PKCS8(1) OpenSSL PKCS8(1) NNAAMMEE openssl-pkcs8, pkcs8 - PKCS#8 format private key conversion tool SSYYNNOOPPSSIISS ooppeennssssll ppkkccss88 [--ttooppkk88] [--iinnffoorrmm PPEEMM||DDEERR] [--oouuttffoorrmm PPEEMM||DDEERR] [--iinn ffiillee-- nnaammee] [--ppaassssiinn aarrgg] [--oouutt ffiilleennaammee] [--ppaassssoouutt aarrgg] [--nnooiitteerr] [--nnooccrryypptt] [--nnoooocctt] [--eemmbbeedd] [--nnssddbb] [--vv22 aallgg] [--vv22pprrff aallgg] [--vv11 aallgg] [--eennggiinnee iidd] DDEESSCCRRIIPPTTIIOONN The ppkkccss88 command processes private keys in PKCS#8 format. It can han- dle both unencrypted PKCS#8 PrivateKeyInfo format and EncryptedPri- vateKeyInfo format with a variety of PKCS#5 (v1.5 and v2.0) and PKCS#12 algorithms. CCOOMMMMAANNDD OOPPTTIIOONNSS --ttooppkk88 Normally a PKCS#8 private key is expected on input and a tradi- tional format private key will be written. With the --ttooppkk88 option the situation is reversed: it reads a traditional format private key and writes a PKCS#8 format key. --iinnffoorrmm DDEERR||PPEEMM This specifies the input format. If a PKCS#8 format key is expected on input then either a DDEERR or PPEEMM encoded version of a PKCS#8 key will be expected. Otherwise the DDEERR or PPEEMM format of the tradi- tional format private key is used. --oouuttffoorrmm DDEERR||PPEEMM This specifies the output format, the options have the same meaning as the --iinnffoorrmm option. --iinn ffiilleennaammee This specifies the input filename to read a key from or standard input if this option is not specified. If the key is encrypted a pass phrase will be prompted for. --ppaassssiinn aarrgg the input file password source. For more information about the for- mat of aarrgg see the PPAASSSS PPHHRRAASSEE AARRGGUUMMEENNTTSS section in _o_p_e_n_s_s_l(1). --oouutt ffiilleennaammee This specifies the output filename to write a key to or standard output by default. If any encryption options are set then a pass phrase will be prompted for. The output filename should nnoott be the same as the input filename. --ppaassssoouutt aarrgg the output file password source. For more information about the format of aarrgg see the PPAASSSS PPHHRRAASSEE AARRGGUUMMEENNTTSS section in _o_p_e_n_s_s_l(1). --nnooccrryypptt PKCS#8 keys generated or input are normally PKCS#8 EncryptedPri- vateKeyInfo structures using an appropriate password based encryp- tion algorithm. With this option an unencrypted PrivateKeyInfo structure is expected or output. This option does not encrypt pri- vate keys at all and should only be used when absolutely necessary. Certain software such as some versions of Java code signing soft- ware used unencrypted private keys. --nnoooocctt This option generates RSA private keys in a broken format that some software uses. Specifically the private key should be enclosed in a OCTET STRING but some software just includes the structure itself without the surrounding OCTET STRING. --eemmbbeedd This option generates DSA keys in a broken format. The DSA parame- ters are embedded inside the PrivateKey structure. In this form the OCTET STRING contains an ASN1 SEQUENCE consisting of two struc- tures: a SEQUENCE containing the parameters and an ASN1 INTEGER containing the private key. --nnssddbb This option generates DSA keys in a broken format compatible with Netscape private key databases. The PrivateKey contains a SEQUENCE consisting of the public and private keys respectively. --vv22 aallgg This option enables the use of PKCS#5 v2.0 algorithms. Normally PKCS#8 private keys are encrypted with the password based encryp- tion algorithm called ppbbeeWWiitthhMMDD55AAnnddDDEESS--CCBBCC this uses 56 bit DES encryption but it was the strongest encryption algorithm supported in PKCS#5 v1.5. Using the --vv22 option PKCS#5 v2.0 algorithms are used which can use any encryption algorithm such as 168 bit triple DES or 128 bit RC2 however not many implementations support PKCS#5 v2.0 yet. If you are just using private keys with OpenSSL then this doesn't matter. The aallgg argument is the encryption algorithm to use, valid values include ddeess, ddeess33 and rrcc22. It is recommended that ddeess33 is used. --vv22pprrff aallgg This option sets the PRF algorithm to use with PKCS#5 v2.0. A typi- cal value values would be hhmmaaccWWiitthhSSHHAA225566. If this option isn't set then the default for the cipher is used or hhmmaaccWWiitthhSSHHAA11 if there is no default. --vv11 aallgg This option specifies a PKCS#5 v1.5 or PKCS#12 algorithm to use. A complete list of possible algorithms is included below. --eennggiinnee iidd specifying an engine (by its unique iidd string) will cause ppkkccss88 to attempt to obtain a functional reference to the specified engine, thus initialising it if needed. The engine will then be set as the default for all available algorithms. NNOOTTEESS The encrypted form of a PEM encode PKCS#8 files uses the following headers and footers: -----BEGIN ENCRYPTED PRIVATE KEY----- -----END ENCRYPTED PRIVATE KEY----- The unencrypted form uses: -----BEGIN PRIVATE KEY----- -----END PRIVATE KEY----- Private keys encrypted using PKCS#5 v2.0 algorithms and high iteration counts are more secure that those encrypted using the traditional SSLeay compatible formats. So if additional security is considered important the keys should be converted. The default encryption is only 56 bits because this is the encryption that most current implementations of PKCS#8 will support. Some software may use PKCS#12 password based encryption algorithms with PKCS#8 format private keys: these are handled automatically but there is no option to produce them. It is possible to write out DER encoded encrypted private keys in PKCS#8 format because the encryption details are included at an ASN1 level whereas the traditional format includes them at a PEM level. PPKKCCSS##55 vv11..55 aanndd PPKKCCSS##1122 aallggoorriitthhmmss.. Various algorithms can be used with the --vv11 command line option, including PKCS#5 v1.5 and PKCS#12. These are described in more detail below. PPBBEE--MMDD22--DDEESS PPBBEE--MMDD55--DDEESS These algorithms were included in the original PKCS#5 v1.5 specifi- cation. They only offer 56 bits of protection since they both use DES. PPBBEE--SSHHAA11--RRCC22--6644 PPBBEE--MMDD22--RRCC22--6644 PPBBEE--MMDD55--RRCC22--6644 PPBBEE--SSHHAA11--DDEESS These algorithms are not mentioned in the original PKCS#5 v1.5 specification but they use the same key derivation algorithm and are supported by some software. They are mentioned in PKCS#5 v2.0. They use either 64 bit RC2 or 56 bit DES. PPBBEE--SSHHAA11--RRCC44--112288 PPBBEE--SSHHAA11--RRCC44--4400 PPBBEE--SSHHAA11--33DDEESS PPBBEE--SSHHAA11--22DDEESS PPBBEE--SSHHAA11--RRCC22--112288 PPBBEE--SSHHAA11--RRCC22--4400 These algorithms use the PKCS#12 password based encryption algo- rithm and allow strong encryption algorithms like triple DES or 128 bit RC2 to be used. EEXXAAMMPPLLEESS Convert a private from traditional to PKCS#5 v2.0 format using triple DES: openssl pkcs8 -in key.pem -topk8 -v2 des3 -out enckey.pem Convert a private from traditional to PKCS#5 v2.0 format using AES with 256 bits in CBC mode and hhmmaaccWWiitthhSSHHAA225566 PRF: openssl pkcs8 -in key.pem -topk8 -v2 aes-256-cbc -v2prf hmacWithSHA256 -out enckey.pem Convert a private key to PKCS#8 using a PKCS#5 1.5 compatible algorithm (DES): openssl pkcs8 -in key.pem -topk8 -out enckey.pem Convert a private key to PKCS#8 using a PKCS#12 compatible algorithm (3DES): openssl pkcs8 -in key.pem -topk8 -out enckey.pem -v1 PBE-SHA1-3DES Read a DER unencrypted PKCS#8 format private key: openssl pkcs8 -inform DER -nocrypt -in key.der -out key.pem Convert a private key from any PKCS#8 format to traditional format: openssl pkcs8 -in pk8.pem -out key.pem SSTTAANNDDAARRDDSS Test vectors from this PKCS#5 v2.0 implementation were posted to the pkcs-tng mailing list using triple DES, DES and RC2 with high iteration counts, several people confirmed that they could decrypt the private keys produced and Therefore it can be assumed that the PKCS#5 v2.0 implementation is reasonably accurate at least as far as these algo- rithms are concerned. The format of PKCS#8 DSA (and other) private keys is not well docu- mented: it is hidden away in PKCS#11 v2.01, section 11.9. OpenSSL's default DSA PKCS#8 private key format complies with this standard. BBUUGGSS There should be an option that prints out the encryption algorithm in use and other details such as the iteration count. PKCS#8 using triple DES and PKCS#5 v2.0 should be the default private key format for OpenSSL: for compatibility several of the utilities use the old format at present. SSEEEE AALLSSOO _d_s_a(1), _r_s_a(1), _g_e_n_r_s_a(1), _g_e_n_d_s_a(1) 1.0.2u 2019-12-20 PKCS8(1)