Add SHA-384/512 and HMAC-SHA-384/512 crypto hash

1 files changed, 614 insertions, 0 deletions

diff --git a/lib/sha512.c b/lib/sha512.c
new file mode 100644
index 00000000..e46e4c98
--- /dev/null
+++ b/lib/sha512.c
@@ -0,0 +1,614 @@
+/*
+ *	BIRD Library -- SHA-512 and SHA-384 Hash Functions,
+ *			HMAC-SHA-512 and HMAC-SHA-384 Functions
+ *
+ *	(c) 2015 CZ.NIC z.s.p.o.
+ *
+ *	Based on the code from libgcrypt-1.6.0, which is
+ *	(c) 2003, 2006, 2008, 2009 Free Software Foundation, Inc.
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#include "lib/sha256.h"
+#include "lib/sha512.h"
+#include "lib/unaligned.h"
+
+static uint sha512_transform(void *context, const byte *data, size_t nblks);
+
+void
+sha512_init(struct sha512_context *ctx)
+{
+  struct sha512_state *hd = &ctx->state;
+
+  hd->h0 = UINT64_C(0x6a09e667f3bcc908);
+  hd->h1 = UINT64_C(0xbb67ae8584caa73b);
+  hd->h2 = UINT64_C(0x3c6ef372fe94f82b);
+  hd->h3 = UINT64_C(0xa54ff53a5f1d36f1);
+  hd->h4 = UINT64_C(0x510e527fade682d1);
+  hd->h5 = UINT64_C(0x9b05688c2b3e6c1f);
+  hd->h6 = UINT64_C(0x1f83d9abfb41bd6b);
+  hd->h7 = UINT64_C(0x5be0cd19137e2179);
+
+  ctx->bctx.nblocks = 0;
+  ctx->bctx.nblocks_high = 0;
+  ctx->bctx.count = 0;
+  ctx->bctx.blocksize = 128;
+  ctx->bctx.transform = sha512_transform;
+}
+
+void
+sha384_init(struct sha384_context *ctx)
+{
+  struct sha512_state *hd = &ctx->state;
+
+  hd->h0 = UINT64_C(0xcbbb9d5dc1059ed8);
+  hd->h1 = UINT64_C(0x629a292a367cd507);
+  hd->h2 = UINT64_C(0x9159015a3070dd17);
+  hd->h3 = UINT64_C(0x152fecd8f70e5939);
+  hd->h4 = UINT64_C(0x67332667ffc00b31);
+  hd->h5 = UINT64_C(0x8eb44a8768581511);
+  hd->h6 = UINT64_C(0xdb0c2e0d64f98fa7);
+  hd->h7 = UINT64_C(0x47b5481dbefa4fa4);
+
+  ctx->bctx.nblocks = 0;
+  ctx->bctx.nblocks_high = 0;
+  ctx->bctx.count = 0;
+  ctx->bctx.blocksize = 128;
+  ctx->bctx.transform = sha512_transform;
+}
+
+void sha512_update(struct sha512_context *ctx, const byte *in_buf, size_t in_len)
+{
+  sha256_update(&ctx->bctx, in_buf, in_len);
+}
+
+static inline u64
+ROTR(u64 x, u64 n)
+{
+  return ((x >> n) | (x << (64 - n)));
+}
+
+static inline u64
+Ch(u64 x, u64 y, u64 z)
+{
+  return ((x & y) ^ ( ~x & z));
+}
+
+static inline u64
+Maj(u64 x, u64 y, u64 z)
+{
+  return ((x & y) ^ (x & z) ^ (y & z));
+}
+
+static inline u64
+Sum0(u64 x)
+{
+  return (ROTR (x, 28) ^ ROTR (x, 34) ^ ROTR (x, 39));
+}
+
+static inline u64
+Sum1 (u64 x)
+{
+  return (ROTR (x, 14) ^ ROTR (x, 18) ^ ROTR (x, 41));
+}
+
+static const u64 k[] =
+{
+    UINT64_C(0x428a2f98d728ae22), UINT64_C(0x7137449123ef65cd),
+    UINT64_C(0xb5c0fbcfec4d3b2f), UINT64_C(0xe9b5dba58189dbbc),
+    UINT64_C(0x3956c25bf348b538), UINT64_C(0x59f111f1b605d019),
+    UINT64_C(0x923f82a4af194f9b), UINT64_C(0xab1c5ed5da6d8118),
+    UINT64_C(0xd807aa98a3030242), UINT64_C(0x12835b0145706fbe),
+    UINT64_C(0x243185be4ee4b28c), UINT64_C(0x550c7dc3d5ffb4e2),
+    UINT64_C(0x72be5d74f27b896f), UINT64_C(0x80deb1fe3b1696b1),
+    UINT64_C(0x9bdc06a725c71235), UINT64_C(0xc19bf174cf692694),
+    UINT64_C(0xe49b69c19ef14ad2), UINT64_C(0xefbe4786384f25e3),
+    UINT64_C(0x0fc19dc68b8cd5b5), UINT64_C(0x240ca1cc77ac9c65),
+    UINT64_C(0x2de92c6f592b0275), UINT64_C(0x4a7484aa6ea6e483),
+    UINT64_C(0x5cb0a9dcbd41fbd4), UINT64_C(0x76f988da831153b5),
+    UINT64_C(0x983e5152ee66dfab), UINT64_C(0xa831c66d2db43210),
+    UINT64_C(0xb00327c898fb213f), UINT64_C(0xbf597fc7beef0ee4),
+    UINT64_C(0xc6e00bf33da88fc2), UINT64_C(0xd5a79147930aa725),
+    UINT64_C(0x06ca6351e003826f), UINT64_C(0x142929670a0e6e70),
+    UINT64_C(0x27b70a8546d22ffc), UINT64_C(0x2e1b21385c26c926),
+    UINT64_C(0x4d2c6dfc5ac42aed), UINT64_C(0x53380d139d95b3df),
+    UINT64_C(0x650a73548baf63de), UINT64_C(0x766a0abb3c77b2a8),
+    UINT64_C(0x81c2c92e47edaee6), UINT64_C(0x92722c851482353b),
+    UINT64_C(0xa2bfe8a14cf10364), UINT64_C(0xa81a664bbc423001),
+    UINT64_C(0xc24b8b70d0f89791), UINT64_C(0xc76c51a30654be30),
+    UINT64_C(0xd192e819d6ef5218), UINT64_C(0xd69906245565a910),
+    UINT64_C(0xf40e35855771202a), UINT64_C(0x106aa07032bbd1b8),
+    UINT64_C(0x19a4c116b8d2d0c8), UINT64_C(0x1e376c085141ab53),
+    UINT64_C(0x2748774cdf8eeb99), UINT64_C(0x34b0bcb5e19b48a8),
+    UINT64_C(0x391c0cb3c5c95a63), UINT64_C(0x4ed8aa4ae3418acb),
+    UINT64_C(0x5b9cca4f7763e373), UINT64_C(0x682e6ff3d6b2b8a3),
+    UINT64_C(0x748f82ee5defb2fc), UINT64_C(0x78a5636f43172f60),
+    UINT64_C(0x84c87814a1f0ab72), UINT64_C(0x8cc702081a6439ec),
+    UINT64_C(0x90befffa23631e28), UINT64_C(0xa4506cebde82bde9),
+    UINT64_C(0xbef9a3f7b2c67915), UINT64_C(0xc67178f2e372532b),
+    UINT64_C(0xca273eceea26619c), UINT64_C(0xd186b8c721c0c207),
+    UINT64_C(0xeada7dd6cde0eb1e), UINT64_C(0xf57d4f7fee6ed178),
+    UINT64_C(0x06f067aa72176fba), UINT64_C(0x0a637dc5a2c898a6),
+    UINT64_C(0x113f9804bef90dae), UINT64_C(0x1b710b35131c471b),
+    UINT64_C(0x28db77f523047d84), UINT64_C(0x32caab7b40c72493),
+    UINT64_C(0x3c9ebe0a15c9bebc), UINT64_C(0x431d67c49c100d4c),
+    UINT64_C(0x4cc5d4becb3e42b6), UINT64_C(0x597f299cfc657e2a),
+    UINT64_C(0x5fcb6fab3ad6faec), UINT64_C(0x6c44198c4a475817)
+};
+
+/*
+ * Transform the message W which consists of 16 64-bit-words
+ */
+static uint
+sha512_transform_block(struct sha512_state *hd, const byte *data)
+{
+  u64 a, b, c, d, e, f, g, h;
+  u64 w[16];
+  int t;
+
+  /* get values from the chaining vars */
+  a = hd->h0;
+  b = hd->h1;
+  c = hd->h2;
+  d = hd->h3;
+  e = hd->h4;
+  f = hd->h5;
+  g = hd->h6;
+  h = hd->h7;
+
+  for ( t = 0; t < 16; t++ )
+    w[t] = get_u64(data + t * 8);
+
+#define S0(x) (ROTR((x),1) ^ ROTR((x),8) ^ ((x)>>7))
+#define S1(x) (ROTR((x),19) ^ ROTR((x),61) ^ ((x)>>6))
+
+  for (t = 0; t < 80 - 16; )
+  {
+    u64 t1, t2;
+
+    /* Performance on a AMD Athlon(tm) Dual Core Processor 4050e
+         with gcc 4.3.3 using gcry_md_hash_buffer of each 10000 bytes
+         initialized to 0,1,2,3...255,0,... and 1000 iterations:
+
+         Not unrolled with macros:  440ms
+         Unrolled with macros:      350ms
+         Unrolled with inline:      330ms
+     */
+#if 0 /* Not unrolled.  */
+    t1 = h + Sum1 (e) + Ch(e, f, g) + k[t] + w[t%16];
+    w[t%16] += S1 (w[(t - 2)%16]) + w[(t - 7)%16] + S0 (w[(t - 15)%16]);
+    t2 = Sum0 (a) + Maj(a, b, c);
+    h = g;
+    g = f;
+    f = e;
+    e = d + t1;
+    d = c;
+    c = b;
+    b = a;
+    a = t1 + t2;
+    t++;
+#else /* Unrolled to interweave the chain variables.  */
+    t1 = h + Sum1 (e) + Ch(e, f, g) + k[t] + w[0];
+    w[0] += S1 (w[14]) + w[9] + S0 (w[1]);
+    t2 = Sum0 (a) + Maj(a, b, c);
+    d += t1;
+    h = t1 + t2;
+
+    t1 = g + Sum1 (d) + Ch(d, e, f) + k[t+1] + w[1];
+    w[1] += S1 (w[15]) + w[10] + S0 (w[2]);
+    t2 = Sum0 (h) + Maj(h, a, b);
+    c += t1;
+    g  = t1 + t2;
+
+    t1 = f + Sum1 (c) + Ch(c, d, e) + k[t+2] + w[2];
+    w[2] += S1 (w[0]) + w[11] + S0 (w[3]);
+    t2 = Sum0 (g) + Maj(g, h, a);
+    b += t1;
+    f  = t1 + t2;
+
+    t1 = e + Sum1 (b) + Ch(b, c, d) + k[t+3] + w[3];
+    w[3] += S1 (w[1]) + w[12] + S0 (w[4]);
+    t2 = Sum0 (f) + Maj(f, g, h);
+    a += t1;
+    e  = t1 + t2;
+
+    t1 = d + Sum1 (a) + Ch(a, b, c) + k[t+4] + w[4];
+    w[4] += S1 (w[2]) + w[13] + S0 (w[5]);
+    t2 = Sum0 (e) + Maj(e, f, g);
+    h += t1;
+    d  = t1 + t2;
+
+    t1 = c + Sum1 (h) + Ch(h, a, b) + k[t+5] + w[5];
+    w[5] += S1 (w[3]) + w[14] + S0 (w[6]);
+    t2 = Sum0 (d) + Maj(d, e, f);
+    g += t1;
+    c  = t1 + t2;
+
+    t1 = b + Sum1 (g) + Ch(g, h, a) + k[t+6] + w[6];
+    w[6] += S1 (w[4]) + w[15] + S0 (w[7]);
+    t2 = Sum0 (c) + Maj(c, d, e);
+    f += t1;
+    b  = t1 + t2;
+
+    t1 = a + Sum1 (f) + Ch(f, g, h) + k[t+7] + w[7];
+    w[7] += S1 (w[5]) + w[0] + S0 (w[8]);
+    t2 = Sum0 (b) + Maj(b, c, d);
+    e += t1;
+    a  = t1 + t2;
+
+    t1 = h + Sum1 (e) + Ch(e, f, g) + k[t+8] + w[8];
+    w[8] += S1 (w[6]) + w[1] + S0 (w[9]);
+    t2 = Sum0 (a) + Maj(a, b, c);
+    d += t1;
+    h  = t1 + t2;
+
+    t1 = g + Sum1 (d) + Ch(d, e, f) + k[t+9] + w[9];
+    w[9] += S1 (w[7]) + w[2] + S0 (w[10]);
+    t2 = Sum0 (h) + Maj(h, a, b);
+    c += t1;
+    g  = t1 + t2;
+
+    t1 = f + Sum1 (c) + Ch(c, d, e) + k[t+10] + w[10];
+    w[10] += S1 (w[8]) + w[3] + S0 (w[11]);
+    t2 = Sum0 (g) + Maj(g, h, a);
+    b += t1;
+    f  = t1 + t2;
+
+    t1 = e + Sum1 (b) + Ch(b, c, d) + k[t+11] + w[11];
+    w[11] += S1 (w[9]) + w[4] + S0 (w[12]);
+    t2 = Sum0 (f) + Maj(f, g, h);
+    a += t1;
+    e  = t1 + t2;
+
+    t1 = d + Sum1 (a) + Ch(a, b, c) + k[t+12] + w[12];
+    w[12] += S1 (w[10]) + w[5] + S0 (w[13]);
+    t2 = Sum0 (e) + Maj(e, f, g);
+    h += t1;
+    d  = t1 + t2;
+
+    t1 = c + Sum1 (h) + Ch(h, a, b) + k[t+13] + w[13];
+    w[13] += S1 (w[11]) + w[6] + S0 (w[14]);
+    t2 = Sum0 (d) + Maj(d, e, f);
+    g += t1;
+    c  = t1 + t2;
+
+    t1 = b + Sum1 (g) + Ch(g, h, a) + k[t+14] + w[14];
+    w[14] += S1 (w[12]) + w[7] + S0 (w[15]);
+    t2 = Sum0 (c) + Maj(c, d, e);
+    f += t1;
+    b  = t1 + t2;
+
+    t1 = a + Sum1 (f) + Ch(f, g, h) + k[t+15] + w[15];
+    w[15] += S1 (w[13]) + w[8] + S0 (w[0]);
+    t2 = Sum0 (b) + Maj(b, c, d);
+    e += t1;
+    a  = t1 + t2;
+
+    t += 16;
+#endif
+  }
+
+  for (; t < 80; )
+  {
+    u64 t1, t2;
+
+#if 0 /* Not unrolled.  */
+    t1 = h + Sum1 (e) + Ch(e, f, g) + k[t] + w[t%16];
+    t2 = Sum0 (a) + Maj(a, b, c);
+    h = g;
+    g = f;
+    f = e;
+    e = d + t1;
+    d = c;
+    c = b;
+    b = a;
+    a = t1 + t2;
+    t++;
+#else /* Unrolled to interweave the chain variables.  */
+    t1 = h + Sum1 (e) + Ch(e, f, g) + k[t] + w[0];
+    t2 = Sum0 (a) + Maj(a, b, c);
+    d += t1;
+    h  = t1 + t2;
+
+    t1 = g + Sum1 (d) + Ch(d, e, f) + k[t+1] + w[1];
+    t2 = Sum0 (h) + Maj(h, a, b);
+    c += t1;
+    g  = t1 + t2;
+
+    t1 = f + Sum1 (c) + Ch(c, d, e) + k[t+2] + w[2];
+    t2 = Sum0 (g) + Maj(g, h, a);
+    b += t1;
+    f  = t1 + t2;
+
+    t1 = e + Sum1 (b) + Ch(b, c, d) + k[t+3] + w[3];
+    t2 = Sum0 (f) + Maj(f, g, h);
+    a += t1;
+    e  = t1 + t2;
+
+    t1 = d + Sum1 (a) + Ch(a, b, c) + k[t+4] + w[4];
+    t2 = Sum0 (e) + Maj(e, f, g);
+    h += t1;
+    d  = t1 + t2;
+
+    t1 = c + Sum1 (h) + Ch(h, a, b) + k[t+5] + w[5];
+    t2 = Sum0 (d) + Maj(d, e, f);
+    g += t1;
+    c  = t1 + t2;
+
+    t1 = b + Sum1 (g) + Ch(g, h, a) + k[t+6] + w[6];
+    t2 = Sum0 (c) + Maj(c, d, e);
+    f += t1;
+    b  = t1 + t2;
+
+    t1 = a + Sum1 (f) + Ch(f, g, h) + k[t+7] + w[7];
+    t2 = Sum0 (b) + Maj(b, c, d);
+    e += t1;
+    a  = t1 + t2;
+
+    t1 = h + Sum1 (e) + Ch(e, f, g) + k[t+8] + w[8];
+    t2 = Sum0 (a) + Maj(a, b, c);
+    d += t1;
+    h  = t1 + t2;
+
+    t1 = g + Sum1 (d) + Ch(d, e, f) + k[t+9] + w[9];
+    t2 = Sum0 (h) + Maj(h, a, b);
+    c += t1;
+    g  = t1 + t2;
+
+    t1 = f + Sum1 (c) + Ch(c, d, e) + k[t+10] + w[10];
+    t2 = Sum0 (g) + Maj(g, h, a);
+    b += t1;
+    f  = t1 + t2;
+
+    t1 = e + Sum1 (b) + Ch(b, c, d) + k[t+11] + w[11];
+    t2 = Sum0 (f) + Maj(f, g, h);
+    a += t1;
+    e  = t1 + t2;
+
+    t1 = d + Sum1 (a) + Ch(a, b, c) + k[t+12] + w[12];
+    t2 = Sum0 (e) + Maj(e, f, g);
+    h += t1;
+    d  = t1 + t2;
+
+    t1 = c + Sum1 (h) + Ch(h, a, b) + k[t+13] + w[13];
+    t2 = Sum0 (d) + Maj(d, e, f);
+    g += t1;
+    c  = t1 + t2;
+
+    t1 = b + Sum1 (g) + Ch(g, h, a) + k[t+14] + w[14];
+    t2 = Sum0 (c) + Maj(c, d, e);
+    f += t1;
+    b  = t1 + t2;
+
+    t1 = a + Sum1 (f) + Ch(f, g, h) + k[t+15] + w[15];
+    t2 = Sum0 (b) + Maj(b, c, d);
+    e += t1;
+    a  = t1 + t2;
+
+    t += 16;
+#endif
+  }
+
+  /* Update chaining vars.  */
+  hd->h0 += a;
+  hd->h1 += b;
+  hd->h2 += c;
+  hd->h3 += d;
+  hd->h4 += e;
+  hd->h5 += f;
+  hd->h6 += g;
+  hd->h7 += h;
+
+  return /* burn_stack */ (8 + 16) * sizeof(u64) + sizeof(u32) + 3 * sizeof(void*);
+}
+
+static uint
+sha512_transform(void *context, const byte *data, size_t nblks)
+{
+  struct sha512_context *ctx = context;
+  uint burn;
+
+  do
+  {
+    burn = sha512_transform_block(&ctx->state, data) + 3 * sizeof(void*);
+    data += 128;
+  }
+  while(--nblks);
+
+  return burn;
+}
+
+/* The routine final terminates the computation and
+ * returns the digest.
+ * The handle is prepared for a new cycle, but adding bytes to the
+ * handle will the destroy the returned buffer.
+ * Returns: 64 bytes representing the digest.  When used for sha384,
+ * we take the leftmost 48 of those bytes.
+ */
+byte *
+sha512_final(struct sha512_context *ctx)
+{
+  u64 t, th, msb, lsb;
+  byte *p;
+
+  sha256_update(&ctx->bctx, NULL, 0); /* flush */ ;
+
+  t = ctx->bctx.nblocks;
+  /* if (sizeof t == sizeof ctx->bctx.nblocks) */
+  th = ctx->bctx.nblocks_high;
+  /* else */
+  /*   th = ctx->bctx.nblocks >> 64; In case we ever use u128  */
+
+  /* multiply by 128 to make a byte count */
+  lsb = t << 7;
+  msb = (th << 7) | (t >> 57);
+  /* add the count */
+  t = lsb;
+  if ((lsb += ctx->bctx.count) < t)
+    msb++;
+  /* multiply by 8 to make a bit count */
+  t = lsb;
+  lsb <<= 3;
+  msb <<= 3;
+  msb |= t >> 61;
+
+  if (ctx->bctx.count < 112)
+  {						/* enough room */
+    ctx->bctx.buf[ctx->bctx.count++] = 0x80;	/* pad */
+    while(ctx->bctx.count < 112)
+      ctx->bctx.buf[ctx->bctx.count++] = 0;	/* pad */
+  }
+  else
+  {						/* need one extra block */
+    ctx->bctx.buf[ctx->bctx.count++] = 0x80;	/* pad character */
+    while(ctx->bctx.count < 128)
+      ctx->bctx.buf[ctx->bctx.count++] = 0;
+    sha256_update(&ctx->bctx, NULL, 0); 	/* flush */ ;
+    memset(ctx->bctx.buf, 0, 112);		/* fill next block with zeroes */
+  }
+  /* append the 128 bit count */
+  put_u64(ctx->bctx.buf + 112, msb);
+  put_u64(ctx->bctx.buf + 120, lsb);
+  sha512_transform(ctx, ctx->bctx.buf, 1);
+
+  p = ctx->bctx.buf;
+#define X(a) do { put_u64(p, ctx->state.h##a); p += 8; } while(0)
+  X (0);
+  X (1);
+  X (2);
+  X (3);
+  X (4);
+  X (5);
+  /* Note that these last two chunks are included even for SHA384.
+     We just ignore them. */
+  X (6);
+  X (7);
+#undef X
+
+  return ctx->bctx.buf;
+}
+
+
+/*
+ * 	SHA512-HMAC
+ */
+
+static void
+sha512_hash_buffer(byte *outbuf, const byte *buffer, size_t length)
+{
+  struct sha512_context hd_tmp;
+
+  sha512_init(&hd_tmp);
+  sha512_update(&hd_tmp, buffer, length);
+  memcpy(outbuf, sha512_final(&hd_tmp), SHA512_SIZE);
+}
+
+void
+sha512_hmac_init(struct sha512_hmac_context *ctx, const byte *key, size_t keylen)
+{
+  byte keybuf[SHA512_BLOCK_SIZE], buf[SHA512_BLOCK_SIZE];
+
+  /* Hash the key if necessary */
+  if (keylen <= SHA512_BLOCK_SIZE)
+  {
+    memcpy(keybuf, key, keylen);
+    bzero(keybuf + keylen, SHA512_BLOCK_SIZE - keylen);
+  }
+  else
+  {
+    sha512_hash_buffer(keybuf, key, keylen);
+    bzero(keybuf + SHA512_SIZE, SHA512_BLOCK_SIZE - SHA512_SIZE);
+  }
+
+  /* Initialize the inner digest */
+  sha512_init(&ctx->ictx);
+  int i;
+  for (i = 0; i < SHA512_BLOCK_SIZE; i++)
+    buf[i] = keybuf[i] ^ 0x36;
+  sha512_update(&ctx->ictx, buf, SHA512_BLOCK_SIZE);
+
+  /* Initialize the outer digest */
+  sha512_init(&ctx->octx);
+  for (i = 0; i < SHA512_BLOCK_SIZE; i++)
+    buf[i] = keybuf[i] ^ 0x5c;
+  sha512_update(&ctx->octx, buf, SHA512_BLOCK_SIZE);
+}
+
+void sha512_hmac_update(struct sha512_hmac_context *ctx, const byte *buf, size_t buflen)
+{
+  /* Just update the inner digest */
+  sha512_update(&ctx->ictx, buf, buflen);
+}
+
+byte *sha512_hmac_final(struct sha512_hmac_context *ctx)
+{
+  /* Finish the inner digest */
+  byte *isha = sha512_final(&ctx->ictx);
+
+  /* Finish the outer digest */
+  sha512_update(&ctx->octx, isha, SHA512_SIZE);
+  return sha512_final(&ctx->octx);
+}
+
+
+/*
+ * 	SHA384-HMAC
+ */
+
+static void
+sha384_hash_buffer(byte *outbuf, const byte *buffer, size_t length)
+{
+  struct sha384_context hd_tmp;
+
+  sha384_init(&hd_tmp);
+  sha384_update(&hd_tmp, buffer, length);
+  memcpy(outbuf, sha384_final(&hd_tmp), SHA384_SIZE);
+}
+
+void
+sha384_hmac_init(struct sha384_hmac_context *ctx, const byte *key, size_t keylen)
+{
+  byte keybuf[SHA384_BLOCK_SIZE], buf[SHA384_BLOCK_SIZE];
+
+  /* Hash the key if necessary */
+  if (keylen <= SHA384_BLOCK_SIZE)
+  {
+    memcpy(keybuf, key, keylen);
+    bzero(keybuf + keylen, SHA384_BLOCK_SIZE - keylen);
+  }
+  else
+  {
+    sha384_hash_buffer(keybuf, key, keylen);
+    bzero(keybuf + SHA384_SIZE, SHA384_BLOCK_SIZE - SHA384_SIZE);
+  }
+
+  /* Initialize the inner digest */
+  sha384_init(&ctx->ictx);
+  int i;
+  for (i = 0; i < SHA384_BLOCK_SIZE; i++)
+    buf[i] = keybuf[i] ^ 0x36;
+  sha384_update(&ctx->ictx, buf, SHA384_BLOCK_SIZE);
+
+  /* Initialize the outer digest */
+  sha384_init(&ctx->octx);
+  for (i = 0; i < SHA384_BLOCK_SIZE; i++)
+    buf[i] = keybuf[i] ^ 0x5c;
+  sha384_update(&ctx->octx, buf, SHA384_BLOCK_SIZE);
+}
+
+void sha384_hmac_update(struct sha384_hmac_context *ctx, const byte *buf, size_t buflen)
+{
+  /* Just update the inner digest */
+  sha384_update(&ctx->ictx, buf, buflen);
+}
+
+byte *sha384_hmac_final(struct sha384_hmac_context *ctx)
+{
+  /* Finish the inner digest */
+  byte *isha = sha384_final(&ctx->ictx);
+
+  /* Finish the outer digest */
+  sha384_update(&ctx->octx, isha, SHA384_SIZE);
+  return sha384_final(&ctx->octx);
+}