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 <martin@strongswan.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/poly1305_generic.c b/crypto/poly1305_generic.c
index 9c1159b..387b5c8 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 @@
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_setkey(struct crypto_shash *tfm,
const u8 *key, unsigned int keylen)
{
- struct poly1305_ctx *ctx = crypto_shash_ctx(tfm);
+ /* 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;
+}
- if (keylen != POLY1305_KEY_SIZE) {
- crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
- return -EINVAL;
- }
-
+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 @@
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 @@
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_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 @@
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 @@
.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,
},
};