5 openssl-pkcs8 - PKCS#8 format private key conversion tool
12 [B<-inform> B<DER>|B<PEM>]
13 [B<-outform> B<DER>|B<PEM>]
21 [B<-writerand> I<file>]
33 =for openssl ifdef engine scrypt scrypt_N scrypt_r scrypt_p
37 This command processes private keys in PKCS#8 format. It can handle
38 both unencrypted PKCS#8 PrivateKeyInfo format and EncryptedPrivateKeyInfo
39 format with a variety of PKCS#5 (v1.5 and v2.0) and PKCS#12 algorithms.
47 Print out a usage message.
51 Normally a PKCS#8 private key is expected on input and a private key will be
52 written to the output file. With the B<-topk8> option the situation is
53 reversed: it reads a private key and writes a PKCS#8 format key.
55 =item B<-inform> B<DER>|B<PEM>, B<-outform> B<DER>|B<PEM>
57 The input and formats; the default is B<PEM>.
58 See L<openssl(1)/Format Options> for details.
60 If a key is being converted from PKCS#8 form (i.e. the B<-topk8> option is
61 not used) then the input file must be in PKCS#8 format. An encrypted
62 key is expected unless B<-nocrypt> is included.
64 If B<-topk8> is not used and B<PEM> mode is set the output file will be an
65 unencrypted private key in PKCS#8 format. If the B<-traditional> option is
66 used then a traditional format private key is written instead.
68 If B<-topk8> is not used and B<DER> mode is set the output file will be an
69 unencrypted private key in traditional DER format.
71 If B<-topk8> is used then any supported private key can be used for the input
72 file in a format specified by B<-inform>. The output file will be encrypted
73 PKCS#8 format using the specified encryption parameters unless B<-nocrypt>
79 When this option is present and B<-topk8> is not a traditional format private
82 =item B<-in> I<filename>
84 This specifies the input filename to read a key from or standard input if this
85 option is not specified. If the key is encrypted a pass phrase will be
88 =item B<-passin> I<arg>, B<-passout> I<arg>
90 The password source for the input and output file.
91 For more information about the format of B<arg>
92 see L<openssl(1)/Pass Phrase Options>.
94 =item B<-out> I<filename>
96 This specifies the output filename to write a key to or standard output by
97 default. If any encryption options are set then a pass phrase will be
98 prompted for. The output filename should B<not> be the same as the input
101 =item B<-iter> I<count>
103 When creating new PKCS#8 containers, use a given number of iterations on
104 the password in deriving the encryption key for the PKCS#8 output.
105 High values increase the time required to brute-force a PKCS#8 container.
109 PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo
110 structures using an appropriate password based encryption algorithm. With
111 this option an unencrypted PrivateKeyInfo structure is expected or output.
112 This option does not encrypt private keys at all and should only be used
113 when absolutely necessary. Certain software such as some versions of Java
114 code signing software used unencrypted private keys.
116 =item B<-rand> I<files>, B<-writerand> I<file>
118 See L<openssl(1)/Random State Options> for more information.
122 This option sets the PKCS#5 v2.0 algorithm.
124 The I<alg> argument is the encryption algorithm to use, valid values include
125 B<aes128>, B<aes256> and B<des3>. If this option isn't specified then B<aes256>
128 =item B<-v2prf> I<alg>
130 This option sets the PRF algorithm to use with PKCS#5 v2.0. A typical value
131 value would be B<hmacWithSHA256>. If this option isn't set then the default
132 for the cipher is used or B<hmacWithSHA256> if there is no default.
134 Some implementations may not support custom PRF algorithms and may require
135 the B<hmacWithSHA1> option to work.
139 This option indicates a PKCS#5 v1.5 or PKCS#12 algorithm should be used. Some
140 older implementations may not support PKCS#5 v2.0 and may require this option.
141 If not specified PKCS#5 v2.0 form is used.
143 =item B<-engine> I<id>
145 Specifying an engine (by its unique I<id> string) will cause this command
146 to attempt to obtain a functional reference to the specified engine,
147 thus initialising it if needed. The engine will then be set as the default
148 for all available algorithms.
152 Uses the B<scrypt> algorithm for private key encryption using default
153 parameters: currently N=16384, r=8 and p=1 and AES in CBC mode with a 256 bit
154 key. These parameters can be modified using the B<-scrypt_N>, B<-scrypt_r>,
155 B<-scrypt_p> and B<-v2> options.
157 =item B<-scrypt_N> I<N>, B<-scrypt_r> I<r>, B<-scrypt_p> I<p>
159 Sets the scrypt I<N>, I<r> or I<p> parameters.
165 By default, when converting a key to PKCS#8 format, PKCS#5 v2.0 using 256 bit
166 AES with HMAC and SHA256 is used.
168 Some older implementations do not support PKCS#5 v2.0 format and require
169 the older PKCS#5 v1.5 form instead, possibly also requiring insecure weak
170 encryption algorithms such as 56 bit DES.
172 Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
173 counts are more secure that those encrypted using the traditional
174 SSLeay compatible formats. So if additional security is considered
175 important the keys should be converted.
177 It is possible to write out DER encoded encrypted private keys in
178 PKCS#8 format because the encryption details are included at an ASN1
179 level whereas the traditional format includes them at a PEM level.
181 =head1 PKCS#5 V1.5 AND PKCS#12 ALGORITHMS
183 Various algorithms can be used with the B<-v1> command line option,
184 including PKCS#5 v1.5 and PKCS#12. These are described in more detail
189 =item B<PBE-MD2-DES PBE-MD5-DES>
191 These algorithms were included in the original PKCS#5 v1.5 specification.
192 They only offer 56 bits of protection since they both use DES.
194 =item B<PBE-SHA1-RC2-64>, B<PBE-MD2-RC2-64>, B<PBE-MD5-RC2-64>, B<PBE-SHA1-DES>
196 These algorithms are not mentioned in the original PKCS#5 v1.5 specification
197 but they use the same key derivation algorithm and are supported by some
198 software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or
201 =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>
203 These algorithms use the PKCS#12 password based encryption algorithm and
204 allow strong encryption algorithms like triple DES or 128 bit RC2 to be used.
210 Convert a private key to PKCS#8 format using default parameters (AES with
211 256 bit key and B<hmacWithSHA256>):
213 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
215 Convert a private key to PKCS#8 unencrypted format:
217 openssl pkcs8 -in key.pem -topk8 -nocrypt -out enckey.pem
219 Convert a private key to PKCS#5 v2.0 format using triple DES:
221 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
223 Convert a private key to PKCS#5 v2.0 format using AES with 256 bits in CBC
224 mode and B<hmacWithSHA512> PRF:
226 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA512 -out enckey.pem
228 Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
231 openssl pkcs8 -in key.pem -topk8 -v1 PBE-MD5-DES -out enckey.pem
233 Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
236 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
238 Read a DER unencrypted PKCS#8 format private key:
240 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
242 Convert a private key from any PKCS#8 encrypted format to traditional format:
244 openssl pkcs8 -in pk8.pem -traditional -out key.pem
246 Convert a private key to PKCS#8 format, encrypting with AES-256 and with
247 one million iterations of the password:
249 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -iter 1000000 -out pk8.pem
253 Test vectors from this PKCS#5 v2.0 implementation were posted to the
254 pkcs-tng mailing list using triple DES, DES and RC2 with high iteration
255 counts, several people confirmed that they could decrypt the private
256 keys produced and Therefore it can be assumed that the PKCS#5 v2.0
257 implementation is reasonably accurate at least as far as these
258 algorithms are concerned.
260 The format of PKCS#8 DSA (and other) private keys is not well documented:
261 it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA
262 PKCS#8 private key format complies with this standard.
266 There should be an option that prints out the encryption algorithm
267 in use and other details such as the iteration count.
274 L<openssl-genrsa(1)>,
279 The B<-iter> option was added in OpenSSL 1.1.0.
283 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
285 Licensed under the Apache License 2.0 (the "License"). You may not use
286 this file except in compliance with the License. You can obtain a copy
287 in the file LICENSE in the source distribution or at
288 L<https://www.openssl.org/source/license.html>.