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What is RSA?
The Core Idea of Asymmetric Encryption: RSA uses a pair of mathematically related keys — a public key and a private key. The public key can be openly distributed and is used to encrypt data; the private key must be kept strictly confidential and is used to decrypt data or create digital signatures.
History and Status: RSA was proposed in 1977 by three cryptographers at MIT — Ron Rivest, Adi Shamir, and Leonard Adleman — after whom the algorithm is named. It was the first algorithm capable of both data encryption and digital signatures, and remains widely used in SSL/TLS certificates, SSH login, online banking, and digital signatures.
Mathematical Principle: RSA security is based on the difficulty of the integer factorization problem — multiplying two large primes is easy, but factoring their product is extremely difficult. Common key sizes are 2048-bit and 4096-bit.
Common Questions About RSA
What key size should I choose? At least 2048 bits is currently recommended for industry use. For higher security requirements, choose 4096 bits. 1024-bit is no longer considered secure and should not be used in production environments.
Why can't RSA encrypt large files directly? RSA is relatively slow and has a maximum encryption length limit (related to key size). The typical approach is to use RSA to encrypt a random symmetric key (such as an AES key), then use AES to encrypt the large file. This is the classic hybrid encryption pattern.
What's the difference between PKCS#1 v1.5 and OAEP? PKCS#1 v1.5 is a classic padding scheme with good compatibility but known attack vectors; OAEP (Optimal Asymmetric Encryption Padding) is a more secure padding scheme based on a Feistel network structure, providing provable security. OAEP is recommended.
How does digital signing work? To sign, the sender encrypts a message digest with their private key (creating a signature); to verify, the recipient decrypts the signature with the corresponding public key, ensuring the message came from the private key holder.
Data Security and Privacy
🔒 Local Browser Processing: Our RSA tool runs entirely in your browser. All key generation, encryption, and decryption operations are performed locally in the JavaScript engine. Your plaintext, ciphertext, public keys, and private keys are never uploaded to any server, nor are they recorded in any logs. The tool works even without an internet connection.
🛡️ Safe Usage Recommendations: When handling sensitive data with this tool, we recommend using privacy mode with browser extensions disabled, and ensuring your device is free of malware. Do not process highly sensitive information on public or untrusted computers. Clear your browser cache after use.
⚡ High-Performance Computing: RSA key generation is relatively slow, but encryption and decryption speeds are more than sufficient for daily development and testing. Our tool uses a standard JavaScript implementation that can generate 2048-bit keys in seconds on a typical laptop.
🌐 Open Source & Transparent: We use industry-standard encryption implementations, with algorithm logic fully transparent to all users, ensuring no hidden behavior. Data security and privacy are our core commitments.
⚠️ Legal Compliance Notice: Please ensure you comply with the laws and regulations of your country and region when using this tool. This tool is intended for legal data protection, development testing, and learning research purposes only. Any use for illegal purposes is strictly prohibited.