5 pkcs8 - PKCS#8 format private key conversion tool
32 The B<pkcs8> command processes private keys in PKCS#8 format. It can handle
33 both unencrypted PKCS#8 PrivateKeyInfo format and EncryptedPrivateKeyInfo
34 format with a variety of PKCS#5 (v1.5 and v2.0) and PKCS#12 algorithms.
36 =head1 COMMAND OPTIONS
42 Print out a usage message.
46 Normally a PKCS#8 private key is expected on input and a traditional format
47 private key will be written. With the B<-topk8> option the situation is
48 reversed: it reads a traditional format private key and writes a PKCS#8
51 =item B<-inform DER|PEM>
53 This specifies the input format. If a PKCS#8 format key is expected on input
54 then either a B<DER> or B<PEM> encoded version of a PKCS#8 key will be
55 expected. Otherwise the B<DER> or B<PEM> format of the traditional format
58 =item B<-outform DER|PEM>
60 This specifies the output format, the options have the same meaning as the
65 This specifies the input filename to read a key from or standard input if this
66 option is not specified. If the key is encrypted a pass phrase will be
71 the input file password source. For more information about the format of B<arg>
72 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
74 =item B<-out filename>
76 This specifies the output filename to write a key to or standard output by
77 default. If any encryption options are set then a pass phrase will be
78 prompted for. The output filename should B<not> be the same as the input
83 the output file password source. For more information about the format of B<arg>
84 see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)>.
88 When creating new PKCS#8 containers, use a given number of iterations on
89 the password in deriving the encryption key for the PKCS#8 output.
90 High values increase the time required to brute-force a PKCS#8 container.
94 PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo
95 structures using an appropriate password based encryption algorithm. With
96 this option an unencrypted PrivateKeyInfo structure is expected or output.
97 This option does not encrypt private keys at all and should only be used
98 when absolutely necessary. Certain software such as some versions of Java
99 code signing software used unencrypted private keys.
103 This option sets the PKCS#5 v2.0 algorithm.
105 The B<alg> argument is the encryption algorithm to use, valid values include
106 B<aes128>, B<aes256> and B<des3>. If this option isn't specified then B<aes256>
111 This option sets the PRF algorithm to use with PKCS#5 v2.0. A typical value
112 value would be B<hmacWithSHA256>. If this option isn't set then the default
113 for the cipher is used or B<hmacWithSHA256> if there is no default.
115 Some implementations may not support custom PRF algorithms and may require
116 the B<hmacWithSHA1> option to work.
120 This option indicates a PKCS#5 v1.5 or PKCS#12 algorithm should be used. Some
121 older implementations may not support PKCS#5 v2.0 and may require this option.
122 If not specified PKCS#5 v2.0 for is used.
126 specifying an engine (by its unique B<id> string) will cause B<pkcs8>
127 to attempt to obtain a functional reference to the specified engine,
128 thus initialising it if needed. The engine will then be set as the default
129 for all available algorithms.
133 uses the B<scrypt> algorithm for private key encryption using default
134 parameters: currently N=16384, r=8 and p=1 and AES in CBC mode with a 256 bit
135 key. These parameters can be modified using the B<-scrypt_N>, B<-scrypt_r>,
136 B<-scrypt_p> and B<-v2> options.
138 B<-scrypt_N N> B<-scrypt_r r> B<-scrypt_p p>
140 sets the scrypt B<N>, B<r> or B<p> parameters.
146 By default, when converting a key to PKCS#8 format, PKCS#5 v2.0 using 256 bit
147 AES with HMAC and SHA256 is used.
149 Some older implementations do not support PKCS#5 v2.0 format and require
150 the older PKCS#5 v1.5 form instead, possibly also requiring insecure weak
151 encryption algorithms such as 56 bit DES.
153 The encrypted form of a PEM encode PKCS#8 files uses the following
156 -----BEGIN ENCRYPTED PRIVATE KEY-----
157 -----END ENCRYPTED PRIVATE KEY-----
159 The unencrypted form uses:
161 -----BEGIN PRIVATE KEY-----
162 -----END PRIVATE KEY-----
164 Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
165 counts are more secure that those encrypted using the traditional
166 SSLeay compatible formats. So if additional security is considered
167 important the keys should be converted.
169 It is possible to write out DER encoded encrypted private keys in
170 PKCS#8 format because the encryption details are included at an ASN1
171 level whereas the traditional format includes them at a PEM level.
173 =head1 PKCS#5 v1.5 and PKCS#12 algorithms.
175 Various algorithms can be used with the B<-v1> command line option,
176 including PKCS#5 v1.5 and PKCS#12. These are described in more detail
181 =item B<PBE-MD2-DES PBE-MD5-DES>
183 These algorithms were included in the original PKCS#5 v1.5 specification.
184 They only offer 56 bits of protection since they both use DES.
186 =item B<PBE-SHA1-RC2-64 PBE-MD2-RC2-64 PBE-MD5-RC2-64 PBE-SHA1-DES>
188 These algorithms are not mentioned in the original PKCS#5 v1.5 specification
189 but they use the same key derivation algorithm and are supported by some
190 software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or
193 =item B<PBE-SHA1-RC4-128 PBE-SHA1-RC4-40 PBE-SHA1-3DES PBE-SHA1-2DES PBE-SHA1-RC2-128 PBE-SHA1-RC2-40>
195 These algorithms use the PKCS#12 password based encryption algorithm and
196 allow strong encryption algorithms like triple DES or 128 bit RC2 to be used.
202 Convert a private from traditional to PKCS#5 v2.0 format using triple
205 openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
207 Convert a private from traditional to PKCS#5 v2.0 format using AES with
208 256 bits in CBC mode and B<hmacWithSHA256> PRF:
210 openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA256 -out enckey.pem
212 Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
215 openssl pkcs8 -in key.pem -topk8 -out enckey.pem
217 Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
220 openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
222 Read a DER unencrypted PKCS#8 format private key:
224 openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
226 Convert a private key from any PKCS#8 format to traditional format:
228 openssl pkcs8 -in pk8.pem -out key.pem
230 Convert a private key to PKCS#8 format, encrypting with AES-256 and with
231 one million iterations of the password:
233 openssl pkcs8 -in raw.pem -topk8 -v2 aes-256-cbc -iter 1000000 -out pk8.pem
237 Test vectors from this PKCS#5 v2.0 implementation were posted to the
238 pkcs-tng mailing list using triple DES, DES and RC2 with high iteration
239 counts, several people confirmed that they could decrypt the private
240 keys produced and Therefore it can be assumed that the PKCS#5 v2.0
241 implementation is reasonably accurate at least as far as these
242 algorithms are concerned.
244 The format of PKCS#8 DSA (and other) private keys is not well documented:
245 it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA
246 PKCS#8 private key format complies with this standard.
250 There should be an option that prints out the encryption algorithm
251 in use and other details such as the iteration count.
253 PKCS#8 using triple DES and PKCS#5 v2.0 should be the default private
254 key format for OpenSSL: for compatibility several of the utilities use
255 the old format at present.
259 L<dsa(1)>, L<rsa(1)>, L<genrsa(1)>,
264 The B<-iter> option was added to OpenSSL 1.1.0.
268 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
270 Licensed under the OpenSSL license (the "License"). You may not use
271 this file except in compliance with the License. You can obtain a copy
272 in the file LICENSE in the source distribution or at
273 L<https://www.openssl.org/source/license.html>.