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fix: The final frame can not be larger than the Frame Length #166

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Merged
merged 5 commits into from
Apr 7, 2020
Merged

fix: The final frame can not be larger than the Frame Length #166

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163fd88
Add validation to ensure the length of the final frame in the final
WesleyRosenblum Mar 26, 2020
b58b5c1
Validate that frame length is positive for framed data
WesleyRosenblum Mar 27, 2020
5346309
Reverting removal of variable frame length code
WesleyRosenblum Apr 2, 2020
b8d754e
Reverting removal of variable frame length code
WesleyRosenblum Apr 2, 2020
6e38615
Fix spacing after if
WesleyRosenblum Apr 2, 2020
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5 changes: 5 additions & 0 deletions src/main/java/com/amazonaws/encryptionsdk/internal/FrameDecryptionHandler.java
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Original file line number Diff line number Diff line change
Expand Up @@ -133,6 +133,11 @@ public ProcessingSummary processBytes(final byte[] in, final int off, final int
int protectedContentLen = -1;
if (currentFrameHeaders_.isFinalFrame()) {
protectedContentLen = currentFrameHeaders_.getFrameContentLength();

// The final frame should not be able to exceed the frameLength
if (frameSize_ > 0 && protectedContentLen > frameSize_) {
throw new BadCiphertextException("Final frame length exceeds frame length.");
}
} else {
protectedContentLen = frameSize_;
}
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2 changes: 1 addition & 1 deletion src/main/java/com/amazonaws/encryptionsdk/model/CiphertextHeaders.java
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Expand Up @@ -859,4 +859,4 @@ public void setHeaderNonce(final byte[] headerNonce) {
public void setHeaderTag(final byte[] headerTag) {
headerTag_ = headerTag.clone();
}
}
}
19 changes: 18 additions & 1 deletion src/test/java/com/amazonaws/encryptionsdk/internal/FrameDecryptionHandlerTest.java
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Expand Up @@ -15,11 +15,14 @@

import static org.junit.Assert.assertTrue;

import java.nio.ByteBuffer;
import java.security.SecureRandom;

import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import com.amazonaws.encryptionsdk.TestUtils;
import com.amazonaws.encryptionsdk.exception.BadCiphertextException;
import org.junit.Before;
import org.junit.Test;

Expand Down Expand Up @@ -72,4 +75,18 @@ public void decryptMaxContentLength() {
frameDecryptionHandler_.processBytes(in, 0, in.length, out, 0);
frameDecryptionHandler_.processBytes(in, 0, Integer.MAX_VALUE, out, 0);
}
}

@Test(expected = BadCiphertextException.class)
public void finalFrameLengthTooLarge() {

final ByteBuffer byteBuffer = ByteBuffer.allocate(25);
byteBuffer.put(TestUtils.unsignedBytesToSignedBytes(
new int[] {255, 255, 255, 255, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}));
byteBuffer.putInt(AwsCrypto.getDefaultFrameSize() + 1);

final byte[] in = byteBuffer.array();
final byte[] out = new byte[in.length];

frameDecryptionHandler_.processBytes(in, 0, in.length, out, 0);
}
}