From: Eric Biggers Date: Sat, 12 Jul 2025 23:22:55 +0000 (-0700) Subject: lib/crypto: sha1: Add HMAC support X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4cbc84471bb606ddfaf424709dd8d56b56d7ae7b;p=thirdparty%2Flinux.git lib/crypto: sha1: Add HMAC support Add HMAC support to the SHA-1 library, again following what was done for SHA-2. Besides providing the basis for a more streamlined "hmac(sha1)" shash, this will also be useful for multiple in-kernel users such as net/sctp/auth.c, net/ipv6/seg6_hmac.c, and security/keys/trusted-keys/trusted_tpm1.c. Those are currently using crypto_shash, but using the library functions would be much simpler. Reviewed-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250712232329.818226-5-ebiggers@kernel.org Signed-off-by: Eric Biggers --- diff --git a/include/crypto/sha1.h b/include/crypto/sha1.h index 387f6123a05e8..162a529ec8413 100644 --- a/include/crypto/sha1.h +++ b/include/crypto/sha1.h @@ -96,4 +96,122 @@ void sha1_final(struct sha1_ctx *ctx, u8 out[SHA1_DIGEST_SIZE]); */ void sha1(const u8 *data, size_t len, u8 out[SHA1_DIGEST_SIZE]); +/** + * struct hmac_sha1_key - Prepared key for HMAC-SHA1 + * @istate: private + * @ostate: private + */ +struct hmac_sha1_key { + struct sha1_block_state istate; + struct sha1_block_state ostate; +}; + +/** + * struct hmac_sha1_ctx - Context for computing HMAC-SHA1 of a message + * @sha_ctx: private + * @ostate: private + */ +struct hmac_sha1_ctx { + struct sha1_ctx sha_ctx; + struct sha1_block_state ostate; +}; + +/** + * hmac_sha1_preparekey() - Prepare a key for HMAC-SHA1 + * @key: (output) the key structure to initialize + * @raw_key: the raw HMAC-SHA1 key + * @raw_key_len: the key length in bytes. All key lengths are supported. + * + * Note: the caller is responsible for zeroizing both the struct hmac_sha1_key + * and the raw key once they are no longer needed. + * + * Context: Any context. + */ +void hmac_sha1_preparekey(struct hmac_sha1_key *key, + const u8 *raw_key, size_t raw_key_len); + +/** + * hmac_sha1_init() - Initialize an HMAC-SHA1 context for a new message + * @ctx: (output) the HMAC context to initialize + * @key: the prepared HMAC key + * + * If you don't need incremental computation, consider hmac_sha1() instead. + * + * Context: Any context. + */ +void hmac_sha1_init(struct hmac_sha1_ctx *ctx, const struct hmac_sha1_key *key); + +/** + * hmac_sha1_init_usingrawkey() - Initialize an HMAC-SHA1 context for a new + * message, using a raw key + * @ctx: (output) the HMAC context to initialize + * @raw_key: the raw HMAC-SHA1 key + * @raw_key_len: the key length in bytes. All key lengths are supported. + * + * If you don't need incremental computation, consider hmac_sha1_usingrawkey() + * instead. + * + * Context: Any context. + */ +void hmac_sha1_init_usingrawkey(struct hmac_sha1_ctx *ctx, + const u8 *raw_key, size_t raw_key_len); + +/** + * hmac_sha1_update() - Update an HMAC-SHA1 context with message data + * @ctx: the HMAC context to update; must have been initialized + * @data: the message data + * @data_len: the data length in bytes + * + * This can be called any number of times. + * + * Context: Any context. + */ +static inline void hmac_sha1_update(struct hmac_sha1_ctx *ctx, + const u8 *data, size_t data_len) +{ + sha1_update(&ctx->sha_ctx, data, data_len); +} + +/** + * hmac_sha1_final() - Finish computing an HMAC-SHA1 value + * @ctx: the HMAC context to finalize; must have been initialized + * @out: (output) the resulting HMAC-SHA1 value + * + * After finishing, this zeroizes @ctx. So the caller does not need to do it. + * + * Context: Any context. + */ +void hmac_sha1_final(struct hmac_sha1_ctx *ctx, u8 out[SHA1_DIGEST_SIZE]); + +/** + * hmac_sha1() - Compute HMAC-SHA1 in one shot, using a prepared key + * @key: the prepared HMAC key + * @data: the message data + * @data_len: the data length in bytes + * @out: (output) the resulting HMAC-SHA1 value + * + * If you're using the key only once, consider using hmac_sha1_usingrawkey(). + * + * Context: Any context. + */ +void hmac_sha1(const struct hmac_sha1_key *key, + const u8 *data, size_t data_len, u8 out[SHA1_DIGEST_SIZE]); + +/** + * hmac_sha1_usingrawkey() - Compute HMAC-SHA1 in one shot, using a raw key + * @raw_key: the raw HMAC-SHA1 key + * @raw_key_len: the key length in bytes. All key lengths are supported. + * @data: the message data + * @data_len: the data length in bytes + * @out: (output) the resulting HMAC-SHA1 value + * + * If you're using the key multiple times, prefer to use hmac_sha1_preparekey() + * followed by multiple calls to hmac_sha1() instead. + * + * Context: Any context. + */ +void hmac_sha1_usingrawkey(const u8 *raw_key, size_t raw_key_len, + const u8 *data, size_t data_len, + u8 out[SHA1_DIGEST_SIZE]); + #endif /* _CRYPTO_SHA1_H */ diff --git a/lib/crypto/sha1.c b/lib/crypto/sha1.c index 0fe9ca8d0653b..5904e4ae85d24 100644 --- a/lib/crypto/sha1.c +++ b/lib/crypto/sha1.c @@ -1,8 +1,9 @@ // SPDX-License-Identifier: GPL-2.0 /* - * SHA-1 library functions + * SHA-1 and HMAC-SHA1 library functions */ +#include #include #include #include @@ -10,6 +11,7 @@ #include #include #include +#include static const struct sha1_block_state sha1_iv = { .h = { SHA1_H0, SHA1_H1, SHA1_H2, SHA1_H3, SHA1_H4 }, @@ -197,7 +199,7 @@ void sha1_update(struct sha1_ctx *ctx, const u8 *data, size_t len) } EXPORT_SYMBOL_GPL(sha1_update); -void sha1_final(struct sha1_ctx *ctx, u8 out[SHA1_DIGEST_SIZE]) +static void __sha1_final(struct sha1_ctx *ctx, u8 out[SHA1_DIGEST_SIZE]) { u64 bitcount = ctx->bytecount << 3; size_t partial = ctx->bytecount % SHA1_BLOCK_SIZE; @@ -214,6 +216,11 @@ void sha1_final(struct sha1_ctx *ctx, u8 out[SHA1_DIGEST_SIZE]) for (size_t i = 0; i < SHA1_DIGEST_SIZE; i += 4) put_unaligned_be32(ctx->state.h[i / 4], out + i); +} + +void sha1_final(struct sha1_ctx *ctx, u8 out[SHA1_DIGEST_SIZE]) +{ + __sha1_final(ctx, out); memzero_explicit(ctx, sizeof(*ctx)); } EXPORT_SYMBOL_GPL(sha1_final); @@ -228,6 +235,101 @@ void sha1(const u8 *data, size_t len, u8 out[SHA1_DIGEST_SIZE]) } EXPORT_SYMBOL_GPL(sha1); +static void __hmac_sha1_preparekey(struct sha1_block_state *istate, + struct sha1_block_state *ostate, + const u8 *raw_key, size_t raw_key_len) +{ + union { + u8 b[SHA1_BLOCK_SIZE]; + unsigned long w[SHA1_BLOCK_SIZE / sizeof(unsigned long)]; + } derived_key = { 0 }; + + if (unlikely(raw_key_len > SHA1_BLOCK_SIZE)) + sha1(raw_key, raw_key_len, derived_key.b); + else + memcpy(derived_key.b, raw_key, raw_key_len); + + for (size_t i = 0; i < ARRAY_SIZE(derived_key.w); i++) + derived_key.w[i] ^= REPEAT_BYTE(HMAC_IPAD_VALUE); + *istate = sha1_iv; + sha1_blocks(istate, derived_key.b, 1); + + for (size_t i = 0; i < ARRAY_SIZE(derived_key.w); i++) + derived_key.w[i] ^= REPEAT_BYTE(HMAC_OPAD_VALUE ^ + HMAC_IPAD_VALUE); + *ostate = sha1_iv; + sha1_blocks(ostate, derived_key.b, 1); + + memzero_explicit(&derived_key, sizeof(derived_key)); +} + +void hmac_sha1_preparekey(struct hmac_sha1_key *key, + const u8 *raw_key, size_t raw_key_len) +{ + __hmac_sha1_preparekey(&key->istate, &key->ostate, + raw_key, raw_key_len); +} +EXPORT_SYMBOL_GPL(hmac_sha1_preparekey); + +void hmac_sha1_init(struct hmac_sha1_ctx *ctx, const struct hmac_sha1_key *key) +{ + ctx->sha_ctx.state = key->istate; + ctx->sha_ctx.bytecount = SHA1_BLOCK_SIZE; + ctx->ostate = key->ostate; +} +EXPORT_SYMBOL_GPL(hmac_sha1_init); + +void hmac_sha1_init_usingrawkey(struct hmac_sha1_ctx *ctx, + const u8 *raw_key, size_t raw_key_len) +{ + __hmac_sha1_preparekey(&ctx->sha_ctx.state, &ctx->ostate, + raw_key, raw_key_len); + ctx->sha_ctx.bytecount = SHA1_BLOCK_SIZE; +} +EXPORT_SYMBOL_GPL(hmac_sha1_init_usingrawkey); + +void hmac_sha1_final(struct hmac_sha1_ctx *ctx, u8 out[SHA1_DIGEST_SIZE]) +{ + /* Generate the padded input for the outer hash in ctx->sha_ctx.buf. */ + __sha1_final(&ctx->sha_ctx, ctx->sha_ctx.buf); + memset(&ctx->sha_ctx.buf[SHA1_DIGEST_SIZE], 0, + SHA1_BLOCK_SIZE - SHA1_DIGEST_SIZE); + ctx->sha_ctx.buf[SHA1_DIGEST_SIZE] = 0x80; + *(__be32 *)&ctx->sha_ctx.buf[SHA1_BLOCK_SIZE - 4] = + cpu_to_be32(8 * (SHA1_BLOCK_SIZE + SHA1_DIGEST_SIZE)); + + /* Compute the outer hash, which gives the HMAC value. */ + sha1_blocks(&ctx->ostate, ctx->sha_ctx.buf, 1); + for (size_t i = 0; i < SHA1_DIGEST_SIZE; i += 4) + put_unaligned_be32(ctx->ostate.h[i / 4], out + i); + + memzero_explicit(ctx, sizeof(*ctx)); +} +EXPORT_SYMBOL_GPL(hmac_sha1_final); + +void hmac_sha1(const struct hmac_sha1_key *key, + const u8 *data, size_t data_len, u8 out[SHA1_DIGEST_SIZE]) +{ + struct hmac_sha1_ctx ctx; + + hmac_sha1_init(&ctx, key); + hmac_sha1_update(&ctx, data, data_len); + hmac_sha1_final(&ctx, out); +} +EXPORT_SYMBOL_GPL(hmac_sha1); + +void hmac_sha1_usingrawkey(const u8 *raw_key, size_t raw_key_len, + const u8 *data, size_t data_len, + u8 out[SHA1_DIGEST_SIZE]) +{ + struct hmac_sha1_ctx ctx; + + hmac_sha1_init_usingrawkey(&ctx, raw_key, raw_key_len); + hmac_sha1_update(&ctx, data, data_len); + hmac_sha1_final(&ctx, out); +} +EXPORT_SYMBOL_GPL(hmac_sha1_usingrawkey); + #ifdef sha1_mod_init_arch static int __init sha1_mod_init(void) { @@ -242,5 +344,5 @@ static void __exit sha1_mod_exit(void) module_exit(sha1_mod_exit); #endif -MODULE_DESCRIPTION("SHA-1 library functions"); +MODULE_DESCRIPTION("SHA-1 and HMAC-SHA1 library functions"); MODULE_LICENSE("GPL");