57 lines
1.7 KiB
C
57 lines
1.7 KiB
C
/*
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* XChaCha20-Poly1305 AEAD
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* Copyright (c) 2026 Cristian Cezar Moisés
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*
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* Implements:
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* - ChaCha20 (RFC 8439)
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* - HChaCha20 (draft-irtf-cfrg-xchacha-03 §2.2)
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* - XChaCha20 (draft-irtf-cfrg-xchacha-03 §2.3)
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* - Poly1305 (RFC 8439 §2.5)
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* - XChaCha20-Poly1305 AEAD (draft-irtf-cfrg-xchacha-03 §2.4)
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*
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* Constant-time implementation: no secret-dependent branches or memory
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* accesses. Verified against RFC 8439 test vectors and Wycheproof corpus.
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*/
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#ifndef ZUPTSDK_XCHACHA20_POLY1305_H
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#define ZUPTSDK_XCHACHA20_POLY1305_H
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#include <stddef.h>
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#include <stdint.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define ZSDK_XCHACHA20_POLY1305_KEYBYTES 32
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#define ZSDK_XCHACHA20_POLY1305_NONCEBYTES 24
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#define ZSDK_XCHACHA20_POLY1305_TAGBYTES 16
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/* Encrypt: ciphertext_len = plaintext_len; tag is 16 bytes appended.
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* out buffer size must be >= plaintext_len + 16. */
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void zsdk_xchacha20_poly1305_encrypt(
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uint8_t *out, /* [out] ciphertext || tag */
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const uint8_t *plaintext,
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size_t plaintext_len,
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const uint8_t *aad,
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size_t aad_len,
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const uint8_t key[32],
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const uint8_t nonce[24]);
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/* Decrypt: returns 0 on success, -1 on tag mismatch (out untouched).
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* out buffer size must be >= ciphertext_len - 16. */
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int zsdk_xchacha20_poly1305_decrypt(
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uint8_t *out, /* [out] plaintext */
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const uint8_t *ciphertext, /* ciphertext || tag */
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size_t ciphertext_len, /* includes 16-byte tag */
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const uint8_t *aad,
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size_t aad_len,
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const uint8_t key[32],
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const uint8_t nonce[24]);
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#ifdef __cplusplus
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}
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#endif
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#endif
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