// 
// Decompiled by Procyon v0.6.0
// 

package com.google.crypto.tink.subtle;

import com.google.crypto.tink.internal.Util;
import java.util.Arrays;
import java.nio.ByteBuffer;
import java.security.GeneralSecurityException;
import com.google.crypto.tink.prf.Prf;
import java.security.Key;
import javax.crypto.spec.SecretKeySpec;
import com.google.crypto.tink.InsecureSecretKeyAccess;
import com.google.crypto.tink.aead.AesCtrHmacAeadKey;
import com.google.crypto.tink.Mac;
import com.google.crypto.tink.AccessesPartialKey;
import com.google.crypto.tink.Aead;

@AccessesPartialKey
public final class EncryptThenAuthenticate implements Aead
{
    private final IndCpaCipher cipher;
    private final Mac mac;
    private final int macLength;
    private final byte[] outputPrefix;
    
    public EncryptThenAuthenticate(final IndCpaCipher cipher, final Mac mac, final int macLength) {
        this(cipher, mac, macLength, new byte[0]);
    }
    
    private EncryptThenAuthenticate(final IndCpaCipher cipher, final Mac mac, final int macLength, final byte[] outputPrefix) {
        this.cipher = cipher;
        this.mac = mac;
        this.macLength = macLength;
        this.outputPrefix = outputPrefix;
    }
    
    public static Aead create(final AesCtrHmacAeadKey key) throws GeneralSecurityException {
        return new EncryptThenAuthenticate(new AesCtrJceCipher(key.getAesKeyBytes().toByteArray(InsecureSecretKeyAccess.get()), key.getParameters().getIvSizeBytes()), new PrfMac(new PrfHmacJce("HMAC" + key.getParameters().getHashType(), new SecretKeySpec(key.getHmacKeyBytes().toByteArray(InsecureSecretKeyAccess.get()), "HMAC")), key.getParameters().getTagSizeBytes()), key.getParameters().getTagSizeBytes(), key.getOutputPrefix().toByteArray());
    }
    
    public static Aead newAesCtrHmac(final byte[] aesCtrKey, final int ivSize, final String hmacAlgorithm, final byte[] hmacKey, final int tagSize) throws GeneralSecurityException {
        final IndCpaCipher cipher = new AesCtrJceCipher(aesCtrKey, ivSize);
        final SecretKeySpec hmacKeySpec = new SecretKeySpec(hmacKey, "HMAC");
        final Mac hmac = new PrfMac(new PrfHmacJce(hmacAlgorithm, hmacKeySpec), tagSize);
        return new EncryptThenAuthenticate(cipher, hmac, tagSize);
    }
    
    @Override
    public byte[] encrypt(final byte[] plaintext, final byte[] associatedData) throws GeneralSecurityException {
        final byte[] ciphertext = this.cipher.encrypt(plaintext);
        byte[] ad = associatedData;
        if (ad == null) {
            ad = new byte[0];
        }
        final byte[] adLengthInBits = Arrays.copyOf(ByteBuffer.allocate(8).putLong(8L * ad.length).array(), 8);
        final byte[] macValue = this.mac.computeMac(Bytes.concat(new byte[][] { ad, ciphertext, adLengthInBits }));
        return Bytes.concat(new byte[][] { this.outputPrefix, ciphertext, macValue });
    }
    
    @Override
    public byte[] decrypt(final byte[] ciphertext, final byte[] associatedData) throws GeneralSecurityException {
        if (ciphertext.length < this.macLength + this.outputPrefix.length) {
            throw new GeneralSecurityException("Decryption failed (ciphertext too short).");
        }
        if (!Util.isPrefix(this.outputPrefix, ciphertext)) {
            throw new GeneralSecurityException("Decryption failed (OutputPrefix mismatch).");
        }
        final byte[] rawCiphertext = Arrays.copyOfRange(ciphertext, this.outputPrefix.length, ciphertext.length - this.macLength);
        final byte[] macValue = Arrays.copyOfRange(ciphertext, ciphertext.length - this.macLength, ciphertext.length);
        byte[] ad = associatedData;
        if (ad == null) {
            ad = new byte[0];
        }
        final byte[] adLengthInBits = Arrays.copyOf(ByteBuffer.allocate(8).putLong(8L * ad.length).array(), 8);
        this.mac.verifyMac(macValue, Bytes.concat(new byte[][] { ad, rawCiphertext, adLengthInBits }));
        return this.cipher.decrypt(rawCiphertext);
    }
}