Let token key IDs be UTF-8 byte strings instead of just an integer

This makes key IDs vastly more expressive. Max size is 255 bytes,
and UTF-8 form is enforced by checking that the byte sequence can be
identity-transformed to and from a string with UTF-8 encoding.

In addition, we now protect the integrity of the key ID by supplying
it as the AAD parameter to the key sealing and opening operations.

Reduce v1 token max length of `enc` part to 255, since this is always
an X25519 public key, which is never bigger than 32 bytes (but may
be _less_ if the random `BigInteger` is small enough, so we still have
to encode the length).

3 files changed, 23 insertions, 15 deletions

diff --git a/vespaclient-java/src/main/java/com/yahoo/vespa/security/tool/crypto/DecryptTool.java b/vespaclient-java/src/main/java/com/yahoo/vespa/security/tool/crypto/DecryptTool.java
index 23543486e1b..af59784bfe0 100644
--- a/vespaclient-java/src/main/java/com/yahoo/vespa/security/tool/crypto/DecryptTool.java
+++ b/vespaclient-java/src/main/java/com/yahoo/vespa/security/tool/crypto/DecryptTool.java
@@ -13,9 +13,12 @@ import org.apache.commons.cli.Option;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Paths;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Optional;
 
+import static com.yahoo.security.ArrayUtils.toUtf8Bytes;
+
 /**
  * Tooling for decrypting a file using a private key that corresponds to the public key used
  * to originally encrypt the file.
@@ -85,16 +88,19 @@ public class DecryptTool implements Tool {
             }
             var inputArg   = leftoverArgs[0];
             var maybeKeyId = Optional.ofNullable(arguments.hasOption(KEY_ID_OPTION)
-                                                 ? Integer.parseInt(arguments.getOptionValue(KEY_ID_OPTION))
+                                                 ? arguments.getOptionValue(KEY_ID_OPTION)
                                                  : null);
             var outputArg   = CliUtils.optionOrThrow(arguments, OUTPUT_FILE_OPTION);
             var privKeyPath = Paths.get(CliUtils.optionOrThrow(arguments, RECIPIENT_PRIVATE_KEY_FILE_OPTION));
             var tokenString = CliUtils.optionOrThrow(arguments, TOKEN_OPTION);
             var sealedSharedKey = SealedSharedKey.fromTokenString(tokenString.strip());
-            if (maybeKeyId.isPresent() && (maybeKeyId.get() != sealedSharedKey.keyId())) {
-                throw new IllegalArgumentException(("Key ID specified with --key-id (%d) does not match key ID " +
-                                                    "used when generating the supplied token (%d)")
-                                                    .formatted(maybeKeyId.get(), sealedSharedKey.keyId()));
+            if (maybeKeyId.isPresent()) {
+                byte[] myKeyIdBytes = toUtf8Bytes(maybeKeyId.get());
+                if (!Arrays.equals(myKeyIdBytes, sealedSharedKey.keyId())) {
+                    // Don't include raw key bytes array verbatim in message (may contain control chars etc).
+                    throw new IllegalArgumentException("Key ID specified with --key-id does not match key ID " +
+                                                       "used when generating the supplied token");
+                }
             }
             var privateKey   = KeyUtils.fromBase64EncodedX25519PrivateKey(Files.readString(privKeyPath).strip());
             var secretShared = SharedKeyGenerator.fromSealedKey(sealedSharedKey, privateKey);
diff --git a/vespaclient-java/src/main/java/com/yahoo/vespa/security/tool/crypto/EncryptTool.java b/vespaclient-java/src/main/java/com/yahoo/vespa/security/tool/crypto/EncryptTool.java
index 5437e8cf9fe..cb16151c9b6 100644
--- a/vespaclient-java/src/main/java/com/yahoo/vespa/security/tool/crypto/EncryptTool.java
+++ b/vespaclient-java/src/main/java/com/yahoo/vespa/security/tool/crypto/EncryptTool.java
@@ -14,6 +14,8 @@ import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.List;
 
+import static com.yahoo.security.ArrayUtils.toUtf8Bytes;
+
 /**
  * Tooling to encrypt a file using a public key, emitting a non-secret token that can be
  * passed on to a recipient holding the corresponding private key.
@@ -77,7 +79,7 @@ public class EncryptTool implements Tool {
             var outputPath = Paths.get(CliUtils.optionOrThrow(arguments, OUTPUT_FILE_OPTION));
 
             var recipientPubKey = KeyUtils.fromBase64EncodedX25519PublicKey(CliUtils.optionOrThrow(arguments, RECIPIENT_PUBLIC_KEY_OPTION).strip());
-            int keyId  = Integer.parseInt(CliUtils.optionOrThrow(arguments, KEY_ID_OPTION));
+            var keyId  = toUtf8Bytes(CliUtils.optionOrThrow(arguments, KEY_ID_OPTION));
             var shared = SharedKeyGenerator.generateForReceiverPublicKey(recipientPubKey, keyId);
             var cipher = SharedKeyGenerator.makeAesGcmEncryptionCipher(shared);
 
diff --git a/vespaclient-java/src/test/java/com/yahoo/vespa/security/tool/CryptoToolsTest.java b/vespaclient-java/src/test/java/com/yahoo/vespa/security/tool/CryptoToolsTest.java
index 55d0a10e660..a3651888441 100644
--- a/vespaclient-java/src/test/java/com/yahoo/vespa/security/tool/CryptoToolsTest.java
+++ b/vespaclient-java/src/test/java/com/yahoo/vespa/security/tool/CryptoToolsTest.java
@@ -144,10 +144,10 @@ public class CryptoToolsTest {
 
     private static final String TEST_PRIV_KEY     = "4qGcntygFn_a3uqeBa1PbDlygQ-cpOuNznTPIz9ftWE";
     private static final String TEST_PUB_KEY      = "ROAH_S862tNMpbJ49lu1dPXFCPHFIXZK30pSrMZEmEg";
-    // Token created for the above public key (matching the above private key), using key id 1
-    private static final String TEST_TOKEN        = "AQAAAQAgwyxd7bFNQB_2LdL3bw-xFlvrxXhs7WWNVCKZ4" +
-                                                    "EFeNVtu42JMwM74bMN4E46v6mYcfQNPzcMGaP22Wl2cTnji0A";
-    private static final int    TEST_TOKEN_KEY_ID = 1;
+    // Token created for the above public key (matching the above private key), using key id "my key ID"
+    private static final String TEST_TOKEN        = "AQlteSBrZXkgSUQgAtTxJJdmv3eUoW5Z3NJSdZ3poKPEkW0SJOG" +
+                                                    "QXP6CaC5XfyAVoUlK_NyYIMsJKyNYKU6WmagZpVG2zQGFJoqiFA";
+    private static final String TEST_TOKEN_KEY_ID = "my key ID";
 
     @Test
     void encrypt_fails_with_error_message_if_no_input_file_is_given() throws IOException {
@@ -177,7 +177,7 @@ public class CryptoToolsTest {
                                    "--output-file",                "foo",
                                    "--recipient-private-key-file", absPathOf(privKeyFile),
                                    "--token",                      TEST_TOKEN,
-                                   "--key-id",                     Integer.toString(TEST_TOKEN_KEY_ID)),
+                                   "--key-id",                     TEST_TOKEN_KEY_ID),
                 "Invalid command line arguments: Expected exactly 1 file argument to decrypt\n");
     }
 
@@ -191,7 +191,7 @@ public class CryptoToolsTest {
                                    "--output-file",                "foo",
                                    "--recipient-private-key-file", absPathOf(privKeyFile),
                                    "--token",                      TEST_TOKEN,
-                                   "--key-id",                     Integer.toString(TEST_TOKEN_KEY_ID)),
+                                   "--key-id",                     TEST_TOKEN_KEY_ID),
                 "Invalid command line arguments: Input file 'no-such-file' does not exist\n");
     }
 
@@ -208,9 +208,9 @@ public class CryptoToolsTest {
                                    "--output-file",                "foo",
                                    "--recipient-private-key-file", absPathOf(privKeyFile),
                                    "--token",                      TEST_TOKEN,
-                                   "--key-id",                     Integer.toString(TEST_TOKEN_KEY_ID + 1)),
-                "Invalid command line arguments: Key ID specified with --key-id (2) does not match " +
-                        "key ID used when generating the supplied token (1)\n");
+                                   "--key-id",                     TEST_TOKEN_KEY_ID + "-wrong"),
+                "Invalid command line arguments: Key ID specified with --key-id does not " +
+                        "match key ID used when generating the supplied token\n");
     }
 
     @Test