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Bugs/fix tpm parser (#31)
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* Modify pubArea for ECC alg parsing error of TPM Attestation

* Refactor TPM PubArea extraction code

* Add unit test for TPM ECC attestation
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@kj84park
kj84park authored Sep 16, 2022
1 parent 78f78c6 commit a22f388
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Showing 3 changed files with 136 additions and 58 deletions.
5 changes: 4 additions & 1 deletion ...c/main/java/com/linecorp/line/auth/fido/fido2/server/attestation/tpm/TpmKeyAlgorithm.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,8 @@

import java.util.Arrays;

import com.linecorp.line.auth.fido.fido2.server.error.InternalErrorCode;
import com.linecorp.line.auth.fido.fido2.server.exception.FIDO2ServerRuntimeException;
import lombok.AllArgsConstructor;
import lombok.Getter;

Expand All @@ -32,6 +34,7 @@ public static TpmKeyAlgorithm fromValue(int value) {
return Arrays.stream(TpmKeyAlgorithm.values())
.filter(e -> e.value == value)
.findFirst()
.get();
.orElseThrow(() -> new FIDO2ServerRuntimeException(InternalErrorCode.TPM_ATTESTATION_DATA_INVALID));

}
}
161 changes: 106 additions & 55 deletions server/src/main/java/com/linecorp/line/auth/fido/fido2/server/attestation/tpm/TpmParser.java
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Expand Up @@ -16,10 +16,13 @@

package com.linecorp.line.auth.fido.fido2.server.attestation.tpm;

import com.linecorp.line.auth.fido.fido2.server.error.InternalErrorCode;
import com.linecorp.line.auth.fido.fido2.server.exception.FIDO2ServerRuntimeException;
import com.linecorp.line.auth.fido.fido2.server.util.UnsignedUtil;

import java.io.ByteArrayInputStream;
import java.io.IOException;

import com.linecorp.line.auth.fido.fido2.server.util.UnsignedUtil;
import java.nio.ByteBuffer;

public class TpmParser {
public static CertInfo parseCertInfo(byte[] certInfo) throws IOException {
Expand Down Expand Up @@ -89,27 +92,48 @@ public static CertInfo parseCertInfo(byte[] certInfo) throws IOException {
}

public static PubArea parsePubArea(byte[] pubArea) throws IOException {
ByteArrayInputStream pubAreaInputStream = new ByteArrayInputStream(pubArea);
switch (TpmKeyAlgorithm.fromValue(extractTpmKeyAlgType(pubAreaInputStream))) {
case RSA: {
return createPubAreaForRSA(pubAreaInputStream);
}
case ECC: {
return createPubAreaForECC(pubAreaInputStream);
}
}
throw new FIDO2ServerRuntimeException(InternalErrorCode.TPM_ATTESTATION_DATA_INVALID);
}

private static int extractTpmKeyAlgType(ByteArrayInputStream inputStream) throws IOException {
byte[] typeBytes = new byte[2];
inputStream.read(typeBytes);
return UnsignedUtil.readUINT16BE(typeBytes);
}

private static PubArea createPubAreaForRSA(ByteArrayInputStream inputStream) throws IOException {
return createPubAreaBuilder(TpmKeyAlgorithm.RSA, inputStream)
.parameters(extractParametersForRSA(inputStream))
.unique(extractUniqueBytesForRSA(inputStream))
.build();
}

private static PubArea createPubAreaForECC(ByteArrayInputStream inputStream) throws IOException {
return createPubAreaBuilder(TpmKeyAlgorithm.ECC, inputStream)
.parameters(extractParametersForECC(inputStream))
.unique(extractUniqueBytesForECC(inputStream))
.build();
}

private static PubArea.PubAreaBuilder createPubAreaBuilder(TpmKeyAlgorithm tpmKeyAlgType, ByteArrayInputStream inputStream) throws IOException {
byte[] nameAlgBytes = new byte[2];
byte[] objectAttributesBytes = new byte[4];
byte[] authPolicyLengthBytes = new byte[2];
byte[] symmetricBytes = new byte[2];
byte[] schemeBytes = new byte[2];
byte[] keyBitsBytes; // rsa key
byte[] exponentBytes; // rsa key
byte[] curveIdBytes; // ecc key
byte[] kdfBytes; //ecc key
byte[] uniqueLengthBytes = new byte[2];
byte[] uniqueBytes;

ByteArrayInputStream inputStream = new ByteArrayInputStream(pubArea);

inputStream.read(typeBytes); // type
int type = UnsignedUtil.readUINT16BE(typeBytes);
inputStream.read(nameAlgBytes); // name alg
inputStream.read(nameAlgBytes);
TpmHashAlgorithm nameAlg =
TpmHashAlgorithm.fromValue(UnsignedUtil.readUINT16BE(nameAlgBytes));
inputStream.read(objectAttributesBytes); // object attributes

inputStream.read(objectAttributesBytes);
int objectAttributesFlags = (int) UnsignedUtil.readUINT32BE(objectAttributesBytes);
ObjectAttributes objectAttributes = parseObjectAttributes(objectAttributesFlags);
// skip auth policy
Expand All @@ -119,50 +143,77 @@ public static PubArea parsePubArea(byte[] pubArea) throws IOException {
inputStream.skip(authPolicyLength);
}

// read parameters depending on the key type
Parameters parameters = null;
if (type == TpmKeyAlgorithm.RSA.getValue()) {
keyBitsBytes = new byte[2];
exponentBytes = new byte[4];
inputStream.read(symmetricBytes);
inputStream.read(schemeBytes);
inputStream.read(keyBitsBytes);
inputStream.read(exponentBytes);
parameters = new RsaParameters();
parameters.setSymmetric(symmetricBytes);
parameters.setScheme(TpmSignatureAlgorithm.fromValue(UnsignedUtil.readUINT16BE(schemeBytes)));
((RsaParameters) parameters).setKeyBits(keyBitsBytes);
((RsaParameters) parameters).setExponent(exponentBytes);
} else if (type == TpmKeyAlgorithm.ECC.getValue()) {
curveIdBytes = new byte[2];
kdfBytes = new byte[2];
inputStream.read(symmetricBytes);
inputStream.read(schemeBytes);
inputStream.read(curveIdBytes);
inputStream.read(kdfBytes);
parameters = new EccParameters();
parameters.setSymmetric(symmetricBytes);
parameters.setScheme(TpmSignatureAlgorithm.fromValue(UnsignedUtil.readUINT16BE(schemeBytes)));
((EccParameters) parameters).setCurveId(TpmEccCurve.fromValue(UnsignedUtil.readUINT16BE(curveIdBytes)));
((EccParameters) parameters).setKdf(kdfBytes);
} else {
// invalid
}
return PubArea
.builder()
.type(tpmKeyAlgType)
.nameAlg(nameAlg)
.objectAttributes(objectAttributes);
}

private static Parameters extractParametersForRSA(ByteArrayInputStream inputStream) throws IOException {
byte[] symmetricBytes = new byte[2];
byte[] schemeBytes = new byte[2];
byte[] keyBitsBytes = new byte[2];
byte[] exponentBytes = new byte[4];

inputStream.read(symmetricBytes);
inputStream.read(schemeBytes);
inputStream.read(keyBitsBytes);
inputStream.read(exponentBytes);

// read unique (key value)
Parameters parameters = new RsaParameters();
parameters.setSymmetric(symmetricBytes);
parameters.setScheme(TpmSignatureAlgorithm.fromValue(UnsignedUtil.readUINT16BE(schemeBytes)));
((RsaParameters) parameters).setKeyBits(keyBitsBytes);
((RsaParameters) parameters).setExponent(exponentBytes);
return parameters;
}

private static byte[] extractUniqueBytesForRSA(ByteArrayInputStream inputStream) throws IOException {
byte[] uniqueLengthBytes = new byte[2];
inputStream.read(uniqueLengthBytes);
int uniqueLength = UnsignedUtil.readUINT16BE(uniqueLengthBytes);
uniqueBytes = new byte[uniqueLength];
byte[] uniqueBytes = new byte[uniqueLength];
inputStream.read(uniqueBytes);
return uniqueBytes;
}

return PubArea
.builder()
.type(TpmKeyAlgorithm.fromValue(type))
.nameAlg(nameAlg)
.objectAttributes(objectAttributes)
.parameters(parameters)
.unique(uniqueBytes)
.build();
private static Parameters extractParametersForECC(ByteArrayInputStream inputStream) throws IOException {
byte[] symmetricBytes = new byte[2];
byte[] schemeBytes = new byte[2];
byte[] curveIdBytes = new byte[2];
byte[] kdfBytes = new byte[2];

inputStream.read(symmetricBytes);
inputStream.read(schemeBytes);
inputStream.read(curveIdBytes);
inputStream.read(kdfBytes);

Parameters parameters = new EccParameters();
parameters.setSymmetric(symmetricBytes);
parameters.setScheme(TpmSignatureAlgorithm.fromValue(UnsignedUtil.readUINT16BE(schemeBytes)));
((EccParameters) parameters).setCurveId(TpmEccCurve.fromValue(UnsignedUtil.readUINT16BE(curveIdBytes)));
((EccParameters) parameters).setKdf(kdfBytes);
return parameters;
}

private static byte[] extractUniqueBytesForECC(ByteArrayInputStream inputStream) throws IOException {
byte[] xLengthBytes = new byte[2];
inputStream.read(xLengthBytes);
int xLength = UnsignedUtil.readUINT16BE(xLengthBytes);
byte[] xBytes = new byte[xLength];
inputStream.read(xBytes);

byte[] yLengthBytes = new byte[2];
inputStream.read(yLengthBytes);
int yLength = UnsignedUtil.readUINT16BE(yLengthBytes);
byte[] yBytes = new byte[yLength];
inputStream.read(yBytes);

return ByteBuffer.allocate(xLength + yLength)
.put(xBytes)
.put(yBytes)
.array();
}

public static ClockInfo parseClockInfo(byte[] clockInfo) throws IOException {
Expand Down
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