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crypto: poly1305 - Pass key as first two message blocks to each desc_ctx

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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 <martin@strongswan.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Martin Willi
2015-06-16 11:34:16 +02:00
committed by Herbert Xu
parent 8f69b76387
commit c2b7b20aed
3 changed files with 146 additions and 128 deletions
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97
crypto/poly1305_generic.c
View File

@@ -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;
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;
}
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);
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,
},
};