diff --git a/security/keymint/aidl/vts/functional/KeyMintTest.cpp b/security/keymint/aidl/vts/functional/KeyMintTest.cpp
index d41d270..caac346 100644
--- a/security/keymint/aidl/vts/functional/KeyMintTest.cpp
+++ b/security/keymint/aidl/vts/functional/KeyMintTest.cpp
@@ -71,6 +71,12 @@
 
 bool check_patchLevels = false;
 
+// The maximum number of times we'll attempt to verify that corruption
+// of an ecrypted blob results in an error. Retries are necessary as there
+// is a small (roughly 1/256) chance that corrupting ciphertext still results
+// in valid PKCS7 padding.
+constexpr size_t kMaxPaddingCorruptionRetries = 8;
+
 template <TagType tag_type, Tag tag, typename ValueT>
 bool contains(const vector<KeyParameter>& set, TypedTag<tag_type, tag> ttag,
               ValueT expected_value) {
@@ -4376,11 +4382,22 @@
     string ciphertext = EncryptMessage(message, params);
     EXPECT_EQ(16U, ciphertext.size());
     EXPECT_NE(ciphertext, message);
-    ++ciphertext[ciphertext.size() / 2];
 
-    EXPECT_EQ(ErrorCode::OK, Begin(KeyPurpose::DECRYPT, params));
-    string plaintext;
-    EXPECT_EQ(ErrorCode::INVALID_INPUT_LENGTH, Finish(message, &plaintext));
+    for (size_t i = 0; i < kMaxPaddingCorruptionRetries; ++i) {
+        ++ciphertext[ciphertext.size() / 2];
+
+        EXPECT_EQ(ErrorCode::OK, Begin(KeyPurpose::DECRYPT, params));
+        string plaintext;
+        ErrorCode error = Finish(message, &plaintext);
+        if (error == ErrorCode::INVALID_INPUT_LENGTH) {
+            // This is the expected error, we can exit the test now.
+            return;
+        } else {
+            // Very small chance we got valid decryption, so try again.
+            ASSERT_EQ(error, ErrorCode::OK);
+        }
+    }
+    FAIL() << "Corrupt ciphertext should have failed to decrypt by now.";
 }
 
 vector<uint8_t> CopyIv(const AuthorizationSet& set) {
@@ -5343,15 +5360,27 @@
     string ciphertext = EncryptMessage(message, BlockMode::ECB, PaddingMode::PKCS7);
     EXPECT_EQ(8U, ciphertext.size());
     EXPECT_NE(ciphertext, message);
-    ++ciphertext[ciphertext.size() / 2];
 
     AuthorizationSetBuilder begin_params;
     begin_params.push_back(TAG_BLOCK_MODE, BlockMode::ECB);
     begin_params.push_back(TAG_PADDING, PaddingMode::PKCS7);
-    EXPECT_EQ(ErrorCode::OK, Begin(KeyPurpose::DECRYPT, begin_params));
-    string plaintext;
-    EXPECT_EQ(ErrorCode::OK, Update(ciphertext, &plaintext));
-    EXPECT_EQ(ErrorCode::INVALID_ARGUMENT, Finish(&plaintext));
+
+    for (size_t i = 0; i < kMaxPaddingCorruptionRetries; ++i) {
+        ++ciphertext[ciphertext.size() / 2];
+
+        EXPECT_EQ(ErrorCode::OK, Begin(KeyPurpose::DECRYPT, begin_params));
+        string plaintext;
+        EXPECT_EQ(ErrorCode::OK, Update(ciphertext, &plaintext));
+        ErrorCode error = Finish(&plaintext);
+        if (error == ErrorCode::INVALID_ARGUMENT) {
+            // This is the expected error, we can exit the test now.
+            return;
+        } else {
+            // Very small chance we got valid decryption, so try again.
+            ASSERT_EQ(error, ErrorCode::OK);
+        }
+    }
+    FAIL() << "Corrupt ciphertext should have failed to decrypt by now.";
 }
 
 struct TripleDesTestVector {
@@ -5679,16 +5708,27 @@
     string ciphertext = EncryptMessage(message, BlockMode::CBC, PaddingMode::PKCS7, &iv);
     EXPECT_EQ(8U, ciphertext.size());
     EXPECT_NE(ciphertext, message);
-    ++ciphertext[ciphertext.size() / 2];
 
     auto begin_params = AuthorizationSetBuilder()
                                 .BlockMode(BlockMode::CBC)
                                 .Padding(PaddingMode::PKCS7)
                                 .Authorization(TAG_NONCE, iv);
-    EXPECT_EQ(ErrorCode::OK, Begin(KeyPurpose::DECRYPT, begin_params));
-    string plaintext;
-    EXPECT_EQ(ErrorCode::OK, Update(ciphertext, &plaintext));
-    EXPECT_EQ(ErrorCode::INVALID_ARGUMENT, Finish(&plaintext));
+
+    for (size_t i = 0; i < kMaxPaddingCorruptionRetries; ++i) {
+        ++ciphertext[ciphertext.size() / 2];
+        EXPECT_EQ(ErrorCode::OK, Begin(KeyPurpose::DECRYPT, begin_params));
+        string plaintext;
+        EXPECT_EQ(ErrorCode::OK, Update(ciphertext, &plaintext));
+        ErrorCode error = Finish(&plaintext);
+        if (error == ErrorCode::INVALID_ARGUMENT) {
+            // This is the expected error, we can exit the test now.
+            return;
+        } else {
+            // Very small chance we got valid decryption, so try again.
+            ASSERT_EQ(error, ErrorCode::OK);
+        }
+    }
+    FAIL() << "Corrupt ciphertext should have failed to decrypt by now.";
 }
 
 /*
diff --git a/security/keymint/aidl/vts/functional/VtsRemotelyProvisionedComponentTests.cpp b/security/keymint/aidl/vts/functional/VtsRemotelyProvisionedComponentTests.cpp
index a177317..78f8f08 100644
--- a/security/keymint/aidl/vts/functional/VtsRemotelyProvisionedComponentTests.cpp
+++ b/security/keymint/aidl/vts/functional/VtsRemotelyProvisionedComponentTests.cpp
@@ -335,8 +335,7 @@
         ASSERT_TRUE(deviceInfoMap->asMap());
 
         auto& signingKey = bccContents->back().pubKey;
-        auto macKey = verifyAndParseCoseSign1(/* ignore_signature = */ false, signedMac->asArray(),
-                                              signingKey,
+        auto macKey = verifyAndParseCoseSign1(signedMac->asArray(), signingKey,
                                               cppbor::Array()  // SignedMacAad
                                                       .add(challenge_)
                                                       .add(std::move(deviceInfoMap))
diff --git a/security/keymint/support/remote_prov_utils.cpp b/security/keymint/support/remote_prov_utils.cpp
index da10eb2..33f1ed3 100644
--- a/security/keymint/support/remote_prov_utils.cpp
+++ b/security/keymint/support/remote_prov_utils.cpp
@@ -78,7 +78,7 @@
     return EekChain{eekChain.encode(), pub_key, priv_key};
 }
 
-ErrMsgOr<bytevec> verifyAndParseCoseSign1Cwt(bool ignoreSignature, const cppbor::Array* coseSign1,
+ErrMsgOr<bytevec> verifyAndParseCoseSign1Cwt(const cppbor::Array* coseSign1,
                                              const bytevec& signingCoseKey, const bytevec& aad) {
     if (!coseSign1 || coseSign1->size() != kCoseSign1EntryCount) {
         return "Invalid COSE_Sign1";
@@ -115,27 +115,22 @@
     auto serializedKey = parsedPayload->asMap()->get(-4670552)->clone();
     if (!serializedKey || !serializedKey->asBstr()) return "Could not find key entry";
 
-    if (!ignoreSignature) {
-        bool selfSigned = signingCoseKey.empty();
-        auto key = CoseKey::parseEd25519(selfSigned ? serializedKey->asBstr()->value()
-                                                    : signingCoseKey);
-        if (!key) return "Bad signing key: " + key.moveMessage();
+    bool selfSigned = signingCoseKey.empty();
+    auto key =
+            CoseKey::parseEd25519(selfSigned ? serializedKey->asBstr()->value() : signingCoseKey);
+    if (!key) return "Bad signing key: " + key.moveMessage();
 
-        bytevec signatureInput = cppbor::Array()
-                                         .add("Signature1")
-                                         .add(*protectedParams)
-                                         .add(aad)
-                                         .add(*payload)
-                                         .encode();
+    bytevec signatureInput =
+            cppbor::Array().add("Signature1").add(*protectedParams).add(aad).add(*payload).encode();
 
-        if (!ED25519_verify(signatureInput.data(), signatureInput.size(), signature->value().data(),
-                            key->getBstrValue(CoseKey::PUBKEY_X)->data())) {
-            return "Signature verification failed";
-        }
+    if (!ED25519_verify(signatureInput.data(), signatureInput.size(), signature->value().data(),
+                        key->getBstrValue(CoseKey::PUBKEY_X)->data())) {
+        return "Signature verification failed";
     }
 
     return serializedKey->asBstr()->value();
 }
+
 ErrMsgOr<std::vector<BccEntryData>> validateBcc(const cppbor::Array* bcc) {
     if (!bcc || bcc->size() == 0) return "Invalid BCC";
 
@@ -148,8 +143,7 @@
         if (!entry || entry->size() != kCoseSign1EntryCount) {
             return "Invalid BCC entry " + std::to_string(i) + ": " + prettyPrint(entry);
         }
-        auto payload = verifyAndParseCoseSign1Cwt(false /* ignoreSignature */, entry,
-                                                  std::move(prevKey), bytevec{} /* AAD */);
+        auto payload = verifyAndParseCoseSign1Cwt(entry, std::move(prevKey), bytevec{} /* AAD */);
         if (!payload) {
             return "Failed to verify entry " + std::to_string(i) + ": " + payload.moveMessage();
         }