Transport Layer Security by Mrinal Wadhwa @ null Banglore Meet, August 2011

1. Transport Layer
Security
Mrinal Wadhwa
http://www.mrinalwadhwa.com

2. SSL v1
before 1995, internal to Netscape, never released

3. SSL v2
draft published in FEB 1995
SSL 0.2 PROTOCOL SPECIFICATION
http://www.mozilla.org/projects/security/pki/nss/ssl/draft02.html

4. SSL v3
draft published in NOV 1996
The SSL Protocol Version 3.0
http://www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt

5. TLS 1.0
RFC 2446 - in Jan 1999
The TLS Protocol Version 1.0
http://tools.ietf.org/html/rfc2246

6. TLS 1.1
RFC 4346 - in April 2006
The Transport Layer Security (TLS) Protocol Version 1.1
http://tools.ietf.org/html/rfc4346

7. TLS 1.2
RFC 5246 - in August 2008
The Transport Layer Security (TLS) Protocol Version 1.2
http://tools.ietf.org/html/rfc5246

8. "The TLS protocol provides communications security
over the Internet. The protocol allows client/server
applications to communicate in a way that is designed to
prevent eavesdropping, tampering, or message forgery."
- The Transport Layer Security (TLS) Protocol Version 1.2

9. Record Protocol
http://tools.ietf.org/html/rfc5246#section-6

10. The Record Protocol takes messages to be transmitted, fragments the
data into manageable blocks, optionally compresses the data, applies
a MAC, encrypts, and transmits the result. Received data is
decrypted, verified, decompressed, reassembled, and then delivered to
higher-level clients.

11. struct {
ConnectionEnd entity;
PRFAlgorithm prf_algorithm;
BulkCipherAlgorithm bulk_cipher_algorithm;
CipherType cipher_type;
uint8 enc_key_length;
uint8 block_length;
uint8 fixed_iv_length;
uint8 record_iv_length;
MACAlgorithm mac_algorithm;
uint8 mac_length;
uint8 mac_key_length;
CompressionMethod compression_algorithm;
opaque master_secret[48];
opaque client_random[32];
opaque server_random[32];
} SecurityParameters;

12. Change Cipher Spec
Protocol
http://tools.ietf.org/html/rfc5246#section-7.1

13. Alert Protocol
http://tools.ietf.org/html/rfc5246#section-7.2

14. Handshake Protocol
a simplified discussion
http://tools.ietf.org/html/rfc5246#section-7.3

15. Hello Request
http://tools.ietf.org/html/rfc5246#section-7.4.1.1
struct { } HelloRequest;

16. Client Hello
http://tools.ietf.org/html/rfc5246#section-7.4.1.2
struct {
ProtocolVersion client_version;
Random random;
SessionID session_id;
CipherSuite cipher_suites<2..2^16-2>;
CompressionMethod compression_methods<1..2^8-1>;
select (extensions_present) {
case false:
struct {};
case true:
Extension extensions<0..2^16-1>;
};
} ClientHello;

17. CIPHER SUITES
TLS_RSA_WITH_AES_128_CBC_SHA
"The connection is encrypted using AES_128_CBC, with SHA1 for
message authentication and RSA as the key exchange mechanism."
Mandatory Cipher Suites - http://tools.ietf.org/html/rfc5246#section-9
Cipher Suite Definitions - http://tools.ietf.org/html/rfc5246#appendix-C

18. CIPHER SUITES
TLS_RSA_WITH_AES_128_CBC_SHA
Key Exchange - RSA
Cipher - AES_128_CBC
Mac - SHA (HMAC-SHA1)

19. Server Hello
http://tools.ietf.org/html/rfc5246#section-7.4.1.3
struct {
ProtocolVersion server_version;
Random random;
SessionID session_id;
CipherSuite cipher_suite;
CompressionMethod compression_method;
select (extensions_present) {
case false:
struct {};
case true:
Extension extensions<0..2^16-1>;
};
} ServerHello;

20. Server Certificate
http://tools.ietf.org/html/rfc5246#section-7.4.2
opaque ASN.1Cert<1..2^24-1>;
struct {
ASN.1Cert certificate_list<0..2^24-1>;
} Certificate;

21. Server Hello Done
http://tools.ietf.org/html/rfc5246#section-7.4.5
struct { } ServerHelloDone;

22. Client Key Exchange Message
http://tools.ietf.org/html/rfc5246#section-7.4.7
struct {
select (KeyExchangeAlgorithm) {
case rsa:
EncryptedPreMasterSecret;
case dhe_dss:
case dhe_rsa:
case dh_dss:
case dh_rsa:
case dh_anon:
ClientDiffieHellmanPublic;
} exchange_keys;
} ClientKeyExchange;

23. Finished
http://tools.ietf.org/html/rfc5246#section-7.4.9
struct {
opaque verify_data[verify_data_length];
} Finished;

24. ?

25. - mrinalwadhwa.com
- email@mrinalwadhwa.com
- @mrinal
- github.com/mrinalwadhwa