From Cryptography to Communication Security - A Classical Introduction to Cryptography: Applications for Communications Security - page 296

Client Server

nonce C
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−→
ServerHello :cipher suite

ClientHello :acceptable cipher suites

,

nonce S
←−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

, certi cate ,

select cipher suite

ClientKeyExchange :RSA ENC ( pre master secret )
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−→ decrypt

pre master secret

(key derivation)

MAC ( handshake messages )
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−→

check

)
←−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

MAC ( handshake messages

check

(open tunnel)

Figure 12.6. A typical SSL handshake.

The client and the server can then communicate through a protected channel.

A typical handshake session is illustrated in Fig. 12.6.

12.3.2 Cipher Suites

A cipher suite includes a key agreement algorithm, a symmetric cipher algorithm, and
a hash function. In Figs. 12.7 and 12.8 are a few standard cipher suite definitions for
TLS. In addition, an update of TLS integrates AES by specifying the cipher suites of
Fig. 12.9 (see Ref. [46]).

We notice that RC4 is the only stream cipher. It is used with two different key
lengths: 40 and 128 bits.

All block ciphers use blocks of 8 bytes, except AES which uses 16 bytes. They are
all used in CBC mode with an initial vector.

CipherSuite Key Exchange Cipher Hash

NULL NULL NULL

TLS NULL WITH NULL NULL

TLS RSA WITH NULL MD5 RSA NULL MD5

RSA NULL SHA-1

TLS RSA WITH NULL SHA

RSA RC4 40 MD5

TLS RSA EXPORT WITH RC4 40 MD5

RSA RC4 128 MD5

TLS RSA WITH RC4 128 MD5

TLS RSA WITH RC4 128 SHA RSA RC4 128 SHA-1

RSA RC2 40 MD5

TLS RSA EXPORT WITH RC2 CBC 40 MD5

RSA IDEA SHA-1

TLS RSA WITH IDEA CBC SHA

RSA DES40 SHA-1

TLS RSA EXPORT WITH DES40 CBC SHA

TLS RSA WITH DES CBC SHA RSA DES SHA-1

RSA 3DES EDE SHA-1

TLS RSA WITH 3DES EDE CBC SHA

Figure 12.7. Standard TLS cipher suites with NULL or RSA key exchange.