Library: Crypto
Package: Cipher
Header: Poco/Crypto/Cipher.h
Description
Represents the abstract base class from which all implementations of symmetric/asymmetric encryption algorithms must inherit. Use the CipherFactory class to obtain an instance of this class:
CipherFactory& factory = CipherFactory::defaultFactory(); // Creates a 256-bit AES cipher Cipher* pCipher = factory.createCipher(CipherKey("aes-256")); Cipher* pRSACipher = factory.createCipher(RSAKey(RSAKey::KL_1024, RSAKey::EXP_SMALL));
Check the different Key constructors on how to initialize/create a key. The above example auto-generates random keys.
Note that you won't be able to decrypt data encrypted with a random key once the Cipher is destroyed unless you persist the generated key and IV. An example usage for random keys is to encrypt data saved in a temporary file.
Once your key is set up, you can use the Cipher object to encrypt or decrypt strings or, in conjunction with a CryptoInputStream or a CryptoOutputStream, to encrypt streams of data.
Since encrypted strings will contain arbitrary binary data that will cause problems in applications that are not binary-safe (eg., when sending encrypted data in e-mails), the encryptString() and decryptString() can encode (or decode, respectively) encrypted data using a "transport encoding". Supported encodings are Base64 and BinHex.
The following example encrypts and decrypts a string utilizing Base64 encoding:
std::string plainText = "This is my secret information"; std::string encrypted = pCipher->encryptString(plainText, Cipher::ENC_BASE64); std::string decrypted = pCipher->decryptString(encrypted, Cipher::ENC_BASE64);
In order to encrypt a stream of data (eg. to encrypt files), you can use a CryptoStream:
// Create an output stream that will encrypt all data going through it // and write pass it to the underlying file stream. Poco::FileOutputStream sink("encrypted.dat"); CryptoOutputStream encryptor(sink, pCipher->createEncryptor()); Poco::FileInputStream source("source.txt"); Poco::StreamCopier::copyStream(source, encryptor); // Always close output streams to flush all internal buffers encryptor.close(); sink.close();
Inheritance
Direct Base Classes: Poco::RefCountedObject
All Base Classes: Poco::RefCountedObject
Known Derived Classes: EVPCipherImpl, CipherImpl, RSACipherImpl
Member Summary
Member Functions: createDecryptor, createEncryptor, decrypt, decryptString, encrypt, encryptString, name
Inherited Functions: duplicate, referenceCount, release
Types Aliases
ByteVec
using ByteVec = std::vector < unsigned char >;
Ptr
using Ptr = Poco::AutoPtr < Cipher >;
Enumerations
Encoding
Transport encoding to use for encryptString() and decryptString().
ENC_NONE = 0x00
Plain binary output
ENC_BASE64 = 0x01
Base64-encoded output
ENC_BINHEX = 0x02
BinHex-encoded output
ENC_BASE64_NO_LF = 0x81
Base64-encoded output, no linefeeds
ENC_BINHEX_NO_LF = 0x82
BinHex-encoded output, no linefeeds
Constructors
Cipher
Cipher();
Creates a new Cipher object.
Destructor
~Cipher
virtual ~Cipher();
Destroys the Cipher.
Member Functions
createDecryptor
virtual CryptoTransform::Ptr createDecryptor() = 0;
Creates a decryptor object to be used with a CryptoStream.
createEncryptor
virtual CryptoTransform::Ptr createEncryptor() = 0;
Creates an encryptor object to be used with a CryptoStream.
decrypt
virtual void decrypt(
std::istream & source,
std::ostream & sink,
Encoding encoding = ENC_NONE,
bool padding = true
);
Directly decrypt an input stream that is encoded with the given encoding.
decryptString
virtual std::string decryptString(
const std::string & str,
Encoding encoding = ENC_NONE,
bool padding = true
);
Directly decrypt a string that is encoded with the given encoding.
encrypt
virtual void encrypt(
std::istream & source,
std::ostream & sink,
Encoding encoding = ENC_NONE,
bool padding = true
);
Directly encrypts an input stream and encodes it using the given encoding.
encryptString
virtual std::string encryptString(
const std::string & str,
Encoding encoding = ENC_NONE,
bool padding = true
);
Directly encrypt a string and encode it using the given encoding.
name
virtual const std::string & name() const = 0;
Returns the name of the Cipher.