Public exponent
A public exponent is the exponent component of an RSA public key used for modular exponentiation during encryption or signature verification.
Hacking Cryptography
The public exponent is the RSA exponent included in the public key and used for modular exponentiation during encryption or signature verification.
- How it is used
- Deploys e as the public RSA parameter for encryption and signature verification.
- How deep it goes
- Explains selection, modular inversion, exponentiation, and e = 3 padding attacks, but defers the full decryption proof.
- Examples
- Uses a numerical RSA key-generation example and Go implementations and tests built around e = 3.
- What you can do after
- Operate RSA parameter generation and diagnose signature-forgery risk caused by weak PKCS#1 v1.5 validation.
Real-World Cryptography
A public exponent is the RSA exponent included in the public key and used for modular exponentiation during encryption.
- How it is used
- Uses the public exponent to encrypt messages in RSA asymmetric encryption.
- How deep it goes
- Explains modular exponentiation, gives a small calculation, and stops short of fully deriving the private exponent.
- Examples
- Uses m = 2, e = 2, and p = 5 to demonstrate ciphertext = 4.
- What you can do after
- Evaluate RSA encryption as modular exponentiation using a published exponent and distinguish it from private-key decryption.
Related concepts
- Bleichenbacher's e=3 forgery attackused by · Bleichenbacher's e=3 forgery attack is an RSA signature-forgery attack that exploits lax validation of PKCS #1 v1.5 signature padding when the public exponent is 3.
- textbook rsaused by · Textbook RSA is an unpadded RSA method that directly applies modular exponentiation to a message representative for encryption or signing.
- signature forgery attackconfigures · A signature forgery attack produces a signature that a verifier accepts as authentic without authorization from the legitimate signer's private key.
- private keyconfigures · A private key is the secret component of an asymmetric cryptographic key pair used by its holder for operations such as authentication, decryption, or digital signing.
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