5 pkcs8 - PKCS#8 format private key conversion tool
17 [B<-passout password>]
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
60 =item B<-passin password>
62 the input file password. Since certain utilities like "ps" make the command line
63 visible this option should be used with caution.
65 =item B<-envpassin var>
67 read the input file password from the environment variable B<var>.
69 =item B<-out filename>
71 This specifies the output filename to write a key to or standard output by
72 default. If any encryption options are set then a pass phrase will be
73 prompted for. The output filename should B<not> be the same as the input
76 =item B<-passout password>
78 the output file password. Since certain utilities like "ps" make the command line
79 visible this option should be used with caution.
81 =item B<-envpassout var>
83 read the output file password from the environment variable B<var>.
87 PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo
88 structures using an appropriate password based encryption algorithm. With
89 this option an unencrypted PrivateKeyInfo structure is expected or output.
90 This option does not encrypt private keys at all and should only be used
91 when absolutely necessary. Certain software such as some versions of Java
92 code signing software used unencrypted private keys.
96 This option generates private keys in a broken format that some software
97 uses. Specifically the private key should be enclosed in a OCTET STRING
98 but some software just includes the structure itself without the
99 surrounding OCTET STRING.
103 This option enables the use of PKCS#5 v2.0 algorithms. Normally PKCS#8
104 private keys are encrypted with the password based encryption algorithm
105 called B<pbeWithMD5AndDES-CBC> this uses 56 bit DES encryption but it
106 was the strongest encryption algorithm supported in PKCS#5 v1.5. Using
107 the B<-v2> option PKCS#5 v2.0 algorithms are used which can use any
108 encryption algorithm such as 168 bit triple DES or 128 bit RC2 however
109 not many implementations support PKCS#5 v2.0 yet. If you are just using
110 private keys with OpenSSL then this doesn't matter.
112 The B<alg> argument is the encryption algorithm to use, valid values include
113 B<des>, B<des3> and B<rc2>. It is recommended that B<des3> is used.
117 This option specifies a PKCS#5 v1.5 or PKCS#12 algorithm to use. A complete
118 list of possible algorithms is included below.
124 The encrypted form of a PEM encode PKCS#8 files uses the following
127 -----BEGIN ENCRYPTED PRIVATE KEY-----
128 -----END ENCRYPTED PRIVATE KEY-----
130 The unencrypted form uses:
132 -----BEGIN PRIVATE KEY-----
133 -----END PRIVATE KEY-----
135 Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
136 counts are more secure that those encrypted using the traditional
137 SSLeay compatible formats. So if additional security is considered
138 important the keys should be converted.
140 The default encryption is only 56 bits because this is the encryption
141 that most current implementations of PKCS#8 will support.
143 Some software may use PKCS#12 password based encryption algorithms
144 with PKCS#8 format private keys: these are handled automatically
145 but there is no option to produce them.
147 It is possible to write out DER encoded encrypted private keys in
148 PKCS#8 format because the encryption details are included at an ASN1
149 level whereas the traditional format includes them at a PEM level.
151 =head1 PKCS#5 v1.5 and PKCS#12 algorithms.
153 Various algorithms can be used with the B<-v1> command line option,
154 including PKCS#5 v1.5 and PKCS#12. These are described in more detail
159 =item B<PBE-MD2-DES PBE-MD5-DES>
161 These algorithms were included in the original PKCS#5 v1.5 specification.
162 They only offer 56 bits of protection since they both use DES.
164 =item B<PBE-SHA1-RC2-64 PBE-MD2-RC2-64 PBE-MD5-RC2-64 PBE-SHA1-DES>
166 These algorithms are not mentioned in the original PKCS#5 v1.5 specification
167 but they use the same key derivation algorithm and are supported by some
168 software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or
171 =item B<PBE-SHA1-RC4-128 PBE-SHA1-RC4-40 PBE-SHA1-3DES PBE-SHA1-2DES PBE-SHA1-RC2-128 PBE-SHA1-RC2-40>
173 These algorithms use the PKCS#12 password based encryption algorithm and
174 allow strong encryption algorithms like triple DES or 128 bit RC2 to be used.
180 Convert a private from traditional to PKCS#5 v2.0 format using triple
183 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
185 Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
188 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
190 Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
193 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
195 Read a DER unencrypted PKCS#8 format private key:
197 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
199 Convert a private key from any PKCS#8 format to traditional format:
201 openssl pkcs8 -in pk8.pem -out key.pem
205 Test vectors from this implementation were posted to the pkcs-tng mailing
206 list using triple DES, DES and RC2 with high iteration counts, several
207 people confirmed that they could decrypt the private keys produced and
208 Therefore it can be assumed that the PKCS#5 v2.0 implementation is
209 reasonably accurate at least as far as these algorithms are concerned.
213 There should be an option that prints out the encryption algorithm
214 in use and other details such as the iteration count.
216 PKCS#8 using triple DES and PKCS#5 v2.0 should be the default private
217 key format for OpenSSL: for compatibility several of the utilities use
218 the old format at present.
222 L<dsa(1)|dsa(1)>, L<rsa(1)|rsa(1)>, L<genrsa(1)|genrsa(1)>,
223 L<gendsa(1)|gendsa(1)>