e/Running key cipher

Information
has gloss	eng: In classical cryptography, the running key cipher is a type of polyalphabetic substitution cipher in which a text, typically from a book, is used to provide a very long keystream. Usually, the book to be used would be agreed ahead of time, while the passage to use would be chosen randomly for each message and secretly indicated somewhere in the message.
lexicalization	eng: running key cipher
lexicalization	eng: Running-key cipher
instance of	c/Classical ciphers