Andrew Boyson / crypto

A simple library to support serving https.

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explanation.txt@24:cb43290fc439, 2020-04-01 (annotated)

Committer:
andrewboyson
Date:
Wed Apr 01 12:48:52 2020 +0000
Revision:
24:cb43290fc439
Parent:
19:f22327e8be7b 
Added check so that if the client closes the TCP connection before the TLS connection is established then respond that we have finished and the TCP connection is to be closed.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
andrewboyson 19:f22327e8be7b 1 Ciper and MAC keys lengths
andrewboyson 19:f22327e8be7b 2 ==========================
andrewboyson 19:f22327e8be7b 3
andrewboyson 19:f22327e8be7b 4 Key IV Block
andrewboyson 19:f22327e8be7b 5 Cipher Type Material Size Size
andrewboyson 19:f22327e8be7b 6 ------------ ------ -------- ---- -----
andrewboyson 19:f22327e8be7b 7 NULL Stream 0 0 N/A
andrewboyson 19:f22327e8be7b 8 RC4_128 Stream 16 0 N/A
andrewboyson 19:f22327e8be7b 9 3DES_EDE_CBC Block 24 8 8
andrewboyson 19:f22327e8be7b 10 AES_128_CBC Block 16 16 16
andrewboyson 19:f22327e8be7b 11 AES_256_CBC Block 32 16 16
andrewboyson 19:f22327e8be7b 12
andrewboyson 19:f22327e8be7b 13
andrewboyson 19:f22327e8be7b 14 MAC Algorithm mac_length mac_key_length
andrewboyson 19:f22327e8be7b 15 -------- ----------- ---------- --------------
andrewboyson 19:f22327e8be7b 16 NULL N/A 0 0
andrewboyson 19:f22327e8be7b 17 MD5 HMAC-MD5 16 16
andrewboyson 19:f22327e8be7b 18 SHA HMAC-SHA1 20 20
andrewboyson 19:f22327e8be7b 19 SHA256 HMAC-SHA256 32 32
andrewboyson 19:f22327e8be7b 20
andrewboyson 19:f22327e8be7b 21
andrewboyson 6:819c17738dc2 22 Names
andrewboyson 6:819c17738dc2 23 =====
andrewboyson 0:be515c9019e3 24 SHA
andrewboyson 0:be515c9019e3 25 secure hash algorithm
andrewboyson 0:be515c9019e3 26 - it is deterministic, meaning that the same message always results in the same hash
andrewboyson 0:be515c9019e3 27 - it is quick to compute the hash value for any given message
andrewboyson 0:be515c9019e3 28 - it is infeasible to generate a message that yields a given hash value
andrewboyson 0:be515c9019e3 29 - it is infeasible to find two different messages with the same hash value
andrewboyson 0:be515c9019e3 30 - a small change to a message should change the hash value so extensively that
andrewboyson 0:be515c9019e3 31 the new hash value appears uncorrelated with the old hash value (avalanche effect)
andrewboyson 0:be515c9019e3 32
andrewboyson 0:be515c9019e3 33 HMAC
andrewboyson 0:be515c9019e3 34 keyed-hash message authentication code or hash-based message authentication code
andrewboyson 0:be515c9019e3 35 - it is a message authentication code (MAC) involving a cryptographic hash function and a secret cryptographic key.
andrewboyson 0:be515c9019e3 36 - it may be used to simultaneously verify both the data integrity and the authentication of a message
andrewboyson 2:82268409e83f 37 - used to sign a message with a symmetrical key
andrewboyson 6:819c17738dc2 38
andrewboyson 6:819c17738dc2 39
andrewboyson 6:819c17738dc2 40 Links
andrewboyson 6:819c17738dc2 41 =====
andrewboyson 6:819c17738dc2 42 https://tls.ulfheim.net/
andrewboyson 6:819c17738dc2 43
andrewboyson 2:82268409e83f 44 Full RSA handshake
andrewboyson 2:82268409e83f 45 ===================
andrewboyson 8:5e66a6b4b38c 46 ClientHello -=> use session id to jump to short handshake
andrewboyson 8:5e66a6b4b38c 47 <=- ServerHello
andrewboyson 8:5e66a6b4b38c 48 <=- Certificate
andrewboyson 8:5e66a6b4b38c 49 <=- ServerHelloDone
andrewboyson 6:819c17738dc2 50
andrewboyson 8:5e66a6b4b38c 51 ClientKeyExchange -=> start asynchronous sha256 decryption
andrewboyson 6:819c17738dc2 52 ChangeCipherSpec --> switch to encrypedIn
andrewboyson 8:5e66a6b4b38c 53 Finished -=> store the encrypted verify message
andrewboyson 6:819c17738dc2 54
andrewboyson 6:819c17738dc2 55 sha256 decrypted --> prepare the keys and decrypt the verify message
andrewboyson 2:82268409e83f 56 <-- ChangeCipherSpec
andrewboyson 8:5e66a6b4b38c 57 <=- Finished
andrewboyson 2:82268409e83f 58
andrewboyson 2:82268409e83f 59
andrewboyson 2:82268409e83f 60 Short RSA handshake
andrewboyson 2:82268409e83f 61 ===================
andrewboyson 8:5e66a6b4b38c 62 ClientHello -=>
andrewboyson 8:5e66a6b4b38c 63 <=- ServerHello
andrewboyson 2:82268409e83f 64 <-- ChangeCipherSpec
andrewboyson 8:5e66a6b4b38c 65 <=- Finished
andrewboyson 14:03a0b8fd6ddc 66 ChangeCipherSpec --> switch to encrypedIn
andrewboyson 8:5e66a6b4b38c 67 Finished -=>
andrewboyson 2:82268409e83f 68