[BE] 이메일 전송 및 인증로직 추가

backend/build.gradle

@@ -46,6 +46,15 @@ dependencies {
 
 	testImplementation 'com.squareup.okhttp3:mockwebserver:4.12.0'
 	implementation 'org.springframework.boot:spring-boot-starter-actuator'
+
+	// Mockito + AssertJ
+	testImplementation "org.mockito:mockito-junit-jupiter:5.12.0"
+	testImplementation "org.assertj:assertj-core:3.26.3"
+
+	// GreenMail: SMTP 가짜 서버
+	testImplementation "com.icegreen:greenmail:1.6.14"
+
+
 	// spring-retry
 	implementation 'org.springframework.retry:spring-retry'
 
@@ -60,6 +69,17 @@ dependencies {
 	// backtesting library
 	implementation 'org.ta4j:ta4j-core:0.15'
 
+	// mail
+	implementation 'org.springframework.boot:spring-boot-starter-mail'
+
+	//validation
+	implementation 'commons-validator:commons-validator:1.10.0'
+
+	// Redis
+	implementation 'org.springframework.boot:spring-boot-starter-data-redis'
+
+	// Thymleaf
+	implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
 }
 
 jacoco {

backend/src/main/java/org/sejongisc/backend/auth/config/EmailProperties.java

@@ -0,0 +1,33 @@
+package org.sejongisc.backend.auth.config;
+
+import java.time.Duration;
+import lombok.Getter;
+import lombok.Setter;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.Configuration;
+
+@ConfigurationProperties(prefix = "email")
+@Getter
+@Setter
+@Configuration
+public class EmailProperties {
+  private Duration codeExpire;
+  private Duration verifiedExpire;
+  private KeyPrefix keyPrefix;
+  private Code code;
+
+  @Setter
+  @Getter
+  public static class KeyPrefix {
+    private String verify;
+    private String verified;
+  }
+
+  @Setter
+  @Getter
+  public static class Code {
+    private String charset;   // 문자 세트
+    private int length;       // 기본 길이
+  }
+
+}

backend/src/main/java/org/sejongisc/backend/auth/controller/EmailController.java

@@ -0,0 +1,74 @@
+package org.sejongisc.backend.auth.controller;
+
+
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import lombok.RequiredArgsConstructor;
+import org.sejongisc.backend.auth.service.EmailService;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+@Tag(
+    name = "메일 API",
+    description = "메일 관련 API 제공"
+)
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("/api/email")
+public class EmailController {
+  private final EmailService emailService;
+
+  @Operation(
+      summary = "메일전송",
+      description = """
+          ## 인증(JWT): **불필요**
+
+          ## 요청 파라미터 (String)
+          - **`email`**: 회원 이메일
+
+          ## 반환값 (ResponseEntity<String>)
+          - **`message`**: 전송완료 메세지
+
+          ## 에러코드
+          - **`EMAIL_INVALID_EMAIL`**: 유효하지 않은 이메일입니다
+          - **`DUPLICATE_EMAIL`**: 이미 존재하는 이메일입니다
+          - **`EMAIL_ALREADY_VERIFIED`**: 24시간 내에 인증된 이메일입니다
+          """
+  )
+  @PostMapping("/send")
+  public ResponseEntity<String> sendEmail(@RequestParam String email) {
+    emailService.sendEmail(email);
+    return ResponseEntity.ok("메일 전송을 요청하였습니다.");
+  }
+
+
+  @Operation(
+      summary = "이메일 인증",
+      description = """
+          ## 인증(JWT): **불필요**
+
+          ## 요청 파라미터 (String)
+          - **`email`**: 회원 이메일
+          - **`code`**: 이메일 인증 코드
+
+          ## 반환값 (ResponseEntity<String>)
+          - **`message`**: 인증 완료 메시지
+
+          ## 에러코드
+          - **`EMAIL_CODE_MISMATCH`**: 이메일 인증 코드가 일치하지 않습니다
+          - **`EMAIL_CODE_NOT_FOUND`**: 이메일 인증 코드를 찾을 수 없습니다
+          """
+  )
+  @PostMapping("/verify")
+  public ResponseEntity<String> verifyEmail(@RequestParam String email, @RequestParam String code) {
+    emailService.verifyEmail(email, code);
+    return ResponseEntity.ok("이메일 인증이 완료되었습니다.");
+  }
+
+
+
+}

backend/src/main/java/org/sejongisc/backend/auth/service/EmailService.java

@@ -0,0 +1,134 @@
+package org.sejongisc.backend.auth.service;
+
+import jakarta.mail.Message;
+import jakarta.mail.MessagingException;
+import jakarta.mail.internet.InternetAddress;
+import jakarta.mail.internet.MimeMessage;
+import jakarta.validation.constraints.Email;
+import java.security.SecureRandom;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.validator.routines.EmailValidator;
+import org.sejongisc.backend.auth.config.EmailProperties;
+import org.sejongisc.backend.common.exception.CustomException;
+import org.sejongisc.backend.common.exception.ErrorCode;
+import org.sejongisc.backend.user.dao.UserRepository;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.mail.MailSendException;
+import org.springframework.mail.javamail.JavaMailSender;
+import org.springframework.scheduling.annotation.Async;
+import org.springframework.stereotype.Service;
+import org.springframework.validation.annotation.Validated;
+import org.thymeleaf.context.Context;
+import org.thymeleaf.spring6.SpringTemplateEngine;
+
+@Slf4j
+@Service
+@RequiredArgsConstructor
+@Validated
+public class EmailService {
+  private final JavaMailSender mailSender;
+  private final RedisTemplate<String, String> redisTemplate;
+  private final SpringTemplateEngine templateEngine;
+  private final UserRepository userRepository;
+  private final EmailProperties emailProperties;
+
+  // 메일 발신자
+  @Value("${spring.mail.username}")
+  private String from;
+
+  // 메세지 만들기
+  private MimeMessage createMessage(String email, String code) throws MessagingException {
+    MimeMessage message = mailSender.createMimeMessage();
+    message.setFrom(new InternetAddress(from));
+    message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(email));
+    message.setSubject("세투연 이메일 인증 메일입니다.");
+
+    Context context = new Context();
+    context.setVariable("email", email);
+    context.setVariable("code", code);
+
+    String body = templateEngine.process("mail/verificationEmail", context);
+    message.setText(body, "UTF-8", "html");
+
+    return message;
+
+  }
+
+  // 메일 발송
+  public void sendEmail(@Email String email) {
+
+    // 이미 24시간 내 인증된 이메일인지 확인
+    String verifiedKey = emailProperties.getKeyPrefix().getVerified() + email;
+    if (Boolean.TRUE.equals(redisTemplate.hasKey(verifiedKey))) {
+      throw new CustomException(ErrorCode.EMAIL_ALREADY_VERIFIED);
+    }
+
+    // 이메일 형식 검증
+    if (!EmailValidator.getInstance().isValid(email)) {
+      throw new CustomException(ErrorCode.EMAIL_INVALID_EMAIL);
+    }
+
+    // 중복 이메일 검증
+    if (userRepository.existsByEmail(email)) {
+      throw new CustomException(ErrorCode.DUPLICATE_EMAIL);
+    }
+
+    // 인증코드 생성
+      String code = generateCode();
+
+    // Redis에 인증 코드 저장 (유효시간: 3분)
+    redisTemplate.opsForValue().set(emailProperties.getKeyPrefix().getVerify() + email, code, emailProperties.getCodeExpire());
+
+    // 메일 발송
+    try {
+      MimeMessage message = createMessage(email, code);
+      mailSender.send(message);
+    } catch (MessagingException e) {
+      log.error("메일전송이 실패하였습니다", e);
+      throw new MailSendException("failed to send mail", e);
+    }
+
+  }
+
+  // 코드확인
+  public void verifyEmail(String email, String code) {
+    String key = emailProperties.getKeyPrefix().getVerify()+ email;
+
+    String storedCode = redisTemplate.opsForValue().get(key);
+    if (storedCode == null) throw new CustomException(ErrorCode.EMAIL_CODE_NOT_FOUND);
+    if (!storedCode.equals(code)) throw new CustomException(ErrorCode.EMAIL_CODE_MISMATCH);
+
+
+    // 인증 성공 시 Redis에서 코드 삭제
+    redisTemplate.delete(key);
+
+    // 인증 완료 상태 저장 (24시간 유효)
+    redisTemplate.opsForValue().set(
+        emailProperties.getKeyPrefix().getVerified() + email,
+        "true",
+        emailProperties.getVerifiedExpire()
+    );
+
+
+  }
+
+  // 이메일 인증 코드 생성
+  private String generateCode() {
+    String charset = emailProperties.getCode().getCharset();
+    int len = emailProperties.getCode().getLength();
+
+    SecureRandom rnd = new SecureRandom();
+    StringBuilder sb = new StringBuilder(len);
+
+    for (int i = 0; i < len; i++) {
+      sb.append(charset.charAt(rnd.nextInt(charset.length())));
+    }
+    return sb.toString();
+  }
+
+
+
+
+}

backend/src/main/java/org/sejongisc/backend/common/auth/config/SecurityConfig.java

@@ -48,6 +48,8 @@ public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Excepti
                                     "/api/auth/reissue",
                                     "/v3/api-docs/**",
                                     "/swagger-ui/**",
+
+                                    "/api/email/**",
                                     "/swagger-resources/**",
                                     "/webjars/**").permitAll()
                             .requestMatchers(HttpMethod.OPTIONS, "/**").permitAll()

backend/src/main/java/org/sejongisc/backend/common/exception/ErrorCode.java

@@ -50,8 +50,11 @@ public enum ErrorCode {
 
   INVALID_ACCESS_TOKEN(HttpStatus.UNAUTHORIZED, "유효하지 않은 엑세스 토큰입니다."),
 
-  EXPIRED_ACCESS_TOKEN(HttpStatus.UNAUTHORIZED, "엑세스 토큰이 만료되었습니다. 재발급이 필요합니다."),
-
+  // EMAIL
+  EMAIL_CODE_NOT_FOUND(HttpStatus.NOT_FOUND, "이메일 인증 코드를 찾을 수 없습니다"),
+  EMAIL_CODE_MISMATCH(HttpStatus.BAD_REQUEST, "인증 코드가 일치하지 않습니다."),
+  EMAIL_INVALID_EMAIL(HttpStatus.BAD_REQUEST, "유효하지 않은 이메일입니다"),
+  EMAIL_ALREADY_VERIFIED(HttpStatus.BAD_REQUEST, "24시간 이내에 이미 인증된 이메일입니다."),
 
   // USER