diff options
Diffstat (limited to 'Crypto/src/crypto/engines/IesEngine.cs')
| -rw-r--r-- | Crypto/src/crypto/engines/IesEngine.cs | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/Crypto/src/crypto/engines/IesEngine.cs b/Crypto/src/crypto/engines/IesEngine.cs new file mode 100644 index 000000000..c49b2a9ee --- /dev/null +++ b/Crypto/src/crypto/engines/IesEngine.cs @@ -0,0 +1,236 @@ +using System; + +using Org.BouncyCastle.Crypto.Parameters; +using Org.BouncyCastle.Math; + +namespace Org.BouncyCastle.Crypto.Engines +{ + /** + * support class for constructing intergrated encryption ciphers + * for doing basic message exchanges on top of key agreement ciphers + */ + public class IesEngine + { + private readonly IBasicAgreement agree; + private readonly IDerivationFunction kdf; + private readonly IMac mac; + private readonly BufferedBlockCipher cipher; + private readonly byte[] macBuf; + + private bool forEncryption; + private ICipherParameters privParam, pubParam; + private IesParameters param; + + /** + * set up for use with stream mode, where the key derivation function + * is used to provide a stream of bytes to xor with the message. + * + * @param agree the key agreement used as the basis for the encryption + * @param kdf the key derivation function used for byte generation + * @param mac the message authentication code generator for the message + */ + public IesEngine( + IBasicAgreement agree, + IDerivationFunction kdf, + IMac mac) + { + this.agree = agree; + this.kdf = kdf; + this.mac = mac; + this.macBuf = new byte[mac.GetMacSize()]; +// this.cipher = null; + } + + /** + * set up for use in conjunction with a block cipher to handle the + * message. + * + * @param agree the key agreement used as the basis for the encryption + * @param kdf the key derivation function used for byte generation + * @param mac the message authentication code generator for the message + * @param cipher the cipher to used for encrypting the message + */ + public IesEngine( + IBasicAgreement agree, + IDerivationFunction kdf, + IMac mac, + BufferedBlockCipher cipher) + { + this.agree = agree; + this.kdf = kdf; + this.mac = mac; + this.macBuf = new byte[mac.GetMacSize()]; + this.cipher = cipher; + } + + /** + * Initialise the encryptor. + * + * @param forEncryption whether or not this is encryption/decryption. + * @param privParam our private key parameters + * @param pubParam the recipient's/sender's public key parameters + * @param param encoding and derivation parameters. + */ + public void Init( + bool forEncryption, + ICipherParameters privParameters, + ICipherParameters pubParameters, + ICipherParameters iesParameters) + { + this.forEncryption = forEncryption; + this.privParam = privParameters; + this.pubParam = pubParameters; + this.param = (IesParameters)iesParameters; + } + + private byte[] DecryptBlock( + byte[] in_enc, + int inOff, + int inLen, + byte[] z) + { + byte[] M = null; + KeyParameter macKey = null; + KdfParameters kParam = new KdfParameters(z, param.GetDerivationV()); + int macKeySize = param.MacKeySize; + + kdf.Init(kParam); + + inLen -= mac.GetMacSize(); + + if (cipher == null) // stream mode + { + byte[] Buffer = GenerateKdfBytes(kParam, inLen + (macKeySize / 8)); + + M = new byte[inLen]; + + for (int i = 0; i != inLen; i++) + { + M[i] = (byte)(in_enc[inOff + i] ^ Buffer[i]); + } + + macKey = new KeyParameter(Buffer, inLen, (macKeySize / 8)); + } + else + { + int cipherKeySize = ((IesWithCipherParameters)param).CipherKeySize; + byte[] Buffer = GenerateKdfBytes(kParam, (cipherKeySize / 8) + (macKeySize / 8)); + + cipher.Init(false, new KeyParameter(Buffer, 0, (cipherKeySize / 8))); + + M = cipher.DoFinal(in_enc, inOff, inLen); + + macKey = new KeyParameter(Buffer, (cipherKeySize / 8), (macKeySize / 8)); + } + + byte[] macIV = param.GetEncodingV(); + + mac.Init(macKey); + mac.BlockUpdate(in_enc, inOff, inLen); + mac.BlockUpdate(macIV, 0, macIV.Length); + mac.DoFinal(macBuf, 0); + + inOff += inLen; + + for (int t = 0; t < macBuf.Length; t++) + { + if (macBuf[t] != in_enc[inOff + t]) + { + throw (new InvalidCipherTextException("IMac codes failed to equal.")); + } + } + + return M; + } + + private byte[] EncryptBlock( + byte[] input, + int inOff, + int inLen, + byte[] z) + { + byte[] C = null; + KeyParameter macKey = null; + KdfParameters kParam = new KdfParameters(z, param.GetDerivationV()); + int c_text_length = 0; + int macKeySize = param.MacKeySize; + + if (cipher == null) // stream mode + { + byte[] Buffer = GenerateKdfBytes(kParam, inLen + (macKeySize / 8)); + + C = new byte[inLen + mac.GetMacSize()]; + c_text_length = inLen; + + for (int i = 0; i != inLen; i++) + { + C[i] = (byte)(input[inOff + i] ^ Buffer[i]); + } + + macKey = new KeyParameter(Buffer, inLen, (macKeySize / 8)); + } + else + { + int cipherKeySize = ((IesWithCipherParameters)param).CipherKeySize; + byte[] Buffer = GenerateKdfBytes(kParam, (cipherKeySize / 8) + (macKeySize / 8)); + + cipher.Init(true, new KeyParameter(Buffer, 0, (cipherKeySize / 8))); + + c_text_length = cipher.GetOutputSize(inLen); + byte[] tmp = new byte[c_text_length]; + + int len = cipher.ProcessBytes(input, inOff, inLen, tmp, 0); + len += cipher.DoFinal(tmp, len); + + C = new byte[len + mac.GetMacSize()]; + c_text_length = len; + + Array.Copy(tmp, 0, C, 0, len); + + macKey = new KeyParameter(Buffer, (cipherKeySize / 8), (macKeySize / 8)); + } + + byte[] macIV = param.GetEncodingV(); + + mac.Init(macKey); + mac.BlockUpdate(C, 0, c_text_length); + mac.BlockUpdate(macIV, 0, macIV.Length); + // + // return the message and it's MAC + // + mac.DoFinal(C, c_text_length); + return C; + } + + private byte[] GenerateKdfBytes( + KdfParameters kParam, + int length) + { + byte[] buf = new byte[length]; + + kdf.Init(kParam); + + kdf.GenerateBytes(buf, 0, buf.Length); + + return buf; + } + + public byte[] ProcessBlock( + byte[] input, + int inOff, + int inLen) + { + agree.Init(privParam); + + BigInteger z = agree.CalculateAgreement(pubParam); + + // TODO Is a fixed length result expected? + byte[] zBytes = z.ToByteArrayUnsigned(); + + return forEncryption + ? EncryptBlock(input, inOff, inLen, zBytes) + : DecryptBlock(input, inOff, inLen, zBytes); + } + } + +} |