1 files changed, 479 insertions, 0 deletions
diff --git a/src/der_enc.cpp b/src/der_enc.cpp
new file mode 100644
index 000000000..c4a7245ff
--- /dev/null
+++ b/src/der_enc.cpp
@@ -0,0 +1,479 @@
+/*************************************************
+* DER Encoder Source File                        *
+* (C) 1999-2006 The Botan Project                *
+*************************************************/
+
+#include <botan/der_enc.h>
+#include <botan/asn1_int.h>
+#include <botan/bigint.h>
+#include <botan/bit_ops.h>
+#include <botan/parsing.h>
+#include <algorithm>
+
+namespace Botan {
+
+namespace {
+
+/*************************************************
+* DER encode an ASN.1 type tag                   *
+*************************************************/
+SecureVector<byte> encode_tag(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   if((class_tag | 0xE0) != 0xE0)
+      throw Encoding_Error("DER_Encoder: Invalid class tag " +
+                           to_string(class_tag));
+
+   SecureVector<byte> encoded_tag;
+   if(type_tag <= 30)
+      encoded_tag.append((byte)(type_tag | class_tag));
+   else
+      {
+      u32bit blocks = high_bit(type_tag) + 6;
+      blocks = (blocks - (blocks % 7)) / 7;
+
+      encoded_tag.append(class_tag | 0x1F);
+      for(u32bit k = 0; k != blocks - 1; ++k)
+         encoded_tag.append(0x80 | ((type_tag >> 7*(blocks-k-1)) & 0x7F));
+      encoded_tag.append(type_tag & 0x7F);
+      }
+
+   return encoded_tag;
+   }
+
+/*************************************************
+* DER encode an ASN.1 length field               *
+*************************************************/
+SecureVector<byte> encode_length(u32bit length)
+   {
+   SecureVector<byte> encoded_length;
+   if(length <= 127)
+      encoded_length.append((byte)length);
+   else
+      {
+      const u32bit top_byte = significant_bytes(length);
+      encoded_length.append((byte)(0x80 | top_byte));
+      for(u32bit j = 4-top_byte; j != 4; ++j)
+         encoded_length.append(get_byte(j, length));
+      }
+   return encoded_length;
+   }
+
+/*************************************************
+* A comparison functor for sorting SET objects   *
+*************************************************/
+class DER_Cmp
+   {
+   public:
+      bool operator()(const MemoryRegion<byte>&,
+                      const MemoryRegion<byte>&) const;
+   };
+
+/*************************************************
+* Compare two encodings, as specified by X.690   *
+*************************************************/
+bool DER_Cmp::operator()(const MemoryRegion<byte>& a,
+                         const MemoryRegion<byte>& b) const
+   {
+   if(a.size() < b.size()) return true;
+   if(a.size() > b.size()) return false;
+
+   for(u32bit j = 0; j != a.size(); ++j)
+      {
+      if(a[j] < b[j]) return true;
+      if(a[j] > b[j]) return false;
+      }
+   return false;
+   }
+
+}
+
+/*************************************************
+* Return the encoded SEQUENCE/SET                *
+*************************************************/
+SecureVector<byte> DER_Encoder::DER_Sequence::get_contents()
+   {
+   const ASN1_Tag real_class_tag = ASN1_Tag(class_tag | CONSTRUCTED);
+
+   SecureVector<byte> encoded_tag = encode_tag(type_tag, real_class_tag);
+
+   if(is_a_set)
+      {
+      std::sort(set_contents.begin(), set_contents.end(), DER_Cmp());
+      for(u32bit j = 0; j != set_contents.size(); ++j)
+         contents.append(set_contents[j]);
+      set_contents.clear();
+      }
+
+   SecureVector<byte> encoded_length = encode_length(contents.size());
+
+   SecureVector<byte> retval;
+   retval.append(encoded_tag);
+   retval.append(encoded_length);
+   retval.append(contents);
+   contents.destroy();
+   return retval;
+   }
+
+/*************************************************
+* Add an encoded value to the SEQUENCE/SET       *
+*************************************************/
+void DER_Encoder::DER_Sequence::add_bytes(const byte data[], u32bit length)
+   {
+   if(is_a_set)
+      {
+      set_contents.push_back(SecureVector<byte>(data, length));
+      }
+   else
+      contents.append(data, length);
+   }
+
+/*************************************************
+* Return the type and class taggings             *
+*************************************************/
+ASN1_Tag DER_Encoder::DER_Sequence::tag_of() const
+   {
+   return ASN1_Tag(type_tag | class_tag);
+   }
+
+/*************************************************
+* DER_Sequence Constructor                       *
+*************************************************/
+DER_Encoder::DER_Sequence::DER_Sequence(ASN1_Tag t1, ASN1_Tag t2, bool b) :
+   type_tag(t1), class_tag(t2), is_a_set(b)
+   {
+   }
+
+/*************************************************
+* Return the encoded contents                    *
+*************************************************/
+SecureVector<byte> DER_Encoder::get_contents()
+   {
+   if(sequence_level != 0)
+      throw Invalid_State("DER_Encoder: Sequence hasn't been marked done");
+
+   SecureVector<byte> retval;
+   retval = contents;
+   contents.destroy();
+   return retval;
+   }
+
+/*************************************************
+* Start a new ASN.1 SEQUENCE/SET/EXPLICIT        *
+*************************************************/
+DER_Encoder& DER_Encoder::start_cons(ASN1_Tag type_tag, ASN1_Tag class_tag,
+                                     bool is_a_set)
+   {
+   ++sequence_level;
+   subsequences.push_back(DER_Sequence(type_tag, class_tag, is_a_set));
+   return (*this);
+   }
+
+/*************************************************
+* Finish the current ASN.1 SEQUENCE/SET/EXPLICIT *
+*************************************************/
+DER_Encoder& DER_Encoder::end_cons(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   if(sequence_level == 0)
+      throw Invalid_State("DER_Encoder::end_cons: No such sequence");
+   sequence_level--;
+   if(subsequences[sequence_level].tag_of() != ASN1_Tag(type_tag | class_tag))
+      throw Invalid_Argument("DER_Encoder::end_cons: Tag mismatch");
+
+   SecureVector<byte> seq = subsequences[sequence_level].get_contents();
+   subsequences.pop_back();
+   add_raw_octets(seq);
+   return (*this);
+   }
+
+/*************************************************
+* Start a new ASN.1 SEQUENCE                     *
+*************************************************/
+DER_Encoder& DER_Encoder::start_sequence(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return start_cons(type_tag, class_tag, false);
+   }
+
+/*************************************************
+* Finish the current ASN.1 SEQUENCE              *
+*************************************************/
+DER_Encoder& DER_Encoder::end_sequence(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return end_cons(type_tag, class_tag);
+   }
+
+/*************************************************
+* Start a new ASN.1 SET                          *
+*************************************************/
+DER_Encoder& DER_Encoder::start_set(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return start_cons(type_tag, class_tag, true);
+   }
+
+/*************************************************
+* Finish the current ASN.1 SET                   *
+*************************************************/
+DER_Encoder& DER_Encoder::end_set(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return end_cons(type_tag, class_tag);
+   }
+
+/*************************************************
+* Start a new ASN.1 SEQUENCE                     *
+*************************************************/
+DER_Encoder& DER_Encoder::start_sequence()
+   {
+   return start_sequence(SEQUENCE, UNIVERSAL);
+   }
+
+/*************************************************
+* Finish the current ASN.1 SEQUENCE              *
+*************************************************/
+DER_Encoder& DER_Encoder::end_sequence()
+   {
+   return end_sequence(SEQUENCE, UNIVERSAL);
+   }
+
+/*************************************************
+* Start a new ASN.1 SET                          *
+*************************************************/
+DER_Encoder& DER_Encoder::start_set()
+   {
+   return start_set(SET, UNIVERSAL);
+   }
+
+/*************************************************
+* Finish the current ASN.1 SET                   *
+*************************************************/
+DER_Encoder& DER_Encoder::end_set()
+   {
+   return end_set(SET, UNIVERSAL);
+   }
+
+/*************************************************
+* Start a new ASN.1 EXPLICIT encoding            *
+*************************************************/
+DER_Encoder& DER_Encoder::start_explicit(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return start_cons(type_tag, class_tag, false);
+   }
+
+/*************************************************
+* Finish the current ASN.1 EXPLICIT encoding     *
+*************************************************/
+DER_Encoder& DER_Encoder::end_explicit(ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return end_cons(type_tag, class_tag);
+   }
+
+/*************************************************
+* Write raw octets into the stream               *
+*************************************************/
+DER_Encoder& DER_Encoder::add_raw_octets(const MemoryRegion<byte>& octets)
+   {
+   return add_raw_octets(octets.begin(), octets.size());
+   }
+
+/*************************************************
+* Write raw octets into the stream               *
+*************************************************/
+DER_Encoder& DER_Encoder::add_raw_octets(const byte octets[], u32bit length)
+   {
+   if(sequence_level == 0)
+      contents.append(octets, length);
+   else
+      subsequences[sequence_level-1].add_bytes(octets, length);
+   return (*this);
+   }
+
+/*************************************************
+* Encode a NULL object                           *
+*************************************************/
+DER_Encoder& DER_Encoder::encode_null()
+   {
+   return add_object(NULL_TAG, UNIVERSAL, 0, 0);
+   }
+
+/*************************************************
+* DER encode a BOOLEAN                           *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(bool is_true)
+   {
+   return encode(is_true, BOOLEAN, UNIVERSAL);
+   }
+
+/*************************************************
+* DER encode a small INTEGER                     *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(u32bit n)
+   {
+   return encode(BigInt(n), INTEGER, UNIVERSAL);
+   }
+
+/*************************************************
+* DER encode a small INTEGER                     *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(const BigInt& n)
+   {
+   return encode(n, INTEGER, UNIVERSAL);
+   }
+
+/*************************************************
+* DER encode an OCTET STRING or BIT STRING       *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(const MemoryRegion<byte>& octets,
+                                 ASN1_Tag real_type)
+   {
+   return encode(octets.begin(), octets.size(),
+                 real_type, real_type, UNIVERSAL);
+   }
+
+/*************************************************
+* Encode this object                             *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(const byte octets[], u32bit length,
+                                 ASN1_Tag real_type)
+   {
+   return encode(octets, length, real_type, real_type, UNIVERSAL);
+   }
+
+/*************************************************
+* DER encode a BOOLEAN                           *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(bool is_true,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   byte val = is_true ? 0xFF : 0x00;
+   return add_object(type_tag, class_tag, &val, 1);
+   }
+
+/*************************************************
+* DER encode a small INTEGER                     *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(u32bit n,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return encode(BigInt(n), type_tag, class_tag);
+   }
+
+/*************************************************
+* DER encode an INTEGER                          *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(const BigInt& n,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   if(n == 0)
+      return add_object(type_tag, class_tag, 0);
+
+   bool extra_zero = (n.bits() % 8 == 0);
+   SecureVector<byte> contents(extra_zero + n.bytes());
+   BigInt::encode(contents.begin() + extra_zero, n);
+   if(n < 0)
+      {
+      for(u32bit j = 0; j != contents.size(); ++j)
+         contents[j] = ~contents[j];
+      for(u32bit j = contents.size(); j > 0; --j)
+         if(++contents[j-1])
+            break;
+      }
+
+   return add_object(type_tag, class_tag, contents);
+   }
+
+/*************************************************
+* DER encode an OCTET STRING or BIT STRING       *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(const MemoryRegion<byte>& octets,
+                                 ASN1_Tag real_type,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   return encode(octets.begin(), octets.size(),
+                 real_type, type_tag, class_tag);
+   }
+
+/*************************************************
+* DER encode an OCTET STRING or BIT STRING       *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(const byte octets[], u32bit length,
+                                 ASN1_Tag real_type,
+                                 ASN1_Tag type_tag, ASN1_Tag class_tag)
+   {
+   if(real_type != OCTET_STRING && real_type != BIT_STRING)
+      throw Invalid_Argument("DER_Encoder: Invalid tag for byte/bit string");
+
+   if(real_type == BIT_STRING)
+      {
+      SecureVector<byte> encoded;
+      encoded.append(0);
+      encoded.append(octets, length);
+      return add_object(type_tag, class_tag, encoded);
+      }
+   else
+      return add_object(type_tag, class_tag, octets, length);
+   }
+
+/*************************************************
+* Request for an object to encode itself         *
+*************************************************/
+DER_Encoder& DER_Encoder::encode(const ASN1_Object& obj)
+   {
+   obj.encode_into(*this);
+   return (*this);
+   }
+
+/*************************************************
+* Write the encoding of the octet(s)             *
+*************************************************/
+DER_Encoder& DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag,
+                                     const byte rep[], u32bit length)
+   {
+   SecureVector<byte> encoded_tag = encode_tag(type_tag, class_tag);
+   SecureVector<byte> encoded_length = encode_length(length);
+
+   SecureVector<byte> buffer;
+   buffer.append(encoded_tag);
+   buffer.append(encoded_length);
+   buffer.append(rep, length);
+
+   return add_raw_octets(buffer);
+   }
+
+/*************************************************
+* Write the encoding of the octet(s)             *
+*************************************************/
+DER_Encoder& DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag,
+                                     const MemoryRegion<byte>& rep_buf)
+   {
+   const byte* rep = rep_buf.begin();
+   const u32bit rep_len = rep_buf.size();
+   return add_object(type_tag, class_tag, rep, rep_len);
+   }
+
+/*************************************************
+* Write the encoding of the octet(s)             *
+*************************************************/
+DER_Encoder& DER_Encoder::add_object(ASN1_Tag type_tag, ASN1_Tag class_tag,
+                                     const std::string& rep_str)
+   {
+   const byte* rep = (const byte*)rep_str.c_str();
+   const u32bit rep_len = rep_str.size();
+   return add_object(type_tag, class_tag, rep, rep_len);
+   }
+
+/*************************************************
+* Write the encoding of the octet                *
+*************************************************/
+DER_Encoder& DER_Encoder::add_object(ASN1_Tag type_tag,
+                                     ASN1_Tag class_tag, byte rep)
+   {
+   return add_object(type_tag, class_tag, &rep, 1);
+   }
+
+/*************************************************
+* DER_Encoder Constructor                        *
+*************************************************/
+DER_Encoder::DER_Encoder()
+    {
+   sequence_level = 0;
+   }
+
+}