crypt.1 (2694B)
1 .\" enigma (aka. crypt) man page written by Joerg Wunsch. 2 .\" 3 .\" Since enigma itself is distributed in the Public Domain, 4 .\" this file is also. 5 .Dd September 19, 2019 6 .Dt CRYPT 1 7 .Os 8 .Sh NAME 9 .Nm crypt 10 .Nd very simple file encryption 11 .Sh SYNOPSIS 12 .Nm 13 .Op Fl ks 14 .Op Ar password 15 .Sh DESCRIPTION 16 The 17 .Nm 18 utility is a 19 .Em very 20 simple encryption program that utilises a secret key. 21 It encrypts or decrypts data from standard input, 22 and writes the result to standard output. 23 Its operation is fully symmetrical; 24 feeding it encrypted data using the same secret key will decrypt it. 25 .Pp 26 By default 27 .Nm 28 prompts the user on the controlling terminal for the secret key. 29 This is the only safe way of providing it. 30 Alternatively, the key can be set with the 31 .Ar password 32 operand, which can easily be spotted by other users running 33 .Xr ps 1 . 34 The key can also be provided by setting the environment variable 35 .Ev CrYpTkEy 36 and specifying the option 37 .Fl k . 38 This option is provided for compatibility with other implementations, 39 as environment variables can also be examined with 40 .Xr ps 1 . 41 .Pp 42 When option 43 .Fl s 44 is passed, 45 the encryption engine is modified in a way that is supposedly more 46 secure, but incompatible with other implementations. 47 .Ss Warning 48 The cryptographic value of 49 .Nm 50 is worse than useless; 51 attacks against its encryption scheme have been documented since 1984, 52 and there are various tools that can break it in an automated process. 53 This implementation is provided only as a learning exercise and for 54 compatibility with systems providing their own implementation. 55 For real encryption, use 56 .Xr openssl 1 57 or 58 .Xr gpg 1 . 59 .Sh ENVIRONMENT 60 .Bl -tag -width "CrYpTkEy" 61 .It Ev CrYpTkEy 62 used to obtain the secret key when option 63 .Fl k 64 has been given. 65 .El 66 .Sh EXAMPLES 67 Encrypt this manual with the secret key 68 .Ar XXX 69 and store it in the file 70 .Pa encrypted . 71 .Bd -literal -offset indent 72 $ man crypt | crypt > encrypted 73 Enter key: XXX (key not echoed) 74 .Ed 75 .Pp 76 Decrypt the previously created file. 77 .Bd -literal -offset indent 78 $ crypt XXX < encrypted 79 .Ed 80 .Sh SEE ALSO 81 .Xr gpg 1 , 82 .Xr openssl 1 , 83 .Xr ps 1 84 .Rs 85 .%A J. A. Reeds 86 .%A P. J. Weinberger 87 .%J AT&T Bell Laboratories Technical Journal 88 .%I AT&T Bell Laboratories 89 .%R File Security and the UNIX System Crypt Command 90 .%D October 1984 91 .%P pp. 1673-1683 92 .Re 93 .Sh HISTORY 94 .An Robert Morris 95 wrote the original 96 .Nm 97 for 98 .At v3 . 99 It was later updated by 100 .An Dennis Richie 101 and 102 .An James Reeds 103 for 104 .At v7 . 105 .Sh AUTHORS 106 .An -nosplit 107 The 108 .Nm 109 utility is maintained by 110 .An Stephen Gregoratto Aq Mt dev@sgregoratto.me . 111 It is based on the public domain implementation in the Crypt Breaker's 112 Workbench by 113 .An Robert W. Baldwin , 114 with changes made by the 115 .Fx 116 developers.