5 pkcs8 - PKCS#8 format private key conversion tool
35 The B<pkcs8> command processes private keys in PKCS#8 format. It can handle
36 both unencrypted PKCS#8 PrivateKeyInfo format and EncryptedPrivateKeyInfo
37 format with a variety of PKCS#5 (v1.5 and v2.0) and PKCS#12 algorithms.
45 Print out a usage message.
49 Normally a PKCS#8 private key is expected on input and a private key will be
50 written to the output file. With the B<-topk8> option the situation is
51 reversed: it reads a private key and writes a PKCS#8 format key.
53 =item B<-inform DER|PEM>
55 This specifies the input format: see L<KEY FORMATS> for more details.
57 =item B<-outform DER|PEM>
59 This specifies the output format: see L<KEY FORMATS> for more details.
63 When this option is present and B<-topk8> is not a traditional format private
68 This specifies the input filename to read a key from or standard input if this
69 option is not specified. If the key is encrypted a pass phrase will be
74 The input file password source. For more information about the format of B<arg>
75 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
77 =item B<-out filename>
79 This specifies the output filename to write a key to or standard output by
80 default. If any encryption options are set then a pass phrase will be
81 prompted for. The output filename should B<not> be the same as the input
86 The output file password source. For more information about the format of B<arg>
87 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
91 When creating new PKCS#8 containers, use a given number of iterations on
92 the password in deriving the encryption key for the PKCS#8 output.
93 High values increase the time required to brute-force a PKCS#8 container.
97 PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo
98 structures using an appropriate password based encryption algorithm. With
99 this option an unencrypted PrivateKeyInfo structure is expected or output.
100 This option does not encrypt private keys at all and should only be used
101 when absolutely necessary. Certain software such as some versions of Java
102 code signing software used unencrypted private keys.
104 =item B<-rand file...>
106 A file or files containing random data used to seed the random number
108 Multiple files can be specified separated by an OS-dependent character.
109 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
112 =item [B<-writerand file>]
114 Writes random data to the specified I<file> upon exit.
115 This can be used with a subsequent B<-rand> flag.
119 This option sets the PKCS#5 v2.0 algorithm.
121 The B<alg> argument is the encryption algorithm to use, valid values include
122 B<aes128>, B<aes256> and B<des3>. If this option isn't specified then B<aes256>
127 This option sets the PRF algorithm to use with PKCS#5 v2.0. A typical value
128 value would be B<hmacWithSHA256>. If this option isn't set then the default
129 for the cipher is used or B<hmacWithSHA256> if there is no default.
131 Some implementations may not support custom PRF algorithms and may require
132 the B<hmacWithSHA1> option to work.
136 This option indicates a PKCS#5 v1.5 or PKCS#12 algorithm should be used. Some
137 older implementations may not support PKCS#5 v2.0 and may require this option.
138 If not specified PKCS#5 v2.0 form is used.
142 Specifying an engine (by its unique B<id> string) will cause B<pkcs8>
143 to attempt to obtain a functional reference to the specified engine,
144 thus initialising it if needed. The engine will then be set as the default
145 for all available algorithms.
149 Uses the B<scrypt> algorithm for private key encryption using default
150 parameters: currently N=16384, r=8 and p=1 and AES in CBC mode with a 256 bit
151 key. These parameters can be modified using the B<-scrypt_N>, B<-scrypt_r>,
152 B<-scrypt_p> and B<-v2> options.
154 =item B<-scrypt_N N> B<-scrypt_r r> B<-scrypt_p p>
156 Sets the scrypt B<N>, B<r> or B<p> parameters.
162 Various different formats are used by the pkcs8 utility. These are detailed
165 If a key is being converted from PKCS#8 form (i.e. the B<-topk8> option is
166 not used) then the input file must be in PKCS#8 format. An encrypted
167 key is expected unless B<-nocrypt> is included.
169 If B<-topk8> is not used and B<PEM> mode is set the output file will be an
170 unencrypted private key in PKCS#8 format. If the B<-traditional> option is
171 used then a traditional format private key is written instead.
173 If B<-topk8> is not used and B<DER> mode is set the output file will be an
174 unencrypted private key in traditional DER format.
176 If B<-topk8> is used then any supported private key can be used for the input
177 file in a format specified by B<-inform>. The output file will be encrypted
178 PKCS#8 format using the specified encryption parameters unless B<-nocrypt>
183 By default, when converting a key to PKCS#8 format, PKCS#5 v2.0 using 256 bit
184 AES with HMAC and SHA256 is used.
186 Some older implementations do not support PKCS#5 v2.0 format and require
187 the older PKCS#5 v1.5 form instead, possibly also requiring insecure weak
188 encryption algorithms such as 56 bit DES.
190 The encrypted form of a PEM encode PKCS#8 files uses the following
193 -----BEGIN ENCRYPTED PRIVATE KEY-----
194 -----END ENCRYPTED PRIVATE KEY-----
196 The unencrypted form uses:
198 -----BEGIN PRIVATE KEY-----
199 -----END PRIVATE KEY-----
201 Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
202 counts are more secure that those encrypted using the traditional
203 SSLeay compatible formats. So if additional security is considered
204 important the keys should be converted.
206 It is possible to write out DER encoded encrypted private keys in
207 PKCS#8 format because the encryption details are included at an ASN1
208 level whereas the traditional format includes them at a PEM level.
210 =head1 PKCS#5 v1.5 and PKCS#12 algorithms.
212 Various algorithms can be used with the B<-v1> command line option,
213 including PKCS#5 v1.5 and PKCS#12. These are described in more detail
218 =item B<PBE-MD2-DES PBE-MD5-DES>
220 These algorithms were included in the original PKCS#5 v1.5 specification.
221 They only offer 56 bits of protection since they both use DES.
223 =item B<PBE-SHA1-RC2-64 PBE-MD2-RC2-64 PBE-MD5-RC2-64 PBE-SHA1-DES>
225 These algorithms are not mentioned in the original PKCS#5 v1.5 specification
226 but they use the same key derivation algorithm and are supported by some
227 software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or
230 =item B<PBE-SHA1-RC4-128 PBE-SHA1-RC4-40 PBE-SHA1-3DES PBE-SHA1-2DES PBE-SHA1-RC2-128 PBE-SHA1-RC2-40>
232 These algorithms use the PKCS#12 password based encryption algorithm and
233 allow strong encryption algorithms like triple DES or 128 bit RC2 to be used.
239 Convert a private key to PKCS#8 format using default parameters (AES with
240 256 bit key and B<hmacWithSHA256>):
242 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
244 Convert a private key to PKCS#8 unencrypted format:
246 openssl pkcs8 -in key.pem -topk8 -nocrypt -out enckey.pem
248 Convert a private key to PKCS#5 v2.0 format using triple DES:
250 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
252 Convert a private key to PKCS#5 v2.0 format using AES with 256 bits in CBC
253 mode and B<hmacWithSHA512> PRF:
255 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA512 -out enckey.pem
257 Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
260 openssl pkcs8 -in key.pem -topk8 -v1 PBE-MD5-DES -out enckey.pem
262 Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
265 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
267 Read a DER unencrypted PKCS#8 format private key:
269 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
271 Convert a private key from any PKCS#8 encrypted format to traditional format:
273 openssl pkcs8 -in pk8.pem -traditional -out key.pem
275 Convert a private key to PKCS#8 format, encrypting with AES-256 and with
276 one million iterations of the password:
278 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -iter 1000000 -out pk8.pem
282 Test vectors from this PKCS#5 v2.0 implementation were posted to the
283 pkcs-tng mailing list using triple DES, DES and RC2 with high iteration
284 counts, several people confirmed that they could decrypt the private
285 keys produced and Therefore it can be assumed that the PKCS#5 v2.0
286 implementation is reasonably accurate at least as far as these
287 algorithms are concerned.
289 The format of PKCS#8 DSA (and other) private keys is not well documented:
290 it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA
291 PKCS#8 private key format complies with this standard.
295 There should be an option that prints out the encryption algorithm
296 in use and other details such as the iteration count.
300 L<dsa(1)>, L<rsa(1)>, L<genrsa(1)>,
305 The B<-iter> option was added to OpenSSL 1.1.0.
309 Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
311 Licensed under the OpenSSL license (the "License"). You may not use
312 this file except in compliance with the License. You can obtain a copy
313 in the file LICENSE in the source distribution or at
314 L<https://www.openssl.org/source/license.html>.