2 {- OpenSSL::safe::output_do_not_edit_headers(); -}
6 openssl-pkcs8 - PKCS#8 format private key conversion command
13 [B<-inform> B<DER>|B<PEM>]
14 [B<-outform> B<DER>|B<PEM>]
30 {- $OpenSSL::safe::opt_r_synopsis -}
31 {- $OpenSSL::safe::opt_engine_synopsis -}{- $OpenSSL::safe::opt_provider_synopsis -}
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-format-options(1)> 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>
78 When this option is present and B<-topk8> is not a traditional format private
81 =item B<-in> I<filename>
83 This specifies the input filename to read a key from or standard input if this
84 option is not specified. If the key is encrypted a pass phrase will be
87 =item B<-passin> I<arg>, B<-passout> I<arg>
89 The password source for the input and output file.
90 For more information about the format of B<arg>
91 see L<openssl-passphrase-options(1)>.
93 =item B<-out> I<filename>
95 This specifies the output filename to write a key to or standard output by
96 default. If any encryption options are set then a pass phrase will be
97 prompted for. The output filename should B<not> be the same as the input
100 =item B<-iter> I<count>
102 When creating new PKCS#8 containers, use a given number of iterations on
103 the password in deriving the encryption key for the PKCS#8 output.
104 High values increase the time required to brute-force a PKCS#8 container.
108 PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo
109 structures using an appropriate password based encryption algorithm. With
110 this option an unencrypted PrivateKeyInfo structure is expected or output.
111 This option does not encrypt private keys at all and should only be used
112 when absolutely necessary. Certain software such as some versions of Java
113 code signing software used unencrypted private keys.
117 This option sets the PKCS#5 v2.0 algorithm.
119 The I<alg> argument is the encryption algorithm to use, valid values include
120 B<aes128>, B<aes256> and B<des3>. If this option isn't specified then B<aes256>
123 =item B<-v2prf> I<alg>
125 This option sets the PRF algorithm to use with PKCS#5 v2.0. A typical value
126 value would be B<hmacWithSHA256>. If this option isn't set then the default
127 for the cipher is used or B<hmacWithSHA256> if there is no default.
129 Some implementations may not support custom PRF algorithms and may require
130 the B<hmacWithSHA1> option to work.
134 This option indicates a PKCS#5 v1.5 or PKCS#12 algorithm should be used. Some
135 older implementations may not support PKCS#5 v2.0 and may require this option.
136 If not specified PKCS#5 v2.0 form is used.
140 Uses the B<scrypt> algorithm for private key encryption using default
141 parameters: currently N=16384, r=8 and p=1 and AES in CBC mode with a 256 bit
142 key. These parameters can be modified using the B<-scrypt_N>, B<-scrypt_r>,
143 B<-scrypt_p> and B<-v2> options.
145 =item B<-scrypt_N> I<N>, B<-scrypt_r> I<r>, B<-scrypt_p> I<p>
147 Sets the scrypt I<N>, I<r> or I<p> parameters.
149 {- $OpenSSL::safe::opt_r_item -}
151 {- $OpenSSL::safe::opt_engine_item -}
153 {- $OpenSSL::safe::opt_provider_item -}
159 By default, when converting a key to PKCS#8 format, PKCS#5 v2.0 using 256 bit
160 AES with HMAC and SHA256 is used.
162 Some older implementations do not support PKCS#5 v2.0 format and require
163 the older PKCS#5 v1.5 form instead, possibly also requiring insecure weak
164 encryption algorithms such as 56 bit DES.
166 Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
167 counts are more secure that those encrypted using the traditional
168 SSLeay compatible formats. So if additional security is considered
169 important the keys should be converted.
171 It is possible to write out DER encoded encrypted private keys in
172 PKCS#8 format because the encryption details are included at an ASN1
173 level whereas the traditional format includes them at a PEM level.
175 =head1 PKCS#5 V1.5 AND PKCS#12 ALGORITHMS
177 Various algorithms can be used with the B<-v1> command line option,
178 including PKCS#5 v1.5 and PKCS#12. These are described in more detail
183 =item B<PBE-MD2-DES PBE-MD5-DES>
185 These algorithms were included in the original PKCS#5 v1.5 specification.
186 They only offer 56 bits of protection since they both use DES.
188 =item B<PBE-SHA1-RC2-64>, B<PBE-MD2-RC2-64>, B<PBE-MD5-RC2-64>, B<PBE-SHA1-DES>
190 These algorithms are not mentioned in the original PKCS#5 v1.5 specification
191 but they use the same key derivation algorithm and are supported by some
192 software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or
195 =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>
197 These algorithms use the PKCS#12 password based encryption algorithm and
198 allow strong encryption algorithms like triple DES or 128 bit RC2 to be used.
204 Convert a private key to PKCS#8 format using default parameters (AES with
205 256 bit key and B<hmacWithSHA256>):
207 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
209 Convert a private key to PKCS#8 unencrypted format:
211 openssl pkcs8 -in key.pem -topk8 -nocrypt -out enckey.pem
213 Convert a private key to PKCS#5 v2.0 format using triple DES:
215 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
217 Convert a private key to PKCS#5 v2.0 format using AES with 256 bits in CBC
218 mode and B<hmacWithSHA512> PRF:
220 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA512 -out enckey.pem
222 Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
225 openssl pkcs8 -in key.pem -topk8 -v1 PBE-MD5-DES -out enckey.pem
227 Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
230 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
232 Read a DER unencrypted PKCS#8 format private key:
234 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
236 Convert a private key from any PKCS#8 encrypted format to traditional format:
238 openssl pkcs8 -in pk8.pem -traditional -out key.pem
240 Convert a private key to PKCS#8 format, encrypting with AES-256 and with
241 one million iterations of the password:
243 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -iter 1000000 -out pk8.pem
247 Test vectors from this PKCS#5 v2.0 implementation were posted to the
248 pkcs-tng mailing list using triple DES, DES and RC2 with high iteration
249 counts, several people confirmed that they could decrypt the private
250 keys produced and therefore, it can be assumed that the PKCS#5 v2.0
251 implementation is reasonably accurate at least as far as these
252 algorithms are concerned.
254 The format of PKCS#8 DSA (and other) private keys is not well documented:
255 it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA
256 PKCS#8 private key format complies with this standard.
260 There should be an option that prints out the encryption algorithm
261 in use and other details such as the iteration count.
268 L<openssl-genrsa(1)>,
273 The B<-iter> option was added in OpenSSL 1.1.0.
275 The B<-engine> option was deprecated in OpenSSL 3.0.
279 Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
281 Licensed under the Apache License 2.0 (the "License"). You may not use
282 this file except in compliance with the License. You can obtain a copy
283 in the file LICENSE in the source distribution or at
284 L<https://www.openssl.org/source/license.html>.