5 pkcs8 - PKCS#8 format private key conversion tool
27 The B<pkcs8> command processes private keys in PKCS#8 format. It can handle
28 both unencrypted PKCS#8 PrivateKeyInfo format and EncryptedPrivateKeyInfo
29 format with a variety of PKCS#5 (v1.5 and v2.0) and PKCS#12 algorithms.
31 =head1 COMMAND OPTIONS
37 Normally a PKCS#8 private key is expected on input and a traditional format
38 private key will be written. With the B<-topk8> option the situation is
39 reversed: it reads a traditional format private key and writes a PKCS#8
42 =item B<-inform DER|PEM>
44 This specifies the input format. If a PKCS#8 format key is expected on input
45 then either a B<DER> or B<PEM> encoded version of a PKCS#8 key will be
46 expected. Otherwise the B<DER> or B<PEM> format of the traditional format
49 =item B<-outform DER|PEM>
51 This specifies the output format, the options have the same meaning as the
56 This specifies the input filename to read a key from or standard input if this
57 option is not specified. If the key is encrypted a pass phrase will be
62 the input file password source. For more information about the format of B<arg>
63 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
65 =item B<-out filename>
67 This specifies the output filename to write a key to or standard output by
68 default. If any encryption options are set then a pass phrase will be
69 prompted for. The output filename should B<not> be the same as the input
74 the output file password source. For more information about the format of B<arg>
75 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>.
79 PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo
80 structures using an appropriate password based encryption algorithm. With
81 this option an unencrypted PrivateKeyInfo structure is expected or output.
82 This option does not encrypt private keys at all and should only be used
83 when absolutely necessary. Certain software such as some versions of Java
84 code signing software used unencrypted private keys.
88 This option generates RSA private keys in a broken format that some software
89 uses. Specifically the private key should be enclosed in a OCTET STRING
90 but some software just includes the structure itself without the
91 surrounding OCTET STRING.
95 This option generates DSA keys in a broken format. The DSA parameters are
96 embedded inside the PrivateKey structure. In this form the OCTET STRING
97 contains an ASN1 SEQUENCE consisting of two structures: a SEQUENCE containing
98 the parameters and an ASN1 INTEGER containing the private key.
102 This option generates DSA keys in a broken format compatible with Netscape
103 private key databases. The PrivateKey contains a SEQUENCE consisting of
104 the public and private keys respectively.
108 This option enables the use of PKCS#5 v2.0 algorithms. Normally PKCS#8
109 private keys are encrypted with the password based encryption algorithm
110 called B<pbeWithMD5AndDES-CBC> this uses 56 bit DES encryption but it
111 was the strongest encryption algorithm supported in PKCS#5 v1.5. Using
112 the B<-v2> option PKCS#5 v2.0 algorithms are used which can use any
113 encryption algorithm such as 168 bit triple DES or 128 bit RC2 however
114 not many implementations support PKCS#5 v2.0 yet. If you are just using
115 private keys with OpenSSL then this doesn't matter.
117 The B<alg> argument is the encryption algorithm to use, valid values include
118 B<des>, B<des3> and B<rc2>. It is recommended that B<des3> is used.
122 This option specifies a PKCS#5 v1.5 or PKCS#12 algorithm to use. A complete
123 list of possible algorithms is included below.
129 The encrypted form of a PEM encode PKCS#8 files uses the following
132 -----BEGIN ENCRYPTED PRIVATE KEY-----
133 -----END ENCRYPTED PRIVATE KEY-----
135 The unencrypted form uses:
137 -----BEGIN PRIVATE KEY-----
138 -----END PRIVATE KEY-----
140 Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
141 counts are more secure that those encrypted using the traditional
142 SSLeay compatible formats. So if additional security is considered
143 important the keys should be converted.
145 The default encryption is only 56 bits because this is the encryption
146 that most current implementations of PKCS#8 will support.
148 Some software may use PKCS#12 password based encryption algorithms
149 with PKCS#8 format private keys: these are handled automatically
150 but there is no option to produce them.
152 It is possible to write out DER encoded encrypted private keys in
153 PKCS#8 format because the encryption details are included at an ASN1
154 level whereas the traditional format includes them at a PEM level.
156 =head1 PKCS#5 v1.5 and PKCS#12 algorithms.
158 Various algorithms can be used with the B<-v1> command line option,
159 including PKCS#5 v1.5 and PKCS#12. These are described in more detail
164 =item B<PBE-MD2-DES PBE-MD5-DES>
166 These algorithms were included in the original PKCS#5 v1.5 specification.
167 They only offer 56 bits of protection since they both use DES.
169 =item B<PBE-SHA1-RC2-64 PBE-MD2-RC2-64 PBE-MD5-RC2-64 PBE-SHA1-DES>
171 These algorithms are not mentioned in the original PKCS#5 v1.5 specification
172 but they use the same key derivation algorithm and are supported by some
173 software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or
176 =item B<PBE-SHA1-RC4-128 PBE-SHA1-RC4-40 PBE-SHA1-3DES PBE-SHA1-2DES PBE-SHA1-RC2-128 PBE-SHA1-RC2-40>
178 These algorithms use the PKCS#12 password based encryption algorithm and
179 allow strong encryption algorithms like triple DES or 128 bit RC2 to be used.
185 Convert a private from traditional to PKCS#5 v2.0 format using triple
188 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
190 Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
193 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
195 Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
198 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
200 Read a DER unencrypted PKCS#8 format private key:
202 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
204 Convert a private key from any PKCS#8 format to traditional format:
206 openssl pkcs8 -in pk8.pem -out key.pem
210 Test vectors from this PKCS#5 v2.0 implementation were posted to the
211 pkcs-tng mailing list using triple DES, DES and RC2 with high iteration
212 counts, several people confirmed that they could decrypt the private
213 keys produced and Therefore it can be assumed that the PKCS#5 v2.0
214 implementation is reasonably accurate at least as far as these
215 algorithms are concerned.
217 The format of PKCS#8 DSA (and other) private keys is not well documented:
218 it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA
219 PKCS#8 private key format complies with this standard.
223 There should be an option that prints out the encryption algorithm
224 in use and other details such as the iteration count.
226 PKCS#8 using triple DES and PKCS#5 v2.0 should be the default private
227 key format for OpenSSL: for compatibility several of the utilities use
228 the old format at present.
232 L<dsa(1)|dsa(1)>, L<rsa(1)|rsa(1)>, L<genrsa(1)|genrsa(1)>,
233 L<gendsa(1)|gendsa(1)>