1=pod 2 3=head1 NAME 4 5pkcs8 - PKCS#8 format private key conversion tool 6 7=head1 SYNOPSIS 8 9B<openssl> B<pkcs8> 10[B<-topk8>] 11[B<-inform PEM|DER>] 12[B<-outform PEM|DER>] 13[B<-in filename>] 14[B<-passin arg>] 15[B<-out filename>] 16[B<-passout arg>] 17[B<-noiter>] 18[B<-nocrypt>] 19[B<-nooct>] 20[B<-embed>] 21[B<-nsdb>] 22[B<-v2 alg>] 23[B<-v1 alg>] 24[B<-engine id>] 25 26=head1 DESCRIPTION 27 28The B<pkcs8> command processes private keys in PKCS#8 format. It can handle 29both unencrypted PKCS#8 PrivateKeyInfo format and EncryptedPrivateKeyInfo 30format with a variety of PKCS#5 (v1.5 and v2.0) and PKCS#12 algorithms. 31 32=head1 COMMAND OPTIONS 33 34=over 4 35 36=item B<-topk8> 37 38Normally a PKCS#8 private key is expected on input and a traditional format 39private key will be written. With the B<-topk8> option the situation is 40reversed: it reads a traditional format private key and writes a PKCS#8 41format key. 42 43=item B<-inform DER|PEM> 44 45This specifies the input format. If a PKCS#8 format key is expected on input 46then either a B<DER> or B<PEM> encoded version of a PKCS#8 key will be 47expected. Otherwise the B<DER> or B<PEM> format of the traditional format 48private key is used. 49 50=item B<-outform DER|PEM> 51 52This specifies the output format, the options have the same meaning as the 53B<-inform> option. 54 55=item B<-in filename> 56 57This specifies the input filename to read a key from or standard input if this 58option is not specified. If the key is encrypted a pass phrase will be 59prompted for. 60 61=item B<-passin arg> 62 63the input file password source. For more information about the format of B<arg> 64see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 65 66=item B<-out filename> 67 68This specifies the output filename to write a key to or standard output by 69default. If any encryption options are set then a pass phrase will be 70prompted for. The output filename should B<not> be the same as the input 71filename. 72 73=item B<-passout arg> 74 75the output file password source. For more information about the format of B<arg> 76see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 77 78=item B<-nocrypt> 79 80PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo 81structures using an appropriate password based encryption algorithm. With 82this option an unencrypted PrivateKeyInfo structure is expected or output. 83This option does not encrypt private keys at all and should only be used 84when absolutely necessary. Certain software such as some versions of Java 85code signing software used unencrypted private keys. 86 87=item B<-nooct> 88 89This option generates RSA private keys in a broken format that some software 90uses. Specifically the private key should be enclosed in a OCTET STRING 91but some software just includes the structure itself without the 92surrounding OCTET STRING. 93 94=item B<-embed> 95 96This option generates DSA keys in a broken format. The DSA parameters are 97embedded inside the PrivateKey structure. In this form the OCTET STRING 98contains an ASN1 SEQUENCE consisting of two structures: a SEQUENCE containing 99the parameters and an ASN1 INTEGER containing the private key. 100 101=item B<-nsdb> 102 103This option generates DSA keys in a broken format compatible with Netscape 104private key databases. The PrivateKey contains a SEQUENCE consisting of 105the public and private keys respectively. 106 107=item B<-v2 alg> 108 109This option enables the use of PKCS#5 v2.0 algorithms. Normally PKCS#8 110private keys are encrypted with the password based encryption algorithm 111called B<pbeWithMD5AndDES-CBC> this uses 56 bit DES encryption but it 112was the strongest encryption algorithm supported in PKCS#5 v1.5. Using 113the B<-v2> option PKCS#5 v2.0 algorithms are used which can use any 114encryption algorithm such as 168 bit triple DES or 128 bit RC2 however 115not many implementations support PKCS#5 v2.0 yet. If you are just using 116private keys with OpenSSL then this doesn't matter. 117 118The B<alg> argument is the encryption algorithm to use, valid values include 119B<des>, B<des3> and B<rc2>. It is recommended that B<des3> is used. 120 121=item B<-v1 alg> 122 123This option specifies a PKCS#5 v1.5 or PKCS#12 algorithm to use. A complete 124list of possible algorithms is included below. 125 126=item B<-engine id> 127 128specifying an engine (by it's unique B<id> string) will cause B<req> 129to attempt to obtain a functional reference to the specified engine, 130thus initialising it if needed. The engine will then be set as the default 131for all available algorithms. 132 133=back 134 135=head1 NOTES 136 137The encrypted form of a PEM encode PKCS#8 files uses the following 138headers and footers: 139 140 -----BEGIN ENCRYPTED PRIVATE KEY----- 141 -----END ENCRYPTED PRIVATE KEY----- 142 143The unencrypted form uses: 144 145 -----BEGIN PRIVATE KEY----- 146 -----END PRIVATE KEY----- 147 148Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration 149counts are more secure that those encrypted using the traditional 150SSLeay compatible formats. So if additional security is considered 151important the keys should be converted. 152 153The default encryption is only 56 bits because this is the encryption 154that most current implementations of PKCS#8 will support. 155 156Some software may use PKCS#12 password based encryption algorithms 157with PKCS#8 format private keys: these are handled automatically 158but there is no option to produce them. 159 160It is possible to write out DER encoded encrypted private keys in 161PKCS#8 format because the encryption details are included at an ASN1 162level whereas the traditional format includes them at a PEM level. 163 164=head1 PKCS#5 v1.5 and PKCS#12 algorithms. 165 166Various algorithms can be used with the B<-v1> command line option, 167including PKCS#5 v1.5 and PKCS#12. These are described in more detail 168below. 169 170=over 4 171 172=item B<PBE-MD2-DES PBE-MD5-DES> 173 174These algorithms were included in the original PKCS#5 v1.5 specification. 175They only offer 56 bits of protection since they both use DES. 176 177=item B<PBE-SHA1-RC2-64 PBE-MD2-RC2-64 PBE-MD5-RC2-64 PBE-SHA1-DES> 178 179These algorithms are not mentioned in the original PKCS#5 v1.5 specification 180but they use the same key derivation algorithm and are supported by some 181software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or 18256 bit DES. 183 184=item B<PBE-SHA1-RC4-128 PBE-SHA1-RC4-40 PBE-SHA1-3DES PBE-SHA1-2DES PBE-SHA1-RC2-128 PBE-SHA1-RC2-40> 185 186These algorithms use the PKCS#12 password based encryption algorithm and 187allow strong encryption algorithms like triple DES or 128 bit RC2 to be used. 188 189=back 190 191=head1 EXAMPLES 192 193Convert a private from traditional to PKCS#5 v2.0 format using triple 194DES: 195 196 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem 197 198Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm 199(DES): 200 201 openssl pkcs8 -in key.pem -topk8 -out enckey.pem 202 203Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm 204(3DES): 205 206 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES 207 208Read a DER unencrypted PKCS#8 format private key: 209 210 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem 211 212Convert a private key from any PKCS#8 format to traditional format: 213 214 openssl pkcs8 -in pk8.pem -out key.pem 215 216=head1 STANDARDS 217 218Test vectors from this PKCS#5 v2.0 implementation were posted to the 219pkcs-tng mailing list using triple DES, DES and RC2 with high iteration 220counts, several people confirmed that they could decrypt the private 221keys produced and Therefore it can be assumed that the PKCS#5 v2.0 222implementation is reasonably accurate at least as far as these 223algorithms are concerned. 224 225The format of PKCS#8 DSA (and other) private keys is not well documented: 226it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA 227PKCS#8 private key format complies with this standard. 228 229=head1 BUGS 230 231There should be an option that prints out the encryption algorithm 232in use and other details such as the iteration count. 233 234PKCS#8 using triple DES and PKCS#5 v2.0 should be the default private 235key format for OpenSSL: for compatibility several of the utilities use 236the old format at present. 237 238=head1 SEE ALSO 239 240L<dsa(1)|dsa(1)>, L<rsa(1)|rsa(1)>, L<genrsa(1)|genrsa(1)>, 241L<gendsa(1)|gendsa(1)> 242 243=cut 244