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enc.pod 9.5 KB

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  1. =pod
  2. =head1 NAME
  3. enc - symmetric cipher routines
  4. =head1 SYNOPSIS
  5. B<openssl enc -ciphername>
  6. [B<-in filename>]
  7. [B<-out filename>]
  8. [B<-pass arg>]
  9. [B<-e>]
  10. [B<-d>]
  11. [B<-a/-base64>]
  12. [B<-A>]
  13. [B<-k password>]
  14. [B<-kfile filename>]
  15. [B<-K key>]
  16. [B<-iv IV>]
  17. [B<-S salt>]
  18. [B<-salt>]
  19. [B<-nosalt>]
  20. [B<-z>]
  21. [B<-md>]
  22. [B<-p>]
  23. [B<-P>]
  24. [B<-bufsize number>]
  25. [B<-nopad>]
  26. [B<-debug>]
  27. [B<-none>]
  28. [B<-engine id>]
  29. =head1 DESCRIPTION
  30. The symmetric cipher commands allow data to be encrypted or decrypted
  31. using various block and stream ciphers using keys based on passwords
  32. or explicitly provided. Base64 encoding or decoding can also be performed
  33. either by itself or in addition to the encryption or decryption.
  34. =head1 OPTIONS
  35. =over 4
  36. =item B<-in filename>
  37. the input filename, standard input by default.
  38. =item B<-out filename>
  39. the output filename, standard output by default.
  40. =item B<-pass arg>
  41. the password source. For more information about the format of B<arg>
  42. see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
  43. =item B<-salt>
  44. use a salt in the key derivation routines. This is the default.
  45. =item B<-nosalt>
  46. don't use a salt in the key derivation routines. This option B<SHOULD NOT> be
  47. used except for test purposes or compatibility with ancient versions of OpenSSL
  48. and SSLeay.
  49. =item B<-e>
  50. encrypt the input data: this is the default.
  51. =item B<-d>
  52. decrypt the input data.
  53. =item B<-a>
  54. base64 process the data. This means that if encryption is taking place
  55. the data is base64 encoded after encryption. If decryption is set then
  56. the input data is base64 decoded before being decrypted.
  57. =item B<-base64>
  58. same as B<-a>
  59. =item B<-A>
  60. if the B<-a> option is set then base64 process the data on one line.
  61. =item B<-k password>
  62. the password to derive the key from. This is for compatibility with previous
  63. versions of OpenSSL. Superseded by the B<-pass> argument.
  64. =item B<-kfile filename>
  65. read the password to derive the key from the first line of B<filename>.
  66. This is for compatibility with previous versions of OpenSSL. Superseded by
  67. the B<-pass> argument.
  68. =item B<-nosalt>
  69. do not use a salt
  70. =item B<-salt>
  71. use salt (randomly generated or provide with B<-S> option) when
  72. encrypting (this is the default).
  73. =item B<-S salt>
  74. the actual salt to use: this must be represented as a string of hex digits.
  75. =item B<-K key>
  76. the actual key to use: this must be represented as a string comprised only
  77. of hex digits. If only the key is specified, the IV must additionally specified
  78. using the B<-iv> option. When both a key and a password are specified, the
  79. key given with the B<-K> option will be used and the IV generated from the
  80. password will be taken. It probably does not make much sense to specify
  81. both key and password.
  82. =item B<-iv IV>
  83. the actual IV to use: this must be represented as a string comprised only
  84. of hex digits. When only the key is specified using the B<-K> option, the
  85. IV must explicitly be defined. When a password is being specified using
  86. one of the other options, the IV is generated from this password.
  87. =item B<-p>
  88. print out the key and IV used.
  89. =item B<-P>
  90. print out the key and IV used then immediately exit: don't do any encryption
  91. or decryption.
  92. =item B<-bufsize number>
  93. set the buffer size for I/O
  94. =item B<-nopad>
  95. disable standard block padding
  96. =item B<-debug>
  97. debug the BIOs used for I/O.
  98. =item B<-z>
  99. Compress or decompress clear text using zlib before encryption or after
  100. decryption. This option exists only if OpenSSL with compiled with zlib
  101. or zlib-dynamic option.
  102. =item B<-none>
  103. Use NULL cipher (no encryption or decryption of input).
  104. =back
  105. =head1 NOTES
  106. The program can be called either as B<openssl ciphername> or
  107. B<openssl enc -ciphername>. But the first form doesn't work with
  108. engine-provided ciphers, because this form is processed before the
  109. configuration file is read and any ENGINEs loaded.
  110. Engines which provide entirely new encryption algorithms (such as ccgost
  111. engine which provides gost89 algorithm) should be configured in the
  112. configuration file. Engines, specified in the command line using -engine
  113. options can only be used for hadrware-assisted implementations of
  114. ciphers, which are supported by OpenSSL core or other engine, specified
  115. in the configuration file.
  116. When enc command lists supported ciphers, ciphers provided by engines,
  117. specified in the configuration files are listed too.
  118. A password will be prompted for to derive the key and IV if necessary.
  119. The B<-salt> option should B<ALWAYS> be used if the key is being derived
  120. from a password unless you want compatibility with previous versions of
  121. OpenSSL and SSLeay.
  122. Without the B<-salt> option it is possible to perform efficient dictionary
  123. attacks on the password and to attack stream cipher encrypted data. The reason
  124. for this is that without the salt the same password always generates the same
  125. encryption key. When the salt is being used the first eight bytes of the
  126. encrypted data are reserved for the salt: it is generated at random when
  127. encrypting a file and read from the encrypted file when it is decrypted.
  128. Some of the ciphers do not have large keys and others have security
  129. implications if not used correctly. A beginner is advised to just use
  130. a strong block cipher in CBC mode such as bf or des3.
  131. All the block ciphers normally use PKCS#5 padding also known as standard block
  132. padding: this allows a rudimentary integrity or password check to be
  133. performed. However since the chance of random data passing the test is
  134. better than 1 in 256 it isn't a very good test.
  135. If padding is disabled then the input data must be a multiple of the cipher
  136. block length.
  137. All RC2 ciphers have the same key and effective key length.
  138. Blowfish and RC5 algorithms use a 128 bit key.
  139. =head1 SUPPORTED CIPHERS
  140. Note that some of these ciphers can be disabled at compile time
  141. and some are available only if an appropriate engine is configured
  142. in the configuration file. The output of the B<enc> command run with
  143. unsupported options (for example B<openssl enc -help>) includes a
  144. list of ciphers, supported by your versesion of OpenSSL, including
  145. ones provided by configured engines.
  146. base64 Base 64
  147. bf-cbc Blowfish in CBC mode
  148. bf Alias for bf-cbc
  149. bf-cfb Blowfish in CFB mode
  150. bf-ecb Blowfish in ECB mode
  151. bf-ofb Blowfish in OFB mode
  152. cast-cbc CAST in CBC mode
  153. cast Alias for cast-cbc
  154. cast5-cbc CAST5 in CBC mode
  155. cast5-cfb CAST5 in CFB mode
  156. cast5-ecb CAST5 in ECB mode
  157. cast5-ofb CAST5 in OFB mode
  158. des-cbc DES in CBC mode
  159. des Alias for des-cbc
  160. des-cfb DES in CBC mode
  161. des-ofb DES in OFB mode
  162. des-ecb DES in ECB mode
  163. des-ede-cbc Two key triple DES EDE in CBC mode
  164. des-ede Two key triple DES EDE in ECB mode
  165. des-ede-cfb Two key triple DES EDE in CFB mode
  166. des-ede-ofb Two key triple DES EDE in OFB mode
  167. des-ede3-cbc Three key triple DES EDE in CBC mode
  168. des-ede3 Three key triple DES EDE in ECB mode
  169. des3 Alias for des-ede3-cbc
  170. des-ede3-cfb Three key triple DES EDE CFB mode
  171. des-ede3-ofb Three key triple DES EDE in OFB mode
  172. desx DESX algorithm.
  173. gost89 GOST 28147-89 in CFB mode (provided by ccgost engine)
  174. gost89-cnt `GOST 28147-89 in CNT mode (provided by ccgost engine)
  175. idea-cbc IDEA algorithm in CBC mode
  176. idea same as idea-cbc
  177. idea-cfb IDEA in CFB mode
  178. idea-ecb IDEA in ECB mode
  179. idea-ofb IDEA in OFB mode
  180. rc2-cbc 128 bit RC2 in CBC mode
  181. rc2 Alias for rc2-cbc
  182. rc2-cfb 128 bit RC2 in CFB mode
  183. rc2-ecb 128 bit RC2 in ECB mode
  184. rc2-ofb 128 bit RC2 in OFB mode
  185. rc2-64-cbc 64 bit RC2 in CBC mode
  186. rc2-40-cbc 40 bit RC2 in CBC mode
  187. rc4 128 bit RC4
  188. rc4-64 64 bit RC4
  189. rc4-40 40 bit RC4
  190. rc5-cbc RC5 cipher in CBC mode
  191. rc5 Alias for rc5-cbc
  192. rc5-cfb RC5 cipher in CFB mode
  193. rc5-ecb RC5 cipher in ECB mode
  194. rc5-ofb RC5 cipher in OFB mode
  195. aes-[128|192|256]-cbc 128/192/256 bit AES in CBC mode
  196. aes-[128|192|256] Alias for aes-[128|192|256]-cbc
  197. aes-[128|192|256]-cfb 128/192/256 bit AES in 128 bit CFB mode
  198. aes-[128|192|256]-cfb1 128/192/256 bit AES in 1 bit CFB mode
  199. aes-[128|192|256]-cfb8 128/192/256 bit AES in 8 bit CFB mode
  200. aes-[128|192|256]-ecb 128/192/256 bit AES in ECB mode
  201. aes-[128|192|256]-ofb 128/192/256 bit AES in OFB mode
  202. =head1 EXAMPLES
  203. Just base64 encode a binary file:
  204. openssl base64 -in file.bin -out file.b64
  205. Decode the same file
  206. openssl base64 -d -in file.b64 -out file.bin
  207. Encrypt a file using triple DES in CBC mode using a prompted password:
  208. openssl des3 -salt -in file.txt -out file.des3
  209. Decrypt a file using a supplied password:
  210. openssl des3 -d -salt -in file.des3 -out file.txt -k mypassword
  211. Encrypt a file then base64 encode it (so it can be sent via mail for example)
  212. using Blowfish in CBC mode:
  213. openssl bf -a -salt -in file.txt -out file.bf
  214. Base64 decode a file then decrypt it:
  215. openssl bf -d -salt -a -in file.bf -out file.txt
  216. Decrypt some data using a supplied 40 bit RC4 key:
  217. openssl rc4-40 -in file.rc4 -out file.txt -K 0102030405
  218. =head1 BUGS
  219. The B<-A> option when used with large files doesn't work properly.
  220. There should be an option to allow an iteration count to be included.
  221. The B<enc> program only supports a fixed number of algorithms with
  222. certain parameters. So if, for example, you want to use RC2 with a
  223. 76 bit key or RC4 with an 84 bit key you can't use this program.
  224. =cut