Use SecureRandom for cryptographic operations and remove SHA1PRNG dependency

[jmestwa-coder]

Summary

Replace java.util.Random with SecureRandom in cryptographic usage and remove hardcoded "SHA1PRNG".

Changes

• Use SecureRandom for salt generation in SunJceCrypt
• Replace "SHA1PRNG" with new SecureRandom() in DefaultSecureRandomSupplier

Why

• Random is predictable and not suitable for cryptographic use
• Salt generation requires high-entropy randomness
• Avoid hardcoded PRNG and let JVM choose the appropriate provider

Impact

• No API or behavior changes
• Backward compatible
• Improves randomness quality in security-sensitive paths