# < Summary

Information

Class: | Renci.SshNet.Security.Cryptography.Ciphers.RsaCipher
Assembly: | Renci.SshNet
File(s): | \home\appveyor\projects\ssh-net\src\Renci.SshNet\Security\Cryptography\Ciphers\RsaCipher.cs

Line coverage
91%

Covered lines: | 64
Uncovered lines: | 6
Coverable lines: | 70
Total lines: | 158
Line coverage: | 91.4%

Branch coverage
72%

Covered branches: | 16
Total branches: | 22
Branch coverage: | 72.7%

Method coverage

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# Metrics

Method | Branch coverage | Cyclomatic complexity | Line coverage
--- | --- | --- | ---
.ctor(...) | 50% | 2 | 71.42%
Encrypt(...) | 75% | 4 | 100%
Decrypt(...) | 100% | 1 | 100%
Decrypt(...) | 62.5% | 8 | 86.66%
Transform(...) | 100% | 1 | 100%
Transform(...) | 87.5% | 8 | 93.54%

# File(s)

## \home\appveyor\projects\ssh-net\src\Renci.SshNet\Security\Cryptography\Ciphers\RsaCipher.cs

| # | Line |  | Line coverage
--- | --- | --- | --- | ---
|  | `1` |  | `using System;`
|  | `2` |  | `using Renci.SshNet.Common;`
|  | `3` |  | ``
|  | `4` |  | `namespace Renci.SshNet.Security.Cryptography.Ciphers`
|  | `5` |  | `{`
|  | `6` |  | `/// <summary>`
|  | `7` |  | `/// Implements RSA cipher algorithm.`
|  | `8` |  | `/// </summary>`
|  | `9` |  | `public class RsaCipher : AsymmetricCipher`
|  | `10` |  | `{`
|  | `11` |  | `private readonly RsaKey _key;`
|  | `12` |  | ``
|  | `13` |  | `/// <summary>`
|  | `14` |  | `/// Initializes a new instance of the <see cref="RsaCipher"/> class.`
|  | `15` |  | `/// </summary>`
|  | `16` |  | `/// <param name="key">The RSA key.</param>`
| 2768 | `17` |  | `public RsaCipher(RsaKey key)`
| 2768 | `18` |  | `{`
| 2768 | `19` |  | `if (key is null)`
| 0 | `20` |  | `{`
| 0 | `21` |  | `throw new ArgumentNullException(nameof(key));`
|  | `22` |  | `}`
|  | `23` |  | ``
| 2768 | `24` |  | `_key = key;`
| 2768 | `25` |  | `}`
|  | `26` |  | ``
|  | `27` |  | `/// <summary>`
|  | `28` |  | `/// Encrypts the specified data.`
|  | `29` |  | `/// </summary>`
|  | `30` |  | `/// <param name="input">The data.</param>`
|  | `31` |  | `/// <param name="offset">The zero-based offset in <paramref name="input"/> at which to begin encrypting.</param>`
|  | `32` |  | `/// <param name="length">The number of bytes to encrypt from <paramref name="input"/>.</param>`
|  | `33` |  | `/// <returns>Encrypted data.</returns>`
|  | `34` |  | `public override byte[] Encrypt(byte[] input, int offset, int length)`
| 696 | `35` |  | `{`
|  | `36` |  | `// Calculate signature`
| 696 | `37` |  | `var bitLength = _key.Modulus.BitLength;`
|  | `38` |  | ``
| 696 | `39` |  | `var paddedBlock = new byte[(bitLength / 8) + (bitLength % 8 > 0 ? 1 : 0) - 1];`
|  | `40` |  | ``
| 696 | `41` |  | `paddedBlock[0] = 0x01;`
| 239440 | `42` |  | `for (var i = 1; i < paddedBlock.Length - length - 1; i++)`
| 119024 | `43` |  | `{`
| 119024 | `44` |  | `paddedBlock[i] = 0xFF;`
| 119024 | `45` |  | `}`
|  | `46` |  | ``
| 696 | `47` |  | `Buffer.BlockCopy(input, offset, paddedBlock, paddedBlock.Length - length, length);`
|  | `48` |  | ``
| 696 | `49` |  | `return Transform(paddedBlock);`
| 696 | `50` |  | `}`
|  | `51` |  | ``
|  | `52` |  | `/// <summary>`
|  | `53` |  | `/// Decrypts the specified data.`
|  | `54` |  | `/// </summary>`
|  | `55` |  | `/// <param name="input">The data.</param>`
|  | `56` |  | `/// <returns>`
|  | `57` |  | `/// The decrypted data.`
|  | `58` |  | `/// </returns>`
|  | `59` |  | `/// <exception cref="NotSupportedException">Only block type 01 or 02 are supported.</exception>`
|  | `60` |  | `/// <exception cref="NotSupportedException">Thrown when decrypted block type is not supported.</exception>`
|  | `61` |  | `public override byte[] Decrypt(byte[] input)`
| 1210 | `62` |  | `{`
| 1210 | `63` |  | `return Decrypt(input, 0, input.Length);`
| 1210 | `64` |  | `}`
|  | `65` |  | ``
|  | `66` |  | `/// <summary>`
|  | `67` |  | `/// Decrypts the specified input.`
|  | `68` |  | `/// </summary>`
|  | `69` |  | `/// <param name="input">The input.</param>`
|  | `70` |  | `/// <param name="offset">The zero-based offset in <paramref name="input"/> at which to begin decrypting.</param>`
|  | `71` |  | `/// <param name="length">The number of bytes to decrypt from <paramref name="input"/>.</param>`
|  | `72` |  | `/// <returns>`
|  | `73` |  | `/// The decrypted data.`
|  | `74` |  | `/// </returns>`
|  | `75` |  | `/// <exception cref="NotSupportedException">Only block type 01 or 02 are supported.</exception>`
|  | `76` |  | `/// <exception cref="NotSupportedException">Thrown when decrypted block type is not supported.</exception>`
|  | `77` |  | `public override byte[] Decrypt(byte[] input, int offset, int length)`
| 1210 | `78` |  | `{`
| 1210 | `79` |  | `var paddedBlock = Transform(input, offset, length);`
|  | `80` |  | ``
| 1210 | `81` |  | `if (paddedBlock[0] is not 1 and not 2)`
| 0 | `82` |  | `{`
| 0 | `83` |  | `throw new NotSupportedException("Only block type 01 or 02 are supported.");`
|  | `84` |  | `}`
|  | `85` |  | ``
| 1210 | `86` |  | `var position = 1;`
|  | `87` |  | ``
| 360206 | `88` |  | `while (position < paddedBlock.Length && paddedBlock[position] != 0)`
| 358996 | `89` |  | `{`
| 358996 | `90` |  | `position++;`
| 358996 | `91` |  | `}`
|  | `92` |  | ``
| 1210 | `93` |  | `position++;`
|  | `94` |  | ``
| 1210 | `95` |  | `var result = new byte[paddedBlock.Length - position];`
| 1210 | `96` |  | `Buffer.BlockCopy(paddedBlock, position, result, 0, result.Length);`
| 1210 | `97` |  | `return result;`
| 1210 | `98` |  | `}`
|  | `99` |  | ``
|  | `100` |  | `private byte[] Transform(byte[] data)`
| 696 | `101` |  | `{`
| 696 | `102` |  | `return Transform(data, 0, data.Length);`
| 696 | `103` |  | `}`
|  | `104` |  | ``
|  | `105` |  | `private byte[] Transform(byte[] data, int offset, int length)`
| 1906 | `106` |  | `{`
| 1906 | `107` |  | `Array.Reverse(data, offset, length);`
|  | `108` |  | ``
| 1906 | `109` |  | `var inputBytes = new byte[length + 1];`
| 1906 | `110` |  | `Buffer.BlockCopy(data, offset, inputBytes, 0, length);`
|  | `111` |  | ``
| 1906 | `112` |  | `var input = new BigInteger(inputBytes);`
|  | `113` |  | ``
|  | `114` |  | `BigInteger result;`
|  | `115` |  | ``
| 1906 | `116` |  | `var isPrivate = !_key.D.IsZero;`
|  | `117` |  | ``
| 1906 | `118` |  | `if (isPrivate)`
| 696 | `119` |  | `{`
| 696 | `120` |  | `var random = BigInteger.One;`
| 696 | `121` |  | `var max = _key.Modulus - 1;`
| 696 | `122` |  | `var bitLength = _key.Modulus.BitLength;`
|  | `123` |  | ``
| 696 | `124` |  | `if (max < BigInteger.One)`
| 0 | `125` |  | `{`
| 0 | `126` |  | `throw new SshException("Invalid RSA key.");`
|  | `127` |  | `}`
|  | `128` |  | ``
| 1392 | `129` |  | `while (random <= BigInteger.One || random >= max)`
| 696 | `130` |  | `{`
| 696 | `131` |  | `random = BigInteger.Random(bitLength);`
| 696 | `132` |  | `}`
|  | `133` |  | ``
| 696 | `134` |  | `var blindedInput = BigInteger.PositiveMod(BigInteger.ModPow(random, _key.Exponent, _key.Modulus) * input`
|  | `135` |  | ``
|  | `136` |  | `// mP = ((input Mod p) ^ dP)) Mod p`
| 696 | `137` |  | `var mP = BigInteger.ModPow(blindedInput % _key.P, _key.DP, _key.P);`
|  | `138` |  | ``
|  | `139` |  | `// mQ = ((input Mod q) ^ dQ)) Mod q`
| 696 | `140` |  | `var mQ = BigInteger.ModPow(blindedInput % _key.Q, _key.DQ, _key.Q);`
|  | `141` |  | ``
| 696 | `142` |  | `var h = BigInteger.PositiveMod((mP - mQ) * _key.InverseQ, _key.P);`
|  | `143` |  | ``
| 696 | `144` |  | `var m = (h * _key.Q) + mQ;`
|  | `145` |  | ``
| 696 | `146` |  | `var rInv = BigInteger.ModInverse(random, _key.Modulus);`
|  | `147` |  | ``
| 696 | `148` |  | `result = BigInteger.PositiveMod(m * rInv, _key.Modulus);`
| 696 | `149` |  | `}`
|  | `150` |  | `else`
| 1210 | `151` |  | `{`
| 1210 | `152` |  | `result = BigInteger.ModPow(input, _key.Exponent, _key.Modulus);`
| 1210 | `153` |  | `}`
|  | `154` |  | ``
| 1906 | `155` |  | `return result.ToByteArray().Reverse();`
| 1906 | `156` |  | `}`
|  | `157` |  | `}`
|  | `158` |  | `}`

# Methods/Properties

.ctor(Renci.SshNet.Security.RsaKey)
Encrypt(System.Byte[],System.Int32,System.Int32)
Decrypt(System.Byte[])
Decrypt(System.Byte[],System.Int32,System.Int32)
Transform(System.Byte[])
Transform(System.Byte[],System.Int32,System.Int32)