Botan::PK_Ops::Decryption_with_Padding Class Reference

#include <pk_ops_impl.h>

Inheritance diagram for Botan::PK_Ops::Decryption_with_Padding:

Public Member Functions
virtual size_t	ciphertext_length (size_t ptext_len) const =0
secure_vector< uint8_t >	decrypt (uint8_t &valid_mask, std::span< const uint8_t > ctext) override
virtual size_t	plaintext_length (size_t ctext_len) const =0
	~Decryption_with_Padding () override

Protected Member Functions
	Decryption_with_Padding (std::string_view padding)

Detailed Description

Definition at line 43 of file pk_ops_impl.h.

Constructor & Destructor Documentation

~Decryption_with_Padding()

Botan::PK_Ops::Decryption_with_Padding::~Decryption_with_Padding ( )

overridedefault

Decryption_with_Padding()

Botan::PK_Ops::Decryption_with_Padding::Decryption_with_Padding ( std::string_view padding )

explicitprotected

Definition at line 50 of file pk_ops.cpp.

                                                                             :
      m_padding(EncryptionPaddingScheme::create(padding)) {}

Member Function Documentation

ciphertext_length()

virtual size_t Botan::PK_Ops::Decryption::ciphertext_length ( size_t ptext_len ) const

pure virtualinherited

Given the plaintext length, return an upper bound on the ciphertext length that decrypt() expects for this key and padding.

decrypt()

secure_vector< uint8_t > Botan::PK_Ops::Decryption_with_Padding::decrypt ( uint8_t & valid_mask, std::span< const uint8_t > ctext )

overridevirtual

Implements Botan::PK_Ops::Decryption.

Definition at line 55 of file pk_ops.cpp.

                                                                                                               {
   const secure_vector<uint8_t> raw = raw_decrypt(ctext);
 
   secure_vector<uint8_t> ptext(raw.size());
   auto len = m_padding->unpad(ptext, raw);
 
   valid_mask = CT::Mask<uint8_t>::from_choice(len.has_value()).if_set_return(0xFF);
 
   /*
   This is potentially not const time, depending on how std::vector is
   implemented. But since we are always reducing length, it should
   just amount to setting the member var holding the length. Resizing
   downwards is guaranteed to not change the capacity, and since we
   set ctext to the maximum possible size (equal to the raw input) we
   know that this is always, if anything, resizing smaller than the
   capacity, so no reallocation occurs.
   */
 
   ptext.resize(len.value_or(0));
   return ptext;
}

References Botan::CT::Mask< T >::from_choice().

plaintext_length()

virtual size_t Botan::PK_Ops::Decryption::plaintext_length ( size_t ctext_len ) const

pure virtualinherited

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The documentation for this class was generated from the following files:

• src/lib/pubkey/pk_ops_impl.h
• src/lib/pubkey/pk_ops.cpp