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xen/lib: Introduce SHA2-256
A future change will need to calculate SHA2-256 digests. Introduce an implementation in lib/, derived from Trenchboot which itself is derived from Linux. In order to be useful to other architectures, it is careful with endianness and misaligned accesses as well as being more MISRA friendly, but is only wired up for x86 in the short term. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Acked-by: Roger Pau Monné <roger.pau@citrix.com>
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@@ -0,0 +1,15 @@
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* SHA2-256: https://csrc.nist.gov/pubs/fips/180-2/upd1/final
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*/
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#ifndef XEN_SHA2_H
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#define XEN_SHA2_H
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#include <xen/types.h>
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#define SHA2_256_DIGEST_SIZE 32
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void sha2_256_digest(uint8_t digest[SHA2_256_DIGEST_SIZE],
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const void *msg, size_t len);
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#endif /* XEN_SHA2_H */
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@@ -17,6 +17,7 @@ lib-y += memset.o
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lib-y += muldiv64.o
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lib-y += parse-size.o
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lib-y += rbtree.o
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lib-$(CONFIG_X86) += sha2-256.o
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lib-y += sort.o
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lib-y += strcasecmp.o
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lib-y += strchr.o
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@@ -0,0 +1,264 @@
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* SHA2-256: https://csrc.nist.gov/pubs/fips/180-2/upd1/final
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*
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* Originally derived from Linux. Modified substantially to optimise for size
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* and Xen's expected usecases.
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*/
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#include <xen/bitops.h>
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#include <xen/sha2.h>
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#include <xen/string.h>
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#include <xen/unaligned.h>
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struct sha2_256_state {
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uint32_t state[SHA2_256_DIGEST_SIZE / sizeof(uint32_t)];
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uint8_t buf[64];
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size_t count; /* Byte count. */
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};
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static uint32_t choose(uint32_t x, uint32_t y, uint32_t z)
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{
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return z ^ (x & (y ^ z));
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}
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static uint32_t majority(uint32_t x, uint32_t y, uint32_t z)
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{
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return (x & y) | (z & (x | y));
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}
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static uint32_t e0(uint32_t x)
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{
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return ror32(x, 2) ^ ror32(x, 13) ^ ror32(x, 22);
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}
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static uint32_t e1(uint32_t x)
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{
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return ror32(x, 6) ^ ror32(x, 11) ^ ror32(x, 25);
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}
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static uint32_t s0(uint32_t x)
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{
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return ror32(x, 7) ^ ror32(x, 18) ^ (x >> 3);
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}
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static uint32_t s1(uint32_t x)
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{
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return ror32(x, 17) ^ ror32(x, 19) ^ (x >> 10);
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}
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static uint32_t blend(uint32_t W[16], unsigned int i)
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{
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#define W(i) W[(i) & 15]
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return W(i) += s1(W(i - 2)) + W(i - 7) + s0(W(i - 15));
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#undef W
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}
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static const uint32_t K[] = {
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0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
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0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
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0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
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0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
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0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
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0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
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0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
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0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
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0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
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0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
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0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
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0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
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0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
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0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
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0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
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0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
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};
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static void sha2_256_transform(uint32_t *state, const void *_input)
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{
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const uint32_t *input = _input;
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uint32_t a, b, c, d, e, f, g, h, t1, t2;
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uint32_t W[16];
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unsigned int i;
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for ( i = 0; i < 16; i++ )
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W[i] = get_unaligned_be32(&input[i]);
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a = state[0]; b = state[1]; c = state[2]; d = state[3];
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e = state[4]; f = state[5]; g = state[6]; h = state[7];
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for ( i = 0; i < 16; i += 8 )
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{
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t1 = h + e1(e) + choose(e, f, g) + K[i + 0] + W[i + 0];
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t2 = e0(a) + majority(a, b, c); d += t1; h = t1 + t2;
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t1 = g + e1(d) + choose(d, e, f) + K[i + 1] + W[i + 1];
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t2 = e0(h) + majority(h, a, b); c += t1; g = t1 + t2;
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t1 = f + e1(c) + choose(c, d, e) + K[i + 2] + W[i + 2];
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t2 = e0(g) + majority(g, h, a); b += t1; f = t1 + t2;
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t1 = e + e1(b) + choose(b, c, d) + K[i + 3] + W[i + 3];
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t2 = e0(f) + majority(f, g, h); a += t1; e = t1 + t2;
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t1 = d + e1(a) + choose(a, b, c) + K[i + 4] + W[i + 4];
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t2 = e0(e) + majority(e, f, g); h += t1; d = t1 + t2;
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t1 = c + e1(h) + choose(h, a, b) + K[i + 5] + W[i + 5];
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t2 = e0(d) + majority(d, e, f); g += t1; c = t1 + t2;
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t1 = b + e1(g) + choose(g, h, a) + K[i + 6] + W[i + 6];
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t2 = e0(c) + majority(c, d, e); f += t1; b = t1 + t2;
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t1 = a + e1(f) + choose(f, g, h) + K[i + 7] + W[i + 7];
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t2 = e0(b) + majority(b, c, d); e += t1; a = t1 + t2;
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}
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for ( ; i < 64; i += 8 )
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{
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t1 = h + e1(e) + choose(e, f, g) + K[i + 0] + blend(W, i + 0);
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t2 = e0(a) + majority(a, b, c); d += t1; h = t1 + t2;
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t1 = g + e1(d) + choose(d, e, f) + K[i + 1] + blend(W, i + 1);
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t2 = e0(h) + majority(h, a, b); c += t1; g = t1 + t2;
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t1 = f + e1(c) + choose(c, d, e) + K[i + 2] + blend(W, i + 2);
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t2 = e0(g) + majority(g, h, a); b += t1; f = t1 + t2;
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t1 = e + e1(b) + choose(b, c, d) + K[i + 3] + blend(W, i + 3);
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t2 = e0(f) + majority(f, g, h); a += t1; e = t1 + t2;
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t1 = d + e1(a) + choose(a, b, c) + K[i + 4] + blend(W, i + 4);
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t2 = e0(e) + majority(e, f, g); h += t1; d = t1 + t2;
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t1 = c + e1(h) + choose(h, a, b) + K[i + 5] + blend(W, i + 5);
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t2 = e0(d) + majority(d, e, f); g += t1; c = t1 + t2;
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t1 = b + e1(g) + choose(g, h, a) + K[i + 6] + blend(W, i + 6);
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t2 = e0(c) + majority(c, d, e); f += t1; b = t1 + t2;
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t1 = a + e1(f) + choose(f, g, h) + K[i + 7] + blend(W, i + 7);
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t2 = e0(b) + majority(b, c, d); e += t1; a = t1 + t2;
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}
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state[0] += a; state[1] += b; state[2] += c; state[3] += d;
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state[4] += e; state[5] += f; state[6] += g; state[7] += h;
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}
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static void sha2_256_init(struct sha2_256_state *s)
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{
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*s = (struct sha2_256_state){
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.state = {
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0x6a09e667UL,
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0xbb67ae85UL,
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0x3c6ef372UL,
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0xa54ff53aUL,
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0x510e527fUL,
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0x9b05688cUL,
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0x1f83d9abUL,
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0x5be0cd19UL,
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},
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};
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}
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static void sha2_256_update(struct sha2_256_state *s, const void *msg,
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size_t len)
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{
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unsigned int partial = s->count & 63;
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s->count += len;
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if ( (partial + len) >= 64 )
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{
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if ( partial )
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{
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unsigned int rem = 64 - partial;
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/* Fill the partial block. */
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memcpy(s->buf + partial, msg, rem);
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msg += rem;
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len -= rem;
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sha2_256_transform(s->state, s->buf);
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partial = 0;
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}
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for ( ; len >= 64; msg += 64, len -= 64 )
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sha2_256_transform(s->state, msg);
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}
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/* Remaining data becomes partial. */
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memcpy(s->buf + partial, msg, len);
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}
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static void sha2_256_final(struct sha2_256_state *s, void *_dst)
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{
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uint32_t *dst = _dst;
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unsigned int i, partial = s->count & 63;
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/* Start padding */
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s->buf[partial++] = 0x80;
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if ( partial > 56 )
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{
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/* Need one extra block - pad to 64 */
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memset(s->buf + partial, 0, 64 - partial);
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sha2_256_transform(s->state, s->buf);
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partial = 0;
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}
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/* Pad to 56 */
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memset(s->buf + partial, 0, 56 - partial);
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/* Append the bit count */
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put_unaligned_be64((uint64_t)s->count << 3, &s->buf[56]);
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sha2_256_transform(s->state, s->buf);
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/* Store state in digest */
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for ( i = 0; i < 8; i++ )
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put_unaligned_be32(s->state[i], &dst[i]);
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}
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void sha2_256_digest(uint8_t digest[SHA2_256_DIGEST_SIZE],
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const void *msg, size_t len)
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{
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struct sha2_256_state s;
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sha2_256_init(&s);
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sha2_256_update(&s, msg, len);
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sha2_256_final(&s, digest);
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}
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#ifdef CONFIG_SELF_TESTS
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#include <xen/init.h>
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#include <xen/lib.h>
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static const struct test {
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const char *msg;
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uint8_t digest[SHA2_256_DIGEST_SIZE];
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} tests[] __initconst = {
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{
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.msg = "abc",
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.digest = {
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0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
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0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
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0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
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0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad,
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},
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},
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{
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.msg = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
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.digest = {
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0x24, 0x8d, 0x6a, 0x61, 0xd2, 0x06, 0x38, 0xb8,
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0xe5, 0xc0, 0x26, 0x93, 0x0c, 0x3e, 0x60, 0x39,
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0xa3, 0x3c, 0xe4, 0x59, 0x64, 0xff, 0x21, 0x67,
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0xf6, 0xec, 0xed, 0xd4, 0x19, 0xdb, 0x06, 0xc1,
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},
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},
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};
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static void __init __constructor test_sha2_256(void)
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{
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for ( unsigned int i = 0; i < ARRAY_SIZE(tests); ++i )
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{
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const struct test *t = &tests[i];
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uint8_t res[SHA2_256_DIGEST_SIZE] = {};
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sha2_256_digest(res, t->msg, strlen(t->msg));
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if ( memcmp(res, t->digest, sizeof(t->digest)) == 0 )
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continue;
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panic("%s() msg '%s' failed\n"
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" expected %" STR(SHA2_256_DIGEST_SIZE) "phN\n"
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" got %" STR(SHA2_256_DIGEST_SIZE) "phN\n",
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__func__, t->msg, t->digest, res);
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}
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}
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#endif /* CONFIG_SELF_TESTS */
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