Encode the following message using a shift 4 cipher, as Francis Bacon allegedly did while allegedly writing The Tempest. Note: You may use the encryption tool described here or you may do this by hand.

Francis Bacon

Now encode it using a shift 15 cipher.

The following messages have been encoding using a shift cipher with key 8. Decode.

1. emtkwum bw bpm eiksg ewztl wn kzgxbwozixpg
2. tivociom qa zmlcvlivb

Contrary to what you might think, the goal of a cryptographer is not to decrypt messages. The goal of a cryptographer is to find keys (because a key reveals a whole set of messages).

The following message has been encoded using a shift cipher. What is the key?

n puvyq funyy yrnq gurz

Hint hint: Choose the parts of the message you shift carefully.

Encrypt the following message using an affine cipher in which the slope is 3 and the shift is 2 (encryption key = (3,2)):

attack at dawn

Decrypt the following message assuming it is an affine cipher with a slope of 3 and a shift of 2:

goov wskb ixap kv

Determine the shift and slope for the following affine encryption scheme:

Plain Text	a	b	c	d	e	f	g	h	i	j	k	l	m	n	o	p	q	r	s	t	u	v	w	x	y	z
Encoding	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25
Encrypted Encoding	5	12	19	0	7	14	21	2	9	16	23	4	11	18	25	6	13	20	1	8	15	22	3	10	17	24
Cipher	f	m	t	a	h	o	v	c	j	q	x	e	l	s	z	g	n	u	b	i	p	w	d	k	r	y

Suppose we change the ALPHABET we're encoding to include " "(space). That's one more character. That means we're now doing arithmetic mod 27 instead of mod 26.

Previously (in mod 26) our valid slopes were all the odd numbers minus 13. What is our new set of valid slopes (in mod 27)?