Issue in encoding password with spring security - grails

Question

I am using grails 2.3.0 and facing the weird issue when encoding the password with spring security:
This is my method to encode password:
String encodePassword(String password) {
return springSecurityService.encodePassword(password)
}
and using like that
log.debug encodePassword("mkb")
log.debug encodePassword("mkb")
log.debug encodePassword("mkb")
I am encoding the same password several times and each time I am getting the different encoded password.
logs:
$2a$10$h8T4BxgOeozmH/VSPJl7NeTaF2P0iONpSdqDN7dDFFAG.sy8WG/8K
$2a$10$a7qybaiLF/eNrTSwFohjkezNaJTTDdMEinRYKjxDzEt.OoxaIgFOu
$2a$10$nZVhUT0QTmmbtt22CPtM..cLxU252RGBIMkd5aSd2AFXNTNLQ./6u

Answer 1

That's fine. Looks like you're using BCrypt password hash, this algorithm uses random salt each time you encode password (other hashing algorithms use a 'salt source property', like id). This salt is prepended to hash
So you have:
$2a - salt version
$10 - rounds
$h8T4BxgOeozmH/VSPJl7NeTaF2P0iONpSdqDN7dDFFAG.sy8WG/8K - Base64 for salt+hash, where salt get first 24 characters, and hash takes the rest:
h8T4BxgOeozmH/VSPJl7NeTaF - salt
2P0iONpSdqDN7dDFFAG.sy8WG/8K - hash (10 rounds for salt + password)
See Spring Security's BCrypt sources: https://github.com/spring-projects/spring-security/blob/master/crypto/src/main/java/org/springframework/security/crypto/bcrypt/BCrypt.java
If you need to check user password manually, you have to use passwordEncoder, like:
//dependency injection
def passwordEncoder
//validate
String enteredPassword = params.password
User user = ...
if (!passwordEncoder.isPasswordValid(user.password, enteredPassword, null)) { //validates raw password against hashed
//... wrong password entered
}

Answer 2

Grails spring security describes the process of updating a password at: https://grails-plugins.github.io/grails-spring-security-core/4.0.x/index.html
User user = User.findByUsername(username)
if (!passwordEncoder.matches(password, user.password)) {
flash.message = 'Current password is incorrect'
render view: 'passwordExpired', model: [username: session['SPRING_SECURITY_LAST_USERNAME']]
return
}
if (passwordEncoder.matches(password_new, user.password)) {
flash.message = 'Please choose a different password from your current one'
render view: 'passwordExpired', model: [username: session['SPRING_SECURITY_LAST_USERNAME']]
return
}
Where password or new_password are parameters or method arguments