package com.atlassian.vcache.internal.core;
   
   import java.nio.charset.Charset;
   import java.nio.charset.StandardCharsets;
   import java.security.MessageDigest;
   import java.security.NoSuchAlgorithmException;
   import java.util.Base64;
   
   /**
   * Implementation of {@link ExternalCacheKeyGenerator} that encodes using the <tt>SHA-1</tt> hashing algorithm.
   *
   * @since 1.0.0
   */
  public class Sha1ExternalCacheKeyGenerator extends ExternalCacheKeyGenerator {
      private static final String DIGEST_ALGORITHM = "SHA-1";
      private static final Charset DIGEST_CHARSET = StandardCharsets.UTF_8;
  
      public Sha1ExternalCacheKeyGenerator(String productIdentifier) {
          super(productIdentifier);
      }
  
      @Override
      protected String encode(String plain) {
          try {
              final MessageDigest md = MessageDigest.getInstance(DIGEST_ALGORITHM);
              final byte[] digest = md.digest(plain.getBytes(DIGEST_CHARSET));
              return Base64.getEncoder().encodeToString(digest);
          } catch (NoSuchAlgorithmException e) {
              throw new IllegalStateException("Unable to encode to SHA-1", e);
          }
      }
  }