--- /dev/null
+=pod
+
+=head1 NAME
+
+rsautl - RSA utility
+
+=head1 SYNOPSIS
+
+B<openssl> B<rsautl>
+[B<-in file>]
+[B<-out file>]
+[B<-inkey file>]
+[B<-pubin>]
+[B<-certin>]
+[B<-sign>]
+[B<-verify>]
+[B<-encrypt>]
+[B<-decrypt>]
+[B<-pkcs>]
+[B<-ssl>]
+[B<-raw>]
+[B<-hexdump>]
+[B<-asn1parse>]
+
+=head1 DESCRIPTION
+
+The B<rsautl> command can be used to sign, verify, encrypt and decrypt
+data using the RSA algorithm.
+
+=head1 COMMAND OPTIONS
+
+=over 4
+
+=item B<-in filename>
+
+This specifies the input filename to read data from or standard input
+if this option is not specified.
+
+=item B<-out filename>
+
+specifies the output filename to write to or standard output by
+default.
+
+=item B<-inkey file>
+
+the input key file, by default it should be an RSA private key.
+
+=item B<-pubin>
+
+the input file is an RSA public key.
+
+=item B<-certin>
+
+the input is a certificate containing an RSA public key.
+
+=item B<-sign>
+
+sign the input data and output the signed result. This requires
+and RSA private key.
+
+=item B<-verify>
+
+verify the input data and output the recovered data.
+
+=item B<-encrypt>
+
+encrypt the input data using an RSA public key.
+
+=item B<-decrypt>
+
+decrypt the input data using an RSA private key.
+
+=item B<-pkcs, -oaep, -ssl, -raw>
+
+the padding to use: PKCS#1 v1.5 (the default), PKCS#1 OAEP,
+special padding used in SSL v2 backwards compatible handshakes,
+or no padding, respectively.
+For signatures, only B<-pkcs> and B<-raw> can be used.
+
+=item B<-hexdump>
+
+hex dump the output data.
+
+=item B<-asn1parse>
+
+asn1parse the output data, this is useful when combined with the
+B<-verify> option.
+
+=back
+
+=head1 NOTES
+
+B<rsautl> because it uses the RSA algorithm directly can only be
+used to sign or verify small pieces of data.
+
+=head1 EXAMPLES
+
+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 file -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
+utility in conjunction with B<asn1parse>. Consider the self signed
+example in certs/pca-cert.pem . Running B<asn1parse> 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.
+
+=head1 SEE ALSO
+
+L<dgst(1)|dgst(1)>, L<rsa(1)|rsa(1)>, L<genrsa(1)|genrsa(1)>
projects / cassiopeia.git / blobdiff