1RSAUTL(1) OpenSSL RSAUTL(1)
2
6 openssl-rsautl, rsautl - RSA utility
7
9 openssl rsautl [-help] [-in file] [-out file] [-inkey file] [-keyform
10 PEM|DER|ENGINE] [-pubin] [-certin] [-sign] [-verify] [-encrypt]
11 [-decrypt] [-rand file...] [-writerand file] [-pkcs] [-ssl] [-raw]
12 [-hexdump] [-asn1parse]
13
15 The rsautl command can be used to sign, verify, encrypt and decrypt
16 data using the RSA algorithm.
17
19 -help
20 Print out a usage message.
21 -in filename
23 This specifies the input filename to read data from or standard
24 input if this option is not specified.
25 -out filename
27 Specifies the output filename to write to or standard output by
28 default.
29 -inkey file
31 The input key file, by default it should be an RSA private key.
32 -keyform PEM|DER|ENGINE
34 The key format PEM, DER or ENGINE.
35 -pubin
37 The input file is an RSA public key.
38 -certin
40 The input is a certificate containing an RSA public key.
41 -sign
43 Sign the input data and output the signed result. This requires an
44 RSA private key.
45 -verify
47 Verify the input data and output the recovered data.
48 -encrypt
50 Encrypt the input data using an RSA public key.
51 -decrypt
53 Decrypt the input data using an RSA private key.
54 -rand file...
56 A file or files containing random data used to seed the random
57 number generator. Multiple files can be specified separated by an
58 OS-dependent character. The separator is ; for MS-Windows, , for
59 OpenVMS, and : for all others.
60 [-writerand file]
62 Writes random data to the specified file upon exit. This can be
63 used with a subsequent -rand flag.
64 -pkcs, -oaep, -ssl, -raw
66 The padding to use: PKCS#1 v1.5 (the default), PKCS#1 OAEP, special
67 padding used in SSL v2 backwards compatible handshakes, or no
68 padding, respectively. For signatures, only -pkcs and -raw can be
69 used.
70 -hexdump
72 Hex dump the output data.
73 -asn1parse
75 Parse the ASN.1 output data, this is useful when combined with the
76 -verify option.
77
79 rsautl because it uses the RSA algorithm directly can only be used to
80 sign or verify small pieces of data.
81
83 Sign some data using a private key:
84 openssl rsautl -sign -in file -inkey key.pem -out sig
86 Recover the signed data
88 openssl rsautl -verify -in sig -inkey key.pem
90 Examine the raw signed data:
92 openssl rsautl -verify -in sig -inkey key.pem -raw -hexdump
94 0000 - 00 01 ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
96 0010 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
97 0020 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
98 0030 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
99 0040 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
100 0050 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
101 0060 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
102 0070 - ff ff ff ff 00 68 65 6c-6c 6f 20 77 6f 72 6c 64 .....hello world
103 The PKCS#1 block formatting is evident from this. If this was done
105 using encrypt and decrypt the block would have been of type 2 (the
106 second byte) and random padding data visible instead of the 0xff bytes.
107 It is possible to analyse the signature of certificates using this
109 utility in conjunction with asn1parse. Consider the self signed example
110 in certs/pca-cert.pem . Running asn1parse as follows yields:
111 openssl asn1parse -in pca-cert.pem
113 0:d=0 hl=4 l= 742 cons: SEQUENCE
115 4:d=1 hl=4 l= 591 cons: SEQUENCE
116 8:d=2 hl=2 l= 3 cons: cont [ 0 ]
117 10:d=3 hl=2 l= 1 prim: INTEGER :02
118 13:d=2 hl=2 l= 1 prim: INTEGER :00
119 16:d=2 hl=2 l= 13 cons: SEQUENCE
120 18:d=3 hl=2 l= 9 prim: OBJECT :md5WithRSAEncryption
121 29:d=3 hl=2 l= 0 prim: NULL
122 31:d=2 hl=2 l= 92 cons: SEQUENCE
123 33:d=3 hl=2 l= 11 cons: SET
124 35:d=4 hl=2 l= 9 cons: SEQUENCE
125 37:d=5 hl=2 l= 3 prim: OBJECT :countryName
126 42:d=5 hl=2 l= 2 prim: PRINTABLESTRING :AU
127 ....
128 599:d=1 hl=2 l= 13 cons: SEQUENCE
129 601:d=2 hl=2 l= 9 prim: OBJECT :md5WithRSAEncryption
130 612:d=2 hl=2 l= 0 prim: NULL
131 614:d=1 hl=3 l= 129 prim: BIT STRING
132 The final BIT STRING contains the actual signature. It can be extracted
134 with:
135 openssl asn1parse -in pca-cert.pem -out sig -noout -strparse 614
137 The certificate public key can be extracted with:
139 openssl x509 -in test/testx509.pem -pubkey -noout >pubkey.pem
141 The signature can be analysed with:
143 openssl rsautl -in sig -verify -asn1parse -inkey pubkey.pem -pubin
145 0:d=0 hl=2 l= 32 cons: SEQUENCE
147 2:d=1 hl=2 l= 12 cons: SEQUENCE
148 4:d=2 hl=2 l= 8 prim: OBJECT :md5
149 14:d=2 hl=2 l= 0 prim: NULL
150 16:d=1 hl=2 l= 16 prim: OCTET STRING
151 0000 - f3 46 9e aa 1a 4a 73 c9-37 ea 93 00 48 25 08 b5 .F...Js.7...H%..
152 This is the parsed version of an ASN1 DigestInfo structure. It can be
154 seen that the digest used was md5. The actual part of the certificate
155 that was signed can be extracted with:
156 openssl asn1parse -in pca-cert.pem -out tbs -noout -strparse 4
158 and its digest computed with:
160 openssl md5 -c tbs
162 MD5(tbs)= f3:46:9e:aa:1a:4a:73:c9:37:ea:93:00:48:25:08:b5
163 which it can be seen agrees with the recovered value above.
165
167 dgst(1), rsa(1), genrsa(1)
168
170 Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
171 Licensed under the OpenSSL license (the "License"). You may not use
173 this file except in compliance with the License. You can obtain a copy
174 in the file LICENSE in the source distribution or at
175 <https://www.openssl.org/source/license.html>.
1761.1.1l 2021-09-15 RSAUTL(1)