SSL Handshake

https://labs.portcullis.co.uk/tools/ssl-cipher-suite-enum/

https://github.com/drwetter/testssl.sh https://testssl.sh

pack types:

  C unsigned 8 bit char
  n unsigned short, 16 bit, network order
  a binary string, NULL padded

SSLv2

Client sends

Client hello max 256 bytes for F5! (Bug) https://code.google.com/p/chromium/issues/detail?id=245500 Fixed at least since 09/29/2011

Client-Hello SSLv2:

  #  Header
  n  Message len | 0x8000
   
  # Data. len: message len
  C  Message Type: SSL_MT_CLIENT_HELLO
  n  Client-Version
  n  Cipher spec len
  n  Session-ID len   => 0
  n  challenge len
  a* cipher spec data
  a* session id data  => empty
  a* challenge data

alternative header (3 bytes):

  #  Header
  n  Message len 
  C  Padding (number of bytes added at the end of data part!)

SSLv3 and TLS

  C     record Type      / SSL record type = 22 (SSL3_RT_HANDSHAKE)
  n     SSL Version      
  n     Record len
  
  # Record:
  C     Message Type     / Handshake type
  C     0x00             / Length of data to follow in this record (3 Bytes!)
  n     Message len      / Length rest
  
  ## Data
  n     SSL/TLS Version
  a[32] challenge
  C     session ID len
  n     cipher spec len
  a*    cipher spec
  C     compression method len (1)
  C*    compression method  (0x00)
  n     length extensions
  a*    extensions data 


  ## Extensions: SNI, 
  



  # Hello Extensions format:

  n  extension type
  n  Length extension data
  a* data
  
  
  # data for hello extension sni:
  
  n  len of list (bytes)
  C  Nametype (host_name: 0x00)
  n  len host name
  a* hostname (IDN!)


      $clientHello_extensions = pack(
                                      "n n n C n a[$clientHello{'extension_sni_len'}]",
                                      $clientHello{'extension_type_server_name'},          #n
                                      $clientHello{'extension_len'},            #n
                                      $clientHello{'extension_sni_list_len'},   #n
                                      $clientHello{'extension_sni_type'},       #C
                                      $clientHello{'extension_sni_len'},        #n
                                      $clientHello{'extension_sni_name'},       #a[$clientHello{'extension_sni_len'}]
                                    );


  





         "n a[32] C n a[$clientHello{'cipher_spec_len'}] C C[$clientHello{'compression_method_len'}] a[$clientHello{'extensions_total_len'}]",
         $clientHello{'version'},                  # n
         $clientHello{'challenge'},                # A[32] = gmt + random [4] + [28] Bytes
         $clientHello{'session_id_len'},           # C
         $clientHello{'cipher_spec_len'},          # n
         $clientHello{'cipher_spec'},              # A[$clientHello{'cipher_spec_len'}]
         $clientHello{'compression_method_len'},   # C (0x01)
         $clientHello{'compression_method'},       # C[len] (0x00)
         $clientHello_extensions                   # optional
                             );

https://www-01.ibm.com/support/knowledgecenter/#!/SSB23S_1.1.0.10/com.ibm.ztpf-ztpfdf.doc_put.10/gtps5/s5rcd.html?cp=SSB23S_1.1.0.10%2F0-1-8-2-3

possible handshake types:

   SSL3_MT_HELLO_REQUEST            0   (x'00')
   SSL3_MT_CLIENT_HELLO             1   (x'01')
   SSL3_MT_SERVER_HELLO             2   (x'02')
   SSL3_MT_CERTIFICATE             11   (x'0B')
   SSL3_MT_SERVER_KEY_EXCHANGE     12   (x'0C')
   SSL3_MT_CERTIFICATE_REQUEST     13   (x'0D')
   SSL3_MT_SERVER_DONE             14   (x'0E')
   SSL3_MT_CERTIFICATE_VERIFY      15   (x'0F')
   SSL3_MT_CLIENT_KEY_EXCHANGE     16   (x'10')
   SSL3_MT_FINISHED                20   (x'14') 





      $clientHello{'msg_len'}    = length($clientHello_tmp);
      $clientHello{'record_len'} = $clientHello{'msg_len'} + 4;

      $clientHello = pack(
                           "C n n C C n a*",
                           $clientHello{'record_type'},              # C
                           $clientHello{'record_version'},           # n
                           $clientHello{'record_len'},               # n
                           $clientHello{'msg_type'},                 # C
                           0x00,                                     # C (0x00)
                           $clientHello{'msg_len'},                  # n
                           $clientHello_tmp                          # a
                         );

Server-Hello:

The SSL Handshake Protocol defines the following errors:

NO-CIPHER-ERROR This error is returned by the client to the server when it cannot find a cipher or key size that it supports that is also supported by the server. This error is not recoverable.

send_record

add_to_record

record_as_string

clear_record

challenge

close_notify

->hello

...

build_client_hello

->build_extensions

receive_record

parse_handshake($data)

sslv2_server_hello

   0 char MSG-SERVER-HELLO
   1 char SESSION-ID-HIT
   2 char CERTIFICATE-TYPE
   3 char SERVER-VERSION-MSB
   4 char SERVER-VERSION-LSB
   5 char CERTIFICATE-LENGTH-MSB
   6 char CERTIFICATE-LENGTH-LSB
   7 char CIPHER-SPECS-LENGTH-MSB
   8 char CIPHER-SPECS-LENGTH-LSB
   9 char CONNECTION-ID-LENGTH-MSB
  10 char CONNECTION-ID-LENGTH-LSB
    char CERTIFICATE-DATA[MSB<<8|LSB]
    char CIPHER-SPECS-DATA[MSB<<8|LSB]
    char CONNECTION-ID-DATA[MSB<<8|LSB]

parse_alert