            result = prime * result + Arrays.hashCode(mac);
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj) {
                return true;
            }
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            CipherTextIvMac other = (CipherTextIvMac) obj;
            if (!Arrays.equals(cipherText, other.cipherText)) {
                return false;
            }
            if (!Arrays.equals(iv, other.iv)) {
                return false;
            }
            if (!Arrays.equals(mac, other.mac)) {
                return false;
            }
            return true;
        }
    }

    /**
     * Copy the elements from the start to the end
     *
     * @param from the source
     * @param start the start index to copy
     * @param end the end index to finish
     * @return the new buffer
     */
    private static byte[] copyOfRange(byte[] from, int start, int end) {
        int length = end - start;
        byte[] result = new byte[length];
        System.arraycopy(from, start, result, 0, length);
        return result;
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>me.guozi</groupId>
    <artifactId>java-aes-crypto</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>commons-codec</groupId>
            <artifactId>commons-codec</artifactId>
            <version>1.10</version>
        </dependency>
    </dependencies>

</project>