How Do I Fix the 'Illegal Key Size' Error in Java Cryptography?

Java Cryptography Extension: "Illegal Key Size" Error

Background

When faced with an "Illegal Key Size" error when using Java Cryptography, it is indicative of restricted key sizes imposed by Java's cryptographic policy for export control compliance.

Troubleshooting

Java 9 and Higher

• Unlimited cryptography is enabled by default.
• If the error persists, check if a restricted policy has been configured accidentally.

Java 8 and Earlier

Java 8 Update 161 and Higher

• Unlimited cryptography is also enabled by default.
• If the error occurs, the policy may have been changed. Refer to the instructions below.

Java 8 Update 151 and Higher

• Unlimited cryptography is included but not enabled by default.

• Edit java.security file in /lib/security (or /jre/lib/security for JDK):

  • Uncomment or add line crypto.policy=unlimited
• Restart the JVM.

Before Java 8 Update 151

• Install Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy Files:

  • Download from Oracle
  • Extract and place in the appropriate security directory (/lib/security)
• Restart the JVM.

Additional Notes

• The Unlimited Strength Jurisdiction Policy is required for AES encryption with a key size greater than 128 bits.
• If modifying the policy is not an option, consider switching to a different crypto library that supports unrestricted key sizes.

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