2 {- OpenSSL::safe::output_do_not_edit_headers(); -}
6 openssl-pkcs8 - PKCS#8 format private key conversion tool
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 -}
32 {- $OpenSSL::safe::opt_provider_synopsis -}
34 =for openssl ifdef engine scrypt scrypt_N scrypt_r scrypt_p
38 This command processes private keys in PKCS#8 format. It can handle
39 both unencrypted PKCS#8 PrivateKeyInfo format and EncryptedPrivateKeyInfo
40 format with a variety of PKCS#5 (v1.5 and v2.0) and PKCS#12 algorithms.
48 Print out a usage message.
52 Normally a PKCS#8 private key is expected on input and a private key will be
53 written to the output file. With the B<-topk8> option the situation is
54 reversed: it reads a private key and writes a PKCS#8 format key.
56 =item B<-inform> B<DER>|B<PEM>, B<-outform> B<DER>|B<PEM>
58 The input and formats; the default is B<PEM>.
59 See L<openssl(1)/Format Options> for details.
61 If a key is being converted from PKCS#8 form (i.e. the B<-topk8> option is
62 not used) then the input file must be in PKCS#8 format. An encrypted
63 key is expected unless B<-nocrypt> is included.
65 If B<-topk8> is not used and B<PEM> mode is set the output file will be an
66 unencrypted private key in PKCS#8 format. If the B<-traditional> option is
67 used then a traditional format private key is written instead.
69 If B<-topk8> is not used and B<DER> mode is set the output file will be an
70 unencrypted private key in traditional DER format.
72 If B<-topk8> is used then any supported private key can be used for the input
73 file in a format specified by B<-inform>. The output file will be encrypted
74 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.
118 This option sets the PKCS#5 v2.0 algorithm.
120 The I<alg> argument is the encryption algorithm to use, valid values include
121 B<aes128>, B<aes256> and B<des3>. If this option isn't specified then B<aes256>
124 =item B<-v2prf> I<alg>
126 This option sets the PRF algorithm to use with PKCS#5 v2.0. A typical value
127 value would be B<hmacWithSHA256>. If this option isn't set then the default
128 for the cipher is used or B<hmacWithSHA256> if there is no default.
130 Some implementations may not support custom PRF algorithms and may require
131 the B<hmacWithSHA1> option to work.
135 This option indicates a PKCS#5 v1.5 or PKCS#12 algorithm should be used. Some
136 older implementations may not support PKCS#5 v2.0 and may require this option.
137 If not specified PKCS#5 v2.0 form is used.
141 Uses the B<scrypt> algorithm for private key encryption using default
142 parameters: currently N=16384, r=8 and p=1 and AES in CBC mode with a 256 bit
143 key. These parameters can be modified using the B<-scrypt_N>, B<-scrypt_r>,
144 B<-scrypt_p> and B<-v2> options.
146 =item B<-scrypt_N> I<N>, B<-scrypt_r> I<r>, B<-scrypt_p> I<p>
148 Sets the scrypt I<N>, I<r> or I<p> parameters.
150 {- $OpenSSL::safe::opt_r_item -}
152 {- $OpenSSL::safe::opt_engine_item -}
154 {- $OpenSSL::safe::opt_provider_item -}
160 By default, when converting a key to PKCS#8 format, PKCS#5 v2.0 using 256 bit
161 AES with HMAC and SHA256 is used.
163 Some older implementations do not support PKCS#5 v2.0 format and require
164 the older PKCS#5 v1.5 form instead, possibly also requiring insecure weak
165 encryption algorithms such as 56 bit DES.
167 Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
168 counts are more secure that those encrypted using the traditional
169 SSLeay compatible formats. So if additional security is considered
170 important the keys should be converted.
172 It is possible to write out DER encoded encrypted private keys in
173 PKCS#8 format because the encryption details are included at an ASN1
174 level whereas the traditional format includes them at a PEM level.
176 =head1 PKCS#5 V1.5 AND PKCS#12 ALGORITHMS
178 Various algorithms can be used with the B<-v1> command line option,
179 including PKCS#5 v1.5 and PKCS#12. These are described in more detail
184 =item B<PBE-MD2-DES PBE-MD5-DES>
186 These algorithms were included in the original PKCS#5 v1.5 specification.
187 They only offer 56 bits of protection since they both use DES.
189 =item B<PBE-SHA1-RC2-64>, B<PBE-MD2-RC2-64>, B<PBE-MD5-RC2-64>, B<PBE-SHA1-DES>
191 These algorithms are not mentioned in the original PKCS#5 v1.5 specification
192 but they use the same key derivation algorithm and are supported by some
193 software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or
196 =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 These algorithms use the PKCS#12 password based encryption algorithm and
199 allow strong encryption algorithms like triple DES or 128 bit RC2 to be used.
205 Convert a private key to PKCS#8 format using default parameters (AES with
206 256 bit key and B<hmacWithSHA256>):
208 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
210 Convert a private key to PKCS#8 unencrypted format:
212 openssl pkcs8 -in key.pem -topk8 -nocrypt -out enckey.pem
214 Convert a private key to PKCS#5 v2.0 format using triple DES:
216 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
218 Convert a private key to PKCS#5 v2.0 format using AES with 256 bits in CBC
219 mode and B<hmacWithSHA512> PRF:
221 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA512 -out enckey.pem
223 Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
226 openssl pkcs8 -in key.pem -topk8 -v1 PBE-MD5-DES -out enckey.pem
228 Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
231 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
233 Read a DER unencrypted PKCS#8 format private key:
235 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
237 Convert a private key from any PKCS#8 encrypted format to traditional format:
239 openssl pkcs8 -in pk8.pem -traditional -out key.pem
241 Convert a private key to PKCS#8 format, encrypting with AES-256 and with
242 one million iterations of the password:
244 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -iter 1000000 -out pk8.pem
248 Test vectors from this PKCS#5 v2.0 implementation were posted to the
249 pkcs-tng mailing list using triple DES, DES and RC2 with high iteration
250 counts, several people confirmed that they could decrypt the private
251 keys produced and Therefore it can be assumed that the PKCS#5 v2.0
252 implementation is reasonably accurate at least as far as these
253 algorithms are concerned.
255 The format of PKCS#8 DSA (and other) private keys is not well documented:
256 it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA
257 PKCS#8 private key format complies with this standard.
261 There should be an option that prints out the encryption algorithm
262 in use and other details such as the iteration count.
269 L<openssl-genrsa(1)>,
274 The B<-iter> option was added in OpenSSL 1.1.0.
278 Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
280 Licensed under the Apache License 2.0 (the "License"). You may not use
281 this file except in compliance with the License. You can obtain a copy
282 in the file LICENSE in the source distribution or at
283 L<https://www.openssl.org/source/license.html>.