Crypto: Address PR comments.

Author: bdrodes

cpp/ql/lib/experimental/quantum/OpenSSL/Operations/CipherOperation.qll

@@ -12,9 +12,10 @@ abstract class EvpCipherInitializer extends OperationStep {
     or
     result.asExpr() = this.getArgument(1) and
     type = PrimaryAlgorithmIO() and
-    // Null for the algorithm indicates the algorithm is not actually set
-    // This pattern can occur during a multi-step initialization
-    // TODO/Note: not flowing 0 to the sink, assuming a direct use of NULL for now
+    // Constants that are not equal to zero or
+    // non-constants (e.g., variable accesses, which require data-flow to determine the value)
+    // A zero (null) value typically indicates use of this operation step to initialize
+    // other out parameters in a multi-step initialization.
     (exists(result.asExpr().getValue()) implies result.asExpr().getValue().toInt() != 0)
   }
 
@@ -33,9 +34,10 @@ abstract class EvpEXInitializer extends EvpCipherInitializer {
     result = super.getInput(type)
     or
     (
-      // Null key or nonce indicates the key/nonce is not actually set
-      // This pattern can occur during a multi-step initialization
-      // TODO/Note: not flowing 0 to the sink, assuming a direct use of NULL for now
+      // Constants that are not equal to zero or
+      // non-constants (e.g., variable accesses, which require data-flow to determine the value)
+      // A zero (null) value typically indicates use of this operation step to initialize
+      // other out parameters in a multi-step initialization.
       result.asExpr() = this.getArgument(3) and type = KeyIO()
       or
       result.asExpr() = this.getArgument(4) and type = IVorNonceIO()

cpp/ql/lib/experimental/quantum/OpenSSL/Operations/HashOperation.qll

@@ -12,21 +12,19 @@ private import experimental.quantum.OpenSSL.AlgorithmValueConsumers.OpenSSLAlgor
  * - `EVP_DigestInit_ex`
  * - `EVP_DigestInit_ex2`
  */
-class EvpDigestInitVariantCalls extends OperationStep {
+class EvpDigestInitVariantCalls extends OperationStep instanceof Call {
   EvpDigestInitVariantCalls() {
-    this.(Call).getTarget().getName() in [
-        "EVP_DigestInit", "EVP_DigestInit_ex", "EVP_DigestInit_ex2"
-      ]
+    this.getTarget().getName() in ["EVP_DigestInit", "EVP_DigestInit_ex", "EVP_DigestInit_ex2"]
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(0) and type = ContextIO()
+    result.asExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.(Call).getArgument(1) and type = PrimaryAlgorithmIO()
+    result.asExpr() = this.getArgument(1) and type = PrimaryAlgorithmIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(0) and
+    result.asExpr() = this.getArgument(0) and
     type = ContextIO()
   }
 
@@ -36,17 +34,17 @@ class EvpDigestInitVariantCalls extends OperationStep {
 /**
  * A call to `EVP_DigestUpdate`.
  */
-class EvpDigestUpdateCall extends OperationStep {
-  EvpDigestUpdateCall() { this.(Call).getTarget().getName() = "EVP_DigestUpdate" }
+class EvpDigestUpdateCall extends OperationStep instanceof Call {
+  EvpDigestUpdateCall() { this.getTarget().getName() = "EVP_DigestUpdate" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(0) and type = ContextIO()
+    result.asExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.(Call).getArgument(1) and type = PlaintextIO()
+    result.asExpr() = this.getArgument(1) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(0) and
+    result.asExpr() = this.getArgument(0) and
     type = ContextIO()
   }
 
@@ -64,58 +62,56 @@ abstract class EvpFinalDigestOperationStep extends OperationStep {
  * A call to `EVP_Q_digest`
  * https://docs.openssl.org/3.0/man3/EVP_DigestInit/#synopsis
  */
-class EvpQDigestOperation extends EvpFinalDigestOperationStep {
-  EvpQDigestOperation() { this.(Call).getTarget().getName() = "EVP_Q_digest" }
+class EvpQDigestOperation extends EvpFinalDigestOperationStep instanceof Call {
+  EvpQDigestOperation() { this.getTarget().getName() = "EVP_Q_digest" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(1) and type = PrimaryAlgorithmIO()
+    result.asExpr() = this.getArgument(1) and type = PrimaryAlgorithmIO()
     or
-    result.asExpr() = this.(Call).getArgument(0) and type = ContextIO()
+    result.asExpr() = this.getArgument(0) and type = ContextIO()
     or
-    result.asExpr() = this.(Call).getArgument(3) and type = PlaintextIO()
+    result.asExpr() = this.getArgument(3) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(0) and
+    result.asExpr() = this.getArgument(0) and
     type = ContextIO()
     or
-    result.asDefiningArgument() = this.(Call).getArgument(5) and type = DigestIO()
+    result.asDefiningArgument() = this.getArgument(5) and type = DigestIO()
   }
 }
 
-class EvpDigestOperation extends EvpFinalDigestOperationStep {
-  EvpDigestOperation() { this.(Call).getTarget().getName() = "EVP_Digest" }
+class EvpDigestOperation extends EvpFinalDigestOperationStep instanceof Call {
+  EvpDigestOperation() { this.getTarget().getName() = "EVP_Digest" }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(4) and type = PrimaryAlgorithmIO()
+    result.asExpr() = this.getArgument(4) and type = PrimaryAlgorithmIO()
     or
-    result.asExpr() = this.(Call).getArgument(0) and type = PlaintextIO()
+    result.asExpr() = this.getArgument(0) and type = PlaintextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asDefiningArgument() = this.(Call).getArgument(2) and type = DigestIO()
+    result.asDefiningArgument() = this.getArgument(2) and type = DigestIO()
   }
 }
 
 /**
  * A call to EVP_DigestFinal variants
  */
-class EvpDigestFinalCall extends EvpFinalDigestOperationStep {
+class EvpDigestFinalCall extends EvpFinalDigestOperationStep instanceof Call {
   EvpDigestFinalCall() {
-    this.(Call).getTarget().getName() in [
-        "EVP_DigestFinal", "EVP_DigestFinal_ex", "EVP_DigestFinalXOF"
-      ]
+    this.getTarget().getName() in ["EVP_DigestFinal", "EVP_DigestFinal_ex", "EVP_DigestFinalXOF"]
   }
 
   override DataFlow::Node getInput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(0) and type = ContextIO()
+    result.asExpr() = this.getArgument(0) and type = ContextIO()
   }
 
   override DataFlow::Node getOutput(IOType type) {
-    result.asExpr() = this.(Call).getArgument(0) and
+    result.asExpr() = this.getArgument(0) and
     type = ContextIO()
     or
-    result.asDefiningArgument() = this.(Call).getArgument(1) and type = DigestIO()
+    result.asDefiningArgument() = this.getArgument(1) and type = DigestIO()
   }
 }