openssl-rsautl - RSA command
openssl rsautl [
-help] [
-in file] [
-passin arg] [
-rev] [
-out file] [
-inkey filename|
uri] [
-keyform
DER|
PEM|
P12|
ENGINE] [
-pubin] [
-certin] [
-sign] [
-verify] [
-encrypt] [
-decrypt] [
-pkcs] [
-x931] [
-oaep] [
-raw] [
-hexdump] [
-asn1parse] [
-engine
id] [
-rand files] [
-writerand file] [
-provider name] [
-provider-path path] [
-propquery propq]
This command has been deprecated. The
openssl-pkeyutl(1) command should
be used instead.
This command can be used to sign, verify, encrypt and decrypt data using the RSA
algorithm.
- -help
- Print out a usage message.
-
-in filename
- This specifies the input filename to read data from or
standard input if this option is not specified.
-
-passin arg
- The passphrase used in the output file. See see
openssl-passphrase-options(1).
- -rev
- Reverse the order of the input.
-
-out filename
- Specifies the output filename to write to or standard
output by default.
-
-inkey filename|uri
- The input key, by default it should be an RSA private
key.
-
-keyform
DER|PEM|P12|ENGINE
- The key format; unspecified by default. See
openssl-format-options(1) for details.
- -pubin
- The input file is an RSA public key.
- -certin
- The input is a certificate containing an RSA public
key.
- -sign
- Sign the input data and output the signed result. This
requires an RSA private key.
- -verify
- Verify the input data and output the recovered data.
- -encrypt
- Encrypt the input data using an RSA public key.
- -decrypt
- Decrypt the input data using an RSA private key.
-
-pkcs, -oaep, -x931, -raw
- The padding to use: PKCS#1 v1.5 (the default), PKCS#1 OAEP,
ANSI X9.31, or no padding, respectively. For signatures, only -pkcs
and -raw can be used.
- -hexdump
- Hex dump the output data.
- -asn1parse
- Parse the ASN.1 output data, this is useful when combined
with the -verify option.
-
-engine id
- See "Engine Options" in openssl(1). This
option is deprecated.
-
-rand files, -writerand
file
- See "Random State Options" in openssl(1)
for details.
-
-provider name
-
-provider-path path
-
-propquery propq
- See "Provider Options" in openssl(1),
provider(7), and property(7).
Since this command uses the RSA algorithm directly, it can only be used to sign
or verify small pieces of data.
Examples equivalent to these can be found in the documentation for the
non-deprecated
openssl-pkeyutl(1) command.
Sign some data using a private key:
openssl rsautl -sign -in file -inkey key.pem -out sig
Recover the signed data
openssl rsautl -verify -in sig -inkey key.pem
Examine the raw signed data:
openssl rsautl -verify -in sig -inkey key.pem -raw -hexdump
0000 - 00 01 ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
0010 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
0020 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
0030 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
0040 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
0050 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
0060 - ff ff ff ff ff ff ff ff-ff ff ff ff ff ff ff ff ................
0070 - ff ff ff ff 00 68 65 6c-6c 6f 20 77 6f 72 6c 64 .....hello world
The PKCS#1 block formatting is evident from this. If this was done using encrypt
and decrypt the block would have been of type 2 (the second byte) and random
padding data visible instead of the 0xff bytes.
It is possible to analyse the signature of certificates using this command in
conjunction with
openssl-asn1parse(1). Consider the self signed example
in
certs/pca-cert.pem. Running
openssl-asn1parse(1) as follows
yields:
openssl asn1parse -in pca-cert.pem
0:d=0 hl=4 l= 742 cons: SEQUENCE
4:d=1 hl=4 l= 591 cons: SEQUENCE
8:d=2 hl=2 l= 3 cons: cont [ 0 ]
10:d=3 hl=2 l= 1 prim: INTEGER :02
13:d=2 hl=2 l= 1 prim: INTEGER :00
16:d=2 hl=2 l= 13 cons: SEQUENCE
18:d=3 hl=2 l= 9 prim: OBJECT :md5WithRSAEncryption
29:d=3 hl=2 l= 0 prim: NULL
31:d=2 hl=2 l= 92 cons: SEQUENCE
33:d=3 hl=2 l= 11 cons: SET
35:d=4 hl=2 l= 9 cons: SEQUENCE
37:d=5 hl=2 l= 3 prim: OBJECT :countryName
42:d=5 hl=2 l= 2 prim: PRINTABLESTRING :AU
....
599:d=1 hl=2 l= 13 cons: SEQUENCE
601:d=2 hl=2 l= 9 prim: OBJECT :md5WithRSAEncryption
612:d=2 hl=2 l= 0 prim: NULL
614:d=1 hl=3 l= 129 prim: BIT STRING
The final BIT STRING contains the actual signature. It can be extracted with:
openssl asn1parse -in pca-cert.pem -out sig -noout -strparse 614
The certificate public key can be extracted with:
openssl x509 -in test/testx509.pem -pubkey -noout >pubkey.pem
The signature can be analysed with:
openssl rsautl -in sig -verify -asn1parse -inkey pubkey.pem -pubin
0:d=0 hl=2 l= 32 cons: SEQUENCE
2:d=1 hl=2 l= 12 cons: SEQUENCE
4:d=2 hl=2 l= 8 prim: OBJECT :md5
14:d=2 hl=2 l= 0 prim: NULL
16:d=1 hl=2 l= 16 prim: OCTET STRING
0000 - f3 46 9e aa 1a 4a 73 c9-37 ea 93 00 48 25 08 b5 .F...Js.7...H%..
This is the parsed version of an ASN1 DigestInfo structure. It can be seen that
the digest used was md5. The actual part of the certificate that was signed
can be extracted with:
openssl asn1parse -in pca-cert.pem -out tbs -noout -strparse 4
and its digest computed with:
openssl md5 -c tbs
MD5(tbs)= f3:46:9e:aa:1a:4a:73:c9:37:ea:93:00:48:25:08:b5
which it can be seen agrees with the recovered value above.
openssl(1),
openssl-pkeyutl(1),
openssl-dgst(1),
openssl-rsa(1),
openssl-genrsa(1)
This command was deprecated in OpenSSL 3.0.
The
-engine option was deprecated in OpenSSL 3.0.
Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy in the
file LICENSE in the source distribution or at
<
https://www.openssl.org/source/license.html>.