From c2b7b20aedfa10de3634877c3e4b7bc9a7d6461e Mon Sep 17 00:00:00 2001 From: Martin Willi Date: Tue, 16 Jun 2015 11:34:16 +0200 Subject: crypto: poly1305 - Pass key as first two message blocks to each desc_ctx The Poly1305 authenticator requires a unique key for each generated tag. This implies that we can't set the key per tfm, as multiple users set individual keys. Instead we pass a desc specific key as the first two blocks of the message to authenticate in update(). Signed-off-by: Martin Willi Signed-off-by: Herbert Xu --- crypto/poly1305_generic.c | 97 ++++++++++++++++++++++++++++------------------- 1 file changed, 59 insertions(+), 38 deletions(-) (limited to 'crypto/poly1305_generic.c') diff --git a/crypto/poly1305_generic.c b/crypto/poly1305_generic.c index 9c1159b991f4..387b5c887a80 100644 --- a/crypto/poly1305_generic.c +++ b/crypto/poly1305_generic.c @@ -21,20 +21,21 @@ #define POLY1305_KEY_SIZE 32 #define POLY1305_DIGEST_SIZE 16 -struct poly1305_ctx { +struct poly1305_desc_ctx { /* key */ u32 r[5]; /* finalize key */ u32 s[4]; -}; - -struct poly1305_desc_ctx { /* accumulator */ u32 h[5]; /* partial buffer */ u8 buf[POLY1305_BLOCK_SIZE]; /* bytes used in partial buffer */ unsigned int buflen; + /* r key has been set */ + bool rset; + /* s key has been set */ + bool sset; }; static inline u64 mlt(u64 a, u64 b) @@ -63,6 +64,8 @@ static int poly1305_init(struct shash_desc *desc) memset(dctx->h, 0, sizeof(dctx->h)); dctx->buflen = 0; + dctx->rset = false; + dctx->sset = false; return 0; } @@ -70,42 +73,60 @@ static int poly1305_init(struct shash_desc *desc) static int poly1305_setkey(struct crypto_shash *tfm, const u8 *key, unsigned int keylen) { - struct poly1305_ctx *ctx = crypto_shash_ctx(tfm); - - if (keylen != POLY1305_KEY_SIZE) { - crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN); - return -EINVAL; - } + /* Poly1305 requires a unique key for each tag, which implies that + * we can't set it on the tfm that gets accessed by multiple users + * simultaneously. Instead we expect the key as the first 32 bytes in + * the update() call. */ + return -ENOTSUPP; +} +static void poly1305_setrkey(struct poly1305_desc_ctx *dctx, const u8 *key) +{ /* r &= 0xffffffc0ffffffc0ffffffc0fffffff */ - ctx->r[0] = (le32_to_cpuvp(key + 0) >> 0) & 0x3ffffff; - ctx->r[1] = (le32_to_cpuvp(key + 3) >> 2) & 0x3ffff03; - ctx->r[2] = (le32_to_cpuvp(key + 6) >> 4) & 0x3ffc0ff; - ctx->r[3] = (le32_to_cpuvp(key + 9) >> 6) & 0x3f03fff; - ctx->r[4] = (le32_to_cpuvp(key + 12) >> 8) & 0x00fffff; - - ctx->s[0] = le32_to_cpuvp(key + 16); - ctx->s[1] = le32_to_cpuvp(key + 20); - ctx->s[2] = le32_to_cpuvp(key + 24); - ctx->s[3] = le32_to_cpuvp(key + 28); + dctx->r[0] = (le32_to_cpuvp(key + 0) >> 0) & 0x3ffffff; + dctx->r[1] = (le32_to_cpuvp(key + 3) >> 2) & 0x3ffff03; + dctx->r[2] = (le32_to_cpuvp(key + 6) >> 4) & 0x3ffc0ff; + dctx->r[3] = (le32_to_cpuvp(key + 9) >> 6) & 0x3f03fff; + dctx->r[4] = (le32_to_cpuvp(key + 12) >> 8) & 0x00fffff; +} - return 0; +static void poly1305_setskey(struct poly1305_desc_ctx *dctx, const u8 *key) +{ + dctx->s[0] = le32_to_cpuvp(key + 0); + dctx->s[1] = le32_to_cpuvp(key + 4); + dctx->s[2] = le32_to_cpuvp(key + 8); + dctx->s[3] = le32_to_cpuvp(key + 12); } static unsigned int poly1305_blocks(struct poly1305_desc_ctx *dctx, - struct poly1305_ctx *ctx, const u8 *src, - unsigned int srclen, u32 hibit) + const u8 *src, unsigned int srclen, + u32 hibit) { u32 r0, r1, r2, r3, r4; u32 s1, s2, s3, s4; u32 h0, h1, h2, h3, h4; u64 d0, d1, d2, d3, d4; - r0 = ctx->r[0]; - r1 = ctx->r[1]; - r2 = ctx->r[2]; - r3 = ctx->r[3]; - r4 = ctx->r[4]; + if (unlikely(!dctx->sset)) { + if (!dctx->rset && srclen >= POLY1305_BLOCK_SIZE) { + poly1305_setrkey(dctx, src); + src += POLY1305_BLOCK_SIZE; + srclen -= POLY1305_BLOCK_SIZE; + dctx->rset = true; + } + if (srclen >= POLY1305_BLOCK_SIZE) { + poly1305_setskey(dctx, src); + src += POLY1305_BLOCK_SIZE; + srclen -= POLY1305_BLOCK_SIZE; + dctx->sset = true; + } + } + + r0 = dctx->r[0]; + r1 = dctx->r[1]; + r2 = dctx->r[2]; + r3 = dctx->r[3]; + r4 = dctx->r[4]; s1 = r1 * 5; s2 = r2 * 5; @@ -164,7 +185,6 @@ static int poly1305_update(struct shash_desc *desc, const u8 *src, unsigned int srclen) { struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); - struct poly1305_ctx *ctx = crypto_shash_ctx(desc->tfm); unsigned int bytes; if (unlikely(dctx->buflen)) { @@ -175,14 +195,14 @@ static int poly1305_update(struct shash_desc *desc, dctx->buflen += bytes; if (dctx->buflen == POLY1305_BLOCK_SIZE) { - poly1305_blocks(dctx, ctx, dctx->buf, + poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 1 << 24); dctx->buflen = 0; } } if (likely(srclen >= POLY1305_BLOCK_SIZE)) { - bytes = poly1305_blocks(dctx, ctx, src, srclen, 1 << 24); + bytes = poly1305_blocks(dctx, src, srclen, 1 << 24); src += srclen - bytes; srclen = bytes; } @@ -198,18 +218,20 @@ static int poly1305_update(struct shash_desc *desc, static int poly1305_final(struct shash_desc *desc, u8 *dst) { struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc); - struct poly1305_ctx *ctx = crypto_shash_ctx(desc->tfm); __le32 *mac = (__le32 *)dst; u32 h0, h1, h2, h3, h4; u32 g0, g1, g2, g3, g4; u32 mask; u64 f = 0; + if (unlikely(!dctx->sset)) + return -ENOKEY; + if (unlikely(dctx->buflen)) { dctx->buf[dctx->buflen++] = 1; memset(dctx->buf + dctx->buflen, 0, POLY1305_BLOCK_SIZE - dctx->buflen); - poly1305_blocks(dctx, ctx, dctx->buf, POLY1305_BLOCK_SIZE, 0); + poly1305_blocks(dctx, dctx->buf, POLY1305_BLOCK_SIZE, 0); } /* fully carry h */ @@ -253,10 +275,10 @@ static int poly1305_final(struct shash_desc *desc, u8 *dst) h3 = (h3 >> 18) | (h4 << 8); /* mac = (h + s) % (2^128) */ - f = (f >> 32) + h0 + ctx->s[0]; mac[0] = cpu_to_le32(f); - f = (f >> 32) + h1 + ctx->s[1]; mac[1] = cpu_to_le32(f); - f = (f >> 32) + h2 + ctx->s[2]; mac[2] = cpu_to_le32(f); - f = (f >> 32) + h3 + ctx->s[3]; mac[3] = cpu_to_le32(f); + f = (f >> 32) + h0 + dctx->s[0]; mac[0] = cpu_to_le32(f); + f = (f >> 32) + h1 + dctx->s[1]; mac[1] = cpu_to_le32(f); + f = (f >> 32) + h2 + dctx->s[2]; mac[2] = cpu_to_le32(f); + f = (f >> 32) + h3 + dctx->s[3]; mac[3] = cpu_to_le32(f); return 0; } @@ -275,7 +297,6 @@ static struct shash_alg poly1305_alg = { .cra_flags = CRYPTO_ALG_TYPE_SHASH, .cra_alignmask = sizeof(u32) - 1, .cra_blocksize = POLY1305_BLOCK_SIZE, - .cra_ctxsize = sizeof(struct poly1305_ctx), .cra_module = THIS_MODULE, }, }; -- cgit v1.2.3