.JKS

Файл JKS

Java KeyStore
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A JKS file is a Java KeyStore - an encrypted, password-protected binary that stores private keys and SSL/TLS certificates for Java applications such as Tomcat and Android app signing. You open it with the JDK's built-in keytool command or the free GUI KeyStore Explorer. The format has been deprecated since Java 9 (2017) in favor of PKCS#12 (.p12/.pfx), and the keystore password is required to read anything inside.

Разработчик: Sun Microsystems / Oracle (Java platform) Категория: Зашифрованные файлы MIME: application/octet-stream
ОТКРЫВАЕТСЯ НА Windows macOS Linux
Связанные: .CRYPT · .SDOC · .AXX · .REM

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Последняя проверка: Jul 30, 2026

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Что такое формат файла JKS?

A .jks file is a Java KeyStore - a proprietary binary container that stores cryptographic private keys and X.509 certificates for use by Java applications. The format was introduced by Sun Microsystems as part of the Java Cryptography Architecture (JCA) in the late 1990s and is maintained today by Oracle.

Every .jks file starts with the 4-byte magic number 0xFEEDFEED, followed by a version field (typically 0x00000002). The file is big-endian and holds two entry types: KeyEntry records, containing an encrypted private key plus its certificate chain, and TrustedCertEntry records, which store certificates without encryption. A keyed SHA-1 digest at the end protects integrity - a wrong password or any tampering triggers the familiar *"keystore was tampered with, or password was incorrect"* error.

Private keys are protected by a proprietary password-based encryption (PBE) scheme built on SHA-1, which is considered weak by modern standards. The .jks format is Java-only and not readable by tools such as OpenSSL, which expect PKCS#12 or PEM instead.

Since JDK 9 (2017), Oracle deprecated .jks in favour of .p12 / .pfx, which became the new default keystore type. keytool now emits a migration warning on every JKS store it opens. The JDK's system trust store cacerts has historically shipped as a .jks file. The related .jceks variant (magic 0xCECECECE) offers stronger Triple-DES key protection but remains equally Java-specific.

Безопасность и защита

РИСК: MEDIUM

A JKS file is inert data (no executable code), but it is a SECRET store: it commonly contains private keys whose exposure compromises a server's identity or an app's signing key. Treat it like a password file - never commit it to a public repo, restrict file permissions, and use a strong store password. The format's encryption is weak by modern standards, so a leaked .jks with a poor password can be brute-forced; this is a further reason to migrate to PKCS#12 and to rotate keys if a keystore is ever exposed. Files claiming to be keystores from untrusted sources should not be trusted as your trust store.

Детали формата

в двух словах
ПОЛНОЕ НАЗВАНИЕJava KeyStoreтакже известен как JKS keystore, Java KeyStore file
РАЗРАБОТЧИКSun Microsystems / Oracle (Java platform)с 1990s, with the Java security architecture (Java Cryptography Architecture)
MIME-ТИПapplication/octet-stream
ТИПProprietary binary keystore holding private keys and X.509 certificates, password-protected
СВЯЗАННЫЕ.crypt.sdoc.axx.rem
Это расширение также используется в…
  • Star Wars Jedi Knight game save - Some LucasArts/Raven Star Wars Jedi Knight titles used .jks for saved games; loaded inside the game, unrelated to Java keystores (the obsolete db_name).
MAGIC BYTES · СИГНАТУРА ФАЙЛА
СМЕЩЕНИЕ
00010203
HEX
FEEDFEED
ASCII
····
A JKS file begins with the 32-bit magic number 0xFEEDFEED (FE ED FE ED), followed by a 4-byte version field (usually 0x00000002). The related JCEKS variant uses magic 0xCECECECE. PKCS#12 keystores (.p12/.pfx) instead start with the ASN.1 SEQUENCE byte 0x30 (often 30 82), which is how tools tell a real JKS apart from a PKCS#12 file that happens to carry a .jks name.

Программы, открывающие файлы JKS

Windows3 apps
keytool (JDK) Бесплатно Run 'keytool -list -v -keystore file.jks' (you'll be prompted for the store password) to view entries; -importcert / -genkeypair to modify.
KeyStore Explorer Открытый код Open the .jks in this GUI, enter the password, and browse/edit keys and certificates without memorizing keytool syntax.
Star Wars Jedi Knight (game saves) Платно Only relevant if the .jks is actually a Jedi Knight game save (see also_used_by) - those load inside the game, not via keytool.
macOS2 apps
keytool (JDK) Бесплатно Run 'keytool -list -v -keystore file.jks' (you'll be prompted for the store password) to view entries; -importcert / -genkeypair to modify.
KeyStore Explorer Открытый код Open the .jks in this GUI, enter the password, and browse/edit keys and certificates without memorizing keytool syntax.
Linux2 apps
keytool (JDK) Открытый код Run 'keytool -list -v -keystore file.jks' (you'll be prompted for the store password) to view entries; -importcert / -genkeypair to modify.
KeyStore Explorer Открытый код Open the .jks in this GUI, enter the password, and browse/edit keys and certificates without memorizing keytool syntax.

Технические подробности

глубокая спецификация
Magic bytes0xFEEDFEED (FE ED FE ED) at file offset 0; identifies the file as JKS to tools and validators
Format version field4-byte big-endian integer at offset 4; value 1 or 2 (version 2 is current)
Byte orderBig-endian throughout the entire binary structure
Private-key encryptionProprietary PBE scheme using SHA-1 as a key-derivation primitive; considered cryptographically weak by modern standards
Certificate storageTrustedCertEntry records hold X.509 DER-encoded certificates in plaintext - no per-certificate encryption
Integrity protectionKeyed SHA-1 digest over the entire store content, derived from the store password; detects both tampering and a wrong password
Entry typesTwo types: KeyEntry (encrypted private key + certificate chain) and TrustedCertEntry (bare certificate)
Entry addressingEach entry is identified by a unique string alias; aliases are case-insensitive within a store
MIME typeapplication/x-java-keystore (Java-specific); falls back to application/octet-stream for generic handling
Typical file size1 KB - 50 KB for a few keys and certificates; up to several MB for large trust stores such as cacerts
Primary management toolJDK keytool command-line utility; graphical alternative is KeyStore Explorer
Platform scopePortable across any OS with a JRE or JDK, but the format is Java-specific and not interoperable with OpenSSL or other non-Java PKI tools
Deprecation statusDeprecated by Oracle since JDK 9 (2017); PKCS#12 is now the default keystore type and keytool warns on every JKS store opened
Stronger Sun variantJCEKS (magic 0xCECECECE) - a Sun extension with Triple-DES key wrapping; still Java-only
System trust storeThe JDK cacerts file shipped with every JRE has historically been a JKS keystore holding hundreds of root CA certificates
Выпущен1990s, with the Java security architecture (Java Cryptography Architecture)
Последняя версияJKS format unchanged; deprecated in favor of PKCS#12 (default keystore type since JDK 9, 2017)
Спецификацияdocs.oracle.com

Конвертации JKS

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Часто задаваемые вопросы

What is a .jks file?
A Java KeyStore - an encrypted, password-protected file that stores private keys and SSL/TLS certificates for Java applications (servers, Android app signing). It's managed with the JDK's keytool, not opened as a document.
How do I open a JKS file?
Use the JDK 'keytool' on the command line ('keytool -list -v -keystore file.jks') or a free GUI like KeyStore Explorer. You must know the keystore password - there's no way to read the keys without it.
How do I convert a JKS to PKCS12 (.p12/.pfx)?
Run: keytool -importkeystore -srckeystore in.jks -srcstoretype JKS -destkeystore out.p12 -deststoretype PKCS12. PKCS#12 is the modern, cross-tool standard and the JDK default since Java 9.
Why does keytool say 'keystore was tampered with, or password was incorrect'?
Usually the store password is wrong - the integrity digest is derived from it, so a bad password looks like tampering. It can also mean the file is corrupted or isn't really a JKS.
Is JKS deprecated?
Yes. Since Java 9 (2017) keytool defaults to PKCS#12 and warns that JKS uses a proprietary, weaker format. Existing JKS files still work, but new keystores and migrations should use PKCS#12.
How do I recover the password for a .jks?
There's no official recovery - the store is integrity-bound to its password. You'd need the original password or a brute-force/dictionary tool on a copy, which only works if the password is weak. Otherwise the keys are unrecoverable.

Ссылки

1Oracle - keytool reference (Java KeyStore management)docs.oracle.com
2DigiCert - Convert a JKS keystore to PKCS#12knowledge.digicert.com

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