doc/man1/rsautl.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 openssl-rsautl,
   6 rsautl - RSA utility
   7
   8 =head1 SYNOPSIS
   9
  10 B<openssl> B<rsautl>
  11 [B<-help>]
  12 [B<-in file>]
  13 [B<-out file>]
  14 [B<-inkey file>]
  15 [B<-keyform PEM|DER|ENGINE>]
  16 [B<-pubin>]
  17 [B<-certin>]
  18 [B<-sign>]
  19 [B<-verify>]
  20 [B<-encrypt>]
  21 [B<-decrypt>]
  22 [B<-rand file...>]
  23 [B<-writerand file>]
  24 [B<-pkcs>]
  25 [B<-ssl>]
  26 [B<-raw>]
  27 [B<-hexdump>]
  28 [B<-asn1parse>]
  29
  30 =head1 DESCRIPTION
  31
  32 The B<rsautl> command can be used to sign, verify, encrypt and decrypt
  33 data using the RSA algorithm.
  34
  35 =head1 OPTIONS
  36
  37 =over 4
  38
  39 =item B<-help>
  40
  41 Print out a usage message.
  42
  43 =item B<-in filename>
  44
  45 This specifies the input filename to read data from or standard input
  46 if this option is not specified.
  47
  48 =item B<-out filename>
  49
  50 Specifies the output filename to write to or standard output by
  51 default.
  52
  53 =item B<-inkey file>
  54
  55 The input key file, by default it should be an RSA private key.
  56
  57 =item B<-keyform PEM|DER|ENGINE>
  58
  59 The key format PEM, DER or ENGINE.
  60
  61 =item B<-pubin>
  62
  63 The input file is an RSA public key.
  64
  65 =item B<-certin>
  66
  67 The input is a certificate containing an RSA public key.
  68
  69 =item B<-sign>
  70
  71 Sign the input data and output the signed result. This requires
  72 an RSA private key.
  73
  74 =item B<-verify>
  75
  76 Verify the input data and output the recovered data.
  77
  78 =item B<-encrypt>
  79
  80 Encrypt the input data using an RSA public key.
  81
  82 =item B<-decrypt>
  83
  84 Decrypt the input data using an RSA private key.
  85
  86 =item B<-rand file...>
  87
  88 A file or files containing random data used to seed the random number
  89 generator.
  90 Multiple files can be specified separated by an OS-dependent character.
  91 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
  92 all others.
  93
  94 =item [B<-writerand file>]
  95
  96 Writes random data to the specified I<file> upon exit.
  97 This can be used with a subsequent B<-rand> flag.
  98
  99 =item B<-pkcs, -oaep, -ssl, -raw>
 100
 101 The padding to use: PKCS#1 v1.5 (the default), PKCS#1 OAEP,
 102 special padding used in SSL v2 backwards compatible handshakes,
 103 or no padding, respectively.
 104 For signatures, only B<-pkcs> and B<-raw> can be used.
 105
 106 =item B<-hexdump>
 107
 108 Hex dump the output data.
 109
 110 =item B<-asn1parse>
 111
 112 Parse the ASN.1 output data, this is useful when combined with the
 113 B<-verify> option.
 114
 115 =back
 116
 117 =head1 NOTES
 118
 119 B<rsautl> because it uses the RSA algorithm directly can only be
 120 used to sign or verify small pieces of data.
 121
 122 =head1 EXAMPLES
 123
 124 Sign some data using a private key:
 125
 126  openssl rsautl -sign -in file -inkey key.pem -out sig
 127
 128 Recover the signed data
 129
 130  openssl rsautl -verify -in sig -inkey key.pem
 131
 132 Examine the raw signed data:
 133
 134  openssl rsautl -verify -in sig -inkey key.pem -raw -hexdump
 135
 136  0000 - 00 01 ff ff ff ff ff ff-ff ff ff ff ff ff ff ff   ................
 137  0010 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff   ................
 138  0020 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff   ................
 139  0030 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff   ................
 140  0040 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff   ................
 141  0050 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff   ................
 142  0060 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff   ................
 143  0070 - ff ff ff ff 00 68 65 6c-6c 6f 20 77 6f 72 6c 64   .....hello world
 144
 145 The PKCS#1 block formatting is evident from this. If this was done using
 146 encrypt and decrypt the block would have been of type 2 (the second byte)
 147 and random padding data visible instead of the 0xff bytes.
 148
 149 It is possible to analyse the signature of certificates using this
 150 utility in conjunction with B<asn1parse>. Consider the self signed
 151 example in certs/pca-cert.pem . Running B<asn1parse> as follows yields:
 152
 153  openssl asn1parse -in pca-cert.pem
 154
 155     0:d=0  hl=4 l= 742 cons: SEQUENCE
 156     4:d=1  hl=4 l= 591 cons:  SEQUENCE
 157     8:d=2  hl=2 l=   3 cons:   cont [ 0 ]
 158    10:d=3  hl=2 l=   1 prim:    INTEGER           :02
 159    13:d=2  hl=2 l=   1 prim:   INTEGER           :00
 160    16:d=2  hl=2 l=  13 cons:   SEQUENCE
 161    18:d=3  hl=2 l=   9 prim:    OBJECT            :md5WithRSAEncryption
 162    29:d=3  hl=2 l=   0 prim:    NULL
 163    31:d=2  hl=2 l=  92 cons:   SEQUENCE
 164    33:d=3  hl=2 l=  11 cons:    SET
 165    35:d=4  hl=2 l=   9 cons:     SEQUENCE
 166    37:d=5  hl=2 l=   3 prim:      OBJECT            :countryName
 167    42:d=5  hl=2 l=   2 prim:      PRINTABLESTRING   :AU
 168   ....
 169   599:d=1  hl=2 l=  13 cons:  SEQUENCE
 170   601:d=2  hl=2 l=   9 prim:   OBJECT            :md5WithRSAEncryption
 171   612:d=2  hl=2 l=   0 prim:   NULL
 172   614:d=1  hl=3 l= 129 prim:  BIT STRING
 173
 174
 175 The final BIT STRING contains the actual signature. It can be extracted with:
 176
 177  openssl asn1parse -in pca-cert.pem -out sig -noout -strparse 614
 178
 179 The certificate public key can be extracted with:
 180
 181  openssl x509 -in test/testx509.pem -pubkey -noout >pubkey.pem
 182
 183 The signature can be analysed with:
 184
 185  openssl rsautl -in sig -verify -asn1parse -inkey pubkey.pem -pubin
 186
 187     0:d=0  hl=2 l=  32 cons: SEQUENCE
 188     2:d=1  hl=2 l=  12 cons:  SEQUENCE
 189     4:d=2  hl=2 l=   8 prim:   OBJECT            :md5
 190    14:d=2  hl=2 l=   0 prim:   NULL
 191    16:d=1  hl=2 l=  16 prim:  OCTET STRING
 192       0000 - f3 46 9e aa 1a 4a 73 c9-37 ea 93 00 48 25 08 b5   .F...Js.7...H%..
 193
 194 This is the parsed version of an ASN1 DigestInfo structure. It can be seen that
 195 the digest used was md5. The actual part of the certificate that was signed can
 196 be extracted with:
 197
 198  openssl asn1parse -in pca-cert.pem -out tbs -noout -strparse 4
 199
 200 and its digest computed with:
 201
 202  openssl md5 -c tbs
 203  MD5(tbs)= f3:46:9e:aa:1a:4a:73:c9:37:ea:93:00:48:25:08:b5
 204
 205 which it can be seen agrees with the recovered value above.
 206
 207 =head1 SEE ALSO
 208
 209 L<dgst(1)>, L<rsa(1)>, L<genrsa(1)>
 210
 211 =head1 COPYRIGHT
 212
 213 Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
 214
 215 Licensed under the Apache License 2.0 (the "License").  You may not use
 216 this file except in compliance with the License.  You can obtain a copy
 217 in the file LICENSE in the source distribution or at
 218 L<https://www.openssl.org/source/license.html>.
 219
 220 =cut