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Query for weak encryption: Insufficient key size
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‎java/ql/src/experimental/Security/CWE/CWE-326/InsufficientKeySize.java‎

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public class InsufficientKeySize {
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public void CryptoMethod() {
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KeyGenerator keyGen1 = KeyGenerator.getInstance("AES");
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// BAD: Key size is less than 128
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keyGen1.init(64);
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KeyGenerator keyGen2 = KeyGenerator.getInstance("AES");
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// GOOD: Key size is no less than 128
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keyGen2.init(128);
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KeyPairGenerator keyPairGen1 = KeyPairGenerator.getInstance("RSA");
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// BAD: Key size is less than 2048
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keyPairGen1.initialize(1024);
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KeyPairGenerator keyPairGen2 = KeyPairGenerator.getInstance("RSA");
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// GOOD: Key size is no less than 2048
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keyPairGen2.initialize(2048);
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KeyPairGenerator keyPairGen3 = KeyPairGenerator.getInstance("DSA");
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// BAD: Key size is less than 2048
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keyPairGen3.initialize(1024);
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KeyPairGenerator keyPairGen4 = KeyPairGenerator.getInstance("DSA");
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// GOOD: Key size is no less than 2048
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keyPairGen4.initialize(2048);
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KeyPairGenerator keyPairGen5 = KeyPairGenerator.getInstance("EC");
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// BAD: Key size is less than 224
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ECGenParameterSpec ecSpec1 = new ECGenParameterSpec("secp112r1");
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keyPairGen5.initialize(ecSpec1);
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KeyPairGenerator keyPairGen6 = KeyPairGenerator.getInstance("EC");
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// GOOD: Key size is no less than 224
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ECGenParameterSpec ecSpec2 = new ECGenParameterSpec("secp256r1");
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keyPairGen6.initialize(ecSpec2);
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}
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}

‎java/ql/src/experimental/Security/CWE/CWE-326/InsufficientKeySize.qhelp‎

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<!DOCTYPE qhelp PUBLIC "-//Semmle//qhelp//EN" "qhelp.dtd">
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<qhelp>
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<overview>
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<p>This rule finds uses of encryption algorithms with too small a key size. Encryption algorithms
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are vulnerable to brute force attack when too small a key size is used.</p>
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</overview>
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<recommendation>
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<p>The key should be at least 2048-bit long when using RSA and DSA encryption, 224-bit long when using EC encryption, and 128-bit long when using
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symmetric encryption.</p>
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</recommendation>
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<references>
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<li>
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Wikipedia.
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<a href="http://en.wikipedia.org/wiki/Key_size">Key size</a>
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</li>
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<li>
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SonarSource.
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<a href="https://rules.sonarsource.com/java/type/Vulnerability/RSPEC-4426">Cryptographic keys should be robust</a>
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</li>
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<li>
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CWE.
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<a href="https://cwe.mitre.org/data/definitions/326.html">CWE-326: Inadequate Encryption Strength</a>
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</li>
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<li>
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C# implementation of CodeQL
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<a href="https://github.com/github/codeql/blob/df29a1636555465527d17668c19c202e365cf502/csharp/ql/src/Security%20Features/InsufficientKeySize.ql">codeql/csharp/ql/src/Security Features/InsufficientKeySize.ql</a>
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</li>
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</references>
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</qhelp>

‎java/ql/src/experimental/Security/CWE/CWE-326/InsufficientKeySize.ql‎

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/**
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* @name Weak encryption: Insufficient key size
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* @description Finds uses of encryption algorithms with too small a key size
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* @kind problem
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* @id java/insufficient-key-size
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* @tags security
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* external/cwe/cwe-326
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*/
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import java
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import semmle.code.java.security.Encryption
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import semmle.code.java.dataflow.TaintTracking
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/** The Java class `javax.crypto.KeyGenerator`. */
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class KeyGenerator extends RefType {
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KeyGenerator() { this.hasQualifiedName("javax.crypto", "KeyGenerator") }
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}
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/** The Java class `javax.crypto.KeyGenerator`. */
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class KeyPairGenerator extends RefType {
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KeyPairGenerator() { this.hasQualifiedName("java.security", "KeyPairGenerator") }
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}
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/** The Java class `java.security.spec.ECGenParameterSpec`. */
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class ECGenParameterSpec extends RefType {
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ECGenParameterSpec() { this.hasQualifiedName("java.security.spec", "ECGenParameterSpec") }
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}
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/** The `init` method declared in `javax.crypto.KeyGenerator`. */
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class KeyGeneratorInitMethod extends Method {
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KeyGeneratorInitMethod() {
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getDeclaringType() instanceof KeyGenerator and
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hasName("init")
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}
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}
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/** The `initialize` method declared in `java.security.KeyPairGenerator`. */
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class KeyPairGeneratorInitMethod extends Method {
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KeyPairGeneratorInitMethod() {
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getDeclaringType() instanceof KeyPairGenerator and
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hasName("initialize")
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}
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}
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/** Taint configuration tracking flow from a key generator to a `init` method call. */
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class CryptoKeyGeneratorConfiguration extends TaintTracking::Configuration {
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CryptoKeyGeneratorConfiguration() { this = "CryptoKeyGeneratorConfiguration" }
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override predicate isSource(DataFlow::Node source) {
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exists(JavaxCryptoKeyGenerator jcg | jcg = source.asExpr())
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}
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override predicate isSink(DataFlow::Node sink) {
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exists(MethodAccess ma |
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ma.getMethod() instanceof KeyGeneratorInitMethod and
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sink.asExpr() = ma.getQualifier()
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)
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}
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}
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/** Taint configuration tracking flow from a keypair generator to a `initialize` method call. */
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class KeyPairGeneratorConfiguration extends TaintTracking::Configuration {
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KeyPairGeneratorConfiguration() { this = "KeyPairGeneratorConfiguration" }
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override predicate isSource(DataFlow::Node source) {
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exists(JavaSecurityKeyPairGenerator jkg | jkg = source.asExpr())
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}
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override predicate isSink(DataFlow::Node sink) {
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exists(MethodAccess ma |
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ma.getMethod() instanceof KeyPairGeneratorInitMethod and
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sink.asExpr() = ma.getQualifier()
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)
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}
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}
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/** Holds if an AES `KeyGenerator` is initialized with an insufficient key size. */
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predicate incorrectUseOfAES(MethodAccess ma, string msg) {
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ma.getMethod() instanceof KeyGeneratorInitMethod and
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exists(
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JavaxCryptoKeyGenerator jcg, CryptoKeyGeneratorConfiguration cc, DataFlow::PathNode source,
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DataFlow::PathNode dest
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|
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jcg.getAlgoSpec().(StringLiteral).getValue() = "AES" and
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source.getNode().asExpr() = jcg and
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dest.getNode().asExpr() = ma.getQualifier() and
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cc.hasFlowPath(source, dest)
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) and
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ma.getArgument(0).(IntegerLiteral).getIntValue() < 128 and
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msg = "Key size should be at least 128 bits for AES encryption."
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}
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/** Holds if a DSA `KeyPairGenerator` is initialized with an insufficient key size. */
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predicate incorrectUseOfDSA(MethodAccess ma, string msg) {
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ma.getMethod() instanceof KeyPairGeneratorInitMethod and
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exists(
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JavaSecurityKeyPairGenerator jpg, KeyPairGeneratorConfiguration kc, DataFlow::PathNode source,
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DataFlow::PathNode dest
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|
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jpg.getAlgoSpec().(StringLiteral).getValue() = "DSA" and
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source.getNode().asExpr() = jpg and
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dest.getNode().asExpr() = ma.getQualifier() and
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kc.hasFlowPath(source, dest)
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) and
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ma.getArgument(0).(IntegerLiteral).getIntValue() < 2048 and
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msg = "Key size should be at least 2048 bits for DSA encryption."
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}
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/** Holds if a RSA `KeyPairGenerator` is initialized with an insufficient key size. */
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predicate incorrectUseOfRSA(MethodAccess ma, string msg) {
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ma.getMethod() instanceof KeyPairGeneratorInitMethod and
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exists(
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JavaSecurityKeyPairGenerator jpg, KeyPairGeneratorConfiguration kc, DataFlow::PathNode source,
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DataFlow::PathNode dest
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|
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jpg.getAlgoSpec().(StringLiteral).getValue() = "RSA" and
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source.getNode().asExpr() = jpg and
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dest.getNode().asExpr() = ma.getQualifier() and
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kc.hasFlowPath(source, dest)
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) and
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ma.getArgument(0).(IntegerLiteral).getIntValue() < 2048 and
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msg = "Key size should be at least 2048 bits for RSA encryption."
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}
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/** Holds if an EC `KeyPairGenerator` is initialized with an insufficient key size. */
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predicate incorrectUseOfEC(MethodAccess ma, string msg) {
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ma.getMethod() instanceof KeyPairGeneratorInitMethod and
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exists(
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JavaSecurityKeyPairGenerator jpg, KeyPairGeneratorConfiguration kc, DataFlow::PathNode source,
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DataFlow::PathNode dest, ClassInstanceExpr cie
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|
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jpg.getAlgoSpec().(StringLiteral).getValue().matches("EC%") and //ECC variants such as ECDH and ECDSA
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source.getNode().asExpr() = jpg and
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dest.getNode().asExpr() = ma.getQualifier() and
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kc.hasFlowPath(source, dest) and
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exists(VariableAssign va |
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ma.getArgument(0).(VarAccess).getVariable() = va.getDestVar() and
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va.getSource() = cie and
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cie.getArgument(0)
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.(StringLiteral)
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.getRepresentedString()
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.regexpCapture(".*[a-zA-Z]+([0-9]+)[a-zA-Z]+.*", 1)
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.toInt() < 224
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)
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) and
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msg = "Key size should be at least 224 bits for EC encryption."
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}
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from Expr e, string msg
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where
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incorrectUseOfAES(e, msg) or
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incorrectUseOfDSA(e, msg) or
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incorrectUseOfRSA(e, msg) or
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incorrectUseOfEC(e, msg)
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select e, msg

‎java/ql/src/semmle/code/java/security/Encryption.qll‎

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override Expr getAlgoSpec() { result = this.(ConstructorCall).getArgument(0) }
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}
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/** Method call to the Java class `java.security.KeyPairGenerator`. */
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class JavaSecurityKeyPairGenerator extends JavaxCryptoAlgoSpec {
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JavaSecurityKeyPairGenerator() {
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exists(Method m | m.getAReference() = this |
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m.getDeclaringType().getQualifiedName() = "java.security.KeyPairGenerator" and
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m.getName() = "getInstance"
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)
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}
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override Expr getAlgoSpec() { result = this.(MethodAccess).getArgument(0) }
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}

‎java/ql/test/experimental/query-tests/security/CWE-326/InsufficientKeySize.expected‎

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| InsufficientKeySize.java:9:9:9:24 | init(...) | Key size should be at least 128 bits for AES encryption. |
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| InsufficientKeySize.java:17:9:17:36 | initialize(...) | Key size should be at least 2048 bits for RSA encryption. |
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| InsufficientKeySize.java:25:9:25:36 | initialize(...) | Key size should be at least 2048 bits for DSA encryption. |
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| InsufficientKeySize.java:34:9:34:39 | initialize(...) | Key size should be at least 224 bits for EC encryption. |

‎java/ql/test/experimental/query-tests/security/CWE-326/InsufficientKeySize.java‎

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import java.security.KeyPairGenerator;
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import java.security.spec.ECGenParameterSpec;
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import javax.crypto.KeyGenerator;
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public class InsufficientKeySize {
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public void CryptoMethod() {
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KeyGenerator keyGen1 = KeyGenerator.getInstance("AES");
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// BAD: Key size is less than 128
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keyGen1.init(64);
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KeyGenerator keyGen2 = KeyGenerator.getInstance("AES");
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// GOOD: Key size is no less than 128
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keyGen2.init(128);
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KeyPairGenerator keyPairGen1 = KeyPairGenerator.getInstance("RSA");
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// BAD: Key size is less than 2048
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keyPairGen1.initialize(1024);
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KeyPairGenerator keyPairGen2 = KeyPairGenerator.getInstance("RSA");
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// GOOD: Key size is no less than 2048
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keyPairGen2.initialize(2048);
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KeyPairGenerator keyPairGen3 = KeyPairGenerator.getInstance("DSA");
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// BAD: Key size is less than 2048
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keyPairGen3.initialize(1024);
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KeyPairGenerator keyPairGen4 = KeyPairGenerator.getInstance("DSA");
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// GOOD: Key size is no less than 2048
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keyPairGen4.initialize(2048);
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KeyPairGenerator keyPairGen5 = KeyPairGenerator.getInstance("EC");
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// BAD: Key size is less than 224
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ECGenParameterSpec ecSpec1 = new ECGenParameterSpec("secp112r1");
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keyPairGen5.initialize(ecSpec1);
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KeyPairGenerator keyPairGen6 = KeyPairGenerator.getInstance("EC");
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// GOOD: Key size is no less than 224
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ECGenParameterSpec ecSpec2 = new ECGenParameterSpec("secp256r1");
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keyPairGen6.initialize(ecSpec2);
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}
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}

‎java/ql/test/experimental/query-tests/security/CWE-326/InsufficientKeySize.qlref‎

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experimental/Security/CWE/CWE-326/InsufficientKeySize.ql

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