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85 lines
2.4 KiB
C++
85 lines
2.4 KiB
C++
// Copyright (c) 2017-2022 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_CRYPTO_CHACHA20_H
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#define BITCOIN_CRYPTO_CHACHA20_H
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#include <cstdlib>
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#include <stdint.h>
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// classes for ChaCha20 256-bit stream cipher developed by Daniel J. Bernstein
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// https://cr.yp.to/chacha/chacha-20080128.pdf */
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/** ChaCha20 cipher that only operates on multiples of 64 bytes. */
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class ChaCha20Aligned
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{
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private:
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uint32_t input[12];
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public:
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ChaCha20Aligned();
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/** Initialize a cipher with specified 32-byte key. */
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ChaCha20Aligned(const unsigned char* key32);
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/** set 32-byte key. */
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void SetKey32(const unsigned char* key32);
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/** set the 64-bit nonce. */
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void SetIV(uint64_t iv);
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/** set the 64bit block counter (pos seeks to byte position 64*pos). */
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void Seek64(uint64_t pos);
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/** outputs the keystream of size <64*blocks> into <c> */
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void Keystream64(unsigned char* c, size_t blocks);
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/** enciphers the message <input> of length <64*blocks> and write the enciphered representation into <output>
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* Used for encryption and decryption (XOR)
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*/
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void Crypt64(const unsigned char* input, unsigned char* output, size_t blocks);
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};
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/** Unrestricted ChaCha20 cipher. */
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class ChaCha20
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{
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private:
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ChaCha20Aligned m_aligned;
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unsigned char m_buffer[64] = {0};
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unsigned m_bufleft{0};
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public:
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ChaCha20() = default;
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/** Initialize a cipher with specified 32-byte key. */
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ChaCha20(const unsigned char* key32) : m_aligned(key32) {}
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/** set 32-byte key. */
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void SetKey32(const unsigned char* key32)
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{
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m_aligned.SetKey32(key32);
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m_bufleft = 0;
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}
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/** set the 64-bit nonce. */
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void SetIV(uint64_t iv) { m_aligned.SetIV(iv); }
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/** set the 64bit block counter (pos seeks to byte position 64*pos). */
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void Seek64(uint64_t pos)
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{
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m_aligned.Seek64(pos);
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m_bufleft = 0;
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}
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/** outputs the keystream of size <bytes> into <c> */
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void Keystream(unsigned char* c, size_t bytes);
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/** enciphers the message <input> of length <bytes> and write the enciphered representation into <output>
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* Used for encryption and decryption (XOR)
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*/
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void Crypt(const unsigned char* input, unsigned char* output, size_t bytes);
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};
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#endif // BITCOIN_CRYPTO_CHACHA20_H
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