Manual: openssl-rsautl

OPENSSL-RSAUTL(1SSL)					   OpenSSL					OPENSSL-RSAUTL(1SSL)

NAME
       openssl-rsautl - RSA command

SYNOPSIS
       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]
       [-provparam [name:]key=value] [-propquery propq]

DESCRIPTION
       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.

OPTIONS
       -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
	   By  default	a  private  key	 is read from the key input.  With this option a public key is read instead.  If the
	   input contains no public key but a private key, its public part is used.

       -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.

	   Note:  because  of  protection  against Bleichenbacher attacks, decryption using PKCS#1 v1.5 mode will not return
	   errors in case padding check failed.	 Use -raw and inspect the returned value manually to check if the padding is
	   correct.

       -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
       -provparam [name:]key=value
       -propquery propq
	   See "Provider Options" in openssl(1), provider(7), and property(7).

NOTES
       Since this command uses the RSA algorithm directly, it can only be used to sign or verify small pieces of data.

EXAMPLES
       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.

SEE ALSO
       openssl(1), openssl-pkeyutl(1), openssl-dgst(1), openssl-rsa(1), openssl-genrsa(1)

HISTORY
       This command was deprecated in OpenSSL 3.0.

       The -engine option was deprecated in OpenSSL 3.0.

COPYRIGHT
       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
       .

3.5.5							 2026-01-27					OPENSSL-RSAUTL(1SSL)