Improve qhelp for broken crypto algo queries

Previously it focussed too much on the risk of data being decrypted,
and didn't explain why using weak algorithms is a problem in other
contexts.

cpp/ql/src/Security/CWE/CWE-327/BrokenCryptoAlgorithm.qhelp

@@ -3,11 +3,15 @@
   "qhelp.dtd">
 <qhelp>
 <overview>
-<p>Using broken or weak cryptographic algorithms can leave data vulnerable to being decrypted.</p>
+<p>Using broken or weak cryptographic algorithms may compromise security guarantees such as confidentiality, integrity, and authenticity.</p>
 
-<p>Many cryptographic algorithms provided by cryptography libraries are known to be weak, or 
+<p>Many cryptographic algorithms are known to be weak or flawed. The security guarantees of a system often rely on the underlying cryptography, so using a weak algorithm can have severe consequences. For example:
-flawed. Using such an algorithm means that an attacker may be able to easily decrypt the encrypted
+</p>
-data.</p>
+<ul>
+  <li>If a weak encryption algorithm is used, an attacker may be able to decrypt sensitive data.</li>
+  <li>If a weak hashing algorithm is used to protect data integrity, an attacker may be able to craft a malicious input that has the same hash as a benign one.</li>
+  <li>If a weak algorithm is used for digital signatures, an attacker may be able to forge signatures and impersonate legitimate users.</li>
+</ul>
 
 </overview>
 <recommendation>

java/ql/src/Security/CWE/CWE-327/BrokenCryptoAlgorithm.qhelp

@@ -3,11 +3,15 @@
   "qhelp.dtd">
 <qhelp>
 <overview>
-<p>Using broken or weak cryptographic algorithms can leave data vulnerable to being decrypted.</p>
+<p>Using broken or weak cryptographic algorithms may compromise security guarantees such as confidentiality, integrity, and authenticity.</p>
 
-<p>Many cryptographic algorithms provided by cryptography libraries are known to be weak, or 
+<p>Many cryptographic algorithms are known to be weak or flawed. The security guarantees of a system often rely on the underlying cryptography, so using a weak algorithm can have severe consequences. For example:
-flawed. Using such an algorithm means that an attacker may be able to easily decrypt the encrypted
+</p>
-data.</p>
+<ul>
+  <li>If a weak encryption algorithm is used, an attacker may be able to decrypt sensitive data.</li>
+  <li>If a weak hashing algorithm is used to protect data integrity, an attacker may be able to craft a malicious input that has the same hash as a benign one.</li>
+  <li>If a weak algorithm is used for digital signatures, an attacker may be able to forge signatures and impersonate legitimate users.</li>
+</ul>
 
 </overview>
 <recommendation>

javascript/ql/src/Security/CWE-327/BrokenCryptoAlgorithm.qhelp

@@ -4,17 +4,34 @@
 <qhelp>
 	<overview>
 		<p>
-			Using broken or weak cryptographic algorithms can leave data
+			Using broken or weak cryptographic algorithms may compromise
-			vulnerable to being decrypted or forged by an attacker.
+			security guarantees such as confidentiality, integrity, and
+			authenticity.
 		</p>
 
 		<p>
-			Many cryptographic algorithms provided by cryptography
+			Many cryptographic algorithms are known to be weak or flawed. The
-			libraries are known to be weak, or flawed. Using such an
+			security guarantees of a system often rely on the underlying
-			algorithm means that encrypted or hashed data is less
+			cryptography, so using a weak algorithm can have severe consequences.
-			secure than it appears to be.
+			For example:
 		</p>
 
+		<ul>
+			<li>
+			If a weak encryption algorithm is used, an attacker may be able to
+			decrypt sensitive data.
+			</li>
+			<li>
+			If a weak hashing algorithm is used to protect data integrity, an
+			attacker may be able to craft a malicious input that has the same
+			hash as a benign one.
+			</li>
+			<li>
+			If a weak algorithm is used for digital signatures, an attacker may
+			be able to forge signatures and impersonate legitimate users.
+			</li>
+		</ul>
+
 	</overview>
 	<recommendation>
 

python/ql/src/Security/CWE-327/BrokenCryptoAlgorithm.qhelp

@@ -3,18 +3,36 @@
 "qhelp.dtd">
 <qhelp>
      <overview>
+
           <p>
-               Using broken or weak cryptographic algorithms can leave data
+               Using broken or weak cryptographic algorithms may compromise
-               vulnerable to being decrypted or forged by an attacker.
+               security guarantees such as confidentiality, integrity, and
+               authenticity.
           </p>
 
           <p>
-               Many cryptographic algorithms provided by cryptography
+               Many cryptographic algorithms are known to be weak or flawed. The
-               libraries are known to be weak, or flawed. Using such an
+               security guarantees of a system often rely on the underlying
-               algorithm means that encrypted or hashed data is less
+               cryptography, so using a weak algorithm can have severe consequences.
-               secure than it appears to be.
+               For example:
           </p>
 
+          <ul>
+               <li>
+               If a weak encryption algorithm is used, an attacker may be able to
+               decrypt sensitive data.
+               </li>
+               <li>
+               If a weak hashing algorithm is used to protect data integrity, an
+               attacker may be able to craft a malicious input that has the same
+               hash as a benign one.
+               </li>
+               <li>
+               If a weak algorithm is used for digital signatures, an attacker may
+               be able to forge signatures and impersonate legitimate users.
+               </li>
+          </ul>
+
           <p>
                This query alerts on any use of a weak cryptographic algorithm that is
                not a hashing algorithm. Use of broken or weak cryptographic hash

ruby/ql/src/queries/security/cwe-327/BrokenCryptoAlgorithm.qhelp

@@ -4,15 +4,33 @@
 <qhelp>
   <overview>
     <p>
-      Using broken or weak cryptographic algorithms can leave data
+      Using broken or weak cryptographic algorithms may compromise
-      vulnerable to being decrypted or forged by an attacker.
+      security guarantees such as confidentiality, integrity, and
+      authenticity.
     </p>
+
     <p>
-      Many cryptographic algorithms provided by cryptography
+      Many cryptographic algorithms are known to be weak or flawed. The
-      libraries are known to be weak, or flawed. Using such an
+      security guarantees of a system often rely on the underlying
-      algorithm means that encrypted or hashed data is less
+      cryptography, so using a weak algorithm can have severe consequences.
-      secure than it appears to be.
+      For example:
     </p>
+
+    <ul>
+      <li>
+      If a weak encryption algorithm is used, an attacker may be able to
+      decrypt sensitive data.
+      </li>
+      <li>
+      If a weak hashing algorithm is used to protect data integrity, an
+      attacker may be able to craft a malicious input that has the same
+      hash as a benign one.
+      </li>
+      <li>
+      If a weak algorithm is used for digital signatures, an attacker may
+      be able to forge signatures and impersonate legitimate users.
+      </li>
+    </ul>
     <p>
       This query alerts on any use of a weak cryptographic algorithm that is
       not a hashing algorithm. Use of broken or weak cryptographic hash

rust/ql/src/queries/security/CWE-327/BrokenCryptoAlgorithm.qhelp

@@ -3,17 +3,34 @@
 "qhelp.dtd">
 <qhelp>
      <overview>
-          <p>
+		<p>
-               Using broken or weak cryptographic algorithms can leave data
+			Using broken or weak cryptographic algorithms may compromise
-               vulnerable to being decrypted or forged by an attacker.
+			security guarantees such as confidentiality, integrity, and
-          </p>
+			authenticity.
+		</p>
 
-          <p>
+		<p>
-               Many cryptographic algorithms provided by cryptography
+			Many cryptographic algorithms are known to be weak or flawed. The
-               libraries are known to be weak, or flawed. Using such an
+			security guarantees of a system often rely on the underlying
-               algorithm means that encrypted or hashed data is less
+			cryptography, so using a weak algorithm can have severe consequences.
-               secure than it appears to be.
+			For example:
-          </p>
+		</p>
+
+		<ul>
+			<li>
+			If a weak encryption algorithm is used, an attacker may be able to
+			decrypt sensitive data.
+			</li>
+			<li>
+			If a weak hashing algorithm is used to protect data integrity, an
+			attacker may be able to craft a malicious input that has the same
+			hash as a benign one.
+			</li>
+			<li>
+			If a weak algorithm is used for digital signatures, an attacker may
+			be able to forge signatures and impersonate legitimate users.
+			</li>
+		</ul>
 
           <p>
                This query alerts on any use of a weak cryptographic algorithm that is