[marco3k]

Bueno gogleando un poco en www hay convertidores de código y encontré este:
https://www.codeconvert.ai/csharp-to-pascal-converter


y el resultado es este:

Código Delphi [-]
uses
  System.SysUtils,
  System.Classes,
  System.Crypto,
  System.Convert;

function Encrypt(clearText: string): string;
var
  EncryptionKey: string;
  clearBytes: TBytes;
  encryptor: TAesManaged;
  pdb: TRfc2898DeriveBytes;
  ms: TMemoryStream;
  cs: TCryptoStream;
begin
  EncryptionKey := 'MAKV2SPBNI99212';
  clearBytes := TEncoding.Unicode.GetBytes(clearText);
  encryptor := TAesManaged.Create;
  try
    pdb := TRfc2898DeriveBytes.Create(EncryptionKey, [0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76]);
    encryptor.Key := pdb.GetBytes(32);
    encryptor.IV := pdb.GetBytes(16);
    ms := TMemoryStream.Create;
    try
      cs := TCryptoStream.Create(ms, encryptor.CreateEncryptor, CryptoStreamMode.Write);
      try
        cs.Write(clearBytes, 0, Length(clearBytes));
      finally
        cs.Free;
      end;
      clearText := TBase64Encoding.UTF8.EncodeToString(ms.ToArray);
    finally
      ms.Free;
    end;
  finally
    encryptor.Free;
  end;
  Result := clearText;
end;

function Decrypt(cipherText: string): string;
var
  EncryptionKey: string;
  cipherBytes: TBytes;
  encryptor: TAesManaged;
  pdb: TRfc2898DeriveBytes;
  ms: TMemoryStream;
  cs: TCryptoStream;
begin
  EncryptionKey := 'MAKV2SPBNI99212';
  cipherBytes := TBase64Encoding.UTF8.DecodeToBytes(cipherText);
  encryptor := TAesManaged.Create;
  try
    pdb := TRfc2898DeriveBytes.Create(EncryptionKey, [0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76]);
    encryptor.Key := pdb.GetBytes(32);
    encryptor.IV := pdb.GetBytes(16);
    ms := TMemoryStream.Create;
    try
      cs := TCryptoStream.Create(ms, encryptor.CreateDecryptor, CryptoStreamMode.Write);
      try
        cs.Write(cipherBytes, 0, Length(cipherBytes));
      finally
        cs.Free;
      end;
      cipherText := TEncoding.Unicode.GetString(ms.ToArray);
    finally
      ms.Free;
    end;
  finally
    encryptor.Free;
  end;
  Result := cipherText;
end.

Tendrias que probarlo...