Add MD5 to PasswordEncoderFactories

Issue: gh-4674

crypto/src/main/java/org/springframework/security/crypto/factory/PasswordEncoderFactories.java

@@ -19,6 +19,7 @@ package org.springframework.security.crypto.factory;
 import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
 import org.springframework.security.crypto.password.DelegatingPasswordEncoder;
 import org.springframework.security.crypto.password.Md4PasswordEncoder;
+import org.springframework.security.crypto.password.MessageDigestPasswordEncoder;
 import org.springframework.security.crypto.password.NoOpPasswordEncoder;
 import org.springframework.security.crypto.password.PasswordEncoder;
 import org.springframework.security.crypto.password.Pbkdf2PasswordEncoder;
@@ -44,6 +45,7 @@ public class PasswordEncoderFactories {
 	 * <ul>
 	 * <li>bcrypt - {@link BCryptPasswordEncoder} (Also used for encoding)</li>
 	 * <li>MD4 - {@link Md4PasswordEncoder}</li>
+	 * <li>MD5 - {@code new MessageDigestPasswordEncoder("MD5")}</li>
 	 * <li>noop - {@link NoOpPasswordEncoder}</li>
 	 * <li>pbkdf2 - {@link Pbkdf2PasswordEncoder}</li>
 	 * <li>scrypt - {@link SCryptPasswordEncoder}</li>
@@ -57,6 +59,7 @@ public class PasswordEncoderFactories {
 		Map<String,PasswordEncoder> encoders = new HashMap<>();
 		encoders.put(encodingId, new BCryptPasswordEncoder());
 		encoders.put("MD4", new Md4PasswordEncoder());
+		encoders.put("MD5", new MessageDigestPasswordEncoder("MD5"));
 		encoders.put("noop", NoOpPasswordEncoder.getInstance());
 		encoders.put("pbkdf2", new Pbkdf2PasswordEncoder());
 		encoders.put("scrypt", new SCryptPasswordEncoder());

crypto/src/test/java/org/springframework/security/crypto/factory/PasswordEncoderFactoriesTests.java

@@ -50,6 +50,12 @@ public class PasswordEncoderFactoriesTests {
 		assertThat(this.encoder.matches(this.rawPassword, encodedPassword)).isTrue();
 	}
 
+	@Test
+	public void matchesWhenMd5ThenWorks() {
+		String encodedPassword = "{MD5}{aRYR+Yp2xSqtgF+vtjH6jNda6M083iEbP+zCFjLt9IA=}905e382a25eed53e22224223b3581092";
+		assertThat(this.encoder.matches(this.rawPassword, encodedPassword)).isTrue();
+	}
+
 	@Test
 	public void matchesWhenNoopThenWorks() {
 		String encodedPassword = "{noop}password";