keytool - a key and certificate management utility
keytool [commands]
See Commands and Options for a description of these commands with their options.
The keytool command is a key and certificate management utility. It enables users to administer their own public/private key pairs and associated certificates for use in self-authentication (where a user authenticates themselves to other users and services) or data integrity and authentication services, by using digital signatures. The keytool command also enables users to cache the public keys (in the form of certificates) of their communicating peers.
A certificate is a digitally signed statement from one entity (person, company, and so on), which says that the public key (and some other information) of some other entity has a particular value. When data is digitally signed, the signature can be verified to check the data integrity and authenticity. Integrity means that the data hasn't been modified or tampered with, and authenticity means that the data comes from the individual who claims to have created and signed it.
The keytool command also enables users to administer secret keys and passphrases used in symmetric encryption and decryption (Data Encryption Standard). It can also display other security-related information.
The keytool command stores the keys and certificates in a keystore.
The keytool command uses the jdk.certpath.disabledAlgorithms and jdk.security.legacyAlgorithms security properties to determine which algorithms are considered a security risk. It emits warnings when disabled or legacy algorithms are being used. The jdk.certpath.disabledAlgorithms and jdk.security.legacyAlgorithms security properties are defined in the java.security file (located in the JDK's $JAVA_HOME/conf/security directory).
The following notes apply to the descriptions in Commands and Options:
keytool -printcert {-file cert_file} {-v}
When you specify a -printcert command, replace cert_file with the actual file name, as follows: keytool -printcert -file VScert.cer
The keytool commands and their options can be grouped by the tasks that they perform.
Commands for Creating or Adding Data to the Keystore:
Commands for Importing Contents from Another Keystore:
Commands for Generating a Certificate Request:
Commands for Exporting Data:
Commands for Displaying Data:
Commands for Managing the Keystore:
Commands for Displaying Security-related Information:
For example,
keytool -addprovider SunPKCS11 -providerarg some.cfg ...
Note:
For compatibility reasons, the SunPKCS11 provider can still be loaded with -providerclass sun.security.pkcs11.SunPKCS11 even if it is now defined in a module. This is the only module included in the JDK that needs a configuration, and therefore the most widely used with the -providerclass option. For legacy security providers located on classpath and loaded by reflection, -providerclass should still be used.
For example, if MyProvider is a legacy provider loaded via reflection,
keytool -providerclass com.example.MyProvider ...
Use the -gencert command to generate a certificate as a response to a certificate request file (which can be created by the keytool -certreq command). The command reads the request either from infile or, if omitted, from the standard input, signs it by using the alias's private key, and outputs the X.509 certificate into either outfile or, if omitted, to the standard output. When -rfc is specified, the output format is Base64-encoded PEM; otherwise, a binary DER is created.
The -sigalg value specifies the algorithm that should be used to sign the certificate. The startdate argument is the start time and date that the certificate is valid. The days argument tells the number of days for which the certificate should be considered valid.
When dname is provided, it is used as the subject of the generated certificate. Otherwise, the one from the certificate request is used.
The -ext value shows what X.509 extensions will be embedded in the certificate. Read Common Command Options for the grammar of -ext.
The -gencert option enables you to create certificate chains. The following example creates a certificate, e1, that contains three certificates in its certificate chain.
The following commands creates four key pairs named ca, ca1, ca2, and e1:
keytool -alias ca -dname CN=CA -genkeypair -keyalg rsa keytool -alias ca1 -dname CN=CA -genkeypair -keyalg rsa keytool -alias ca2 -dname CN=CA -genkeypair -keyalg rsa keytool -alias e1 -dname CN=E1 -genkeypair -keyalg rsa
The following two commands create a chain of signed certificates; ca signs ca1 and ca1 signs ca2, all of which are self-issued:
keytool -alias ca1 -certreq | keytool -alias ca -gencert -ext san=dns:ca1 | keytool -alias ca1 -importcert keytool -alias ca2 -certreq | keytool -alias ca1 -gencert -ext san=dns:ca2 | keytool -alias ca2 -importcert
The following command creates the certificate e1 and stores it in the e1.cert file, which is signed by ca2. As a result, e1 should contain ca, ca1, and ca2 in its certificate chain:
keytool -alias e1 -certreq | keytool -alias ca2 -gencert > e1.cert
Use the -genkeypair command to generate a key pair (a public key and associated private key). Wraps the public key in an X.509 v3 self-signed certificate, which is stored as a single-element certificate chain. This certificate chain and the private key are stored in a new keystore entry that is identified by its alias.
The -keyalg value specifies the algorithm to be used to generate the key pair, and the -keysize value specifies the size of each key to be generated. The -sigalg value specifies the algorithm that should be used to sign the self-signed certificate. This algorithm must be compatible with the -keyalg value.
The -groupname value specifies the named group (for example, the standard or predefined name of an Elliptic Curve) of the key to be generated. Only one of -groupname and -keysize can be specified.
The -dname value specifies the X.500 Distinguished Name to be associated with the value of -alias, and is used as the issuer and subject fields in the self-signed certificate. If a distinguished name is not provided at the command line, then the user is prompted for one.
The value of -keypass is a password used to protect the private key of the generated key pair. If a password is not provided, then the user is prompted for it. If you press the Return key at the prompt, then the key password is set to the same password as the keystore password. The -keypass value must have at least six characters.
The value of -startdate specifies the issue time of the certificate, also known as the "Not Before" value of the X.509 certificate's Validity field.
The option value can be set in one of these two forms:
([+-]nnn[ymdHMS])+
[yyyy/mm/dd] [HH:MM:SS]
With the first form, the issue time is shifted by the specified value from the current time. The value is a concatenation of a sequence of subvalues. Inside each subvalue, the plus sign (+) means shift forward, and the minus sign (-) means shift backward. The time to be shifted is nnn units of years, months, days, hours, minutes, or seconds (denoted by a single character of y, m, d, H, M, or S respectively). The exact value of the issue time is calculated by using the java.util.GregorianCalendar.add(int field, int amount) method on each subvalue, from left to right. For example, the issue time can be specified by:
Calendar c = new GregorianCalendar(); c.add(Calendar.YEAR, -1); c.add(Calendar.MONTH, 1); c.add(Calendar.DATE, -1); return c.getTime()
With the second form, the user sets the exact issue time in two parts, year/month/day and hour:minute:second (using the local time zone). The user can provide only one part, which means the other part is the same as the current date (or time). The user must provide the exact number of digits shown in the format definition (padding with 0 when shorter). When both date and time are provided, there is one (and only one) space character between the two parts. The hour should always be provided in 24-hour format.
When the option isn't provided, the start date is the current time. The option can only be provided one time.
The value of date specifies the number of days (starting at the date specified by -startdate, or the current date when -startdate isn't specified) for which the certificate should be considered valid.
Use the -genseckey command to generate a secret key and store it in a new KeyStore.SecretKeyEntry identified by alias.
The value of -keyalg specifies the algorithm to be used to generate the secret key, and the value of -keysize specifies the size of the key that is generated. The -keypass value is a password that protects the secret key. If a password is not provided, then the user is prompted for it. If you press the Return key at the prompt, then the key password is set to the same password that is used for the -keystore. The -keypass value must contain at least six characters.
Use the -importcert command to read the certificate or certificate chain (where the latter is supplied in a PKCS#7 formatted reply or in a sequence of X.509 certificates) from -file file, and store it in the keystore entry identified by -alias. If -file file is not specified, then the certificate or certificate chain is read from stdin.
The keytool command can import X.509 v1, v2, and v3 certificates, and PKCS#7 formatted certificate chains consisting of certificates of that type. The data to be imported must be provided either in binary encoding format or in printable encoding format (also known as Base64 encoding) as defined by the Internet RFC 1421 standard. In the latter case, the encoding must be bounded at the beginning by a string that starts with -----BEGIN, and bounded at the end by a string that starts with -----END.
You import a certificate for two reasons: To add it to the list of trusted certificates, and to import a certificate reply received from a certificate authority (CA) as the result of submitting a Certificate Signing Request (CSR) to that CA. See the -certreq command in Commands for Generating a Certificate Request.
The type of import is indicated by the value of the -alias option. If the alias doesn't point to a key entry, then the keytool command assumes you are adding a trusted certificate entry. In this case, the alias shouldn't already exist in the keystore. If the alias does exist, then the keytool command outputs an error because a trusted certificate already exists for that alias, and doesn't import the certificate. If -alias points to a key entry, then the keytool command assumes that you're importing a certificate reply.
Use the -importpass command to imports a passphrase and store it in a new KeyStore.SecretKeyEntry identified by -alias. The passphrase may be supplied via the standard input stream; otherwise the user is prompted for it. The -keypass option provides a password to protect the imported passphrase. If a password is not provided, then the user is prompted for it. If you press the Return key at the prompt, then the key password is set to the same password as that used for the keystore. The -keypass value must contain at least six characters.
Note:
This is the first line of all options:
-srckeystore keystore -destkeystore keystore
Use the -importkeystore command to import a single entry or all entries from a source keystore to a destination keystore.
Note:
If you do not specify -destkeystore when using the keytool -importkeystore command, then the default keystore used is $HOME/.keystore.
When the -srcalias option is provided, the command imports the single entry identified by the alias to the destination keystore. If a destination alias isn't provided with -destalias, then -srcalias is used as the destination alias. If the source entry is protected by a password, then -srckeypass is used to recover the entry. If -srckeypass isn't provided, then the keytool command attempts to use -srcstorepass to recover the entry. If -srcstorepass is not provided or is incorrect, then the user is prompted for a password. The destination entry is protected with -destkeypass. If -destkeypass isn't provided, then the destination entry is protected with the source entry password. For example, most third-party tools require storepass and keypass in a PKCS #12 keystore to be the same. To create a PKCS#12 keystore for these tools, always specify a -destkeypass that is the same as -deststorepass.
If the -srcalias option isn't provided, then all entries in the source keystore are imported into the destination keystore. Each destination entry is stored under the alias from the source entry. If the source entry is protected by a password, then -srcstorepass is used to recover the entry. If -srcstorepass is not provided or is incorrect, then the user is prompted for a password. If a source keystore entry type isn't supported in the destination keystore, or if an error occurs while storing an entry into the destination keystore, then the user is prompted either to skip the entry and continue or to quit. The destination entry is protected with the source entry password.
If the destination alias already exists in the destination keystore, then the user is prompted either to overwrite the entry or to create a new entry under a different alias name.
If the -noprompt option is provided, then the user isn't prompted for a new destination alias. Existing entries are overwritten with the destination alias name. Entries that can't be imported are skipped and a warning is displayed.
Use the -certreq command to generate a Certificate Signing Request (CSR) using the PKCS #10 format.
A CSR is intended to be sent to a CA. The CA authenticates the certificate requestor (usually offline) and returns a certificate or certificate chain to replace the existing certificate chain (initially a self-signed certificate) in the keystore.
The private key associated with alias is used to create the PKCS #10 certificate request. To access the private key, the correct password must be provided. If -keypass isn't provided at the command line and is different from the password used to protect the integrity of the keystore, then the user is prompted for it. If -dname is provided, then it is used as the subject in the CSR. Otherwise, the X.500 Distinguished Name associated with alias is used.
The -sigalg value specifies the algorithm that should be used to sign the CSR.
The CSR is stored in the -file file. If a file is not specified, then the CSR is output to -stdout.
Use the -importcert command to import the response from the CA.
Use the -exportcert command to read a certificate from the keystore that is associated with -alias alias and store it in the -file file. When a file is not specified, the certificate is output to stdout.
By default, the certificate is output in binary encoding. If the -rfc option is specified, then the output in the printable encoding format defined by the Internet RFC 1421 Certificate Encoding Standard.
If -alias refers to a trusted certificate, then that certificate is output. Otherwise, -alias refers to a key entry with an associated certificate chain. In that case, the first certificate in the chain is returned. This certificate authenticates the public key of the entity addressed by -alias.
Use the -list command to print the contents of the keystore entry identified by -alias to stdout. If -alias alias is not specified, then the contents of the entire keystore are printed.
By default, this command prints the SHA-256 fingerprint of a certificate. If the -v option is specified, then the certificate is printed in human-readable format, with additional information such as the owner, issuer, serial number, and any extensions. If the -rfc option is specified, then the certificate contents are printed by using the printable encoding format, as defined by the Internet RFC 1421 Certificate Encoding Standard.
Note:
You can't specify both -v and -rfc in the same command. Otherwise, an error is reported.
Use the -printcert command to read and print the certificate from -file cert_file, the SSL server located at -sslserver server[:port], or the signed JAR file specified by -jarfile JAR_file. It prints its contents in a human-readable format. When a port is not specified, the standard HTTPS port 443 is assumed.
Note:
The -sslserver and -file options can't be provided in the same command. Otherwise, an error is reported. If you don't specify either option, then the certificate is read from stdin.
When-rfc is specified, the keytool command prints the certificate in PEM mode as defined by the Internet RFC 1421 Certificate Encoding standard.
If the certificate is read from a file or stdin, then it might be either binary encoded or in printable encoding format, as defined by the RFC 1421 Certificate Encoding standard.
If the SSL server is behind a firewall, then the -J-Dhttps.proxyHost=proxyhost and -J-Dhttps.proxyPort=proxyport options can be specified on the command line for proxy tunneling.
Note:
This command can be used independently of a keystore. This command does not check for the weakness of a certificate's signature algorithm if it is a trusted certificate in the user keystore (specified by -keystore) or in the cacerts keystore (if -trustcacerts is specified).
Use the -printcertreq command to print the contents of a PKCS #10 format certificate request, which can be generated by the keytool -certreq command. The command reads the request from file. If there is no file, then the request is read from the standard input.
Use the -printcrl command to read the Certificate Revocation List (CRL) from -file crl . A CRL is a list of the digital certificates that were revoked by the CA that issued them. The CA generates the crl file.
Note:
This command can be used independently of a keystore. This command attempts to verify the CRL using a certificate from the user keystore (specified by -keystore) or the cacerts keystore (if -trustcacerts is specified), and will print out a warning if it cannot be verified.
Use the -storepasswd command to change the password used to protect the integrity of the keystore contents. The new password is set by -new arg and must contain at least six characters.
Use the -keypasswd command to change the password (under which private/secret keys identified by -alias are protected) from -keypass old_keypass to -new new_keypass. The password value must contain at least six characters.
If the -keypass option isn't provided at the command line and the -keypass password is different from the keystore password (-storepass arg), then the user is prompted for it.
If the -new option isn't provided at the command line, then the user is prompted for it.
Use the -delete command to delete the -alias alias entry from the keystore. When not provided at the command line, the user is prompted for the alias.
Use the -changealias command to move an existing keystore entry from -alias alias to a new -destalias alias. If a destination alias is not provided, then the command prompts you for one. If the original entry is protected with an entry password, then the password can be supplied with the -keypass option. If a key password is not provided, then the -storepass (if provided) is attempted first. If the attempt fails, then the user is prompted for a password.
Use the -showinfo command to display various security-related information. The -tls option displays TLS configurations, such as the list of enabled protocols and cipher suites.
You can use --help to display a list of keytool commands or to display help information about a specific keytool command.
keytool --help
keytool -<command> --help
The -v option can appear for all commands except --help. When the -v option appears, it signifies verbose mode, which means that more information is provided in the output.
The -Joption argument can appear for any command. When the -Joption is used, the specified option string is passed directly to the Java interpreter. This option doesn't contain any spaces. It's useful for adjusting the execution environment or memory usage. For a list of possible interpreter options, enter java -h or java -X at the command line.
These options can appear for all commands operating on a keystore:
If the JKS storetype is used and a keystore file doesn't yet exist, then certain keytool commands can result in a new keystore file being created. For example, if keytool -genkeypair is called and the -keystore option isn't specified, the default keystore file named .keystore is created in the user's home directory if it doesn't already exist. Similarly, if the -keystore ks_file option is specified but ks_file doesn't exist, then it is created. For more information on the JKS storetype, see the KeyStore Implementation section in KeyStore aliases.
Note that the input stream from the -keystore option is passed to the KeyStore.load method. If NONE is specified as the URL, then a null stream is passed to the KeyStore.load method. NONE should be specified if the keystore isn't file-based. For example, when the keystore resides on a hardware token device.
If the modifier env or file isn't specified, then the password has the value argument, which must contain at least six characters. Otherwise, the password is retrieved as follows:
Note: All other options that require passwords, such as -keypass, -srckeypass, -destkeypass, -srcstorepass, and -deststorepass, accept the env and file modifiers. Remember to separate the password option and the modifier with a colon (:).
The password must be provided to all commands that access the keystore contents. For such commands, when the -storepass option isn't provided at the command line, the user is prompted for it.
When retrieving information from the keystore, the password is optional. If a password is not specified, then the integrity of the retrieved information can't be verified and a warning is displayed.
A pre-configured options file is a Java properties file that can be specified with the -conf option. Each property represents the default option(s) for a keytool command using "keytool.command_name" as the property name. A special property named "keytool.all" represents the default option(s) applied to all commands. A property value can include ${prop} which will be expanded to the system property associated with it. If an option value includes white spaces inside, it should be surrounded by quotation marks (" or '). All property names must be in lower case.
When keytool is launched with a pre-configured options file, the value for "keytool.all" (if it exists) is prepended to the keytool command line first, with the value for the command name (if it exists) comes next, and the existing options on the command line at last. For a single-valued option, this allows the property for a specific command to override the "keytool.all" value, and the value specified on the command line to override both. For multiple-valued options, all of them will be used by keytool.
For example, given the following file named preconfig:
# A tiny pre-configured options file
keytool.all = -keystore ${user.home}/ks
keytool.list = -v
keytool.genkeypair = -keyalg rsa
keytool -conf preconfig -list is identical to
keytool -keystore ~/ks -v -list
keytool -conf preconfig -genkeypair -alias me is identical to
keytool -keystore ~/ks -keyalg rsa -genkeypair -alias me
keytool -conf preconfig -genkeypair -alias you -keyalg ec is identical to
keytool -keystore ~/ks -keyalg rsa -genkeypair -alias you -keyalg ec
which is equivalent to
keytool -keystore ~/ks -genkeypair -alias you -keyalg ec
because -keyalg is a single-valued option and the ec value specified on the command line overrides the preconfigured options file.
The following examples show the defaults for various option values:
-alias "mykey" -keysize 2048 (when using -genkeypair and -keyalg is "RSA", "DSA", or "RSASSA-PSS") 256 (when using -genkeypair and -keyalg is "EC") 255 (when using -genkeypair and -keyalg is "EdDSA") 56 (when using -genseckey and -keyalg is "DES") 168 (when using -genseckey and -keyalg is "DESede") -validity 90 -keystore <the file named .keystore in the user's home directory> -destkeystore <the file named .keystore in the user's home directory> -storetype <the value of the "keystore.type" property in the security properties file, which is returned by the static getDefaultType method in java.security.KeyStore> -file stdin (if reading) stdout (if writing) -protected false
When generating a certificate or a certificate request, the default signature algorithm (-sigalg option) is derived from the algorithm of the underlying private key to provide an appropriate level of security strength as follows:
| keyalg | keysize |
default sigalg
|
| DSA | any size |
SHA256withDSA
|
| RSA | <= 3072 |
SHA256withRSA
|
| <= 7680 |
SHA384withRSA
| |
| > 7680 |
SHA512withRSA
| |
| EC | < 384 |
SHA256withECDSA
|
| < 512 |
SHA384withECDSA
| |
| = 512 |
SHA512withECDSA
| |
| RSASSA-PSS | <= 3072 |
RSASSA-PSS (with SHA-256)
|
| <= 7680 |
RSASSA-PSS (with SHA-384)
| |
| > 7680 |
RSASSA-PSS (with SHA-512)
| |
| EdDSA | 255 |
Ed25519
|
| 448 |
Ed448
| |
| Ed25519 | 255 |
Ed25519
|
| Ed448 | 448 |
Ed448
|
Note:
To improve out of the box security, default key size and signature algorithm names are periodically updated to stronger values with each release of the JDK. If interoperability with older releases of the JDK is important, make sure that the defaults are supported by those releases. Alternatively, you can use the -keysize or -sigalg options to override the default values at your own risk.
The keytool command supports these named extensions. The names aren't case-sensitive.
The full form is ca:{true|false}[,pathlen:len] or len, which is short for ca:true,pathlen:len.
When len is omitted, the resulting value is ca:true.
usage(, usage)*
usage can be one of the following:
Provided there is no ambiguity, the usage argument can be abbreviated with the first few letters (such as dig for digitalSignature) or in camel-case style (such as dS for digitalSignature or cRLS for cRLSign). The usage values are case-sensitive.
usage(, usage)*
usage can be one of the following:
Provided there is no ambiguity, the usage argument can be abbreviated with the first few letters or in camel-case style. The usage values are case-sensitive.
type:value(, type:value)*
type can be one of the following:
The value argument is the string format value for the type.
Same as SAN or SubjectAlternativeName.
method:location-type:location-value(, method:location-type:location-value)*
method can be one of the following:
The location-type and location-value arguments can be any type:value supported by the SubjectAlternativeName extension.
Same as SIA or SubjectInfoAccess.
The method argument can be one of the following:
When name is OID, the value is the hexadecimal dumped Definite Encoding Rules (DER) encoding of the extnValue for the extension excluding the OCTET STRING type and length bytes. Other than standard hexadecimal numbers (0-9, a-f, A-F), any extra characters are ignored in the HEX string. Therefore, both 01:02:03:04 and 01020304 are accepted as identical values. When there is no value, the extension has an empty value field.
A special name honored, used only in -gencert, denotes how the extensions included in the certificate request should be honored. The value for this name is a comma-separated list of all (all requested extensions are honored), name{:[critical|non-critical]} (the named extension is honored, but it uses a different isCritical attribute), and -name (used with all, denotes an exception). Requested extensions aren't honored by default.
If, besides the-ext honored option, another named or OID -ext option is provided, this extension is added to those already honored. However, if this name (or OID) also appears in the honored value, then its value and criticality override that in the request. If an extension of the same type is provided multiple times through either a name or an OID, only the last extension is used.
The subjectKeyIdentifier extension is always created. For non-self-signed certificates, the authorityKeyIdentifier is created.
CAUTION:
Users should be aware that some combinations of extensions (and other certificate fields) may not conform to the Internet standard. See Certificate Conformance Warning.
The following examples describe the sequence actions in creating a keystore for managing public/private key pairs and certificates from trusted entities.
Create a keystore and then generate the key pair.
You can enter the command as a single line such as the following:
keytool -genkeypair -dname "cn=myname, ou=mygroup, o=mycompany, c=mycountry" -alias business -keyalg rsa -keypass password -keystore /working/mykeystore -storepass password -validity 180
The command creates the keystore named mykeystore in the working directory (provided it doesn't already exist), and assigns it the password specified by -keypass. It generates a public/private key pair for the entity whose distinguished name is myname, mygroup, mycompany, and a two-letter country code of mycountry. It uses the RSA key generation algorithm to create the keys; both are 2048 bits
The command uses the default SHA256withRSA signature algorithm to create a self-signed certificate that includes the public key and the distinguished name information. The certificate is valid for 180 days, and is associated with the private key in a keystore entry referred to by -alias business. The private key is assigned the password specified by -keypass.
The command is significantly shorter when the option defaults are accepted. In this case, only -keyalg is required, and the defaults are used for unspecified options that have default values. You are prompted for any required values. You could have the following:
keytool -genkeypair -keyalg rsa
In this case, a keystore entry with the alias mykey is created, with a newly generated key pair and a certificate that is valid for 90 days. This entry is placed in your home directory in a keystore named .keystore . .keystore is created if it doesn't already exist. You are prompted for the distinguished name information, the keystore password, and the private key password.
Note:
The rest of the examples assume that you responded to the prompts with values equal to those specified in the first -genkeypair command. For example, a distinguished name of cn=myname, ou=mygroup, o=mycompany, c=mycountry).
Note:
Generating the key pair created a self-signed certificate; however, a certificate is more likely to be trusted by others when it is signed by a CA.
To get a CA signature, complete the following process:
keytool -certreq -file myname.csr
This creates a CSR for the entity identified by the default alias mykey and puts the request in the file named myname.csr.
The CA authenticates you, the requestor (usually offline), and returns a certificate, signed by them, authenticating your public key. In some cases, the CA returns a chain of certificates, each one authenticating the public key of the signer of the previous certificate in the chain.
To import a certificate for the CA, complete the following process:
The cacerts keystore ships with a set of root certificates issued by the CAs of the Oracle Java Root Certificate program [http://www.oracle.com/technetwork/java/javase/javasecarootcertsprogram-1876540.html]. If you request a signed certificate from a CA, and a certificate authenticating that CA's public key hasn't been added to cacerts, then you must import a certificate from that CA as a trusted certificate.
A certificate from a CA is usually self-signed or signed by another CA. If it is signed by another CA, you need a certificate that authenticates that CA's public key.
For example, you have obtained a X.cer file from a company that is a CA and the file is supposed to be a self-signed certificate that authenticates that CA's public key. Before you import it as a trusted certificate, you should ensure that the certificate is valid by:
Only when the fingerprints are equal is it assured that the certificate wasn't replaced in transit with somebody else's certificate (such as an attacker's certificate). If such an attack takes place, and you didn't check the certificate before you imported it, then you would be trusting anything that the attacker signed.
If you trust that the certificate is valid, then you can add it to your keystore by entering the following command:
keytool -importcert -alias alias -file *X*.cer`
This command creates a trusted certificate entry in the keystore from the data in the CA certificate file and assigns the values of the alias to the entry.
After you import a certificate that authenticates the public key of the CA that you submitted your certificate signing request to (or there is already such a certificate in the cacerts file), you can import the certificate reply and replace your self-signed certificate with a certificate chain.
The certificate chain is one of the following:
For example, if you sent your certificate signing request to DigiCert, then you can import their reply by entering the following command:
Note:
In this example, the returned certificate is named DCmyname.cer.
keytool -importcert -trustcacerts -file DCmyname.cer
Note:
If you used the jarsigner command to sign a Java Archive (JAR) file, then clients that use the file will want to authenticate your signature.
One way that clients can authenticate you is by importing your public key certificate into their keystore as a trusted entry. You can then export the certificate and supply it to your clients.
For example:
Note:
In this example, the entry has an alias of mykey.
keytool -exportcert -alias mykey -file myname.cer
Use the importkeystore command to import an entire keystore into another keystore. This imports all entries from the source keystore, including keys and certificates, to the destination keystore with a single command. You can use this command to import entries from a different type of keystore. During the import, all new entries in the destination keystore will have the same alias names and protection passwords (for secret keys and private keys). If the keytool command can't recover the private keys or secret keys from the source keystore, then it prompts you for a password. If it detects alias duplication, then it asks you for a new alias, and you can specify a new alias or simply allow the keytool command to overwrite the existing one.
For example, import entries from a typical JKS type keystore key.jks into a PKCS #11 type hardware-based keystore, by entering the following command:
keytool -importkeystore -srckeystore key.jks -destkeystore NONE -srcstoretype JKS -deststoretype PKCS11 -srcstorepass password -deststorepass password
The importkeystore command can also be used to import a single entry from a source keystore to a destination keystore. In this case, besides the options you used in the previous example, you need to specify the alias you want to import. With the -srcalias option specified, you can also specify the destination alias name, protection password for a secret or private key, and the destination protection password you want as follows:
keytool -importkeystore -srckeystore key.jks -destkeystore NONE -srcstoretype JKS -deststoretype PKCS11 -srcstorepass password -deststorepass password -srcalias myprivatekey -destalias myoldprivatekey -srckeypass password -destkeypass password -noprompt
The following are keytool commands used to generate key pairs and certificates for three entities:
Ensure that you store all the certificates in the same keystore.
keytool -genkeypair -keystore root.jks -alias root -ext bc:c -keyalg rsa keytool -genkeypair -keystore ca.jks -alias ca -ext bc:c -keyalg rsa keytool -genkeypair -keystore server.jks -alias server -keyalg rsa keytool -keystore root.jks -alias root -exportcert -rfc > root.pem keytool -storepass password -keystore ca.jks -certreq -alias ca | keytool -storepass password -keystore root.jks -gencert -alias root -ext BC=0 -rfc > ca.pem keytool -keystore ca.jks -importcert -alias ca -file ca.pem keytool -storepass password -keystore server.jks -certreq -alias server | keytool -storepass password -keystore ca.jks -gencert -alias ca -ext ku:c=dig,kE -rfc > server.pem cat root.pem ca.pem server.pem | keytool -keystore server.jks -importcert -alias server
Key entries: Each entry holds very sensitive cryptographic key information, which is stored in a protected format to prevent unauthorized access. Typically, a key stored in this type of entry is a secret key, or a private key accompanied by the certificate chain for the corresponding public key. See Certificate Chains. The keytool command can handle both types of entries, while the jarsigner tool only handles the latter type of entry, that is private keys and their associated certificate chains.
Trusted certificate entries: Each entry contains a single public key certificate that belongs to another party. The entry is called a trusted certificate because the keystore owner trusts that the public key in the certificate belongs to the identity identified by the subject (owner) of the certificate. The issuer of the certificate vouches for this, by signing the certificate.
An alias is specified when you add an entity to the keystore with the -genseckey command to generate a secret key, the -genkeypair command to generate a key pair (public and private key), or the -importcert command to add a certificate or certificate chain to the list of trusted certificates. Subsequent keytool commands must use this same alias to refer to the entity.
For example, you can use the alias duke to generate a new public/private key pair and wrap the public key into a self-signed certificate with the following command. See Certificate Chains.
keytool -genkeypair -alias duke -keyalg rsa -keypass passwd
This example specifies an initial passwd required by subsequent commands to access the private key associated with the alias duke. If you later want to change Duke's private key password, use a command such as the following:
keytool -keypasswd -alias duke -keypass passwd -new newpasswd
This changes the initial passwd to newpasswd. A password shouldn't be specified on a command line or in a script unless it is for testing purposes, or you are on a secure system. If you don't specify a required password option on a command line, then you are prompted for it.
Currently, two command-line tools (keytool and jarsigner) make use of keystore implementations. Because the KeyStore class is public, users can write additional security applications that use it.
In JDK 9 and later, the default keystore implementation is PKCS12. This is a cross platform keystore based on the RSA PKCS12 Personal Information Exchange Syntax Standard. This standard is primarily meant for storing or transporting a user's private keys, certificates, and miscellaneous secrets. There is another built-in implementation, provided by Oracle. It implements the keystore as a file with a proprietary keystore type (format) named JKS. It protects each private key with its individual password, and also protects the integrity of the entire keystore with a (possibly different) password.
Keystore implementations are provider-based. More specifically, the application interfaces supplied by KeyStore are implemented in terms of a Service Provider Interface (SPI). That is, there is a corresponding abstract KeystoreSpi class, also in the java.security package, which defines the Service Provider Interface methods that providers must implement. The term provider refers to a package or a set of packages that supply a concrete implementation of a subset of services that can be accessed by the Java Security API. To provide a keystore implementation, clients must implement a provider and supply a KeystoreSpi subclass implementation, as described in Steps to Implement and Integrate a Provider.
Applications can choose different types of keystore implementations from different providers, using the getInstance factory method supplied in the KeyStore class. A keystore type defines the storage and data format of the keystore information, and the algorithms used to protect private/secret keys in the keystore and the integrity of the keystore. Keystore implementations of different types aren't compatible.
The keytool command works on any file-based keystore implementation. It treats the keystore location that is passed to it at the command line as a file name and converts it to a FileInputStream, from which it loads the keystore information.)The jarsigner commands can read a keystore from any location that can be specified with a URL.
For keytool and jarsigner, you can specify a keystore type at the command line, with the -storetype option.
If you don't explicitly specify a keystore type, then the tools choose a keystore implementation based on the value of the keystore.type property specified in the security properties file. The security properties file is called java.security, and resides in the security properties directory:
Each tool gets the keystore.type value and then examines all the currently installed providers until it finds one that implements a keystores of that type. It then uses the keystore implementation from that provider.The KeyStore class defines a static method named getDefaultType that lets applications retrieve the value of the keystore.type property. The following line of code creates an instance of the default keystore type as specified in the keystore.type property:
KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
The default keystore type is pkcs12, which is a cross-platform keystore based on the RSA PKCS12 Personal Information Exchange Syntax Standard. This is specified by the following line in the security properties file:
keystore.type=pkcs12
To have the tools utilize a keystore implementation other than the default, you can change that line to specify a different keystore type. For example, if you want to use the Oracle's jks keystore implementation, then change the line to the following:
keystore.type=jks
Note:
Case doesn't matter in keystore type designations. For example, JKS would be considered the same as jks.
Public key cryptography requires access to users' public keys. In a large-scale networked environment, it is impossible to guarantee that prior relationships between communicating entities were established or that a trusted repository exists with all used public keys. Certificates were invented as a solution to this public key distribution problem. Now a Certification Authority (CA) can act as a trusted third party. CAs are entities such as businesses that are trusted to sign (issue) certificates for other entities. It is assumed that CAs only create valid and reliable certificates because they are bound by legal agreements. There are many public Certification Authorities, such as DigiCert, Comodo, Entrust, and so on.
You can also run your own Certification Authority using products such as Microsoft Certificate Server or the Entrust CA product for your organization. With the keytool command, it is possible to display, import, and export certificates. It is also possible to generate self-signed certificates.
The keytool command currently handles X.509 certificates.
All X.509 certificates have the following data, in addition to the signature:
CN=Java Duke, OU=Java Software Division, O=Oracle Corporation, C=US
These refer to the subject's common name (CN), organizational unit (OU), organization (O), and country (C).
When keys are first generated, the chain starts off containing a single element, a self-signed certificate. See -genkeypair in Commands. A self-signed certificate is one for which the issuer (signer) is the same as the subject. The subject is the entity whose public key is being authenticated by the certificate. Whenever the -genkeypair command is called to generate a new public/private key pair, it also wraps the public key into a self-signed certificate.
Later, after a Certificate Signing Request (CSR) was generated with the -certreq command and sent to a Certification Authority (CA), the response from the CA is imported with -importcert, and the self-signed certificate is replaced by a chain of certificates. At the bottom of the chain is the certificate (reply) issued by the CA authenticating the subject's public key. The next certificate in the chain is one that authenticates the CA's public key.
In many cases, this is a self-signed certificate, which is a certificate from the CA authenticating its own public key, and the last certificate in the chain. In other cases, the CA might return a chain of certificates. In this case, the bottom certificate in the chain is the same (a certificate signed by the CA, authenticating the public key of the key entry), but the second certificate in the chain is a certificate signed by a different CA that authenticates the public key of the CA you sent the CSR to. The next certificate in the chain is a certificate that authenticates the second CA's key, and so on, until a self-signed root certificate is reached. Each certificate in the chain (after the first) authenticates the public key of the signer of the previous certificate in the chain.
Many CAs only return the issued certificate, with no supporting chain, especially when there is a flat hierarchy (no intermediates CAs). In this case, the certificate chain must be established from trusted certificate information already stored in the keystore.
A different reply format (defined by the PKCS #7 standard) includes the supporting certificate chain in addition to the issued certificate. Both reply formats can be handled by the keytool command.
The top-level (root) CA certificate is self-signed. However, the trust into the root's public key doesn't come from the root certificate itself, but from other sources such as a newspaper. This is because anybody could generate a self-signed certificate with the distinguished name of, for example, the DigiCert root CA. The root CA public key is widely known. The only reason it is stored in a certificate is because this is the format understood by most tools, so the certificate in this case is only used as a vehicle to transport the root CA's public key. Before you add the root CA certificate to your keystore, you should view it with the -printcert option and compare the displayed fingerprint with the well-known fingerprint obtained from a newspaper, the root CA's Web page, and so on.
The cacerts file represents a system-wide keystore with CA certificates. System administrators can configure and manage that file with the keytool command by specifying jks as the keystore type. The cacerts keystore file ships with a default set of root CA certificates. For Linux, OS X, and Windows, you can list the default certificates with the following command:
keytool -list -cacerts
The initial password of the cacerts keystore file is changeit. System administrators should change that password and the default access permission of that file upon installing the SDK.
Note:
It is important to verify your cacerts file. Because you trust the CAs in the cacerts file as entities for signing and issuing certificates to other entities, you must manage the cacerts file carefully. The cacerts file should contain only certificates of the CAs you trust. It is your responsibility to verify the trusted root CA certificates bundled in the cacerts file and make your own trust decisions.
To remove an untrusted CA certificate from the cacerts file, use the -delete option of the keytool command. You can find the cacerts file in the JDK's $JAVA_HOME/lib/security directory. Contact your system administrator if you don't have permission to edit this file.
Certificates read by the -importcert and -printcert commands can be in either this format or binary encoded. The -exportcert command by default outputs a certificate in binary encoding, but will instead output a certificate in the printable encoding format, when the -rfc option is specified.
The -list command by default prints the SHA-256 fingerprint of a certificate. If the -v option is specified, then the certificate is printed in human-readable format. If the -rfc option is specified, then the certificate is output in the printable encoding format.
In its printable encoding format, the encoded certificate is bounded at the beginning and end by the following text:
-----BEGIN CERTIFICATE----- encoded certificate goes here. -----END CERTIFICATE-----
When you supply a distinguished name string as the value of a -dname option, such as for the -genkeypair command, the string must be in the following format:
CN=cName, OU=orgUnit, O=org, L=city, S=state, C=countryCode
All the following items represent actual values and the previous keywords are abbreviations for the following:
CN=commonName OU=organizationUnit O=organizationName L=localityName S=stateName C=country
A sample distinguished name string is:
CN=Mark Smith, OU=Java, O=Oracle, L=Cupertino, S=California, C=US
A sample command using such a string is:
keytool -genkeypair -dname "CN=Mark Smith, OU=Java, O=Oracle, L=Cupertino, S=California, C=US" -alias mark -keyalg rsa
Case doesn't matter for the keyword abbreviations. For example, CN, cn, and Cn are all treated the same.
Order matters; each subcomponent must appear in the designated order. However, it isn't necessary to have all the subcomponents. You can use a subset, for example:
CN=Smith, OU=Java, O=Oracle, C=US
If a distinguished name string value contains a comma, then the comma must be escaped by a backslash (\) character when you specify the string on a command line, as in:
cn=Jack, ou=Java\, Product Development, o=Oracle, c=US
It is never necessary to specify a distinguished name string on a command line. When the distinguished name is needed for a command, but not supplied on the command line, the user is prompted for each of the subcomponents. In this case, a comma doesn't need to be escaped by a backslash (\).
Important: Be sure to check a certificate very carefully before importing it as a trusted certificate.
Windows Example:
View the certificate first with the -printcert command or the -importcert command without the -noprompt option. Ensure that the displayed certificate fingerprints match the expected ones. For example, suppose someone sends or emails you a certificate that you put it in a file named \tmp\cert. Before you consider adding the certificate to your list of trusted certificates, you can execute a -printcert command to view its fingerprints, as follows:
keytool -printcert -file \tmp\cert Owner: CN=ll, OU=ll, O=ll, L=ll, S=ll, C=ll Issuer: CN=ll, OU=ll, O=ll, L=ll, S=ll, C=ll Serial Number: 59092b34 Valid from: Thu Jun 24 18:01:13 PDT 2016 until: Wed Jun 23 17:01:13 PST 2016 Certificate Fingerprints: SHA-1: 20:B6:17:FA:EF:E5:55:8A:D0:71:1F:E8:D6:9D:C0:37:13:0E:5E:FE SHA-256: 90:7B:70:0A:EA:DC:16:79:92:99:41:FF:8A:FE:EB:90: 17:75:E0:90:B2:24:4D:3A:2A:16:A6:E4:11:0F:67:A4
Linux Example:
View the certificate first with the -printcert command or the -importcert command without the -noprompt option. Ensure that the displayed certificate fingerprints match the expected ones. For example, suppose someone sends or emails you a certificate that you put it in a file named /tmp/cert. Before you consider adding the certificate to your list of trusted certificates, you can execute a -printcert command to view its fingerprints, as follows:
keytool -printcert -file /tmp/cert Owner: CN=ll, OU=ll, O=ll, L=ll, S=ll, C=ll Issuer: CN=ll, OU=ll, O=ll, L=ll, S=ll, C=ll Serial Number: 59092b34 Valid from: Thu Jun 24 18:01:13 PDT 2016 until: Wed Jun 23 17:01:13 PST 2016 Certificate Fingerprints: SHA-1: 20:B6:17:FA:EF:E5:55:8A:D0:71:1F:E8:D6:9D:C0:37:13:0E:5E:FE SHA-256: 90:7B:70:0A:EA:DC:16:79:92:99:41:FF:8A:FE:EB:90: 17:75:E0:90:B2:24:4D:3A:2A:16:A6:E4:11:0F:67:A4
Then call or otherwise contact the person who sent the certificate and compare the fingerprints that you see with the ones that they show. Only when the fingerprints are equal is it guaranteed that the certificate wasn't replaced in transit with somebody else's certificate such as an attacker's certificate. If such an attack took place, and you didn't check the certificate before you imported it, then you would be trusting anything the attacker signed, for example, a JAR file with malicious class files inside.
Note:
It isn't required that you execute a -printcert command before importing a certificate. This is because before you add a certificate to the list of trusted certificates in the keystore, the -importcert command prints out the certificate information and prompts you to verify it. You can then stop the import operation. However, you can do this only when you call the -importcert command without the -noprompt option. If the -noprompt option is specified, then there is no interaction with the user.
Most commands that operate on a keystore require the store password. Some commands require a private/secret key password. Passwords can be specified on the command line in the -storepass and -keypass options. However, a password shouldn't be specified on a command line or in a script unless it is for testing, or you are on a secure system. When you don't specify a required password option on a command line, you are prompted for it.
Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile [https://tools.ietf.org/rfc/rfc5280.txt] defined a profile on conforming X.509 certificates, which includes what values and value combinations are valid for certificate fields and extensions.
The keytool command doesn't enforce all of these rules so it can generate certificates that don't conform to the standard, such as self-signed certificates that would be used for internal testing purposes. Certificates that don't conform to the standard might be rejected by the JDK or other applications. Users should ensure that they provide the correct options for -dname, -ext, and so on.
Before you add the certificate to the keystore, the keytool command verifies it by attempting to construct a chain of trust from that certificate to a self-signed certificate (belonging to a root CA), using trusted certificates that are already available in the keystore.
If the -trustcacerts option was specified, then additional certificates are considered for the chain of trust, namely the certificates in a file named cacerts.
If the keytool command fails to establish a trust path from the certificate to be imported up to a self-signed certificate (either from the keystore or the cacerts file), then the certificate information is printed, and the user is prompted to verify it by comparing the displayed certificate fingerprints with the fingerprints obtained from some other (trusted) source of information, which might be the certificate owner. Be very careful to ensure the certificate is valid before importing it as a trusted certificate. The user then has the option of stopping the import operation. If the -noprompt option is specified, then there is no interaction with the user.
When you import a certificate reply, the certificate reply is validated with trusted certificates from the keystore, and optionally, the certificates configured in the cacerts keystore file when the -trustcacerts option is specified.
The methods of determining whether the certificate reply is trusted are as follows:
If the public key in the certificate reply matches the user's public key already stored with alias, then the old certificate chain is replaced with the new certificate chain in the reply. The old chain can only be replaced with a valid keypass, and so the password used to protect the private key of the entry is supplied. If no password is provided, and the private key password is different from the keystore password, the user is prompted for it.
This command was named -import in earlier releases. This old name is still supported in this release. The new name, -importcert, is preferred.