1PKCS8(1)                            OpenSSL                           PKCS8(1)
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NAME

6       openssl-pkcs8, pkcs8 - PKCS#8 format private key conversion tool
7

SYNOPSIS

9       openssl pkcs8 [-help] [-topk8] [-inform PEM|DER] [-outform PEM|DER]
10       [-in filename] [-passin arg] [-out filename] [-passout arg] [-iter
11       count] [-noiter] [-rand file...]  [-writerand file] [-nocrypt]
12       [-traditional] [-v2 alg] [-v2prf alg] [-v1 alg] [-engine id] [-scrypt]
13       [-scrypt_N N] [-scrypt_r r] [-scrypt_p p]
14

DESCRIPTION

16       The pkcs8 command processes private keys in PKCS#8 format. It can
17       handle both unencrypted PKCS#8 PrivateKeyInfo format and
18       EncryptedPrivateKeyInfo format with a variety of PKCS#5 (v1.5 and v2.0)
19       and PKCS#12 algorithms.
20

OPTIONS

22       -help
23           Print out a usage message.
24
25       -topk8
26           Normally a PKCS#8 private key is expected on input and a private
27           key will be written to the output file. With the -topk8 option the
28           situation is reversed: it reads a private key and writes a PKCS#8
29           format key.
30
31       -inform DER|PEM
32           This specifies the input format: see "KEY FORMATS" for more
33           details. The default format is PEM.
34
35       -outform DER|PEM
36           This specifies the output format: see "KEY FORMATS" for more
37           details. The default format is PEM.
38
39       -traditional
40           When this option is present and -topk8 is not a traditional format
41           private key is written.
42
43       -in filename
44           This specifies the input filename to read a key from or standard
45           input if this option is not specified. If the key is encrypted a
46           pass phrase will be prompted for.
47
48       -passin arg
49           The input file password source. For more information about the
50           format of arg see "Pass Phrase Options" in openssl(1).
51
52       -out filename
53           This specifies the output filename to write a key to or standard
54           output by default. If any encryption options are set then a pass
55           phrase will be prompted for. The output filename should not be the
56           same as the input filename.
57
58       -passout arg
59           The output file password source. For more information about the
60           format of arg see "Pass Phrase Options" in openssl(1).
61
62       -iter count
63           When creating new PKCS#8 containers, use a given number of
64           iterations on the password in deriving the encryption key for the
65           PKCS#8 output.  High values increase the time required to brute-
66           force a PKCS#8 container.
67
68       -nocrypt
69           PKCS#8 keys generated or input are normally PKCS#8
70           EncryptedPrivateKeyInfo structures using an appropriate password
71           based encryption algorithm. With this option an unencrypted
72           PrivateKeyInfo structure is expected or output.  This option does
73           not encrypt private keys at all and should only be used when
74           absolutely necessary. Certain software such as some versions of
75           Java code signing software used unencrypted private keys.
76
77       -rand file...
78           A file or files containing random data used to seed the random
79           number generator.  Multiple files can be specified separated by an
80           OS-dependent character.  The separator is ; for MS-Windows, , for
81           OpenVMS, and : for all others.
82
83       [-writerand file]
84           Writes random data to the specified file upon exit.  This can be
85           used with a subsequent -rand flag.
86
87       -v2 alg
88           This option sets the PKCS#5 v2.0 algorithm.
89
90           The alg argument is the encryption algorithm to use, valid values
91           include aes128, aes256 and des3. If this option isn't specified
92           then aes256 is used.
93
94       -v2prf alg
95           This option sets the PRF algorithm to use with PKCS#5 v2.0. A
96           typical value value would be hmacWithSHA256. If this option isn't
97           set then the default for the cipher is used or hmacWithSHA256 if
98           there is no default.
99
100           Some implementations may not support custom PRF algorithms and may
101           require the hmacWithSHA1 option to work.
102
103       -v1 alg
104           This option indicates a PKCS#5 v1.5 or PKCS#12 algorithm should be
105           used.  Some older implementations may not support PKCS#5 v2.0 and
106           may require this option.  If not specified PKCS#5 v2.0 form is
107           used.
108
109       -engine id
110           Specifying an engine (by its unique id string) will cause pkcs8 to
111           attempt to obtain a functional reference to the specified engine,
112           thus initialising it if needed. The engine will then be set as the
113           default for all available algorithms.
114
115       -scrypt
116           Uses the scrypt algorithm for private key encryption using default
117           parameters: currently N=16384, r=8 and p=1 and AES in CBC mode with
118           a 256 bit key. These parameters can be modified using the
119           -scrypt_N, -scrypt_r, -scrypt_p and -v2 options.
120
121       -scrypt_N N -scrypt_r r -scrypt_p p
122           Sets the scrypt N, r or p parameters.
123

KEY FORMATS

125       Various different formats are used by the pkcs8 utility. These are
126       detailed below.
127
128       If a key is being converted from PKCS#8 form (i.e. the -topk8 option is
129       not used) then the input file must be in PKCS#8 format. An encrypted
130       key is expected unless -nocrypt is included.
131
132       If -topk8 is not used and PEM mode is set the output file will be an
133       unencrypted private key in PKCS#8 format. If the -traditional option is
134       used then a traditional format private key is written instead.
135
136       If -topk8 is not used and DER mode is set the output file will be an
137       unencrypted private key in traditional DER format.
138
139       If -topk8 is used then any supported private key can be used for the
140       input file in a format specified by -inform. The output file will be
141       encrypted PKCS#8 format using the specified encryption parameters
142       unless -nocrypt is included.
143

NOTES

145       By default, when converting a key to PKCS#8 format, PKCS#5 v2.0 using
146       256 bit AES with HMAC and SHA256 is used.
147
148       Some older implementations do not support PKCS#5 v2.0 format and
149       require the older PKCS#5 v1.5 form instead, possibly also requiring
150       insecure weak encryption algorithms such as 56 bit DES.
151
152       The encrypted form of a PEM encode PKCS#8 files uses the following
153       headers and footers:
154
155        -----BEGIN ENCRYPTED PRIVATE KEY-----
156        -----END ENCRYPTED PRIVATE KEY-----
157
158       The unencrypted form uses:
159
160        -----BEGIN PRIVATE KEY-----
161        -----END PRIVATE KEY-----
162
163       Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration
164       counts are more secure that those encrypted using the traditional
165       SSLeay compatible formats. So if additional security is considered
166       important the keys should be converted.
167
168       It is possible to write out DER encoded encrypted private keys in
169       PKCS#8 format because the encryption details are included at an ASN1
170       level whereas the traditional format includes them at a PEM level.
171

PKCS#5 v1.5 and PKCS#12 algorithms.

173       Various algorithms can be used with the -v1 command line option,
174       including PKCS#5 v1.5 and PKCS#12. These are described in more detail
175       below.
176
177       PBE-MD2-DES PBE-MD5-DES
178           These algorithms were included in the original PKCS#5 v1.5
179           specification.  They only offer 56 bits of protection since they
180           both use DES.
181
182       PBE-SHA1-RC2-64, PBE-MD2-RC2-64, PBE-MD5-RC2-64, PBE-SHA1-DES
183           These algorithms are not mentioned in the original PKCS#5 v1.5
184           specification but they use the same key derivation algorithm and
185           are supported by some software. They are mentioned in PKCS#5 v2.0.
186           They use either 64 bit RC2 or 56 bit DES.
187
188       PBE-SHA1-RC4-128, PBE-SHA1-RC4-40, PBE-SHA1-3DES, PBE-SHA1-2DES,
189       PBE-SHA1-RC2-128, PBE-SHA1-RC2-40
190           These algorithms use the PKCS#12 password based encryption
191           algorithm and allow strong encryption algorithms like triple DES or
192           128 bit RC2 to be used.
193

EXAMPLES

195       Convert a private key to PKCS#8 format using default parameters (AES
196       with 256 bit key and hmacWithSHA256):
197
198        openssl pkcs8 -in key.pem -topk8 -out enckey.pem
199
200       Convert a private key to PKCS#8 unencrypted format:
201
202        openssl pkcs8 -in key.pem -topk8 -nocrypt -out enckey.pem
203
204       Convert a private key to PKCS#5 v2.0 format using triple DES:
205
206        openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem
207
208       Convert a private key to PKCS#5 v2.0 format using AES with 256 bits in
209       CBC mode and hmacWithSHA512 PRF:
210
211        openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA512 -out enckey.pem
212
213       Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm
214       (DES):
215
216        openssl pkcs8 -in key.pem -topk8 -v1 PBE-MD5-DES -out enckey.pem
217
218       Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm
219       (3DES):
220
221        openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES
222
223       Read a DER unencrypted PKCS#8 format private key:
224
225        openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem
226
227       Convert a private key from any PKCS#8 encrypted format to traditional
228       format:
229
230        openssl pkcs8 -in pk8.pem -traditional -out key.pem
231
232       Convert a private key to PKCS#8 format, encrypting with AES-256 and
233       with one million iterations of the password:
234
235        openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -iter 1000000 -out pk8.pem
236

STANDARDS

238       Test vectors from this PKCS#5 v2.0 implementation were posted to the
239       pkcs-tng mailing list using triple DES, DES and RC2 with high iteration
240       counts, several people confirmed that they could decrypt the private
241       keys produced and therefore, it can be assumed that the PKCS#5 v2.0
242       implementation is reasonably accurate at least as far as these
243       algorithms are concerned.
244
245       The format of PKCS#8 DSA (and other) private keys is not well
246       documented: it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's
247       default DSA PKCS#8 private key format complies with this standard.
248

BUGS

250       There should be an option that prints out the encryption algorithm in
251       use and other details such as the iteration count.
252

SEE ALSO

254       dsa(1), rsa(1), genrsa(1), gendsa(1)
255

HISTORY

257       The -iter option was added in OpenSSL 1.1.0.
258
260       Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
261
262       Licensed under the OpenSSL license (the "License").  You may not use
263       this file except in compliance with the License.  You can obtain a copy
264       in the file LICENSE in the source distribution or at
265       <https://www.openssl.org/source/license.html>.
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2691.1.1l                            2021-09-15                          PKCS8(1)
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