magento-login-to-wp.php

<?php

add_filter( 'check_password', 'fe_magento_check_password', 10, 4 );

function fe_magento_check_password( $check, $password, $hash, $user_id ) {

    if ( $check ) {
    	// the password is already accepted
    	// do nothing further
        return $check;
    }

    // get user Magento password
    $magento_pwd_parts = explode(
        ':',
        get_user_meta( $user_id, 'fe_magento_pwd', true )
    );

    if (
        ! $magento_pwd_parts // the string exploded was empty
        || ! is_array( $magento_pwd_parts ) // result is not an array
        || ! sizeof( $magento_pwd_parts ) // the results are an empty array
    ) {
    	// exit early if we were unable to retrieve a Magento hashed password
    	// from User Meta
        return $check;
    }

    $hash = $magento_pwd_parts['0'];
    $salt = $magento_pwd_parts['1'];

    if ( $hash === hash( 'sha256', $salt.$password ) ) {
        // success, allow the user to log in

        // update WordPress to use this password
        wp_set_password( $password, $user_id );
        // delete Magento password User Meta
        delete_user_meta( $user_id, 'fe_magento_pwd' );

        return true;
    }

    return $check;
}