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. The default
58 =item B<-outform DER|PEM>
60 This specifies the output format: see L<KEY FORMATS> for more details. The default
65 When this option is present and B<-topk8> is not a traditional format private
70 This specifies the input filename to read a key from or standard input if this
71 option is not specified. If the key is encrypted a pass phrase will be
76 The input file password source. For more information about the format of B<arg>
77 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
79 =item B<-out filename>
81 This specifies the output filename to write a key to or standard output by
82 default. If any encryption options are set then a pass phrase will be
83 prompted for. The output filename should B<not> be the same as the input
88 The output file password source. For more information about the format of B<arg>
89 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
93 When creating new PKCS#8 containers, use a given number of iterations on
94 the password in deriving the encryption key for the PKCS#8 output.
95 High values increase the time required to brute-force a PKCS#8 container.
99 PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo
100 structures using an appropriate password based encryption algorithm. With
101 this option an unencrypted PrivateKeyInfo structure is expected or output.
102 This option does not encrypt private keys at all and should only be used
103 when absolutely necessary. Certain software such as some versions of Java
104 code signing software used unencrypted private keys.
106 =item B<-rand file...>
108 A file or files containing random data used to seed the random number
110 Multiple files can be specified separated by an OS-dependent character.
111 The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for
114 =item [B<-writerand file>]
116 Writes random data to the specified I<file> upon exit.
117 This can be used with a subsequent B<-rand> flag.
121 This option sets the PKCS#5 v2.0 algorithm.
123 The B<alg> argument is the encryption algorithm to use, valid values include
124 B<aes128>, B<aes256> and B<des3>. If this option isn't specified then B<aes256>
129 This option sets the PRF algorithm to use with PKCS#5 v2.0. A typical value
130 value would be B<hmacWithSHA256>. If this option isn't set then the default
131 for the cipher is used or B<hmacWithSHA256> if there is no default.
133 Some implementations may not support custom PRF algorithms and may require
134 the B<hmacWithSHA1> option to work.
138 This option indicates a PKCS#5 v1.5 or PKCS#12 algorithm should be used. Some
139 older implementations may not support PKCS#5 v2.0 and may require this option.
140 If not specified PKCS#5 v2.0 form is used.
144 Specifying an engine (by its unique B<id> string) will cause B<pkcs8>
145 to attempt to obtain a functional reference to the specified engine,
146 thus initialising it if needed. The engine will then be set as the default
147 for all available algorithms.
151 Uses the B<scrypt> algorithm for private key encryption using default
152 parameters: currently N=16384, r=8 and p=1 and AES in CBC mode with a 256 bit
153 key. These parameters can be modified using the B<-scrypt_N>, B<-scrypt_r>,
154 B<-scrypt_p> and B<-v2> options.
156 =item B<-scrypt_N N> B<-scrypt_r r> B<-scrypt_p p>
158 Sets the scrypt B<N>, B<r> or B<p> parameters.
164 Various different formats are used by the pkcs8 utility. These are detailed
167 If a key is being converted from PKCS#8 form (i.e. the B<-topk8> option is
168 not used) then the input file must be in PKCS#8 format. An encrypted
169 key is expected unless B<-nocrypt> is included.
171 If B<-topk8> is not used and B<PEM> mode is set the output file will be an
172 unencrypted private key in PKCS#8 format. If the B<-traditional> option is
173 used then a traditional format private key is written instead.
175 If B<-topk8> is not used and B<DER> mode is set the output file will be an
176 unencrypted private key in traditional DER format.
178 If B<-topk8> is used then any supported private key can be used for the input
179 file in a format specified by B<-inform>. The output file will be encrypted
180 PKCS#8 format using the specified encryption parameters unless B<-nocrypt>
185 By default, when converting a key to PKCS#8 format, PKCS#5 v2.0 using 256 bit
186 AES with HMAC and SHA256 is used.
188 Some older implementations do not support PKCS#5 v2.0 format and require
189 the older PKCS#5 v1.5 form instead, possibly also requiring insecure weak
190 encryption algorithms such as 56 bit DES.
192 The encrypted form of a PEM encode PKCS#8 files uses the following
195 -----BEGIN ENCRYPTED PRIVATE KEY-----
196 -----END ENCRYPTED PRIVATE KEY-----
198 The unencrypted form uses:
200 -----BEGIN PRIVATE KEY-----
201 -----END PRIVATE KEY-----
203 Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
204 counts are more secure that those encrypted using the traditional
205 SSLeay compatible formats. So if additional security is considered
206 important the keys should be converted.
208 It is possible to write out DER encoded encrypted private keys in
209 PKCS#8 format because the encryption details are included at an ASN1
210 level whereas the traditional format includes them at a PEM level.
212 =head1 PKCS#5 v1.5 and PKCS#12 algorithms.
214 Various algorithms can be used with the B<-v1> command line option,
215 including PKCS#5 v1.5 and PKCS#12. These are described in more detail
220 =item B<PBE-MD2-DES PBE-MD5-DES>
222 These algorithms were included in the original PKCS#5 v1.5 specification.
223 They only offer 56 bits of protection since they both use DES.
225 =item B<PBE-SHA1-RC2-64 PBE-MD2-RC2-64 PBE-MD5-RC2-64 PBE-SHA1-DES>
227 These algorithms are not mentioned in the original PKCS#5 v1.5 specification
228 but they use the same key derivation algorithm and are supported by some
229 software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or
232 =item B<PBE-SHA1-RC4-128 PBE-SHA1-RC4-40 PBE-SHA1-3DES PBE-SHA1-2DES PBE-SHA1-RC2-128 PBE-SHA1-RC2-40>
234 These algorithms use the PKCS#12 password based encryption algorithm and
235 allow strong encryption algorithms like triple DES or 128 bit RC2 to be used.
241 Convert a private key to PKCS#8 format using default parameters (AES with
242 256 bit key and B<hmacWithSHA256>):
244 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
246 Convert a private key to PKCS#8 unencrypted format:
248 openssl pkcs8 -in key.pem -topk8 -nocrypt -out enckey.pem
250 Convert a private key to PKCS#5 v2.0 format using triple DES:
252 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
254 Convert a private key to PKCS#5 v2.0 format using AES with 256 bits in CBC
255 mode and B<hmacWithSHA512> PRF:
257 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA512 -out enckey.pem
259 Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
262 openssl pkcs8 -in key.pem -topk8 -v1 PBE-MD5-DES -out enckey.pem
264 Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
267 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
269 Read a DER unencrypted PKCS#8 format private key:
271 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
273 Convert a private key from any PKCS#8 encrypted format to traditional format:
275 openssl pkcs8 -in pk8.pem -traditional -out key.pem
277 Convert a private key to PKCS#8 format, encrypting with AES-256 and with
278 one million iterations of the password:
280 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -iter 1000000 -out pk8.pem
284 Test vectors from this PKCS#5 v2.0 implementation were posted to the
285 pkcs-tng mailing list using triple DES, DES and RC2 with high iteration
286 counts, several people confirmed that they could decrypt the private
287 keys produced and Therefore it can be assumed that the PKCS#5 v2.0
288 implementation is reasonably accurate at least as far as these
289 algorithms are concerned.
291 The format of PKCS#8 DSA (and other) private keys is not well documented:
292 it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA
293 PKCS#8 private key format complies with this standard.
297 There should be an option that prints out the encryption algorithm
298 in use and other details such as the iteration count.
302 L<dsa(1)>, L<rsa(1)>, L<genrsa(1)>,
307 The B<-iter> option was added to OpenSSL 1.1.0.
311 Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
313 Licensed under the OpenSSL license (the "License"). You may not use
314 this file except in compliance with the License. You can obtain a copy
315 in the file LICENSE in the source distribution or at
316 L<https://www.openssl.org/source/license.html>.