public string Decrypt(string encryptedBase64)
{
try
{
PayloadComponents components = this.unpackEncryptedBase64Data(encryptedBase64.Replace(@"\", @""));
if (!this.hmacIsValid(components, Key))
{
return("");
}
byte[] key = this.generateKey(components.salt, Key);
byte[] plaintextBytes = new byte[0];
switch (this.aesMode)
{
case AesMode.CTR:
// Yes, we are "encrypting" here. CTR uses the same code in both directions.
plaintextBytes = this.encryptAesCtrLittleEndianNoPadding(components.ciphertext, key, components.iv);
break;
case AesMode.CBC:
plaintextBytes = this.decryptAesCbcPkcs7(components.ciphertext, key, components.iv);
break;
}
return(Encoding.UTF8.GetString(plaintextBytes));
}
catch (Exception ex)
{
logger.Error("Decryption faild for - " + encryptedBase64);
throw new CustomException("Decryption Failed", (int)ErrorCode.CRYPTOGRAPHICFAILED);
}
}
protected byte[] assembleHeader(PayloadComponents components)
{
List <byte> headerBytes = new List <byte>();
headerBytes.AddRange(components.schema);
headerBytes.AddRange(components.options);
headerBytes.AddRange(components.salt);
headerBytes.AddRange(components.hmacSalt);
headerBytes.AddRange(components.iv);
return(headerBytes.ToArray());
}
private bool hmacIsValid(PayloadComponents components, string password)
{
byte[] generatedHmac = this.generateHmac(components, password);
if (generatedHmac.Length != components.hmac.Length)
{
return(false);
}
for (int i = 0; i < components.hmac.Length; i++)
{
if (generatedHmac[i] != components.hmac[i])
{
return(false);
}
}
return(true);
}
protected byte[] generateHmac(PayloadComponents components, string password)
{
List <byte> hmacMessage = new List <byte>();
if (this.hmac_includesHeader)
{
hmacMessage.AddRange(this.assembleHeader(components));
}
hmacMessage.AddRange(components.ciphertext);
byte[] key = this.generateKey(components.hmacSalt, password);
HMAC hmacAlgo = null;
switch (this.hmac_algorithm)
{
case HmacAlgorithm.SHA1:
hmacAlgo = new HMACSHA1(key);
break;
case HmacAlgorithm.SHA256:
hmacAlgo = new HMACSHA256(key);
break;
}
List <byte> hmac = new List <byte>();
hmac.AddRange(hmacAlgo.ComputeHash(hmacMessage.ToArray()));
if (this.hmac_includesPadding)
{
for (int i = hmac.Count; i < Cryptor.hmac_length; i++)
{
hmac.Add(0x00);
}
}
return(hmac.ToArray());
}
public string Encrypt(string plaintext, string password, Schema schemaVersion)
{
this.configureSettings(schemaVersion);
byte[] plaintextBytes = TextEncoding.GetBytes(plaintext);
PayloadComponents components = new PayloadComponents();
components.schema = new byte[] { (byte)schemaVersion };
components.options = new byte[] { (byte)this.options };
components.salt = this.generateRandomBytes(Cryptor.saltLength);
components.hmacSalt = this.generateRandomBytes(Cryptor.saltLength);
components.iv = this.generateRandomBytes(Cryptor.ivLength);
byte[] key = this.generateKey(components.salt, password);
switch (this.aesMode)
{
case AesMode.CTR:
components.ciphertext = this.encryptAesCtrLittleEndianNoPadding(plaintextBytes, key, components.iv);
break;
case AesMode.CBC:
components.ciphertext = this.encryptAesCbcPkcs7(plaintextBytes, key, components.iv);
break;
}
components.hmac = this.generateHmac(components, password);
List <byte> binaryBytes = new List <byte>();
binaryBytes.AddRange(this.assembleHeader(components));
binaryBytes.AddRange(components.ciphertext);
binaryBytes.AddRange(components.hmac);
return(Convert.ToBase64String(binaryBytes.ToArray()));
}
