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quantum-c#: initial support for ECDSA and RSA signatures
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‎csharp/ql/lib/experimental/quantum/Language.qll‎

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@@ -64,3 +64,5 @@ module ArtifactFlowConfig implements Language::DataFlow::ConfigSig {
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}
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module ArtifactFlow = Language::DataFlow::Global<ArtifactFlowConfig>;
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import dotnet

‎csharp/ql/lib/experimental/quantum/dotnet.qll‎

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import dotnet.AlgorithmInstances
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import dotnet.AlgorithmValueConsumers
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import dotnet.FlowAnalysis
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import dotnet.Cryptography

‎csharp/ql/lib/experimental/quantum/dotnet/AlgorithmInstances.qll‎

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private import csharp
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private import experimental.quantum.Language
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private import AlgorithmValueConsumers
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private import Cryptography
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private import FlowAnalysis
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class SigningNamedCurveAlgorithmInstance extends Crypto::EllipticCurveInstance instanceof SigningNamedCurvePropertyAccess
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{
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ECDsaAlgorithmValueConsumer consumer;
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SigningNamedCurveAlgorithmInstance() {
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SigningNamedCurveToSignatureCreateFlow::flow(DataFlow::exprNode(this), consumer.getInputNode())
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}
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ECDsaAlgorithmValueConsumer getConsumer() { result = consumer }
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override string getRawEllipticCurveName() { result = super.getCurveName() }
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override Crypto::TEllipticCurveType getEllipticCurveType() {
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Crypto::ellipticCurveNameToKeySizeAndFamilyMapping(this.getRawEllipticCurveName(), _, result)
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}
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override int getKeySize() {
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Crypto::ellipticCurveNameToKeySizeAndFamilyMapping(this.getRawEllipticCurveName(), result, _)
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}
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}

‎csharp/ql/lib/experimental/quantum/dotnet/AlgorithmValueConsumers.qll‎

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private import csharp
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private import experimental.quantum.Language
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private import AlgorithmInstances
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private import Cryptography
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class ECDsaAlgorithmValueConsumer extends Crypto::AlgorithmValueConsumer {
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ECDsaCreateCall call;
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ECDsaAlgorithmValueConsumer() { this = call.getAlgorithmArg() }
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override Crypto::ConsumerInputDataFlowNode getInputNode() { result.asExpr() = this }
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override Crypto::AlgorithmInstance getAKnownAlgorithmSource() {
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exists(SigningNamedCurveAlgorithmInstance l | l.getConsumer() = this and result = l)
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}
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}

‎csharp/ql/lib/experimental/quantum/dotnet/Cryptography.qll‎

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private import csharp
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// This class models Create calls for the ECDsa and RSA classes in .NET.
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class CryptographyCreateCall extends MethodCall {
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CryptographyCreateCall() {
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this.getTarget().getName() = "Create" and
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this.getQualifier().getType().hasFullyQualifiedName("System.Security.Cryptography", _)
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}
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Expr getAlgorithmArg() {
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this.hasNoArguments() and result = this
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or
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result = this.(ECDsaCreateCallWithParameters).getArgument(0)
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or
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result = this.(ECDsaCreateCallWithECCurve).getArgument(0)
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}
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}
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class ECDsaCreateCall extends CryptographyCreateCall {
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ECDsaCreateCall() { this.getQualifier().getType().hasName("ECDsa") }
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}
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class RSACreateCall extends CryptographyCreateCall {
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RSACreateCall() { this.getQualifier().getType().hasName("RSA") }
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}
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class CryptographyType extends Type {
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CryptographyType() { this.hasFullyQualifiedName("System.Security.Cryptography", _) }
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}
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class ECParameters extends CryptographyType {
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ECParameters() { this.hasName("ECParameters") }
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}
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class RSAParameters extends CryptographyType {
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RSAParameters() { this.hasName("RSAParameters") }
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}
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class ECCurve extends CryptographyType {
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ECCurve() { this.hasName("ECCurve") }
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}
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// This class is used to model the `ECDsa.Create(ECParameters)` call
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class ECDsaCreateCallWithParameters extends ECDsaCreateCall {
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ECDsaCreateCallWithParameters() { this.getArgument(0).getType() instanceof ECParameters }
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}
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class ECDsaCreateCallWithECCurve extends ECDsaCreateCall {
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ECDsaCreateCallWithECCurve() { this.getArgument(0).getType() instanceof ECCurve }
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}
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class SigningNamedCurvePropertyAccess extends PropertyAccess {
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string curveName;
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SigningNamedCurvePropertyAccess() {
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super.getType().getName() = "ECCurve" and
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eccurveNameMapping(super.getProperty().toString().toUpperCase(), curveName)
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}
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string getCurveName() { result = curveName }
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}
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/**
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* Private predicate mapping NIST names to SEC names and leaving all others the same.
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*/
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bindingset[nist]
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private predicate eccurveNameMapping(string nist, string secp) {
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if nist.matches("NIST%")
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then
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nist = "NISTP256" and secp = "secp256r1"
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or
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nist = "NISTP384" and secp = "secp384r1"
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or
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nist = "NISTP521" and secp = "secp521r1"
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else secp = nist
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}
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// OPERATION INSTANCES
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private class ECDsaClass extends Type {
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ECDsaClass() { this.hasFullyQualifiedName("System.Security.Cryptography", "ECDsa") }
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}
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private class RSAClass extends Type {
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RSAClass() { this.hasFullyQualifiedName("System.Security.Cryptography", "RSA") }
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}
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// TODO
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// class ByteArrayTypeUnionReadOnlyByteSpan extends ArrayType {
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// ByteArrayTypeUnionReadOnlyByteSpan() {
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// this.hasFullyQualifiedName("System", "Byte[]") or
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// this.hasFullyQualifiedName("System", "ReadOnlySpan`1") or
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// }
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// }
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abstract class DotNetSigner extends MethodCall {
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DotNetSigner() { this.getTarget().getName().matches(["Verify%", "Sign%"]) }
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Expr getMessageArg() {
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// Both Sign and Verify methods take the message as the first argument.
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// Some cases the message is a hash.
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result = this.getArgument(0)
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}
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Expr getSignatureArg() {
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this.isVerifier() and
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// TODO: Should replace getAChild* with the proper two types byte[] and ReadOnlySpan<byte>
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(result = this.getArgument([1, 3]) and result.getType().getAChild*() instanceof ByteType)
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}
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Expr getSignatureOutput() {
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this.isSigner() and
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result = this
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}
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predicate isSigner() { this.getTarget().getName().matches("Sign%") }
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predicate isVerifier() { this.getTarget().getName().matches("Verify%") }
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}
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private class ECDsaSigner extends DotNetSigner {
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ECDsaSigner() { this.getQualifier().getType() instanceof ECDsaClass }
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}
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private class RSASigner extends DotNetSigner {
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RSASigner() { this.getQualifier().getType() instanceof RSAClass }
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}

‎csharp/ql/lib/experimental/quantum/dotnet/FlowAnalysis.qll‎

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private import csharp
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private import Cryptography
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private import AlgorithmValueConsumers
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/**
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* Flow from a known ECDsa property access to a `ECDsa.Create(sink)` call.
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*/
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module SigningNamedCurveToSignatureCreateFlowConfig implements DataFlow::ConfigSig {
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predicate isSource(DataFlow::Node src) { src.asExpr() instanceof SigningNamedCurvePropertyAccess }
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predicate isSink(DataFlow::Node sink) {
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exists(ECDsaAlgorithmValueConsumer consumer | sink = consumer.getInputNode())
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}
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}
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module SigningNamedCurveToSignatureCreateFlow =
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DataFlow::Global<SigningNamedCurveToSignatureCreateFlowConfig>;
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/**
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* Flow from a known ECDsa property access to a `ECDsa.Create(sink)` call.
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*/
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private module CreateToUseFlowConfig implements DataFlow::ConfigSig {
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predicate isSource(DataFlow::Node src) { src.asExpr() instanceof CryptographyCreateCall }
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predicate isSink(DataFlow::Node sink) { sink.asExpr() instanceof DotNetSigner }
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predicate isAdditionalFlowStep(DataFlow::Node node1, DataFlow::Node node2) {
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node2.asExpr().(DotNetSigner).getQualifier() = node1.asExpr()
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}
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}
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module CryptographyCreateToUseFlow = DataFlow::Global<CreateToUseFlowConfig>;

‎csharp/ql/lib/experimental/quantum/dotnet/OperationInstances.qll‎

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private import csharp
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private import experimental.quantum.Language
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private import DataFlow
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private import FlowAnalysis
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private import Cryptography
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class ECDsaORRSASigningOperationInstance extends Crypto::SignatureOperationInstance instanceof DotNetSigner
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{
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CryptographyCreateCall creator;
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ECDsaORRSASigningOperationInstance() {
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this instanceof DotNetSigner and
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CryptographyCreateToUseFlow::flow(DataFlow::exprNode(creator), DataFlow::exprNode(this))
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}
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// TODO FIXME
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override Crypto::AlgorithmValueConsumer getAnAlgorithmValueConsumer() {
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result = creator.getAlgorithmArg()
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}
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override Crypto::KeyOperationSubtype getKeyOperationSubtype() {
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if super.isSigner()
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then result = Crypto::TSignMode()
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else
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if super.isVerifier()
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then result = Crypto::TVerifyMode()
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else result = Crypto::TUnknownKeyOperationMode()
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}
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// TODO FIXME
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override Crypto::ConsumerInputDataFlowNode getKeyConsumer() {
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result.asExpr() = creator.getAlgorithmArg()
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}
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override Crypto::ConsumerInputDataFlowNode getNonceConsumer() { none() }
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override Crypto::ConsumerInputDataFlowNode getInputConsumer() {
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result.asExpr() = super.getMessageArg()
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}
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override Crypto::ConsumerInputDataFlowNode getSignatureConsumer() {
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result.asExpr() = super.getSignatureArg()
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}
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override Crypto::ArtifactOutputDataFlowNode getOutputArtifact() {
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result.asExpr() = super.getSignatureOutput()
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}
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}

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