SHA2 pipeline with support for 256, 384, and 512 bits

Implemented pipeline around sph sha calls using standard test vectors
for full-byte values.  Did not test or support partial byte values.

1 files changed, 164 insertions, 0 deletions

diff --git a/libqpdf/Pl_SHA2.cc b/libqpdf/Pl_SHA2.cc
new file mode 100644
index 00000000..018f411f
--- /dev/null
+++ b/libqpdf/Pl_SHA2.cc
@@ -0,0 +1,164 @@
+#include <qpdf/Pl_SHA2.hh>
+#include <stdexcept>
+#include <cstdio>
+#include <qpdf/PointerHolder.hh>
+
+Pl_SHA2::Pl_SHA2(int bits, Pipeline* next) :
+    Pipeline("sha2", next),
+    in_progress(false),
+    bits(0)
+{
+    if (bits)
+    {
+        resetBits(bits);
+    }
+}
+
+Pl_SHA2::~Pl_SHA2()
+{
+}
+
+void
+Pl_SHA2::badBits()
+{
+    throw std::logic_error("Pl_SHA2 has unexpected value for bits");
+}
+
+void
+Pl_SHA2::write(unsigned char* buf, size_t len)
+{
+    if (! this->in_progress)
+    {
+        switch (bits)
+        {
+          case 256:
+            sph_sha256_init(&this->ctx256);
+            break;
+          case 384:
+            sph_sha384_init(&this->ctx384);
+            break;
+          case 512:
+            sph_sha512_init(&this->ctx512);
+            break;
+          default:
+            badBits();
+            break;
+        }
+	this->in_progress = true;
+    }
+
+    // Write in chunks in case len is too big to fit in an int.
+    // Assume int is at least 32 bits.
+    static size_t const max_bytes = 1 << 30;
+    size_t bytes_left = len;
+    unsigned char* data = buf;
+    while (bytes_left > 0)
+    {
+	size_t bytes = (bytes_left >= max_bytes ? max_bytes : bytes_left);
+        switch (bits)
+        {
+          case 256:
+            sph_sha256(&this->ctx256, data, bytes);
+            break;
+          case 384:
+            sph_sha384(&this->ctx384, data, bytes);
+            break;
+          case 512:
+            sph_sha512(&this->ctx512, data, bytes);
+            break;
+          default:
+            badBits();
+            break;
+        }
+	bytes_left -= bytes;
+        data += bytes;
+    }
+
+    if (this->getNext(true))
+    {
+        this->getNext()->write(buf, len);
+    }
+}
+
+void
+Pl_SHA2::finish()
+{
+    if (this->getNext(true))
+    {
+        this->getNext()->finish();
+    }
+    switch (bits)
+    {
+      case 256:
+        sph_sha256_close(&this->ctx256, sha256sum);
+        break;
+      case 384:
+        sph_sha384_close(&this->ctx384, sha384sum);
+        break;
+      case 512:
+        sph_sha512_close(&this->ctx512, sha512sum);
+        break;
+      default:
+        badBits();
+        break;
+    }
+    this->in_progress = false;
+}
+
+void
+Pl_SHA2::resetBits(int bits)
+{
+    if (this->in_progress)
+    {
+	throw std::logic_error(
+	    "bit reset requested for in-progress SHA2 Pipeline");
+    }
+    if (! ((bits == 256) || (bits == 384) || (bits == 512)))
+    {
+	throw std::logic_error("Pl_SHA2 called with bits != 256, 384, or 512");
+    }
+    this->bits = bits;
+}
+
+std::string
+Pl_SHA2::getRawDigest()
+{
+    std::string result;
+    switch (bits)
+    {
+      case 256:
+        result = std::string((char*)this->sha256sum, sizeof(this->sha256sum));
+        break;
+      case 384:
+        result = std::string((char*)this->sha384sum, sizeof(this->sha384sum));
+        break;
+      case 512:
+        result = std::string((char*)this->sha512sum, sizeof(this->sha512sum));
+        break;
+      default:
+        badBits();
+        break;
+    }
+    return result;
+}
+
+std::string
+Pl_SHA2::getHexDigest()
+{
+    if (this->in_progress)
+    {
+	throw std::logic_error(
+	    "digest requested for in-progress SHA2 Pipeline");
+    }
+    std::string raw = getRawDigest();
+    size_t raw_size = raw.length();
+    size_t hex_size = 1 + (2 * raw_size);
+    PointerHolder<char> bufp(true, new char[hex_size]);
+    char* buf = bufp.getPointer();
+    buf[hex_size - 1] = '\0';
+    for (unsigned int i = 0; i < raw_size; ++i)
+    {
+        std::sprintf(buf + i * 2, "%02x", (unsigned char)raw[i]);
+    }
+    return buf;
+}