| =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)> |
