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On big endian CPUs, the ChaCha20-based CRNG is using the wrong endianness for the ChaCha20 constants. This doesn't matter cryptographically, but technically it means it's not ChaCha20 anymore. Fix it to always use the standard constants. Cc: linux-crypto@vger.kernel.org Cc: Andy Lutomirski <luto@kernel.org> Cc: Jann Horn <jannh@google.com> Cc: Theodore Ts'o <tytso@mit.edu> Acked-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
105 lines
3.1 KiB
C
105 lines
3.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Common values and helper functions for the ChaCha and XChaCha stream ciphers.
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*
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* XChaCha extends ChaCha's nonce to 192 bits, while provably retaining ChaCha's
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* security. Here they share the same key size, tfm context, and setkey
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* function; only their IV size and encrypt/decrypt function differ.
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*
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* The ChaCha paper specifies 20, 12, and 8-round variants. In general, it is
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* recommended to use the 20-round variant ChaCha20. However, the other
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* variants can be needed in some performance-sensitive scenarios. The generic
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* ChaCha code currently allows only the 20 and 12-round variants.
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*/
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#ifndef _CRYPTO_CHACHA_H
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#define _CRYPTO_CHACHA_H
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#include <asm/unaligned.h>
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#include <linux/types.h>
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/* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */
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#define CHACHA_IV_SIZE 16
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#define CHACHA_KEY_SIZE 32
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#define CHACHA_BLOCK_SIZE 64
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#define CHACHAPOLY_IV_SIZE 12
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#define CHACHA_STATE_WORDS (CHACHA_BLOCK_SIZE / sizeof(u32))
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/* 192-bit nonce, then 64-bit stream position */
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#define XCHACHA_IV_SIZE 32
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void chacha_block_generic(u32 *state, u8 *stream, int nrounds);
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static inline void chacha20_block(u32 *state, u8 *stream)
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{
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chacha_block_generic(state, stream, 20);
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}
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void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
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void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
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static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
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{
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if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
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hchacha_block_arch(state, out, nrounds);
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else
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hchacha_block_generic(state, out, nrounds);
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}
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static inline void chacha_init_consts(u32 *state)
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{
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state[0] = 0x61707865; /* "expa" */
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state[1] = 0x3320646e; /* "nd 3" */
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state[2] = 0x79622d32; /* "2-by" */
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state[3] = 0x6b206574; /* "te k" */
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}
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void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
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static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
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{
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chacha_init_consts(state);
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state[4] = key[0];
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state[5] = key[1];
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state[6] = key[2];
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state[7] = key[3];
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state[8] = key[4];
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state[9] = key[5];
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state[10] = key[6];
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state[11] = key[7];
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state[12] = get_unaligned_le32(iv + 0);
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state[13] = get_unaligned_le32(iv + 4);
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state[14] = get_unaligned_le32(iv + 8);
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state[15] = get_unaligned_le32(iv + 12);
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}
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static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)
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{
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if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
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chacha_init_arch(state, key, iv);
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else
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chacha_init_generic(state, key, iv);
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}
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void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes, int nrounds);
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void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes, int nrounds);
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static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes, int nrounds)
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{
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if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
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chacha_crypt_arch(state, dst, src, bytes, nrounds);
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else
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chacha_crypt_generic(state, dst, src, bytes, nrounds);
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}
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static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes)
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{
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chacha_crypt(state, dst, src, bytes, 20);
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}
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#endif /* _CRYPTO_CHACHA_H */
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