##### SUMMARY
Customer request: When typing the string to encrypt, it shows up as plain text. Since the string is being encrypted, it's safe to assume that it's sensitive (e.g. passwords) and should therefore be hidden. At the very least, maybe this could be a command line option. If it is hidden, I'd prefer to be forced to enter it twice to avoid mismatch. To mitigate this issue, I am currently using "stty -echo", but that shouldn't be necessary.

##### ISSUE TYPE
- Feature Idea

##### COMPONENT NAME
ansible-vault
indent = indent or 10
        block_format_var_name = ""
        if name:
            block_format_var_name = "%s: " % name
        block_format_header = "%s!vault |" % block_format_var_name
        lines = []
        vault_ciphertext = to_text(b_ciphertext)
        lines.append(block_format_header)
        for line in vault_ciphertext.splitlines():
            lines.append('%s%s' % (' ' * indent, line))
        yaml_ciphertext = '\n'.join(lines)
        return yaml_ciphertext
    def execute_encrypt_string(self):
        ''' encrypt the supplied string using the provided vault secret '''
        b_plaintext = None
        
        b_plaintext_list = []
        
        
        args = [x for x in context.CLIARGS['args'] if x != '-']
        
        if context.CLIARGS['encrypt_string_prompt']:
            msg = "String to encrypt: "
            name = None
            name_prompt_response = display.prompt('Variable name (enter for no name): ')
            
            if name_prompt_response != "":