final Cipher cipher = Cipher.getInstance(transformation);
            final GCMParameterSpec gcmSpec = new GCMParameterSpec(getAuthTagLength() * 8, nonce);

            cipher.init(encrypt ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE, keySpec, gcmSpec);
            return cipher;
        } finally {
            // Guaranteed cleanup of all key material
            if (key != null) {

        };
        roleQueryHelperImpl.cipher = cipher;

        Set<String> roleSet;
        boolean encrypted;
        String value;

        encrypted = true;
        value = cipher.encryptoText("");
        roleSet = decodedRoleList(roleQueryHelperImpl, value, encrypted);
        assertEquals(0, roleSet.size());

        encrypted = true;
        value = cipher.encryptoText("role1");

     * @return a decryption cipher
     */
    protected Cipher pollDecryptoCipher() {
        Cipher cipher = decryptoQueue.poll();
        if (cipher == null) {
            final SecretKeySpec sksSpec = new SecretKeySpec(key.getBytes(), algorithm);
            try {
                cipher = Cipher.getInstance(algorithm);
                cipher.init(Cipher.DECRYPT_MODE, sksSpec);
            } catch (final InvalidKeyException e) {

---

<a name="tlsv13_only"></a>
#### ¹ TLSv1.3 Only

Cipher suites that are only available with TLSv1.3.

<a name="http2_naughty"></a>
#### ² HTTP/2 Cipher Suite Denylist

Cipher suites that are [discouraged for use][http2_denylist] with HTTP/2. OkHttp includes them because better suites are not commonly available. For example, none of the better cipher suites listed above shipped with Android 4.4 or Java 7.

        byte[] keybytes = key.getEncoded();
        Cipher cipher = Cipher.getInstance("AES/CBC/NoPadding");
        cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(keybytes, "AES"), new IvParameterSpec(ZERO_IV, 0, ZERO_IV.length));
        if (constant.length != cipher.getBlockSize()) {
            constant = expandNFold(constant, cipher.getBlockSize());
        }
        byte[] enc = constant;

        final int start = dstIndex;
        SMBUtil.writeInt2(this.ciphers != null ? this.ciphers.length : 0, dst, dstIndex);
        dstIndex += 2;

        if (this.ciphers != null) {
            for (final int cipher : this.ciphers) {
                SMBUtil.writeInt2(cipher, dst, dstIndex);
                dstIndex += 2;
            }
        }
        return dstIndex - start;

        return new HMACT64(key);
    }

    /**
     * Get an RC4 cipher instance initialized with the specified key.
     * @param key the encryption key
     * @return RC4 cipher in encryption mode
     */
    public static Cipher getArcfour(final byte[] key) {
        try {
            final Cipher c = Cipher.getInstance("RC4");
            c.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, "RC4"));
            return c;

        @DisplayName("Should encode various cipher counts correctly")
        void testEncodeVariousCipherCounts(int cipherCount) {
            int[] ciphers = new int[cipherCount];
            for (int i = 0; i < cipherCount; i++) {
                ciphers[i] = i + 1;
            }
            EncryptionNegotiateContext context = new EncryptionNegotiateContext(mockConfig, ciphers);

import okhttp3.FallbackTestClientSocketFactory.Companion.TLS_FALLBACK_SCSV

/**
 * An SSLSocketFactory that delegates calls. Sockets created by the delegate are wrapped with ones
 * that will not accept the [TLS_FALLBACK_SCSV] cipher, thus bypassing server-side fallback
 * checks on platforms that support it. Unfortunately this wrapping will disable any
 * reflection-based calls to SSLSocket from Platform.
 */
class FallbackTestClientSocketFactory(

        SecretKeySpec dataKey = new SecretKeySpec(dataHmac, KerberosConstants.RC4_ALGORITHM);

        cipher = Cipher.getInstance(KerberosConstants.RC4_ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, dataKey);

        int plainDataLength = data.length - KerberosConstants.CHECKSUM_SIZE;
        byte[] plainData = cipher.doFinal(data, KerberosConstants.CHECKSUM_SIZE, plainDataLength);