diff --git a/s2a/src/main/java/io/grpc/s2a/handshaker/ProtoUtil.java b/s2a/src/main/java/io/grpc/s2a/handshaker/ProtoUtil.java
index 59e3931d9e6..442c21bf330 100644
--- a/s2a/src/main/java/io/grpc/s2a/handshaker/ProtoUtil.java
+++ b/s2a/src/main/java/io/grpc/s2a/handshaker/ProtoUtil.java
@@ -20,32 +20,6 @@
 
 /** Converts proto messages to Netty strings. */
 final class ProtoUtil {
-  /**
-   * Converts {@link Ciphersuite} to its {@link String} representation.
-   *
-   * @param ciphersuite the {@link Ciphersuite} to be converted.
-   * @return a {@link String} representing the ciphersuite.
-   * @throws AssertionError if the {@link Ciphersuite} is not one of the supported ciphersuites.
-   */
-  static String convertCiphersuite(Ciphersuite ciphersuite) {
-    switch (ciphersuite) {
-      case CIPHERSUITE_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256:
-        return "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256";
-      case CIPHERSUITE_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384:
-        return "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384";
-      case CIPHERSUITE_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256:
-        return "TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256";
-      case CIPHERSUITE_ECDHE_RSA_WITH_AES_128_GCM_SHA256:
-        return "TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256";
-      case CIPHERSUITE_ECDHE_RSA_WITH_AES_256_GCM_SHA384:
-        return "TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384";
-      case CIPHERSUITE_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256:
-        return "TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256";
-      default:
-        throw new AssertionError(
-            String.format("Ciphersuite %d is not supported.", ciphersuite.getNumber()));
-    }
-  }
 
   /**
    * Converts a {@link TLSVersion} object to its {@link String} representation.
diff --git a/s2a/src/test/java/io/grpc/s2a/handshaker/ProtoUtilTest.java b/s2a/src/test/java/io/grpc/s2a/handshaker/ProtoUtilTest.java
index 6d134b43f7a..f54063b9e04 100644
--- a/s2a/src/test/java/io/grpc/s2a/handshaker/ProtoUtilTest.java
+++ b/s2a/src/test/java/io/grpc/s2a/handshaker/ProtoUtilTest.java
@@ -30,47 +30,6 @@
 public final class ProtoUtilTest {
   @Rule public final Expect expect = Expect.create();
 
-  @Test
-  public void convertCiphersuite_success() {
-    expect
-        .that(
-            ProtoUtil.convertCiphersuite(
-                Ciphersuite.CIPHERSUITE_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256))
-        .isEqualTo("TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256");
-    expect
-        .that(
-            ProtoUtil.convertCiphersuite(
-                Ciphersuite.CIPHERSUITE_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384))
-        .isEqualTo("TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384");
-    expect
-        .that(
-            ProtoUtil.convertCiphersuite(
-                Ciphersuite.CIPHERSUITE_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256))
-        .isEqualTo("TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256");
-    expect
-        .that(
-            ProtoUtil.convertCiphersuite(Ciphersuite.CIPHERSUITE_ECDHE_RSA_WITH_AES_128_GCM_SHA256))
-        .isEqualTo("TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256");
-    expect
-        .that(
-            ProtoUtil.convertCiphersuite(Ciphersuite.CIPHERSUITE_ECDHE_RSA_WITH_AES_256_GCM_SHA384))
-        .isEqualTo("TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384");
-    expect
-        .that(
-            ProtoUtil.convertCiphersuite(
-                Ciphersuite.CIPHERSUITE_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256))
-        .isEqualTo("TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256");
-  }
-
-  @Test
-  public void convertCiphersuite_withUnspecifiedCiphersuite_fails() {
-    AssertionError expected =
-        assertThrows(
-            AssertionError.class,
-            () -> ProtoUtil.convertCiphersuite(Ciphersuite.CIPHERSUITE_UNSPECIFIED));
-    expect.that(expected).hasMessageThat().isEqualTo("Ciphersuite 0 is not supported.");
-  }
-
   @Test
   public void convertTlsProtocolVersion_success() {
     expect