jarsigner [ options ] jar-file alias
jarsigner -verify [ options ] jar-file [alias ...]
If you also specified the -strict option, and the jarsigner command detected severe warnings, the message, "jar verified, with signer errors" is displayed.
If you also specified the -strict option, and the jarsigner command detected severe warnings, the message, "jar signed, with signer errors" is displayed.
The JAR feature enables the packaging of class files, images, sounds, and other digital data in a single file for faster and easier distribution. A tool named jar enables developers to produce JAR files. (Technically, any zip file can also be considered a JAR file, although when created by the jar command or processed by the jarsigner command, JAR files also contain a META-INF/MANIFEST.MF file.)
A digital signature is a string of bits that is computed from some data (the data being signed) and the private key of an entity (a person, company, and so on). Similar to a handwritten signature, a digital signature has many useful characteristics:
To generate an entity's signature for a file, the entity must first have a public/private key pair associated with it and one or more certificates that authenticate its public key. A certificate is a digitally signed statement from one entity that says that the public key of another entity has a particular value.
The jarsigner command uses key and certificate information from a keystore to generate digital signatures for JAR files. A keystore is a database of private keys and their associated X.509 certificate chains that authenticate the corresponding public keys. The keytool command is used to create and administer keystores.
The jarsigner command uses an entity's private key to generate a signature. The signed JAR file contains, among other things, a copy of the certificate from the keystore for the public key corresponding to the private key used to sign the file. The jarsigner command can verify the digital signature of the signed JAR file using the certificate inside it (in its signature block file).
The jarsigner command can generate signatures that include a time stamp that lets a systems or deployer (including Java Plug-in) to check whether the JAR file was signed while the signing certificate was still valid. In addition, APIs allow applications to obtain the timestamp information.
At this time, the jarsigner command can only sign JAR files created by the jar command or zip files. JAR files are the same as zip files, except they also have a META-INF/MANIFEST.MF file. A META-INF/MANIFEST.MF file is created when the jarsigner command signs a zip file.
The default jarsigner command behavior is to sign a JAR or zip file. Use the -verify option to verify a signed JAR file.
The jarsigner command also attempts to validate the signer's certificate after signing or verifying. If there is a validation error or any other problem, the command generates warning messages. If you specify the -strict option, then the command treats severe warnings as errors. See Errors and Warnings.
When you use the jarsigner command to sign a JAR file, you must specify the alias for the keystore entry that contains the private key needed to generate the signature. For example, the following command signs the JAR file named MyJARFile.jar with the private key associated with the alias duke in the keystore named mystore in the working directory. Because no output file is specified, it overwrites MyJARFile.jar with the signed JAR file.
jarsigner -keystore /working/mystore -storepass <keystore password>
-keypass <private key password> MyJARFile.jar duke
Keystores are protected with a password, so the store password must be specified. You are prompted for it when you do not specify it on the command line. Similarly, private keys are protected in a keystore with a password, so the private key's password must be specified, and you are prompted for the password when you do not specify it on the command line and it is not the same as the store password.
On Oracle Solaris systems, user.home defaults to the user's home directory.
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 when the KeyStore class is not file based, for example, when it resides on a hardware token device.
Currently, there are two command-line tools that use keystore implementations (keytool and jarsigner), and a GUI-based tool named Policy Tool. Because the KeyStore class is publicly available, JDK users can write additional security applications that use it.
There is a built-in default implementation provided by Oracle that implements the keystore as a file, that uses a proprietary keystore type (format) named JKS. The built-in implementation protects each private key with its individual password and protects the integrity of the entire keystore with a (possibly different) password.
Keystore implementations are provider-based, which means the application interfaces supplied by the KeyStore class are implemented in terms of a Service Provider Interface (SPI). There is a corresponding abstract KeystoreSpi class, also in the java.security package, that 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 How to Implement a Provider in the Java Cryptography Architecture at http://docs.oracle.com/javase/8/docs/technotes/guides/security/crypto/HowToImplAProvider.html
Applications can choose different types of keystore implementations from different providers, with the getInstance factory method in the KeyStore class. A keystore type defines the storage and data format of the keystore information and the algorithms used to protect private keys in the keystore and the integrity of the keystore itself. Keystore implementations of different types are not compatible.
The jarsigner command can read file-based keystores from any location that can be specified using a URL. In addition, the command can read non-file-based keystores such as those provided by MSCAPI on Windows and PKCS11 on all platforms.
For the jarsigner and keytool commands, you can specify a keystore type at the command line with the -storetype option. For Policy Tool, you can specify a keystore type with the Edit command in the KeyStore menu.
If you do not 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 it resides in the JDK security properties directory, java.home/lib/security, where java.home is the runtime environment's directory. The jre directory in the JDK or the top-level directory of the Java Runtime Environment (JRE).
Each tool gets the keystore.type value and then examines all the installed providers until it finds one that implements 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 and applets 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 jks (the proprietary type of the keystore implementation provided by Oracle). This is specified by the following line in the security properties file:
keystore.type=jks
Case does not matter in keystore type designations. For example, JKS is the same as jks.
To have the tools use a keystore implementation other than the default, change that line to specify a different keystore type. For example, if you have a provider package that supplies a keystore implementation for a keystore type called pkcs12, then change the line to the following:
keystore.type=pkcs12
Note: If you use the PKCS 11 provider package, then see "KeyTool" and "JarSigner" in Java PKCS #11 Reference Guide at http://docs.oracle.com/javase/8/docs/technotes/guides/security/p11guide.html
If the signer's public and private keys are DSA keys, then jarsigner signs the JAR file with the SHA1withDSA algorithm. If the signer's keys are RSA keys, then jarsigner attempts to sign the JAR file with the SHA256withRSA algorithm. If the signer's keys are EC keys, then jarsigner signs the JAR file with the SHA256withECDSA algorithm.
These default signature algorithms can be overridden using the -sigalg option.
The base file names for these two files come from the value of the -sigFile option. For example, when the option is -sigFile MKSIGN, the files are named MKSIGN.SF and MKSIGN.DSA
If no -sigfile option appears on the command line, then the base file name for the .SF and .DSA files is the first 8 characters of the alias name specified on the command line, all converted to uppercase. If the alias name has fewer than 8 characters, then the full alias name is used. If the alias name contains any characters that are not allowed in a signature file name, then each such character is converted to an underscore (_) character in forming the file name. Valid characters include letters, digits, underscores, and hyphens.
Signature File
A signature file (.SF file) looks similar to the manifest file that is always included in a JAR file when the jarsigner command is used to sign the file. For each source file included in the JAR file, the .SF file has three lines, such as in the manifest file, that list the following:
In the manifest file, the SHA digest value for each source file is the digest (hash) of the binary data in the source file. In the .SF file, the digest value for a specified source file is the hash of the three lines in the manifest file for the source file.
The signature file, by default, includes a header with a hash of the whole manifest file. The header also contains a hash of the manifest header. The presence of the header enables verification optimization. See JAR File Verification.
Signature Block File
The .SF file is signed and the signature is placed in the signature block file. This file also contains, encoded inside it, the certificate or certificate chain from the keystore that authenticates the public key corresponding to the private key used for signing. The file has the extension .DSA, .RSA, or .EC, depending on the digest algorithm used.
-tsa url
-tsacert alias
-altsigner class
-altsignerpath classpathlist
-tsapolicyid policyid
The verification ensures that the signature stored in each signature block (.DSA) file was generated using the private key corresponding to the public key whose certificate (or certificate chain) also appears in the .DSA file. It also ensures that the signature is a valid signature of the corresponding signature (.SF) file, and thus the .SF file was not tampered with.
The .SF file by default includes a header that contains a hash of the entire manifest file. When the header is present, the verification can check to see whether or not the hash in the header matches the hash of the manifest file. If there is a match, then verification proceeds to the next step.
If there is no match, then a less optimized verification is required to ensure that the hash in each source file information section in the .SF file equals the hash of its corresponding section in the manifest file. See Signature File.
One reason the hash of the manifest file that is stored in the .SF file header might not equal the hash of the current manifest file is that one or more files were added to the JAR file (with the jar tool) after the signature and .SF file were generated. When the jar tool is used to add files, the manifest file is changed by adding sections to it for the new files, but the .SF file is not changed. A verification is still considered successful when none of the files that were in the JAR file when the signature was generated have been changed since then. This happens when the hashes in the non-header sections of the .SF file equal the hashes of the corresponding sections in the manifest file.
If any serious verification failures occur during the verification process, then the process is stopped and a security exception is thrown. The jarsigner command catches and displays the exception.
Note: You should read any addition warnings (or errors if you specified the -strict option), as well as the content of the certificate (by specifying the -verbose and -certs options) to determine if the signature can be trusted.
jarsigner myBundle.jar susan
jarsigner myBundle.jar kevin
When a JAR file is signed multiple times, there are multiple .SF and .DSA files in the resulting JAR file, one pair for each signature. In the previous example, the output JAR file includes files with the following names:
SUSAN.SF
SUSAN.DSA
KEVIN.SF
KEVIN.DSA
A keystore is required when signing. You must explicitly specify a keystore when the default keystore does not exist or if you want to use one other than the default.
A keystore is not required when verifying, but if one is specified or the default exists and the -verbose option was also specified, then additional information is output regarding whether or not any of the certificates used to verify the JAR file are contained in that keystore.
The -keystore argument can be a file name and path specification rather than a URL, in which case it is treated the same as a file: URL, for example, the following are equivalent:
-keystore filePathAndName
-keystore file:filePathAndName
If the Sun PKCS #11 provider was configured in the java.security security properties file (located in the JRE's $JAVA_HOME/lib/security directory), then the keytool and jarsigner tools can operate on the PKCS #11 token by specifying these options:
-keystore NONE
-storetype PKCS11
For example, the following command lists the contents of the configured PKCS#11 token:
keytool -keystore NONE -storetype PKCS11 -list
The PIN for a PCKS #11 token can also be specified with the -storepass option. If none is specified, then the keytool and jarsigner commands prompt for the token PIN. If the token has a protected authentication path (such as a dedicated PIN-pad or a biometric reader), then the -protected option must be specified and no password options can be specified.
If the modifier env or file is not specified, then the password has the value argument. Otherwise, the password is retrieved as follows:
Note: The password should not be specified on the command line or in a script unless it is for testing purposes, or you are on a secure system.
If the modifier env or file is not specified, then the password has the value argument. Otherwise, the password is retrieved as follows:
Note: The password should not be specified on the command line or in a script unless it is for testing purposes, or you are on a secure system.
The characters in the file must come from the set a-zA-Z0-9_-. Only letters, numbers, underscore, and hyphen characters are allowed. All lowercase characters are converted to uppercase for the .SF and .DSA file names.
If no -sigfile option appears on the command line, then the base file name for the .SF and .DSA files is the first 8 characters of the alias name specified on the command line, all converted to upper case. If the alias name has fewer than 8 characters, then the full alias name is used. If the alias name contains any characters that are not valid in a signature file name, then each such character is converted to an underscore (_) character to form the file name.
For a list of standard signature algorithm names, see "Appendix A: Standard Names" in the Java Cryptography Architecture (JCA) Reference Guide at http://docs.oracle.com/javase/8/docs/technotes/guides/security/crypto/CryptoSpec.html#AppA
This algorithm must be compatible with the private key used to sign the JAR file. If this option is not specified, then SHA1withDSA, SHA256withRSA, or SHA256withECDSA are used depending on the type of private key. There must either be a statically installed provider supplying an implementation of the specified algorithm or the user must specify one with the -providerClass option; otherwise, the command will not succeed.
For a list of standard message digest algorithm names, see "Appendix A: Standard Names" in the Java Cryptography Architecture (JCA) Reference Guide at http://docs.oracle.com/javase/8/docs/technotes/guides/security/crypto/CryptoSpec.html#AppA
If this option is not specified, then SHA256 is used. There must either be a statically installed provider supplying an implementation of the specified algorithm or the user must specify one with the -providerClass option; otherwise, the command will not succeed.
The keystore is also examined. If no keystore value is specified on the command line, then the default keystore file (if any) is checked. If the public key certificate for a signer matches an entry in the keystore, then the alias name for the keystore entry for that signer is displayed in parentheses.
By default, this header is added, as an optimization. When the header is present, whenever the JAR file is verified, the verification can first check to see whether the hash in the header matches the hash of the whole manifest file. When there is a match, verification proceeds to the next step. When there is no match, it is necessary to do a less optimized verification that the hash in each source file information section in the .SF file equals the hash of its corresponding section in the manifest file. See JAR File Verification.
The -sectionsonly option is primarily used for testing. It should not be used other than for testing because using it incurs higher overhead.
Used with the -providerArg ConfigFilePath option, the keytool and jarsigner tools install the provider dynamically and use ConfigFilePath for the path to the token configuration file. The following example shows a command to list a PKCS #11 keystore when the Oracle PKCS #11 provider was not configured in the security properties file.
jarsigner -keystore NONE -storetype PKCS11 \
-providerClass sun.security.pkcs11.SunPKCS11 \
-providerArg /mydir1/mydir2/token.config \
-list
For the Oracle PKCS #11 provider, providerName is of the form SunPKCS11-TokenName, where TokenName is the name suffix that the provider instance has been configured with, as detailed in the configuration attributes table. For example, the following command lists the contents of the PKCS #11 keystore provider instance with name suffix SmartCard:
jarsigner -keystore NONE -storetype PKCS11 \
-providerName SunPKCS11-SmartCard \
-list
To generate the time stamp, jarsigner communicates with the TSA with the Time-Stamp Protocol (TSP) defined in RFC 3161. When successful, the time stamp token returned by the TSA is stored with the signature in the signature block file.
The TSA public key certificate must be present in the keystore when using the -tsacert option.
Object identifiers are defined by X.696, which is an ITU Telecommunication Standardization Sector (ITU-T) standard. These identifiers are typically period-separated sets of non-negative digits like 1.2.3.4, for example.
For example, to use the signing mechanism provided by a class named com.sun.sun.jarsigner.AuthSigner, use the jarsigner option -altsigner com.sun.jarsigner.AuthSigner.
An absolute path or a path relative to the current directory can be specified. If classpathlist contains multiple paths or JAR files, then they should be separated with a colon (:) on Oracle Solaris and a semicolon (;) on Windows. This option is not necessary when the class is already in the search path.
The following example shows how to specify the path to a JAR file that contains the class file. The JAR file name is included.
-altsignerpath /home/user/lib/authsigner.jar
The following example shows how to specify the path to the JAR file that contains the class file. The JAR file name is omitted.
-altsignerpath /home/user/classes/com/sun/tools/jarsigner/
If there is a failure, the jarsigner command exits with code 1. If there is no failure, but there are one or more severe warnings, the jarsigner command exits with code 0 when the -strict option is not specified, or exits with the OR-value of the warning codes when the -strict is specified. If there is only informational warnings or no warning at all, the command always exits with code 0.
For example, if a certificate used to sign an entry is expired and has a KeyUsage extension that does not allow it to sign a file, the jarsigner command exits with code 12 (=4+8) when the -strict option is specified.
Note: Exit codes are reused because only the values from 0 to 255 are legal on Unix-based operating systems.
The following sections describes the names, codes, and descriptions of the errors and warnings that the jarsigner command can issue.
Reasons why the jarsigner command issues a severe warning include the certificate used to sign the JAR file has an error or the signed JAR file has other problems.
jarsigner -keystore /working/mystore
-storepass <keystore password>
-keypass <private key password>
-signedjar sbundle.jar bundle.jar jane
There is no -sigfile specified in the previous command so the generated .SF and .DSA files to be placed in the signed JAR file have default names based on the alias name. They are named JANE.SF and JANE.DSA.
If you want to be prompted for the store password and the private key password, then you could shorten the previous command to the following:
jarsigner -keystore /working/mystore
-signedjar sbundle.jar bundle.jar jane
If the keystore is the default keystore (.keystore in your home directory), then you do not need to specify a keystore, as follows:
jarsigner -signedjar sbundle.jar bundle.jar jane
If you want the signed JAR file to overwrite the input JAR file (bundle.jar), then you do not need to specify a -signedjar option, as follows:
jarsigner bundle.jar jane
jarsigner -verify sbundle.jar
When the verification is successful, jar verified is displayed. Otherwise, an error message is displayed. You can get more information when you use the -verbose option. A sample use of jarsigner with the-verbose option follows:
jarsigner -verify -verbose sbundle.jar
198 Fri Sep 26 16:14:06 PDT 1997 META-INF/MANIFEST.MF
199 Fri Sep 26 16:22:10 PDT 1997 META-INF/JANE.SF
1013 Fri Sep 26 16:22:10 PDT 1997 META-INF/JANE.DSA
smk 2752 Fri Sep 26 16:12:30 PDT 1997 AclEx.class
smk 849 Fri Sep 26 16:12:46 PDT 1997 test.class
s = signature was verified
m = entry is listed in manifest
k = at least one certificate was found in keystore
jar verified.
jarsigner -keystore /working/mystore -verify -verbose -certs myTest.jar
198 Fri Sep 26 16:14:06 PDT 1997 META-INF/MANIFEST.MF
199 Fri Sep 26 16:22:10 PDT 1997 META-INF/JANE.SF
1013 Fri Sep 26 16:22:10 PDT 1997 META-INF/JANE.DSA
208 Fri Sep 26 16:23:30 PDT 1997 META-INF/JAVATEST.SF
1087 Fri Sep 26 16:23:30 PDT 1997 META-INF/JAVATEST.DSA
smk 2752 Fri Sep 26 16:12:30 PDT 1997 Tst.class
X.509, CN=Test Group, OU=Java Software, O=Oracle, L=CUP, S=CA, C=US (javatest)
X.509, CN=Jane Smith, OU=Java Software, O=Oracle, L=cup, S=ca, C=us (jane)
s = signature was verified
m = entry is listed in manifest
k = at least one certificate was found in keystore
jar verified.
If the certificate for a signer is not an X.509 certificate, then there is no distinguished name information. In that case, just the certificate type and the alias are shown. For example, if the certificate is a PGP certificate, and the alias is bob, then you would get: PGP, (bob).