Encrypt plaintext into cipher text using specified key.

    CLI example::

        salt myminion boto_kms.encrypt 'alias/mykey' 'myplaindata' '{"aws:username":"myuser"}'

def encrypt(key_id, plaintext, encryption_context=None, grant_tokens=None,
            region=None, key=None, keyid=None, profile=None):
    '''
    Encrypt plaintext into cipher text using specified key.

    CLI example::

        salt myminion boto_kms.encrypt 'alias/mykey' 'myplaindata' '{"aws:username":"myuser"}'
    '''
    conn = _get_conn(region=region, key=key, keyid=keyid, profile=profile)

    r = {}
    try:
        ciphertext = conn.encrypt(
            key_id,
            plaintext,
            encryption_context=encryption_context,
            grant_tokens=grant_tokens
        )
        r['ciphertext'] = ciphertext['CiphertextBlob']
    except boto.exception.BotoServerError as e:
        r['error'] = __utils__['boto.get_error'](e)
    return r