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Padded data should be at least 32 bytes
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/******************************************************************************* | ||
* Copyright (c) 2023 Mountainminds GmbH & Co. KG | ||
* | ||
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | ||
* SOFTWARE. | ||
* | ||
* SPDX-License-Identifier: MIT | ||
*******************************************************************************/ | ||
package com.mountainminds.three4j; | ||
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import java.io.ByteArrayInputStream; | ||
import java.io.ByteArrayOutputStream; | ||
import java.io.DataInputStream; | ||
import java.io.DataOutputStream; | ||
import java.io.IOException; | ||
import java.security.SecureRandom; | ||
import java.util.Random; | ||
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/** | ||
* Internal utility for PKCS#7 padding. | ||
*/ | ||
class PaddedBuffer extends DataOutputStream { | ||
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private static ThreadLocal<Random> RANDOM = new ThreadLocal<>() { | ||
protected Random initialValue() { | ||
return new SecureRandom(); | ||
}; | ||
}; | ||
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private static final int MSG_LEN_MIN = 32; | ||
private static final int PAD_LEN_MIN = 1; | ||
private static final int PAD_LEN_MAX = 255; | ||
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private final Random random; | ||
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PaddedBuffer(Random random) { | ||
super(new ByteArrayOutputStream()); | ||
this.random = random; | ||
} | ||
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PaddedBuffer() { | ||
this(RANDOM.get()); | ||
} | ||
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byte[] withPadding() throws IOException { | ||
var buffer = (ByteArrayOutputStream) out; | ||
int panLenMin = Math.max(PAD_LEN_MIN, MSG_LEN_MIN - buffer.size()); | ||
int padding = random.nextInt(PAD_LEN_MAX - panLenMin + 1) + panLenMin; | ||
for (int i = 0; i < padding; i++) { | ||
write(padding); | ||
} | ||
return buffer.toByteArray(); | ||
} | ||
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static DataInputStream removePadding(byte[] buffer) { | ||
int len = 0xff & buffer[buffer.length - 1]; | ||
return new DataInputStream(new ByteArrayInputStream(buffer, 0, buffer.length - len)); | ||
} | ||
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} |
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105 changes: 105 additions & 0 deletions
105
src/test/java/com/mountainminds/three4j/PaddedBufferTest.java
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/******************************************************************************* | ||
* Copyright (c) 2021 Mountainminds GmbH & Co. KG | ||
* | ||
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | ||
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | ||
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | ||
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | ||
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | ||
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | ||
* SOFTWARE. | ||
* | ||
* SPDX-License-Identifier: MIT | ||
*******************************************************************************/ | ||
package com.mountainminds.three4j; | ||
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import static org.junit.jupiter.api.Assertions.assertArrayEquals; | ||
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import java.io.ByteArrayOutputStream; | ||
import java.io.IOException; | ||
import java.util.Random; | ||
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import org.junit.jupiter.api.Test; | ||
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public class PaddedBufferTest { | ||
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private final Random minRandom = new Random() { | ||
private static final long serialVersionUID = 1L; | ||
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@Override | ||
public int nextInt(int bound) { | ||
return 0; | ||
} | ||
}; | ||
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private final Random maxRandom = new Random() { | ||
private static final long serialVersionUID = 1L; | ||
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@Override | ||
public int nextInt(int bound) { | ||
return bound - 1; | ||
} | ||
}; | ||
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@Test | ||
void finish_should_expand_message_to_at_least_32_bytes() throws IOException { | ||
try (var buffer = new PaddedBuffer(minRandom)) { | ||
buffer.write(0x12); | ||
buffer.write(0x15); | ||
var msg = buffer.withPadding(); | ||
var expected = bytes(0x12, 0x15).nbytes(30, 30).toByteArray(); | ||
assertArrayEquals(expected, msg); | ||
} | ||
} | ||
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@Test | ||
void finish_should_add_at_least_1_byte() throws IOException { | ||
try (var buffer = new PaddedBuffer(minRandom)) { | ||
buffer.write(bytes().nbytes(64, 42).toByteArray()); | ||
var msg = buffer.withPadding(); | ||
var expected = bytes().nbytes(64, 42).nbytes(1, 1).toByteArray(); | ||
assertArrayEquals(expected, msg); | ||
} | ||
} | ||
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@Test | ||
void finish_should_add_at_most_255_bytes() throws IOException { | ||
try (var buffer = new PaddedBuffer(maxRandom)) { | ||
buffer.write(0x42); | ||
buffer.write(0x43); | ||
var msg = buffer.withPadding(); | ||
var expected = bytes(0x42, 0x43).nbytes(255, 255).toByteArray(); | ||
assertArrayEquals(expected, msg); | ||
} | ||
} | ||
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@Test | ||
void removePadding_should_remove_padding_of_length_1() throws IOException { | ||
var data = PaddedBuffer.removePadding(bytes(1, 2, 3).nbytes(1, 1).toByteArray()); | ||
assertArrayEquals(bytes(1, 2, 3).toByteArray(), data.readAllBytes()); | ||
} | ||
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@Test | ||
void removePadding_should_remove_padding_of_length_255() throws IOException { | ||
var data = PaddedBuffer.removePadding(bytes(1, 2, 3).nbytes(255, 255).toByteArray()); | ||
assertArrayEquals(bytes(1, 2, 3).toByteArray(), data.readAllBytes()); | ||
} | ||
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private static Bytes bytes(int... bytes) { | ||
var out = new Bytes(); | ||
for (int b : bytes) { | ||
out.write(0xff & b); | ||
} | ||
return out; | ||
} | ||
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private static class Bytes extends ByteArrayOutputStream { | ||
Bytes nbytes(int count, int value) { | ||
for (int i = 0; i < count; i++) { | ||
write(0xff & value); | ||
} | ||
return this; | ||
} | ||
} | ||
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} |