-topk8
Normally a PKCS#8 private key is expected on input and a traditional format private key will be written. With the -topk8 option the situation is reversed: it reads a traditional format private key and writes a PKCS#8 format key.
-inform DER|PEM
This specifies the input format. If a PKCS#8 format key is expected on input then either a DER or PEM encoded version of a PKCS#8 key will be expected. Otherwise the DER or PEM format of the traditional format private key is used.
-outform DER|PEM
This specifies the output format, the options have the same meaning as the -inform option.
-in filename
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.
-passin arg
the input file password source. For more information about the format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
-out filename
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 not be the same as the input filename.
-passout arg
the output file password source. For more information about the format of arg see the PASS PHRASE ARGUMENTS section in openssl(1).
-nocrypt
PKCS#8 keys generated or input are normally PKCS#8 EncryptedPrivateKeyInfo structures using an appropriate password based encryption algorithm. With this option an unencrypted PrivateKeyInfo structure is expected or output. This option does not encrypt private keys at all and should only be used when absolutely necessary. Certain software such as some versions of Java code signing software used unencrypted private keys.
-nooct
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.
-embed
This option generates DSA keys in a broken format. The DSA parameters are embedded inside the PrivateKey structure. In this form the OCTET STRING contains an ASN1 SEQUENCE consisting of two structures: a SEQUENCE containing the parameters and an ASN1 INTEGER containing the private key.
-nsdb
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.
-v2 alg
This option enables the use of PKCS#5 v2.0 algorithms. Normally PKCS#8 private keys are encrypted with the password based encryption algorithm called
pbeWithMD5AndDES-CBC this uses 56 bit DES encryption but it was the strongest encryption algorithm supported in PKCS#5 v1.5. Using the -v2 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
alg argument is the encryption algorithm to use, valid values include des, des3 and rc2. It is recommended that des3 is used.
-v1 alg
This option specifies a PKCS#5 v1.5 or PKCS#12 algorithm to use. A complete list of possible algorithms is included below.
-engine id
specifying an engine (by its unique id string) will cause pkcs8 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.