org.bouncycastle.operator.bc
Class BcRSAAsymmetricKeyUnwrapper

java.lang.Object
  org.bouncycastle.operator.AsymmetricKeyUnwrapper
      org.bouncycastle.operator.bc.BcAsymmetricKeyUnwrapper
          org.bouncycastle.operator.bc.BcRSAAsymmetricKeyUnwrapper

All Implemented Interfaces:

KeyUnwrapper

public class BcRSAAsymmetricKeyUnwrapper

extends BcAsymmetricKeyUnwrapper

Lightweight unwrapper for RSA PKCS#1 v1.5 () key transport, used by the BC CMS / PKIX recipient implementations.

Bleichenbacher/Marvin note: PKCS#1 v1.5 RSA decryption is inherently vulnerable to adaptive chosen-ciphertext (Bleichenbacher / Marvin) attacks whenever an attacker can submit ciphertexts and distinguish a padding failure from a success -- including only by timing or observable behaviour. This unwrapper reports a decryption/padding failure by throwing (an OperatorException) rather than returning a random key of the expected length, so a service that decrypts attacker-supplied key-transport blobs with a static RSA private key and exposes the outcome (a distinguishable error, or a response-time difference) acts as such an oracle. The lightweight PKCS1Encoding offers a constant-time random-fallback mode (return a random key of the expected length on bad padding instead of throwing); the BC TLS stack wires it for the RSA key-exchange pre-master secret, but it is not applied here, so padding-oracle resistance for CMS/PKIX key transport is left to the protocol or application layer. Where this unwrapper backs an online decryption oracle, prefer RSA-KEM or RSA-OAEP key transport over PKCS#1 v1.5.

Constructor Summary

BcRSAAsymmetricKeyUnwrapper(org.bouncycastle.asn1.x509.AlgorithmIdentifier encAlgId, org.bouncycastle.crypto.params.AsymmetricKeyParameter privateKey)

Method Summary

protected org.bouncycastle.crypto.AsymmetricBlockCipher

createAsymmetricUnwrapper(org.bouncycastle.asn1.ASN1ObjectIdentifier algorithm)

Methods inherited from class org.bouncycastle.operator.bc.BcAsymmetricKeyUnwrapper

generateUnwrappedKey

Methods inherited from class org.bouncycastle.operator.AsymmetricKeyUnwrapper

getAlgorithmIdentifier

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BcRSAAsymmetricKeyUnwrapper

public BcRSAAsymmetricKeyUnwrapper(org.bouncycastle.asn1.x509.AlgorithmIdentifier encAlgId,
                                   org.bouncycastle.crypto.params.AsymmetricKeyParameter privateKey)

Method Detail

createAsymmetricUnwrapper

protected org.bouncycastle.crypto.AsymmetricBlockCipher createAsymmetricUnwrapper(org.bouncycastle.asn1.ASN1ObjectIdentifier algorithm)

Specified by:

createAsymmetricUnwrapper in class BcAsymmetricKeyUnwrapper