xref: /openssl/doc/man1/openssl-pkcs8.pod.in (revision 359efeac) 
1=pod
2{- OpenSSL::safe::output_do_not_edit_headers(); -}
3
4=head1 NAME
5
6openssl-pkcs8 - PKCS#8 format private key conversion command
7
8=head1 SYNOPSIS
9
10B<openssl> B<pkcs8>
11[B<-help>]
12[B<-topk8>]
13[B<-inform> B<DER>|B<PEM>]
14[B<-outform> B<DER>|B<PEM>]
15[B<-in> I<filename>]
16[B<-passin> I<arg>]
17[B<-out> I<filename>]
18[B<-passout> I<arg>]
19[B<-iter> I<count>]
20[B<-noiter>]
21[B<-nocrypt>]
22[B<-traditional>]
23[B<-v2> I<alg>]
24[B<-v2prf> I<alg>]
25[B<-v1> I<alg>]
26[B<-scrypt>]
27[B<-scrypt_N> I<N>]
28[B<-scrypt_r> I<r>]
29[B<-scrypt_p> I<p>]
30{- $OpenSSL::safe::opt_r_synopsis -}
31{- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_provider_synopsis -}
32
33=head1 DESCRIPTION
34
35This command processes private keys in PKCS#8 format. It can handle
36both unencrypted PKCS#8 PrivateKeyInfo format and EncryptedPrivateKeyInfo
37format with a variety of PKCS#5 (v1.5 and v2.0) and PKCS#12 algorithms.
38
39=head1 OPTIONS
40
41=over 4
42
43=item B<-help>
44
45Print out a usage message.
46
47=item B<-topk8>
48
49Normally a PKCS#8 private key is expected on input and a private key will be
50written to the output file. With the B<-topk8> option the situation is
51reversed: it reads a private key and writes a PKCS#8 format key.
52
53=item B<-inform> B<DER>|B<PEM>, B<-outform> B<DER>|B<PEM>
54
55The input and formats; the default is B<PEM>.
56See L<openssl-format-options(1)> for details.
57
58If a key is being converted from PKCS#8 form (i.e. the B<-topk8> option is
59not used) then the input file must be in PKCS#8 format. An encrypted
60key is expected unless B<-nocrypt> is included.
61
62If B<-topk8> is not used and B<PEM> mode is set the output file will be an
63unencrypted private key in PKCS#8 format. If the B<-traditional> option is
64used then a traditional format private key is written instead.
65
66If B<-topk8> is not used and B<DER> mode is set the output file will be an
67unencrypted private key in traditional DER format.
68
69If B<-topk8> is used then any supported private key can be used for the input
70file in a format specified by B<-inform>. The output file will be encrypted
71PKCS#8 format using the specified encryption parameters unless B<-nocrypt>
72is included.
73
74=item B<-traditional>
75
76When this option is present and B<-topk8> is not a traditional format private
77key is written.
78
79=item B<-in> I<filename>
80
81This specifies the input filename to read a key from or standard input if this
82option is not specified. If the key is encrypted a pass phrase will be
83prompted for.
84
85=item B<-passin> I<arg>, B<-passout> I<arg>
86
87The password source for the input and output file.
88For more information about the format of B<arg>
89see L<openssl-passphrase-options(1)>.
90
91=item B<-out> I<filename>
92
93This specifies the output filename to write a key to or standard output by
94default. If any encryption options are set then a pass phrase will be
95prompted for. The output filename should B<not> be the same as the input
96filename.
97
98=item B<-iter> I<count>
99
100When creating new PKCS#8 containers, use a given number of iterations on
101the password in deriving the encryption key for the PKCS#8 output.
102High values increase the time required to brute-force a PKCS#8 container.
103
104=item B<-noiter>
105
106When creating new PKCS#8 containers, use 1 as iteration count.
107
108=item B<-nocrypt>
109
110PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo
111structures using an appropriate password based encryption algorithm. With
112this option an unencrypted PrivateKeyInfo structure is expected or output.
113This option does not encrypt private keys at all and should only be used
114when absolutely necessary. Certain software such as some versions of Java
115code signing software used unencrypted private keys.
116
117=item B<-v2> I<alg>
118
119This option sets the PKCS#5 v2.0 algorithm.
120
121The I<alg> argument is the encryption algorithm to use, valid values include
122B<aes128>, B<aes256> and B<des3>. If this option isn't specified then B<aes256>
123is used.
124
125=item B<-v2prf> I<alg>
126
127This option sets the PRF algorithm to use with PKCS#5 v2.0. A typical value
128value would be B<hmacWithSHA256>. If this option isn't set then the default
129for the cipher is used or B<hmacWithSHA256> if there is no default.
130
131Some implementations may not support custom PRF algorithms and may require
132the B<hmacWithSHA1> option to work.
133
134=item B<-v1> I<alg>
135
136This option indicates a PKCS#5 v1.5 or PKCS#12 algorithm should be used.  Some
137older implementations may not support PKCS#5 v2.0 and may require this option.
138If not specified PKCS#5 v2.0 form is used.
139
140=item B<-scrypt>
141
142Uses the B<scrypt> algorithm for private key encryption using default
143parameters: currently N=16384, r=8 and p=1 and AES in CBC mode with a 256 bit
144key. These parameters can be modified using the B<-scrypt_N>, B<-scrypt_r>,
145B<-scrypt_p> and B<-v2> options.
146
147=item B<-scrypt_N> I<N>, B<-scrypt_r> I<r>, B<-scrypt_p> I<p>
148
149Sets the scrypt I<N>, I<r> or I<p> parameters.
150
151{- $OpenSSL::safe::opt_r_item -}
152
153{- $OpenSSL::safe::opt_engine_item -}
154
155{- $OpenSSL::safe::opt_provider_item -}
156
157=back
158
159=head1 NOTES
160
161By default, when converting a key to PKCS#8 format, PKCS#5 v2.0 using 256 bit
162AES with HMAC and SHA256 is used.
163
164Some older implementations do not support PKCS#5 v2.0 format and require
165the older PKCS#5 v1.5 form instead, possibly also requiring insecure weak
166encryption algorithms such as 56 bit DES.
167
168Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
169counts are more secure that those encrypted using the traditional
170SSLeay compatible formats. So if additional security is considered
171important the keys should be converted.
172
173It is possible to write out DER encoded encrypted private keys in
174PKCS#8 format because the encryption details are included at an ASN1
175level whereas the traditional format includes them at a PEM level.
176
177=head1 PKCS#5 V1.5 AND PKCS#12 ALGORITHMS
178
179Various algorithms can be used with the B<-v1> command line option,
180including PKCS#5 v1.5 and PKCS#12. These are described in more detail
181below.
182
183=over 4
184
185=item B<PBE-MD2-DES PBE-MD5-DES>
186
187These algorithms were included in the original PKCS#5 v1.5 specification.
188They only offer 56 bits of protection since they both use DES.
189
190=item B<PBE-SHA1-RC2-64>, B<PBE-MD2-RC2-64>, B<PBE-MD5-RC2-64>, B<PBE-SHA1-DES>
191
192These algorithms are not mentioned in the original PKCS#5 v1.5 specification
193but they use the same key derivation algorithm and are supported by some
194software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or
19556 bit DES.
196
197=item B<PBE-SHA1-RC4-128>, B<PBE-SHA1-RC4-40>, B<PBE-SHA1-3DES>, B<PBE-SHA1-2DES>, B<PBE-SHA1-RC2-128>, B<PBE-SHA1-RC2-40>
198
199These algorithms use the PKCS#12 password based encryption algorithm and
200allow strong encryption algorithms like triple DES or 128 bit RC2 to be used.
201
202=back
203
204=head1 EXAMPLES
205
206Convert a private key to PKCS#8 format using default parameters (AES with
207256 bit key and B<hmacWithSHA256>):
208
209 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
210
211Convert a private key to PKCS#8 unencrypted format:
212
213 openssl pkcs8 -in key.pem -topk8 -nocrypt -out enckey.pem
214
215Convert a private key to PKCS#5 v2.0 format using triple DES:
216
217 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
218
219Convert a private key to PKCS#5 v2.0 format using AES with 256 bits in CBC
220mode and B<hmacWithSHA512> PRF:
221
222 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA512 -out enckey.pem
223
224Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
225(DES):
226
227 openssl pkcs8 -in key.pem -topk8 -v1 PBE-MD5-DES -out enckey.pem
228
229Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
230(3DES):
231
232 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
233
234Read a DER unencrypted PKCS#8 format private key:
235
236 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
237
238Convert a private key from any PKCS#8 encrypted format to traditional format:
239
240 openssl pkcs8 -in pk8.pem -traditional -out key.pem
241
242Convert a private key to PKCS#8 format, encrypting with AES-256 and with
243one million iterations of the password:
244
245 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -iter 1000000 -out pk8.pem
246
247=head1 STANDARDS
248
249Test vectors from this PKCS#5 v2.0 implementation were posted to the
250pkcs-tng mailing list using triple DES, DES and RC2 with high iteration
251counts, several people confirmed that they could decrypt the private
252keys produced and therefore, it can be assumed that the PKCS#5 v2.0
253implementation is reasonably accurate at least as far as these
254algorithms are concerned.
255
256The format of PKCS#8 DSA (and other) private keys is not well documented:
257it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA
258PKCS#8 private key format complies with this standard.
259
260=head1 BUGS
261
262There should be an option that prints out the encryption algorithm
263in use and other details such as the iteration count.
264
265=head1 SEE ALSO
266
267L<openssl(1)>,
268L<openssl-dsa(1)>,
269L<openssl-rsa(1)>,
270L<openssl-genrsa(1)>,
271L<openssl-gendsa(1)>
272
273=head1 HISTORY
274
275The B<-iter> option was added in OpenSSL 1.1.0.
276
277The B<-engine> option was deprecated in OpenSSL 3.0.
278
279=head1 COPYRIGHT
280
281Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
282
283Licensed under the Apache License 2.0 (the "License").  You may not use
284this file except in compliance with the License.  You can obtain a copy
285in the file LICENSE in the source distribution or at
286L<https://www.openssl.org/source/license.html>.
287
288=cut
289