Botan::FPE Namespace Reference

Functions
BigInt	fe1_decrypt (const BigInt &n, const BigInt &X, const SymmetricKey &key, const std::vector< uint8_t > &tweak)
BigInt	fe1_encrypt (const BigInt &n, const BigInt &X, const SymmetricKey &key, const std::vector< uint8_t > &tweak)

Function Documentation

fe1_decrypt()

BigInt Botan::FPE::fe1_decrypt	(	const BigInt &	n,
		const BigInt &	X,
		const SymmetricKey &	key,
		const std::vector< uint8_t > &	tweak )

Decrypt X from and onto the group Z_n using key and tweak

Parameters

n	the modulus
X	the ciphertext as a BigInt
key	is the key used for encryption
tweak	the same tweak used for encryption

Warning

This function is hardcoded to use only 3 rounds which may be insecure for some values of n. Prefer FPE_FE1 class

Definition at line 193 of file fpe_fe1.cpp.

                                                                                                               {
   FPE_FE1 fpe(n, 3, true, "HMAC(SHA-256)");
   fpe.set_key(key);
   return fpe.decrypt(X, tweak.data(), tweak.size());
}

References Botan::FPE_FE1::decrypt(), Botan::SymmetricAlgorithm::set_key(), and X.

fe1_encrypt()

BigInt Botan::FPE::fe1_encrypt	(	const BigInt &	n,
		const BigInt &	X,
		const SymmetricKey &	key,
		const std::vector< uint8_t > &	tweak )

Format Preserving Encryption using the scheme FE1 from the paper "Format-Preserving Encryption" by Bellare, Rogaway, et al (https://eprint.iacr.org/2009/251)

Encrypt X from and onto the group Z_n using key and tweak

Parameters

n	the modulus
X	the plaintext as a BigInt
key	a random key
tweak	will modify the ciphertext (think of as an IV)

Warning

This function is hardcoded to use only 3 rounds which may be insecure for some values of n. Prefer FPE_FE1 class

Definition at line 187 of file fpe_fe1.cpp.

                                                                                                               {
   FPE_FE1 fpe(n, 3, true, "HMAC(SHA-256)");
   fpe.set_key(key);
   return fpe.encrypt(X, tweak.data(), tweak.size());
}

References Botan::FPE_FE1::encrypt(), Botan::SymmetricAlgorithm::set_key(), and X.