OTP - One Time Password?
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Je mechanizmus, kter doke in chrnit vae pstupov heslo ped
odposlechem. Po sti se nikdy neposl vae heslo, ale jen vtaek - otisk
vaeho hesla. Na vdlenm systmu ke ktermu se pihlaujete vae heslo tak
nen uloeno. Heslo je uloeno jen ve va pamti.
Cel proces probh piblin takto:

Server:                            |      Klient:
  vzva "otp-md5 202 seed"       ---->
                                   |        md5_digest:=md5(heslo+seed)
                                   |
  server zn sprvnou odpov      |        for i:=0 to 202-1 do
  pro poet opakovani 499          |          md5_digest:=md5(md5_digest)
                                   |
                                 <----      64bit_to_6word(md5_digest)
  md5_digest:=6word_to_64bit       |
  for i:=202 to 499-1 do           |
    md5_digest:=md5(md5_digest)    |
                                   |
                                   |
  jestlize se shoduje md5_digest   |
  a to co server zn je uivatel   |
  vputn jinak ne.                |
                                   |
  pi ptm pihlen bude vzva|
  "otp-md5 201 seed"               |

SemTel podporuje z otp podle rfc1938, pouze algoritmus md5. 'Extended Responses'
podle rfc2243 nejsou implementovny.

reference:
  rfc2289 A One-Time Password System. N. Haller, C. Metz, P. Nesser, M.
          Straw. February 1998. (Format: TXT=56495 bytes) (Obsoletes RFC1938)
          (Status: DRAFT STANDARD)
  rfc2243 OTP Extended Responses. C. Metz. November 1997. (Format:
          TXT=19730 bytes) (Status: PROPOSED STANDARD)
  rfc1938 A One-Time Password System. N. Haller & C. Metz. May 1996.
          (Format: TXT=44844 bytes) (Obsoleted by RFC2289) (Status: PROPOSED
          STANDARD)
  rfc1760 The S/KEY One-Time Password System. N. Haller. February 1995.
          (Format: TXT=31124 bytes) (Status: INFORMATIONAL)

  rfc1321 The MD5 Message-Digest Algorithm. R. Rivest. April 1992. (Format:
          TXT=35222 bytes) (Status: INFORMATIONAL)
  rfc1320 The MD4 Message-Digest Algorithm. R. Rivest. April 1992. (Format:
          TXT=32407 bytes) (Status: INFORMATIONAL)
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Verze dokumentu : 0.902
Posledn zmna  : 23.8.1998
