Enhance password memory security using char[] with explicit clearing

src/main/java/com/digitalsanctuary/spring/user/api/UserAPI.java

@@ -103,6 +103,11 @@ public ResponseEntity<JSONResponse> registerUserAccount(@Valid @RequestBody User
 			log.error("Unexpected error during registration.", ex);
 			logAuditEvent("Registration", "Failure", ex.getMessage(), null, request);
 			return buildErrorResponse("System Error!", 5, HttpStatus.INTERNAL_SERVER_ERROR);
+		} finally {
+			// Clear sensitive password data from memory
+			if (userDto != null) {
+				userDto.clearPasswords();
+			}
 		}
 	}
 
@@ -244,6 +249,11 @@ public ResponseEntity<JSONResponse> savePassword(@Valid @RequestBody SavePasswor
 			log.error("Unexpected error during password reset.", ex);
 			logAuditEvent("PasswordReset", "Failure", ex.getMessage(), null, request);
 			return buildErrorResponse("System Error!", 5, HttpStatus.INTERNAL_SERVER_ERROR);
+		} finally {
+			// Clear sensitive password data from memory
+			if (savePasswordDto != null) {
+				savePasswordDto.clearPasswords();
+			}
 		}
 	}
 
@@ -293,6 +303,11 @@ public ResponseEntity<JSONResponse> updatePassword(@AuthenticationPrincipal DSUs
 			log.error("Unexpected error during password update.", ex);
 			logAuditEvent("PasswordUpdate", "Failure", ex.getMessage(), user, request);
 			return buildErrorResponse("System Error!", 5, HttpStatus.INTERNAL_SERVER_ERROR);
+		} finally {
+			// Clear sensitive password data from memory
+			if (passwordDto != null) {
+				passwordDto.clearPasswords();
+			}
 		}
 	}
 

src/main/java/com/digitalsanctuary/spring/user/dto/PasswordDto.java

@@ -1,5 +1,6 @@
 package com.digitalsanctuary.spring.user.dto;
 
+import com.digitalsanctuary.spring.user.util.PasswordSecurityUtil;
 import jakarta.validation.constraints.NotBlank;
 import jakarta.validation.constraints.Size;
 import lombok.Data;
@@ -8,9 +9,13 @@
 /**
  * A new password dto. This object is used for password form actions (change password, forgot password token, save
  * password, etc..).
+ * 
+ * <p>Note: This DTO supports both String and char[] for passwords. The char[] methods are preferred
+ * for enhanced security as they allow explicit memory clearing. String methods are maintained
+ * for backward compatibility.
  */
 @Data
-public class PasswordDto {
+public class PasswordDto implements AutoCloseable {
 
 	/** The old password. */
 	@ToString.Exclude
@@ -26,4 +31,86 @@ public class PasswordDto {
 	/** The token. */
 	private String token;
 
+	/** The old password as char array (for secure handling). */
+	@ToString.Exclude
+	private transient char[] oldPasswordChars;
+
+	/** The new password as char array (for secure handling). */
+	@ToString.Exclude
+	private transient char[] newPasswordChars;
+
+	/**
+	 * Gets the old password as a char array for secure handling.
+	 * If oldPasswordChars is null but oldPassword is set, converts from String.
+	 * 
+	 * @return the old password as char array, or null if not set
+	 */
+	public char[] getOldPasswordChars() {
+		if (oldPasswordChars == null && oldPassword != null) {
+			return PasswordSecurityUtil.toCharArray(oldPassword);
+		}
+		return oldPasswordChars;
+	}
+
+	/**
+	 * Sets the old password from a char array (preferred for security).
+	 * Also updates the String oldPassword field for backward compatibility.
+	 * 
+	 * @param oldPasswordChars the old password as char array
+	 */
+	public void setOldPasswordChars(char[] oldPasswordChars) {
+		this.oldPasswordChars = oldPasswordChars;
+		if (oldPasswordChars != null) {
+			this.oldPassword = PasswordSecurityUtil.toString(oldPasswordChars);
+		} else {
+			this.oldPassword = null;
+		}
+	}
+
+	/**
+	 * Gets the new password as a char array for secure handling.
+	 * If newPasswordChars is null but newPassword is set, converts from String.
+	 * 
+	 * @return the new password as char array, or null if not set
+	 */
+	public char[] getNewPasswordChars() {
+		if (newPasswordChars == null && newPassword != null) {
+			return PasswordSecurityUtil.toCharArray(newPassword);
+		}
+		return newPasswordChars;
+	}
+
+	/**
+	 * Sets the new password from a char array (preferred for security).
+	 * Also updates the String newPassword field for backward compatibility.
+	 * 
+	 * @param newPasswordChars the new password as char array
+	 */
+	public void setNewPasswordChars(char[] newPasswordChars) {
+		this.newPasswordChars = newPasswordChars;
+		if (newPasswordChars != null) {
+			this.newPassword = PasswordSecurityUtil.toString(newPasswordChars);
+		} else {
+			this.newPassword = null;
+		}
+	}
+
+	/**
+	 * Clears sensitive password data from memory.
+	 * This method should be called in a finally block to ensure passwords are cleared.
+	 */
+	public void clearPasswords() {
+		PasswordSecurityUtil.clearPassword(oldPasswordChars);
+		PasswordSecurityUtil.clearPassword(newPasswordChars);
+		oldPasswordChars = null;
+		newPasswordChars = null;
+	}
+
+	/**
+	 * Closes this resource, clearing password data from memory.
+	 */
+	@Override
+	public void close() {
+		clearPasswords();
+	}
 }

src/main/java/com/digitalsanctuary/spring/user/dto/SavePasswordDto.java

@@ -1,29 +1,120 @@
 package com.digitalsanctuary.spring.user.dto;
 
+import com.digitalsanctuary.spring.user.util.PasswordSecurityUtil;
 import jakarta.validation.constraints.NotEmpty;
 import jakarta.validation.constraints.NotNull;
 import lombok.Data;
+import lombok.ToString;
 
 /**
  * Data Transfer Object for saving a new password after password reset.
  * Used in the password reset flow after the user clicks the link in their email
  * and enters a new password.
+ * 
+ * <p>Note: This DTO supports both String and char[] for passwords. The char[] methods are preferred
+ * for enhanced security as they allow explicit memory clearing. String methods are maintained
+ * for backward compatibility.
  */
 @Data
-public class SavePasswordDto {
+public class SavePasswordDto implements AutoCloseable {
 
 	/** The password reset token from the email link. */
 	@NotNull
 	@NotEmpty
 	private String token;
 
 	/** The new password to set. */
+	@ToString.Exclude
 	@NotNull
 	@NotEmpty
 	private String newPassword;
 
 	/** Confirmation of the new password (must match newPassword). */
+	@ToString.Exclude
 	@NotNull
 	@NotEmpty
 	private String confirmPassword;
+
+	/** The new password as char array (for secure handling). */
+	@ToString.Exclude
+	private transient char[] newPasswordChars;
+
+	/** The confirm password as char array (for secure handling). */
+	@ToString.Exclude
+	private transient char[] confirmPasswordChars;
+
+	/**
+	 * Gets the new password as a char array for secure handling.
+	 * If newPasswordChars is null but newPassword is set, converts from String.
+	 * 
+	 * @return the new password as char array, or null if not set
+	 */
+	public char[] getNewPasswordChars() {
+		if (newPasswordChars == null && newPassword != null) {
+			return PasswordSecurityUtil.toCharArray(newPassword);
+		}
+		return newPasswordChars;
+	}
+
+	/**
+	 * Sets the new password from a char array (preferred for security).
+	 * Also updates the String newPassword field for backward compatibility.
+	 * 
+	 * @param newPasswordChars the new password as char array
+	 */
+	public void setNewPasswordChars(char[] newPasswordChars) {
+		this.newPasswordChars = newPasswordChars;
+		if (newPasswordChars != null) {
+			this.newPassword = PasswordSecurityUtil.toString(newPasswordChars);
+		} else {
+			this.newPassword = null;
+		}
+	}
+
+	/**
+	 * Gets the confirm password as a char array for secure handling.
+	 * If confirmPasswordChars is null but confirmPassword is set, converts from String.
+	 * 
+	 * @return the confirm password as char array, or null if not set
+	 */
+	public char[] getConfirmPasswordChars() {
+		if (confirmPasswordChars == null && confirmPassword != null) {
+			return PasswordSecurityUtil.toCharArray(confirmPassword);
+		}
+		return confirmPasswordChars;
+	}
+
+	/**
+	 * Sets the confirm password from a char array (preferred for security).
+	 * Also updates the String confirmPassword field for backward compatibility.
+	 * 
+	 * @param confirmPasswordChars the confirm password as char array
+	 */
+	public void setConfirmPasswordChars(char[] confirmPasswordChars) {
+		this.confirmPasswordChars = confirmPasswordChars;
+		if (confirmPasswordChars != null) {
+			this.confirmPassword = PasswordSecurityUtil.toString(confirmPasswordChars);
+		} else {
+			this.confirmPassword = null;
+		}
+	}
+
+	/**
+	 * Clears sensitive password data from memory.
+	 * This method should be called in a finally block to ensure passwords are cleared.
+	 */
+	public void clearPasswords() {
+		PasswordSecurityUtil.clearPassword(newPasswordChars);
+		PasswordSecurityUtil.clearPassword(confirmPasswordChars);
+		newPasswordChars = null;
+		confirmPasswordChars = null;
+	}
+
+	/**
+	 * Closes this resource, clearing password data from memory.
+	 */
+	@Override
+	public void close() {
+		clearPasswords();
+	}
 }

src/main/java/com/digitalsanctuary/spring/user/dto/UserDto.java

@@ -1,5 +1,6 @@
 package com.digitalsanctuary.spring.user.dto;
 
+import com.digitalsanctuary.spring.user.util.PasswordSecurityUtil;
 import com.digitalsanctuary.spring.user.validation.PasswordMatches;
 import jakarta.validation.constraints.Email;
 import jakarta.validation.constraints.NotBlank;
@@ -10,10 +11,14 @@
 /**
  * A user dto. This object is used for handling user related form data (registration, forms passing in email addresses,
  * etc...).
+ * 
+ * <p>Note: This DTO supports both String and char[] for passwords. The char[] methods are preferred
+ * for enhanced security as they allow explicit memory clearing. String methods are maintained
+ * for backward compatibility.
  */
 @Data
 @PasswordMatches
-public class UserDto {
+public class UserDto implements AutoCloseable {
 
 	/** The first name. */
 	@NotBlank(message = "First name is required")
@@ -44,4 +49,87 @@ public class UserDto {
 
 	/** The role. */
 	private Integer role;
+
+	/** The password as char array (for secure handling). */
+	@ToString.Exclude
+	private transient char[] passwordChars;
+
+	/** The matching password as char array (for secure handling). */
+	@ToString.Exclude
+	private transient char[] matchingPasswordChars;
+
+	/**
+	 * Gets the password as a char array for secure handling.
+	 * If passwordChars is null but password is set, converts from String.
+	 * 
+	 * @return the password as char array, or null if not set
+	 */
+	public char[] getPasswordChars() {
+		if (passwordChars == null && password != null) {
+			return PasswordSecurityUtil.toCharArray(password);
+		}
+		return passwordChars;
+	}
+
+	/**
+	 * Sets the password from a char array (preferred for security).
+	 * Also updates the String password field for backward compatibility.
+	 * 
+	 * @param passwordChars the password as char array
+	 */
+	public void setPasswordChars(char[] passwordChars) {
+		this.passwordChars = passwordChars;
+		if (passwordChars != null) {
+			this.password = PasswordSecurityUtil.toString(passwordChars);
+		} else {
+			this.password = null;
+		}
+	}
+
+	/**
+	 * Gets the matching password as a char array for secure handling.
+	 * If matchingPasswordChars is null but matchingPassword is set, converts from String.
+	 * 
+	 * @return the matching password as char array, or null if not set
+	 */
+	public char[] getMatchingPasswordChars() {
+		if (matchingPasswordChars == null && matchingPassword != null) {
+			return PasswordSecurityUtil.toCharArray(matchingPassword);
+		}
+		return matchingPasswordChars;
+	}
+
+	/**
+	 * Sets the matching password from a char array (preferred for security).
+	 * Also updates the String matchingPassword field for backward compatibility.
+	 * 
+	 * @param matchingPasswordChars the matching password as char array
+	 */
+	public void setMatchingPasswordChars(char[] matchingPasswordChars) {
+		this.matchingPasswordChars = matchingPasswordChars;
+		if (matchingPasswordChars != null) {
+			this.matchingPassword = PasswordSecurityUtil.toString(matchingPasswordChars);
+		} else {
+			this.matchingPassword = null;
+		}
+	}
+
+	/**
+	 * Clears sensitive password data from memory.
+	 * This method should be called in a finally block to ensure passwords are cleared.
+	 */
+	public void clearPasswords() {
+		PasswordSecurityUtil.clearPassword(passwordChars);
+		PasswordSecurityUtil.clearPassword(matchingPasswordChars);
+		passwordChars = null;
+		matchingPasswordChars = null;
+	}
+
+	/**
+	 * Closes this resource, clearing password data from memory.
+	 */
+	@Override
+	public void close() {
+		clearPasswords();
+	}
 }