DefaultStateGenerator->Base64StringKeyGenerator

Rename and move DefaultStateGenerator since it is more generic than just
OAuth.

Fixes gh-4645

crypto/src/main/java/org/springframework/security/crypto/keygen/Base64StringKeyGenerator.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2002-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.security.crypto.keygen;
+
+import java.util.Base64;
+
+/**
+ * A StringKeyGenerator that generates base64-encoded String keys. Delegates to a
+ * {@link BytesKeyGenerator} for the actual key generation.
+ *
+ * @author Joe Grandja
+ * @author Rob Winch
+ * @since 5.0
+ */
+public class Base64StringKeyGenerator implements StringKeyGenerator {
+	private static final int DEFAULT_KEY_LENGTH = 32;
+	private final BytesKeyGenerator keyGenerator;
+	private final Base64.Encoder encoder;
+
+	/**
+	 * Creates an instance with keyLength of 32 bytes and standard Base64 encoding.
+	 */
+	public Base64StringKeyGenerator() {
+		this(DEFAULT_KEY_LENGTH);
+	}
+
+	/**
+	 * Creates an instance with the provided key length in bytes and standard Base64
+	 * encoding.
+	 * @param keyLength the key length in bytes
+	 */
+	public Base64StringKeyGenerator(int keyLength) {
+		this(Base64.getEncoder(), keyLength);
+	}
+
+	/**
+	 * Creates an instance with keyLength of 32 bytes and the provided encoder.
+	 * @param encoder the encoder to use
+	 */
+	public Base64StringKeyGenerator(Base64.Encoder encoder) {
+		this(encoder, DEFAULT_KEY_LENGTH);
+	}
+
+	/**
+	 * Creates an instance with the provided key length and encoder.
+	 * @param encoder the encoder to use
+	 * @param keyLength the key length to use
+	 */
+	public Base64StringKeyGenerator(Base64.Encoder encoder, int keyLength) {
+		if(encoder == null) {
+			throw new IllegalArgumentException("encode cannot be null");
+		}
+		if(keyLength < DEFAULT_KEY_LENGTH) {
+			throw new IllegalArgumentException("keyLength must be greater than or equal to" + DEFAULT_KEY_LENGTH);
+		}
+		this.encoder = encoder;
+		this.keyGenerator = KeyGenerators.secureRandom(keyLength);
+	}
+
+	@Override
+	public String generateKey() {
+		byte[] key = this.keyGenerator.generateKey();
+		byte[] base64EncodedKey = this.encoder.encode(key);
+		return new String(base64EncodedKey);
+	}
+}

crypto/src/test/java/org/springframework/security/crypto/keygen/Base64StringKeyGeneratorTests.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2002-2017 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.crypto.keygen;
+
+import org.junit.Test;
+
+import java.util.Base64;
+
+import static org.assertj.core.api.Assertions.*;
+
+/**
+ * @author Rob Winch
+ * @since 5.0
+ */
+public class Base64StringKeyGeneratorTests {
+	@Test(expected = IllegalArgumentException.class)
+	public void constructorIntWhenLessThan32ThenIllegalArgumentException() {
+		new Base64StringKeyGenerator(31);
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void constructorEncoderWhenEncoderNullThenThrowsIllegalArgumentException() {
+		Base64.Encoder encoder = null;
+		new Base64StringKeyGenerator(null);
+	}
+
+	@Test
+	public void generateKeyWhenDefaultConstructorThen32Bytes() {
+		String result = new Base64StringKeyGenerator().generateKey();
+		assertThat(Base64.getDecoder().decode(result.getBytes())).hasSize(32);
+	}
+
+	@Test
+	public void generateKeyWhenCustomKeySizeThen32Bytes() {
+		int size = 40;
+		String result = new Base64StringKeyGenerator(size).generateKey();
+		assertThat(Base64.getDecoder().decode(result.getBytes())).hasSize(size);
+	}
+
+	@Test
+	public void generateKeyWhenBase64Then32Bytes() {
+		String result = new Base64StringKeyGenerator(Base64.getUrlEncoder()).generateKey();
+		assertThat(Base64.getUrlDecoder().decode(result.getBytes())).hasSize(32);
+	}
+
+	@Test
+	public void generateKeyWhenBase64AndCustomKeySizeThen32Bytes() {
+		int size = 40;
+		String result = new Base64StringKeyGenerator(Base64.getUrlEncoder(), size).generateKey();
+		assertThat(Base64.getUrlDecoder().decode(result.getBytes())).hasSize(size);
+	}
+}