diff --git a/TODO.txt b/TODO.txt
index 0ea9d85..725b2b1 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -16,7 +16,7 @@ Milestone: v0.2.0
[~] User registration
[x] Username validation
- [ ] Password hashing
+ [x] Password hashing
[ ] User API
Milestone: v1.0.0
diff --git a/man/man3/Sha2.3 b/man/man3/Sha2.3
new file mode 100644
index 0000000..adb3bbc
--- /dev/null
+++ b/man/man3/Sha2.3
@@ -0,0 +1,27 @@
+.Dd $Mdocdate: December 19 2022 $
+.Dt SHA2 3
+.Os Telodendria Project
+.Sh NAME
+.Nm Sha2
+.Nd A simple implementation of the SHA2 hashing functions.
+.Sh SYNOPSIS
+.In Sha2.h
+.Ft char *
+.Fn Sha256 "char *"
+.Sh DESCRIPTION
+.Pp
+This API defines simple functions for computing SHA2 hashes. At the
+moment, it only defines
+.Fn Sha256 ,
+which computes the SHA-256 hash of the given C string. It is not trivial
+to implement SHA-512 in ANSI C due to the lack of a 64-bit integer
+type, so that hash function has been omitted.
+.Sh RETURN VALUES
+.Pp
+.Fn Sha256
+returns a string allocated on the heap using the Memory API, or NULL
+if there was an error allocating memory for it. The returned string
+should be freed when it is no longer needed.
+.Sh SEE ALSO
+.Xr Memory 3 ,
+.Xr Base64 3
diff --git a/site/index.html b/site/index.html
index 452da06..fd1d585 100644
--- a/site/index.html
+++ b/site/index.html
@@ -273,6 +273,12 @@ Encode and decode various parts of the HTTP protocol.
Extremely simple HTTP server.
+
+Sha2(3) |
+
+A simple implementation of the SHA2 hashing functions.
+ |
+
diff --git a/src/Sha2.c b/src/Sha2.c
new file mode 100644
index 0000000..03da915
--- /dev/null
+++ b/src/Sha2.c
@@ -0,0 +1,247 @@
+/*
+ * Copyright (C) 2022 Jordan Bancino <@jordan:bancino.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include
+#include
+
+#include
+#include
+
+#include
+
+#if defined(LONG_BIT) && LONG_BIT == 32
+typedef unsigned long uint32_t;
+
+#elif defined(WORD_BIT) && WORD_BIT == 32
+typedef unsigned int uint32_t;
+
+#else
+#error Unable to find suitable integer type for uint32_t
+#endif
+
+#define GET_UINT32(x) \
+ (((uint32_t)(x)[0] << 24) | \
+ ((uint32_t)(x)[1] << 16) | \
+ ((uint32_t)(x)[2] << 8) | \
+ ((uint32_t)(x)[3]))
+
+#define PUT_UINT32(dst, x) { \
+ (dst)[0] = (x) >> 24; \
+ (dst)[1] = (x) >> 16; \
+ (dst)[2] = (x) >> 8; \
+ (dst)[3] = (x); \
+}
+
+#define ROTR(x, n) (((x) >> (n)) | ((x) << (32 - (n))))
+
+#define S0(x) (ROTR(x, 7) ^ ROTR(x, 18) ^ (x >> 3))
+#define S1(x) (ROTR(x, 17) ^ ROTR(x, 19) ^ (x >> 10))
+
+#define T0(x) (ROTR(x, 6) ^ ROTR(x, 11) ^ ROTR(x, 25))
+#define T1(x) (ROTR(x, 2) ^ ROTR(x, 13) ^ ROTR(x, 22))
+
+#define CH(a, b, c) (((a) & (b)) ^ ((~(a)) & (c)))
+#define MAJ(a, b, c) (((a) & (b)) ^ ((a) & (c)) ^ ((b) & (c)))
+#define WW(i) (w[i] = w[i - 16] + S0(w[i - 15]) + w[i - 7] + S1(w[i - 2]))
+
+#define ROUND(a, b, c, d, e, f, g, h, k, w) { \
+ unsigned long tmp0 = h + T0(e) + CH(e, f, g) + k + w; \
+ unsigned long tmp1 = T1(a) + MAJ(a, b, c); \
+ h = tmp0 + tmp1; \
+ d += tmp0; \
+}
+
+typedef struct Sha256Context
+{
+ size_t length;
+ uint32_t state[8];
+ size_t bufLen;
+ unsigned char buffer[64];
+} Sha256Context;
+
+static void
+Sha256Chunk(Sha256Context * context, unsigned char chunk[64])
+{
+ const uint32_t rk[64] = {
+ 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
+ 0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+ 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
+ 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+ 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
+ 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+ 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
+ 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+ 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
+ 0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+ 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
+ };
+
+ uint32_t w[64];
+ uint32_t a, b, c, d, e, f, g, h;
+
+ int i;
+
+ for (i = 0; i < 16; i++)
+ {
+ w[i] = GET_UINT32(&chunk[4 * i]);
+ }
+
+ a = context->state[0];
+ b = context->state[1];
+ c = context->state[2];
+ d = context->state[3];
+ e = context->state[4];
+ f = context->state[5];
+ g = context->state[6];
+ h = context->state[7];
+
+ for (i = 0; i < 16; i += 8)
+ {
+ ROUND(a, b, c, d, e, f, g, h, rk[i], w[i]);
+ ROUND(h, a, b, c, d, e, f, g, rk[i + 1], w[i + 1]);
+ ROUND(g, h, a, b, c, d, e, f, rk[i + 2], w[i + 2]);
+ ROUND(f, g, h, a, b, c, d, e, rk[i + 3], w[i + 3]);
+ ROUND(e, f, g, h, a, b, c, d, rk[i + 4], w[i + 4]);
+ ROUND(d, e, f, g, h, a, b, c, rk[i + 5], w[i + 5]);
+ ROUND(c, d, e, f, g, h, a, b, rk[i + 6], w[i + 6]);
+ ROUND(b, c, d, e, f, g, h, a, rk[i + 7], w[i + 7]);
+ }
+
+ for (i = 16; i < 64; i += 8)
+ {
+ ROUND(a, b, c, d, e, f, g, h, rk[i], WW(i));
+ ROUND(h, a, b, c, d, e, f, g, rk[i + 1], WW(i + 1));
+ ROUND(g, h, a, b, c, d, e, f, rk[i + 2], WW(i + 2));
+ ROUND(f, g, h, a, b, c, d, e, rk[i + 3], WW(i + 3));
+ ROUND(e, f, g, h, a, b, c, d, rk[i + 4], WW(i + 4));
+ ROUND(d, e, f, g, h, a, b, c, rk[i + 5], WW(i + 5));
+ ROUND(c, d, e, f, g, h, a, b, rk[i + 6], WW(i + 6));
+ ROUND(b, c, d, e, f, g, h, a, rk[i + 7], WW(i + 7));
+ }
+
+ context->state[0] += a;
+ context->state[1] += b;
+ context->state[2] += c;
+ context->state[3] += d;
+ context->state[4] += e;
+ context->state[5] += f;
+ context->state[6] += g;
+ context->state[7] += h;
+}
+
+static void
+Sha256Process(Sha256Context * context, unsigned char *data, size_t length)
+{
+ context->length += length;
+
+ if (context->bufLen && context->bufLen + length >= 64)
+ {
+ int len = 64 - context->bufLen;
+
+ memcpy(context->buffer + context->bufLen, data, len);
+ Sha256Chunk(context, context->buffer);
+ data += len;
+ length -= len;
+ context->bufLen = 0;
+ }
+
+ while (length >= 64)
+ {
+ Sha256Chunk(context, data);
+ data += 64;
+ length -= 64;
+ }
+
+ if (length)
+ {
+ memcpy(context->buffer + context->bufLen, data, length);
+ context->bufLen += length;
+ }
+}
+
+char *
+Sha256(char *str)
+{
+ Sha256Context context;
+ size_t i;
+ unsigned char out[32];
+ char *outStr;
+
+ char fill[64];
+ uint32_t fillLen;
+ unsigned char buf[8];
+ uint32_t hiLen;
+ uint32_t loLen;
+
+ if (!str)
+ {
+ return NULL;
+ }
+
+ outStr = Malloc(65);
+ if (!outStr)
+ {
+ return NULL;
+ }
+
+ context.state[0] = 0x6a09e667;
+ context.state[1] = 0xbb67ae85;
+ context.state[2] = 0x3c6ef372;
+ context.state[3] = 0xa54ff53a;
+ context.state[4] = 0x510e527f;
+ context.state[5] = 0x9b05688c;
+ context.state[6] = 0x1f83d9ab;
+ context.state[7] = 0x5be0cd19;
+
+ context.bufLen = 0;
+ context.length = 0;
+ memset(context.buffer, 0, 64);
+
+ Sha256Process(&context, (unsigned char *) str, strlen(str));
+
+ memset(fill, 0, 64);
+ fill[0] = 0x80;
+
+ fillLen = (context.bufLen < 56) ? 56 - context.bufLen : 120 - context.bufLen;
+ hiLen = (unsigned long) (context.length >> 29);
+ loLen = (unsigned long) (context.length << 3);
+
+ PUT_UINT32(&buf[0], hiLen);
+ PUT_UINT32(&buf[4], loLen);
+
+ Sha256Process(&context, (unsigned char *) fill, fillLen);
+ Sha256Process(&context, buf, 8);
+
+ for (i = 0; i < 8; i++)
+ {
+ PUT_UINT32(&out[4 * i], context.state[i]);
+ }
+
+ /* Convert to string */
+ for (i = 0; i < 32; i++)
+ {
+ sprintf(outStr + (2 * i), "%02x", out[i]);
+ }
+
+ return outStr;
+}
diff --git a/src/include/Sha2.h b/src/include/Sha2.h
new file mode 100644
index 0000000..f0e83df
--- /dev/null
+++ b/src/include/Sha2.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2022 Jordan Bancino <@jordan:bancino.net>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef TELODENDRIA_SHA2_H
+#define TELODENDRIA_SHA2_H
+
+extern char *
+ Sha256(char *);
+
+#endif /* TELODENDRIA_SHA2_H */