diff options
| -rw-r--r-- | crypto/src/crypto/engines/RSACoreEngine.cs | 182 |
1 files changed, 86 insertions, 96 deletions
diff --git a/crypto/src/crypto/engines/RSACoreEngine.cs b/crypto/src/crypto/engines/RSACoreEngine.cs index ee0f86c3f..7040899f9 100644 --- a/crypto/src/crypto/engines/RSACoreEngine.cs +++ b/crypto/src/crypto/engines/RSACoreEngine.cs @@ -7,118 +7,102 @@ using Org.BouncyCastle.Utilities; namespace Org.BouncyCastle.Crypto.Engines { - /** - * this does your basic RSA algorithm. - */ - public class RsaCoreEngine + /// <summary>This does your basic RSA algorithm.</summary> + public class RsaCoreEngine : IRsa - { - private RsaKeyParameters key; - private bool forEncryption; - private int bitSize; + { + private RsaKeyParameters m_key; + private bool m_forEncryption; + private int m_bitSize; - private void CheckInitialised() + /** + * initialise the RSA engine. + * + * @param forEncryption true if we are encrypting, false otherwise. + * @param param the necessary RSA key parameters. + */ + public virtual void Init(bool forEncryption, ICipherParameters parameters) { - if (key == null) - throw new InvalidOperationException("RSA engine not initialised"); + if (parameters is ParametersWithRandom withRandom) + { + parameters = withRandom.Parameters; + } + + m_key = parameters as RsaKeyParameters ?? throw new InvalidKeyException("Not an RSA key"); + m_forEncryption = forEncryption; + m_bitSize = m_key.Modulus.BitLength; } /** - * initialise the RSA engine. - * - * @param forEncryption true if we are encrypting, false otherwise. - * @param param the necessary RSA key parameters. - */ - public virtual void Init( - bool forEncryption, - ICipherParameters parameters) - { - if (parameters is ParametersWithRandom withRandom) - { - parameters = withRandom.Parameters; - } - - if (!(parameters is RsaKeyParameters rsaKeyParameters)) - throw new InvalidKeyException("Not an RSA key"); - - this.key = rsaKeyParameters; - this.forEncryption = forEncryption; - this.bitSize = key.Modulus.BitLength; - } - - /** - * Return the maximum size for an input block to this engine. - * For RSA this is always one byte less than the key size on - * encryption, and the same length as the key size on decryption. - * - * @return maximum size for an input block. - */ + * Return the maximum size for an input block to this engine. + * For RSA this is always one byte less than the key size on + * encryption, and the same length as the key size on decryption. + * + * @return maximum size for an input block. + */ public virtual int GetInputBlockSize() - { + { CheckInitialised(); - if (forEncryption) - { - return (bitSize - 1) / 8; - } - - return (bitSize + 7) / 8; - } - - /** - * Return the maximum size for an output block to this engine. - * For RSA this is always one byte less than the key size on - * decryption, and the same length as the key size on encryption. - * - * @return maximum size for an output block. - */ + if (m_forEncryption) + { + return (m_bitSize - 1) / 8; + } + + return (m_bitSize + 7) / 8; + } + + /** + * Return the maximum size for an output block to this engine. + * For RSA this is always one byte less than the key size on + * decryption, and the same length as the key size on encryption. + * + * @return maximum size for an output block. + */ public virtual int GetOutputBlockSize() - { + { CheckInitialised(); - if (forEncryption) - { - return (bitSize + 7) / 8; - } + if (m_forEncryption) + { + return (m_bitSize + 7) / 8; + } - return (bitSize - 1) / 8; - } + return (m_bitSize - 1) / 8; + } - public virtual BigInteger ConvertInput( - byte[] inBuf, - int inOff, - int inLen) - { + public virtual BigInteger ConvertInput(byte[] inBuf, int inOff, int inLen) + { CheckInitialised(); - int maxLength = (bitSize + 7) / 8; + int maxLength = (m_bitSize + 7) / 8; - if (inLen > maxLength) - throw new DataLengthException("input too large for RSA cipher."); + if (inLen > maxLength) + throw new DataLengthException("input too large for RSA cipher."); - BigInteger input = new BigInteger(1, inBuf, inOff, inLen); + BigInteger input = new BigInteger(1, inBuf, inOff, inLen); - if (input.CompareTo(key.Modulus) >= 0) - throw new DataLengthException("input too large for RSA cipher."); + if (input.CompareTo(m_key.Modulus) >= 0) + throw new DataLengthException("input too large for RSA cipher."); - return input; - } + return input; + } public virtual byte[] ConvertOutput(BigInteger result) - { + { CheckInitialised(); - return forEncryption - ? BigIntegers.AsUnsignedByteArray(GetOutputBlockSize(), result) - : BigIntegers.AsUnsignedByteArray(result); - } + return m_forEncryption + ? BigIntegers.AsUnsignedByteArray(GetOutputBlockSize(), result) + : BigIntegers.AsUnsignedByteArray(result); + } public virtual BigInteger ProcessBlock(BigInteger input) - { + { CheckInitialised(); - if (!(key is RsaPrivateCrtKeyParameters crt)) - return input.ModPow(key.Exponent, key.Modulus); + if (!(m_key is RsaPrivateCrtKeyParameters crt)) + return input.ModPow(m_key.Exponent, m_key.Modulus); // // we have the extra factors, use the Chinese Remainder Theorem - the author @@ -126,29 +110,35 @@ namespace Org.BouncyCastle.Crypto.Engines // advice regarding the expression of this. // BigInteger p = crt.P; - BigInteger q = crt.Q; - BigInteger dP = crt.DP; - BigInteger dQ = crt.DQ; - BigInteger qInv = crt.QInv; + BigInteger q = crt.Q; + BigInteger dP = crt.DP; + BigInteger dQ = crt.DQ; + BigInteger qInv = crt.QInv; - // mP = ((input Mod p) ^ dP)) Mod p - BigInteger mP = (input.Remainder(p)).ModPow(dP, p); + // mP = ((input Mod p) ^ dP)) Mod p + BigInteger mP = (input.Remainder(p)).ModPow(dP, p); // mQ = ((input Mod q) ^ dQ)) Mod q BigInteger mQ = (input.Remainder(q)).ModPow(dQ, q); - // h = qInv * (mP - mQ) Mod p - BigInteger h = mP.Subtract(mQ).Multiply(qInv).Mod(p); + // h = qInv * (mP - mQ) Mod p + BigInteger h = mP.Subtract(mQ).Multiply(qInv).Mod(p); // m = h * q + mQ BigInteger m = h.Multiply(q).Add(mQ); - // defence against Arjen Lenstra’s CRT attack - BigInteger check = m.ModPow(crt.PublicExponent, crt.Modulus); + // defence against Arjen Lenstra’s CRT attack + BigInteger check = m.ModPow(crt.PublicExponent, crt.Modulus); if (!check.Equals(input)) throw new InvalidOperationException("RSA engine faulty decryption/signing detected"); return m; - } - } + } + + private void CheckInitialised() + { + if (m_key == null) + throw new InvalidOperationException("RSA engine not initialised"); + } + } } |