[webcrypto] Remove support for AES 192-bit keys (2 of 2)

content/child/webcrypto/shared_crypto.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/child/webcrypto/shared_crypto.h"
 
 #include "base/logging.h"
 #include "content/child/webcrypto/crypto_data.h"
 #include "content/child/webcrypto/jwk.h"
 #include "content/child/webcrypto/platform_crypto.h"
@@ skipping 22 matching lines @@
 
 namespace {
 
 // TODO(eroman): Move this helper to WebCryptoKey.
 bool KeyUsageAllows(const blink::WebCryptoKey& key,
                     const blink::WebCryptoKeyUsage usage) {
   return ((key.usages() & usage) != 0);
 }
 
 bool IsValidAesKeyLengthBits(unsigned int length_bits) {
-  return length_bits == 128 || length_bits == 192 || length_bits == 256;
+  // 192-bit AES is disallowed.
+  return length_bits == 128 || length_bits == 256;
 }
 
 bool IsValidAesKeyLengthBytes(unsigned int length_bytes) {
-  return length_bytes == 16 || length_bytes == 24 || length_bytes == 32;
+  // 192-bit AES is disallowed.
+  return length_bytes == 16 || length_bytes == 32;
 }
 
 const size_t kAesBlockSizeBytes = 16;
 
 Status EncryptDecryptAesCbc(EncryptOrDecrypt mode,
                             const blink::WebCryptoAlgorithm& algorithm,
                             const blink::WebCryptoKey& key,
                             const CryptoData& data,
                             std::vector<uint8>* buffer) {
   platform::SymKey* sym_key;
@@ skipping 152 matching lines @@
 Status ImportKeyRaw(const CryptoData& key_data,
                     const blink::WebCryptoAlgorithm& algorithm,
                     bool extractable,
                     blink::WebCryptoKeyUsageMask usage_mask,
                     blink::WebCryptoKey* key) {
   switch (algorithm.id()) {
     case blink::WebCryptoAlgorithmIdAesCtr:
     case blink::WebCryptoAlgorithmIdAesCbc:
     case blink::WebCryptoAlgorithmIdAesGcm:
     case blink::WebCryptoAlgorithmIdAesKw:
-      if (!IsValidAesKeyLengthBytes(key_data.byte_length()))
-        return Status::ErrorImportAesKeyLength();
+      if (!IsValidAesKeyLengthBytes(key_data.byte_length())) {
+        return key_data.byte_length() == 24
+                   ? Status::ErrorAes192BitUnsupported()
+                   : Status::ErrorImportAesKeyLength();
+      }
     // Fallthrough intentional!
     case blink::WebCryptoAlgorithmIdHmac:
       return platform::ImportKeyRaw(
           algorithm, key_data, extractable, usage_mask, key);
     default:
       return Status::ErrorUnsupported();
   }
 }
 
 // Returns the key format to use for structured cloning.
@@ skipping 389 matching lines @@
     return status;
 
   unsigned int keylen_bytes = 0;
 
   // Get the secret key length in bytes from generation parameters.
   // This resolves any defaults.
   switch (algorithm.id()) {
     case blink::WebCryptoAlgorithmIdAesCbc:
     case blink::WebCryptoAlgorithmIdAesGcm:
     case blink::WebCryptoAlgorithmIdAesKw: {
-      if (!IsValidAesKeyLengthBits(algorithm.aesKeyGenParams()->lengthBits()))
-        return Status::ErrorGenerateKeyLength();
+      if (!IsValidAesKeyLengthBits(algorithm.aesKeyGenParams()->lengthBits())) {
+        return algorithm.aesKeyGenParams()->lengthBits() == 192
+                   ? Status::ErrorAes192BitUnsupported()
+                   : Status::ErrorGenerateKeyLength();
+      }
       keylen_bytes = algorithm.aesKeyGenParams()->lengthBits() / 8;
       break;
     }
     case blink::WebCryptoAlgorithmIdHmac: {
       const blink::WebCryptoHmacKeyGenParams* params =
           algorithm.hmacKeyGenParams();
       DCHECK(params);
       if (params->hasLengthBits()) {
         if (params->optionalLengthBits() % 8)
           return Status::ErrorGenerateKeyLength();
@@ skipping 295 matching lines @@
   if (!ContainsKeyUsages(GetValidKeyUsagesForKeyType(algorithm, key_type),
                          usages))
     return Status::ErrorCreateKeyBadUsages();
 
   return Status::Success();
 }
 
 }  // namespace webcrypto
 
 }  // namespace content