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Diffstat (limited to 'crypto/src/cms/KeyAgreeRecipientInformation.cs')
| -rw-r--r-- | crypto/src/cms/KeyAgreeRecipientInformation.cs | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/crypto/src/cms/KeyAgreeRecipientInformation.cs b/crypto/src/cms/KeyAgreeRecipientInformation.cs new file mode 100644 index 000000000..38a94b0a4 --- /dev/null +++ b/crypto/src/cms/KeyAgreeRecipientInformation.cs @@ -0,0 +1,226 @@ +using System; +using System.Collections; +using System.IO; + +using Org.BouncyCastle.Asn1; +using Org.BouncyCastle.Asn1.Cms; +using Org.BouncyCastle.Asn1.Cms.Ecc; +using Org.BouncyCastle.Asn1.Pkcs; +using Org.BouncyCastle.Asn1.Utilities; +using Org.BouncyCastle.Asn1.X509; +using Org.BouncyCastle.Asn1.X9; +using Org.BouncyCastle.Crypto; +using Org.BouncyCastle.Crypto.Parameters; +using Org.BouncyCastle.Math; +using Org.BouncyCastle.Pkcs; +using Org.BouncyCastle.Security; +using Org.BouncyCastle.X509; + +namespace Org.BouncyCastle.Cms +{ + /** + * the RecipientInfo class for a recipient who has been sent a message + * encrypted using key agreement. + */ + public class KeyAgreeRecipientInformation + : RecipientInformation + { + private KeyAgreeRecipientInfo info; + private Asn1OctetString encryptedKey; + + internal static void ReadRecipientInfo(IList infos, KeyAgreeRecipientInfo info, + CmsSecureReadable secureReadable) + { + try + { + foreach (Asn1Encodable rek in info.RecipientEncryptedKeys) + { + RecipientEncryptedKey id = RecipientEncryptedKey.GetInstance(rek.ToAsn1Object()); + + RecipientID rid = new RecipientID(); + + Asn1.Cms.KeyAgreeRecipientIdentifier karid = id.Identifier; + + Asn1.Cms.IssuerAndSerialNumber iAndSN = karid.IssuerAndSerialNumber; + if (iAndSN != null) + { + rid.Issuer = iAndSN.Name; + rid.SerialNumber = iAndSN.SerialNumber.Value; + } + else + { + Asn1.Cms.RecipientKeyIdentifier rKeyID = karid.RKeyID; + + // Note: 'date' and 'other' fields of RecipientKeyIdentifier appear to be only informational + + rid.SubjectKeyIdentifier = rKeyID.SubjectKeyIdentifier.GetOctets(); + } + + infos.Add(new KeyAgreeRecipientInformation(info, rid, id.EncryptedKey, + secureReadable)); + } + } + catch (IOException e) + { + throw new ArgumentException("invalid rid in KeyAgreeRecipientInformation", e); + } + } + + internal KeyAgreeRecipientInformation( + KeyAgreeRecipientInfo info, + RecipientID rid, + Asn1OctetString encryptedKey, + CmsSecureReadable secureReadable) + : base(info.KeyEncryptionAlgorithm, secureReadable) + { + this.info = info; + this.rid = rid; + this.encryptedKey = encryptedKey; + } + + private AsymmetricKeyParameter GetSenderPublicKey( + AsymmetricKeyParameter receiverPrivateKey, + OriginatorIdentifierOrKey originator) + { + OriginatorPublicKey opk = originator.OriginatorPublicKey; + if (opk != null) + { + return GetPublicKeyFromOriginatorPublicKey(receiverPrivateKey, opk); + } + + OriginatorID origID = new OriginatorID(); + + Asn1.Cms.IssuerAndSerialNumber iAndSN = originator.IssuerAndSerialNumber; + if (iAndSN != null) + { + origID.Issuer = iAndSN.Name; + origID.SerialNumber = iAndSN.SerialNumber.Value; + } + else + { + SubjectKeyIdentifier ski = originator.SubjectKeyIdentifier; + + origID.SubjectKeyIdentifier = ski.GetKeyIdentifier(); + } + + return GetPublicKeyFromOriginatorID(origID); + } + + private AsymmetricKeyParameter GetPublicKeyFromOriginatorPublicKey( + AsymmetricKeyParameter receiverPrivateKey, + OriginatorPublicKey originatorPublicKey) + { + PrivateKeyInfo privInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(receiverPrivateKey); + SubjectPublicKeyInfo pubInfo = new SubjectPublicKeyInfo( + privInfo.AlgorithmID, + originatorPublicKey.PublicKey.GetBytes()); + return PublicKeyFactory.CreateKey(pubInfo); + } + + private AsymmetricKeyParameter GetPublicKeyFromOriginatorID( + OriginatorID origID) + { + // TODO Support all alternatives for OriginatorIdentifierOrKey + // see RFC 3852 6.2.2 + throw new CmsException("No support for 'originator' as IssuerAndSerialNumber or SubjectKeyIdentifier"); + } + + private KeyParameter CalculateAgreedWrapKey( + string wrapAlg, + AsymmetricKeyParameter senderPublicKey, + AsymmetricKeyParameter receiverPrivateKey) + { + DerObjectIdentifier agreeAlgID = keyEncAlg.ObjectID; + + ICipherParameters senderPublicParams = senderPublicKey; + ICipherParameters receiverPrivateParams = receiverPrivateKey; + + if (agreeAlgID.Id.Equals(CmsEnvelopedGenerator.ECMqvSha1Kdf)) + { + byte[] ukmEncoding = info.UserKeyingMaterial.GetOctets(); + MQVuserKeyingMaterial ukm = MQVuserKeyingMaterial.GetInstance( + Asn1Object.FromByteArray(ukmEncoding)); + + AsymmetricKeyParameter ephemeralKey = GetPublicKeyFromOriginatorPublicKey( + receiverPrivateKey, ukm.EphemeralPublicKey); + + senderPublicParams = new MqvPublicParameters( + (ECPublicKeyParameters)senderPublicParams, + (ECPublicKeyParameters)ephemeralKey); + receiverPrivateParams = new MqvPrivateParameters( + (ECPrivateKeyParameters)receiverPrivateParams, + (ECPrivateKeyParameters)receiverPrivateParams); + } + + IBasicAgreement agreement = AgreementUtilities.GetBasicAgreementWithKdf( + agreeAlgID, wrapAlg); + agreement.Init(receiverPrivateParams); + BigInteger agreedValue = agreement.CalculateAgreement(senderPublicParams); + + int wrapKeySize = GeneratorUtilities.GetDefaultKeySize(wrapAlg) / 8; + byte[] wrapKeyBytes = X9IntegerConverter.IntegerToBytes(agreedValue, wrapKeySize); + return ParameterUtilities.CreateKeyParameter(wrapAlg, wrapKeyBytes); + } + + private KeyParameter UnwrapSessionKey( + string wrapAlg, + KeyParameter agreedKey) + { + byte[] encKeyOctets = encryptedKey.GetOctets(); + + IWrapper keyCipher = WrapperUtilities.GetWrapper(wrapAlg); + keyCipher.Init(false, agreedKey); + byte[] sKeyBytes = keyCipher.Unwrap(encKeyOctets, 0, encKeyOctets.Length); + return ParameterUtilities.CreateKeyParameter(GetContentAlgorithmName(), sKeyBytes); + } + + internal KeyParameter GetSessionKey( + AsymmetricKeyParameter receiverPrivateKey) + { + try + { + string wrapAlg = DerObjectIdentifier.GetInstance( + Asn1Sequence.GetInstance(keyEncAlg.Parameters)[0]).Id; + + AsymmetricKeyParameter senderPublicKey = GetSenderPublicKey( + receiverPrivateKey, info.Originator); + + KeyParameter agreedWrapKey = CalculateAgreedWrapKey(wrapAlg, + senderPublicKey, receiverPrivateKey); + + return UnwrapSessionKey(wrapAlg, agreedWrapKey); + } + catch (SecurityUtilityException e) + { + throw new CmsException("couldn't create cipher.", e); + } + catch (InvalidKeyException e) + { + throw new CmsException("key invalid in message.", e); + } + catch (Exception e) + { + throw new CmsException("originator key invalid.", e); + } + } + + /** + * decrypt the content and return an input stream. + */ + public override CmsTypedStream GetContentStream( + ICipherParameters key) + { + if (!(key is AsymmetricKeyParameter)) + throw new ArgumentException("KeyAgreement requires asymmetric key", "key"); + + AsymmetricKeyParameter receiverPrivateKey = (AsymmetricKeyParameter) key; + + if (!receiverPrivateKey.IsPrivate) + throw new ArgumentException("Expected private key", "key"); + + KeyParameter sKey = GetSessionKey(receiverPrivateKey); + + return GetContentFromSessionKey(sKey); + } + } +} |